WESTLAKE CHEMICAL PARTNERS LP, 10-K filed on 3/5/2025
Annual Report
v3.25.0.1
Cover Page - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2024
Feb. 26, 2025
Jun. 30, 2024
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2024    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-36567    
Entity Registrant Name Westlake Chemical Partners LP    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 32-0436529    
Entity Address, Address Line One 2801 Post Oak Boulevard    
Entity Address, Address Line Two Suite 600    
Entity Address, City or Town Houston    
Entity Address, State or Province TX    
Entity Address, Postal Zip Code 77056    
City Area Code 713    
Local Phone Number 585-2900    
Title of 12(b) Security Common units representing limited partner interests    
Trading Symbol WLKP    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 434.9
Entity Common Stock, Shares Outstanding   35,238,556  
Amendment Flag false    
Document Fiscal Year Focus 2024    
Document Fiscal Period Focus FY    
Entity Central Index Key 0001604665    
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Audit Information
12 Months Ended
Dec. 31, 2024
Auditor [Abstract]  
Auditor Name PricewaterhouseCoopers LLP
Auditor Location Houston, Texas
Auditor Firm ID 238
v3.25.0.1
Consolidated Balance Sheets - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Current assets    
Cash and cash equivalents $ 58,316 $ 58,619
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake") 134,557 94,444
Accounts receivable, net—third parties 11,576 18,701
Inventories 4,058 4,432
Prepaid expenses and other current assets 444 442
Total current assets 240,926 226,203
Property, plant and equipment, net 903,588 943,843
Goodwill 5,814 5,814
Deferred charges and other assets, net 137,628 140,982
Total assets 1,287,956 1,316,842
Current liabilities    
Accrued and other liabilities 16,920 24,980
Total current liabilities 55,372 56,335
Deferred income taxes 1,546 1,632
Other liabilities 2,050 2,951
Total liabilities 458,642 460,592
Commitments and contingencies (Note 16)
EQUITY    
Total Westlake Chemical Partners LP partners' capital 276,129 279,934
Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo") 553,185 576,316
Total equity 829,314 856,250
Total liabilities and equity 1,287,956 1,316,842
Affiliated Entity    
Current assets    
Accounts receivable, net—Westlake 31,975 49,565
Current liabilities    
Accounts payable—third parties 20,744 15,166
Nonrelated Party    
Current assets    
Accounts receivable, net—third parties 11,576 18,701
Current liabilities    
Accounts payable—third parties 17,708 16,189
Westlake    
EQUITY    
General partner—Westlake (242,572) (242,572)
Westlake | Affiliated Entity    
Current liabilities    
Long-term debt payable to Westlake 399,674 399,674
Common units | Publicly and Privately Held    
EQUITY    
Limited partners' capital 471,328 473,513
Common units | Westlake    
EQUITY    
Limited partners' capital $ 47,373 $ 48,993
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Consolidated Balance Sheets (Parenthetical) - Common units - shares
Dec. 31, 2024
Dec. 31, 2023
Publicly and Privately Held    
Units issued 21,116,326 21,105,904
Units outstanding 21,116,326 21,105,904
Westlake    
Units issued 14,122,230 14,122,230
Units outstanding 14,122,230 14,122,230
v3.25.0.1
Consolidated Statements of Operations - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Total net sales $ 1,135,896 $ 1,190,791 $ 1,593,147
Cost of sales 716,957 803,332 1,215,782
Gross profit 418,939 387,459 377,365
Selling, general and administrative expenses 28,495 29,751 29,678
Income from operations 390,444 357,708 347,687
Other income (expense)      
Interest expense—Westlake (25,701) (26,501) (13,407)
Other income, net 5,251 4,232 1,566
Income before income taxes 369,994 335,439 335,846
Provision for income taxes 835 813 1,017
Net income 369,159 334,626 334,829
Less: Net income attributable to noncontrolling interest in OpCo 306,767 280,343 270,656
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income $ 62,392 $ 54,283 $ 64,173
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)      
Weighted average limited partner units outstanding (basic and diluted) 35,232,870 35,224,340 35,217,336
Affiliated Entity      
Net co-products, ethylene and other sales—third parties $ 950,801 $ 1,026,655 $ 1,342,910
Nonrelated Party      
Net co-products, ethylene and other sales—third parties 185,095 164,136 250,237
Westlake | Affiliated Entity      
Selling, general and administrative expenses 25,654 27,085 26,621
Other income (expense)      
Interest expense—Westlake (25,701) (26,501) (13,407)
Common units      
Other income (expense)      
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income $ 62,392 $ 54,283 $ 64,173
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)      
Common units $ 1.77 $ 1.54 $ 1.82
Diluted units $ 1.77 $ 1.54 $ 1.82
Weighted average limited partner units outstanding (basic and diluted) 35,232,870 35,224,340 35,217,336
Common units | Publicly and Privately Held      
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)      
Weighted average limited partner units outstanding (basic and diluted) 21,110,640 21,102,110 21,095,106
Common units | Westlake      
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)      
Weighted average limited partner units outstanding (basic and diluted) 14,122,230 14,122,230 14,122,230
v3.25.0.1
Consolidated Statements of Changes in Equity - USD ($)
$ in Thousands
Total
Noncontrolling Interest in OpCo
Westlake
General Partner
Common units
Publicly and Privately Held
Limited Partner
Common units
Westlake
Limited Partner
Equity, beginning balance at Dec. 31, 2021 $ 972,698 $ 678,720 $ (242,572) $ 481,796 $ 54,754
Stockholders' Equity [Roll Forward]          
Net income 334,829 270,656 0 38,439 25,734
Units issued for vested phantom units 190     190  
Distribution to unitholders (66,411)     (39,782) (26,629)
Distribution to noncontrolling interest retained in OpCo by Westlake (337,598) (337,598)      
Equity, ending balance at Dec. 31, 2022 903,708 611,778 (242,572) 480,643 53,859
Stockholders' Equity [Roll Forward]          
Net income 334,626 280,343 0 32,519 21,764
Units issued for vested phantom units 141     141  
Distribution to unitholders (66,420)     (39,790) (26,630)
Distribution to noncontrolling interest retained in OpCo by Westlake (315,805) (315,805)      
Equity, ending balance at Dec. 31, 2023 856,250 576,316 (242,572) 473,513 48,993
Stockholders' Equity [Roll Forward]          
Net income 369,159 306,767 0 37,384 25,008
Units issued for vested phantom units 238     238  
Distribution to unitholders (66,435)     (39,807) (26,628)
Distribution to noncontrolling interest retained in OpCo by Westlake (329,898) (329,898)      
Equity, ending balance at Dec. 31, 2024 $ 829,314 $ 553,185 $ (242,572) $ 471,328 $ 47,373
v3.25.0.1
Consolidated Statements of Cash Flows - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Cash flows from operating activities      
Net income $ 369,159 $ 334,626 $ 334,829
Adjustments to reconcile net income to net cash provided by operating activities:      
Depreciation and amortization 111,899 110,203 121,074
Loss from disposition of property, plant and equipment 2,345 4,933 4,707
Other losses (gains), net (182) (27) 356
Changes in operating assets and liabilities      
Accounts receivable—third parties 7,221 1,332 (14,435)
Net accounts receivable—Westlake 25,737 27,331 74,197
Inventories 374 283 4,183
Prepaid expenses and other current assets (2) (137) 91
Accounts payable—third parties (2,693) 1,569 (17,001)
Accrued and other liabilities (5,821) 4,026 (37,533)
Other, net (23,036) (32,140) (6,732)
Net cash provided by operating activities 485,001 451,999 463,736
Cash flows from investing activities      
Additions to property, plant and equipment (48,971) (46,821) (54,118)
Investments with Westlake under the Investment Management Agreement (40,000) (174,116) (319,884)
Maturities of investments with Westlake under the Investment Management Agreement 0 145,000 362,000
Net cash used for investing activities (88,971) (75,937) (12,002)
Cash flows from financing activities      
Proceeds from debt payable to Westlake 219,000 209,250 32,000
Repayment of debt payable to Westlake (219,000) (209,250) (32,000)
Distributions to noncontrolling interest retained in OpCo by Westlake (329,898) (315,805) (337,598)
Distributions to unitholders (66,435) (66,420) (66,411)
Net cash used for financing activities (396,333) (382,225) (404,009)
Net increase (decrease) in cash and cash equivalents (303) (6,163) 47,725
Cash and cash equivalents at beginning of the year 58,619 64,782 17,057
Cash and cash equivalents at end of the year $ 58,316 $ 58,619 $ 64,782
v3.25.0.1
Description of Business and Significant Accounting Policies
12 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Description of Business and Significant Accounting Policies Description of Business and Significant Accounting Policies
Description of Business
Westlake Chemical Partners LP (the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests.
In connection with the IPO, the Partnership acquired a 10.6% limited partner interest in Westlake Chemical OpCo LP ("OpCo") and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and one common carrier ethylene pipeline (collectively, the "Contributed Assets"). Since the IPO, the Partnership has periodically purchased additional limited partner interest in OpCo. Most recently, on March 29, 2019, the Partnership purchased an additional 4.5% newly-issued limited partner interest in OpCo for approximately $201,445, resulting in an aggregate 22.8% limited partner interest in OpCo, effective January 1, 2019. The remaining 77.2% limited partner interest in OpCo is owned by Westlake Corporation. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.
OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. For more information, see Note 2.
The Partnership sells ethylene production in excess of volumes sold to Westlake, as well as all of the co-products resulting from the ethylene production, including propylene, crude butadiene, pyrolysis gasoline and hydrogen, directly to third parties on either a spot or contract basis. Co-products sold to third parties are transported by rail or truck. Net proceeds (after transportation and other costs) from the sales of ethylene co-products that result from the production of ethylene purchased by Westlake are netted against the ethylene price charged to Westlake under the Ethylene Sales Agreement, thereby reducing the Partnership's exposure to fluctuations in the market prices of these co-products.
Basis of Presentation
The accompanying consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States.
The Partnership holds a 22.8% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 77.2% limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. The Partnership's operations consist exclusively of the variable interest entity's operations and, as such, no additional variable interest entity disclosures are considered necessary. Westlake's retained interest of 77.2% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.
Cash and Cash Equivalents
Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.
Allowance for Credit Losses
The determination of the allowance for credit losses is based on estimation of the amount of accounts receivable that the Partnership believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Partnership's customers, the use of historical experience, the Partnership's accounts receivable aged trial balance, customer specific collectability analysis and an evaluation of economic conditions. The allowance for credit losses is reviewed quarterly. Past due balances over 90 days and high risk accounts, as determined by the analysis of financial strength of customers, are reviewed individually for collectability.
Inventories
Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method.
Property, Plant and Equipment
Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects.
Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $197, $164 and $80 for the years ended December 31, 2024, 2023 and 2022, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposal or retirement of property, plant and equipment are reflected in the statement of operations when the assets are sold or retired.
The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.
Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:
ClassificationYears
Buildings and improvements40
Plant and equipment25
Ethylene pipeline35
Other
3-15
Impairment of Long-Lived Assets
The accounting guidance for the impairment or disposal of long-lived assets requires that the Partnership assess long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Partnership when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the United States and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped by asset group, the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset group. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell.
Impairment of Goodwill
The accounting guidance requires that goodwill be tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying amount. The impairment test for the recorded goodwill was performed in the fourth quarter of 2024 and did not indicate impairment of the goodwill. As of December 31, 2024, the Partnership's recorded goodwill was $5,814. See Note 6 for more information on the Partnership's annual goodwill impairment test.
Turnaround Costs
The Partnership accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which typically ranges from five to eight years. Deferred turnaround costs are presented as a component of deferred charges and other assets, net. The cash outflows related to these costs are included in operating activities in the consolidated statement of cash flows.
Concentration of Credit Risk
Financial instruments which potentially subject the Partnership to concentration of risk consist principally of trade receivables from third-party customers who purchase ethylene and ethylene co-products. The Partnership performs periodic credit evaluations, as applicable, of the customers' financial condition and generally does not require collateral. The Partnership maintains allowances for potential losses, as applicable.
Revenue Recognition
Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement.
The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales.
The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (1) have an original expected duration of one year or less or (2) have only variable consideration that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations.
The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement. The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. See Note 2 for a description of the terms of the Ethylene Sales Agreement. The Partnership's direct commodity price risk is limited to the sales to third parties. See the Partnership's consolidated statements of operations for the disaggregation of net sales to Westlake and net sales to third parties.
Transportation and Freight
Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Partnership on outbound shipments are included in cost of sales in the consolidated statements of operations.
Environmental Costs
Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Partnership's best estimate of its final pro rata share of the liability.
Income Taxes
The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized on a separate tax return basis.
Use of Estimates
The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Other Comprehensive Income
The Partnership has not reported consolidated statements of comprehensive income for the years ended December 31, 2024, 2023 and 2022 due to immateriality of the components of other comprehensive income.
Recently Issued Accounting Pronouncements
Income Taxes (ASU No. 2023-09)
In December 2023, the Financial Accounting Standards Board ("FASB") issued an accounting standards update to require additional tax disclosures under Topic 740 primarily related to the rate reconciliation and income taxes paid disclosures. The amendments in this update will be effective for fiscal years beginning after December 15, 2024 and are to be applied on a prospective basis. Retrospective application is also permitted. The update is not expected to have a material impact on the Partnership's disclosures.
Disaggregation of Income Statement Expenses (ASU No. 2024-03)
In November 2024, the FASB issued an accounting standards update requiring public entities to disclose on an annual and interim basis detailed information about the types of expenses in relevant expense captions presented on the face of the income statement, including amounts for inventory purchases, employee compensation, depreciation and amortization of intangible assets and a qualitative description for remaining amounts not separately disaggregated. Additionally, the update requires disclosure of total selling expenses, and in annual periods, an entity's definition of selling expenses. The amendments in this update are effective for annual reporting periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027 and are to be applied either prospectively or retrospectively. Early adoption is permitted. The Partnership is currently evaluating the impact of the update on the disclosures in the Partnership's financial statements.
Recently Adopted Accounting Standard
Segment Reporting (ASU No. 2023-07)
In November 2023, the FASB issued an accounting standards update requiring public entities to disclose on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker ("CODM"), the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The update also requires that a public entity that has a single reportable segment provide all disclosures required by the update as well as all existing segment disclosures in Topic 280. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 and are to be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Partnership adopted this accounting standard effective for the annual 2024 financial statements, and the adoption resulted in additional segment disclosures (see Note 17) and will result in additional segment disclosures in the Partnership's interim period financial statements thereafter.
v3.25.0.1
Agreements with Westlake and Related Parties
12 Months Ended
Dec. 31, 2024
Equity [Abstract]  
Agreements with Westlake and Related Parties Agreements with Westlake and Related Parties
Ethylene Sales Agreement
OpCo has entered into an ethylene sales agreement with Westlake (the "Ethylene Sales Agreement") with an initial term of 12 years. The Ethylene Sales Agreement requires Westlake to purchase a minimum volume of ethylene each year equal to 95% of OpCo's planned ethylene production per year (the "Minimum Commitment"), subject to certain exceptions and a maximum commitment of 3.8 billion pounds per year. So long as Westlake is not in default under the Ethylene Sales Agreement, if OpCo's actual production exceeds planned production, Westlake has the option to purchase up to 95% of the excess production (the "Excess Production Option").
The fee for each pound of ethylene purchased by Westlake from OpCo up to the Minimum Commitment in any calendar year will equal:
the actual price OpCo pays Westlake to purchase ethane (or other feedstock, such as propane, if applicable) to produce each pound of ethylene, subject to a specified cap and a floor on the amount of feedstock that should be needed to produce each pound of ethylene; plus
the actual price OpCo pays Westlake to purchase natural gas to produce each pound of ethylene, subject to a specified cap and a floor on the amount of natural gas that should be needed to produce each pound of ethylene; plus
OpCo's estimated operating costs (including selling, general and administrative expenses), divided by OpCo's planned ethylene production for the year (in pounds); plus
a five-year average of OpCo's expected future maintenance capital expenditures and other turnaround expenditures, divided by OpCo's planned ethylene production capacity for the year (in pounds); less
the proceeds (on a per pound of ethylene basis) received by OpCo from the sale of co-products (including, but not limited to, propylene, crude butadiene, pyrolysis gasoline and hydrogen) associated with producing the ethylene purchased by Westlake; plus
a $0.10 per pound margin.
The fee for the Excess Production Option, if exercised, equals OpCo's estimated variable operating costs of producing the incremental ethylene, net of revenues from co-products sales plus a $0.10 per pound margin.
The estimated operating costs and the expected future maintenance capital expenditures and other turnaround expenditures will be adjusted at the end of each year, to be applicable for the fee for the next calendar year, to reflect certain changes in forecasted costs.
Under the Ethylene Sales Agreement OpCo has the option to curtail up to approximately 5% of its ethylene production annually in the event OpCo reasonably determines that its sales of such ethylene to third parties during the relevant period would be uneconomic.
Certain of the pricing components that make up the price for ethylene sold under the Ethylene Sales Agreement are modified to reflect the portion of OpCo's production capacity that is used to process Westlake's purge gas instead of producing ethylene. Costs specific to the processing of Westlake's purge gas are recovered under the Services and Secondment Agreement (as described below), and not the Ethylene Sales Agreement.
Pursuant to the Ethylene Sales Agreement, Westlake's obligation to pay for the annual minimum commitment (95% of OpCo's budgeted ethylene production), which is measured on an annual basis, is not reduced for a force majeure event lasting fewer than 45 consecutive days. In the event of a force majeure event, the Partnership recognizes buyer deficiency fees representing fixed margin and unavoided operating and maintenance capital expenditures and maintenance expenses per pound of volume committed by Westlake during the force majeure period. In the event Westlake purchases less than its annual commitment, the Partnership recognizes buyer deficiency fees representing fixed margin and all expenses and expenditures incurred per pound of volume committed but not taken by Westlake. Payment for the buyer deficiency fee is scheduled to be received by the Partnership after the conclusion of the year in which the force majeure event occurred.
The result of the fee structure is that OpCo should generally recover the portion of its total operating costs and maintenance capital expenditures and other turnaround expenditures corresponding to the portion of OpCo's aggregate production that is purchased by Westlake. Any shortfall in recovery of such costs is generally recognized during the period in which the related operating, maintenance or turnaround activities occur and is recoverable from Westlake in the subsequent year. Under the Ethylene Sales Agreement, if production costs billed to Westlake on an annual basis are less than 95% of the actual production costs incurred by OpCo during the contract year, OpCo is entitled to recover the shortfall in such production costs (proportionate to the volume sold to Westlake) in the subsequent year ("Shortfall").
The Ethylene Sales Agreement provides that, if compliance with any law adopted or modified following the IPO results in OpCo incurring additional costs in excess of $500 in any contract year, OpCo is entitled to charge Westlake a monthly surcharge following efforts to mitigate the effects of such matter.
The Ethylene Sales Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated.
Feedstock Supply Agreement
OpCo has entered into a feedstock supply agreement with Westlake, pursuant to which Westlake sells to OpCo ethane and other feedstock in amounts sufficient for OpCo to produce the ethylene to be sold under the Ethylene Sales Agreement (the "Feedstock Supply Agreement"). The Feedstock Supply Agreement provides that OpCo may obtain feedstock from Westlake based on Westlake's total cost of purchasing and delivering the feedstock, including applicable transportation, storage and other costs. Title and risk of loss for all feedstock purchased by OpCo through the Feedstock Supply Agreement passes to OpCo upon delivery to one of three delivery points described in the Feedstock Supply Agreement.
The Feedstock Supply Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated by either party; provided, however, that such agreement can only be renewed in the event the Ethylene Sales Agreement is renewed simultaneously. The Feedstock Supply Agreement may, in certain circumstances, terminate concurrently with the termination of the Ethylene Sales Agreement.
Services and Secondment Agreement
OpCo has entered into a Services and Secondment Agreement with Westlake, pursuant to which OpCo provides Westlake with certain services required for the operation of Westlake's facilities; and Westlake provides OpCo with comprehensive operating services for OpCo's facilities, ranging from services relating to the maintenance and operations of the common facilities necessary for the operation of OpCo's units, to making available certain shared utilities such as electricity and natural gas that are necessary for the operation of OpCo's units. Westlake also seconds employees to OpCo to allow OpCo to operate its facilities. Such seconded employees are under the control of OpCo while they work on OpCo's facilities.
The Services and Secondment Agreement has an initial 12-year term. The Services and Secondment Agreement may be renewed thereafter upon agreement of the parties and shall automatically terminate if the Ethylene Sales Agreement terminates under certain circumstances. Westlake and OpCo each can terminate the Services and Secondment Agreement under certain circumstances, including if the other party materially defaults on the performance of its obligations and such default continues for a 30-day period.
Site Lease Agreements
OpCo has entered into two site lease agreements with Westlake pursuant to which Westlake leases to OpCo the real property underlying Lake Charles Olefins and Calvert City Olefins and grants OpCo rights to access and use certain other portions of Westlake's ethylene production facilities that are necessary to operate OpCo's production facilities. OpCo owes Westlake one dollar per site per year. The site lease agreements each have a term of 50 years. Each of the site lease agreements may be renewed if agreed by the parties.
Omnibus Agreement
The Partnership has entered into an Omnibus Agreement with Westlake that addresses (1) Westlake's indemnification of the Partnership for certain matters, including environmental and tax matters, (2) the provision by Westlake of certain management and other general and administrative services to the Partnership and its general partner and (3) the Partnership's reimbursement to Westlake for such services. The Omnibus Agreement also addresses Westlake's right of first refusal on any proposed transfer of the ethylene production facilities that serve Westlake's other facilities and Westlake's right of first refusal on any proposed transfer of the Partnership's equity interests in OpCo.
Exchange Agreement
OpCo and Westlake are parties to an exchange agreement, which continues on an annual basis, unless and until terminated by either party. Under the exchange agreement, OpCo may require Westlake to deliver up to 200 million pounds of ethylene for OpCo per year from the Site Leases to an ethylene hub in Mt. Belvieu, Texas, for which OpCo would be required to pay an exchange fee of $0.006 per pound.
OpCo Partnership Agreement
The Partnership, OpCo GP and Westlake are parties to an agreement of limited partnership for OpCo (the "OpCo LP Agreement"). The OpCo LP Agreement governs the ownership and management of OpCo and designates OpCo GP as the general partner of OpCo. OpCo GP generally has complete authority to manage OpCo's business and affairs. The Partnership controls OpCo GP, as its sole member, subject to certain approval rights held by Westlake.
Investment Management Agreement
The Partnership, OpCo and Westlake are parties to an Investment Management Agreement that authorizes Westlake to invest the Partnership and OpCo's excess cash with Westlake for durations of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. The Partnership had $134,557 of invested cash under the Investment Management Agreement at December 31, 2024.
v3.25.0.1
Accounts Receivable—Third Parties
12 Months Ended
Dec. 31, 2024
Accounts Receivable, after Allowance for Credit Loss [Abstract]  
Accounts Receivable—Third Parties Accounts Receivable—Third Parties
Accounts receivable—third parties consist of the following:
December 31,
20242023
Trade customers$11,757 $15,622 
Allowance for credit losses(181)(278)
Other receivables— 3,357 
Accounts receivable, net—third parties$11,576 $18,701 
v3.25.0.1
Inventories
12 Months Ended
Dec. 31, 2024
Inventory, Net [Abstract]  
Inventories Inventories
Inventories consist of the following:
December 31,
20242023
Finished products$3,748 $4,147 
Feedstock, additives and chemicals310 285 
Inventories$4,058 $4,432 
v3.25.0.1
Property, Plant and Equipment
12 Months Ended
Dec. 31, 2024
Property, Plant and Equipment, Net [Abstract]  
Property, Plant and Equipment Property, Plant and Equipment
Property, plant and equipment consist of the following:
December 31,
20242023
Building and improvements$18,562 $18,623 
Plant and equipment1,950,479 1,936,295 
Other118,870 112,210 
2,087,911 2,067,128 
Less: Accumulated depreciation(1,237,929)(1,161,032)
849,982 906,096 
Construction in progress53,606 37,747 
Property, plant and equipment, net$903,588 $943,843 
Depreciation expense on property, plant and equipment of $86,253, $84,511 and $94,744 is included in cost of sales in the consolidated statements of operations for the years ended December 31, 2024, 2023 and 2022, respectively.
v3.25.0.1
Goodwill
12 Months Ended
Dec. 31, 2024
Other Assets [Abstract]  
Goodwill Goodwill
The Partnership's goodwill balance was $5,814 at December 31, 2024 and 2023. The Partnership performed its annual goodwill impairment analysis during the fourth quarter of 2024. The Partnership elected to perform a qualitative assessment for its analysis. Based upon this assessment, the Partnership concluded that it is more likely than not that the fair value of the reporting unit exceeds the carrying amount. Factors considered in the qualitative assessment included industry and market considerations, cost factors, including consideration of the Partnership's fixed margin under the Ethylene Sales Agreement, and current and projected financial performance.
v3.25.0.1
Deferred Charges and Other Assets
12 Months Ended
Dec. 31, 2024
Other Assets [Abstract]  
Deferred Charges and Other Assets Deferred Charges and Other Assets
Deferred charges and other assets, net consist of the following:
December 31,
20242023
Turnaround costs, net$129,565 $133,176 
Other8,063 7,806 
Deferred charges and other assets, net$137,628 $140,982 
Amortization expense on deferred charges and other assets of $25,646, $25,692 and $26,330 is included in cost of sales in the consolidated statements of operations for the years ended December 31, 2024, 2023 and 2022, respectively. Certain other assets are amortized over periods ranging from three to twenty years using the straight-line method.
v3.25.0.1
Long-Term Debt
12 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Long-Term Debt Long-Term Debt
Long-term debt payable to Westlake consists of the following:
December 31,
20242023
OpCo Revolver$22,619 $22,619 
MLP Revolver377,055 377,055 
Long-term debt payable to Westlake$399,674 $399,674 
On August 4, 2014, OpCo entered into a $600,000 senior unsecured revolving credit facility agreement with Westlake (as subsequently amended, the "OpCo Revolver"). On July 12, 2022, OpCo entered into the Second Amendment (the "OpCo Revolver Amendment") to the OpCo Revolver. Prior to the OpCo Revolver Amendment, the OpCo Revolver bore interest at the London Interbank Offered Rate ("LIBOR") plus 2.0%. The OpCo Revolver Amendment, among other things, extended the maturity date of the OpCo Revolver from September 25, 2023 to July 12, 2027 and provided for the replacement of LIBOR with the Secured Overnight Financing Rate, as administered by the Federal Reserve Bank of New York ("SOFR"). Borrowings under the OpCo Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the OpCo Revolver is 1.75%. As of December 31, 2024, outstanding borrowings under the OpCo Revolver bore interest at SOFR plus the Applicable Margin and credit spread adjustment.
On April 29, 2015, the Partnership entered into a $300,000 revolving credit facility agreement with an affiliate of Westlake (as subsequently amended, the "MLP Revolver"). In 2017, the Partnership entered into an amendment to the MLP Revolver credit agreement, increasing borrowing capacity from $300,000 to $600,000. On July 12, 2022, the Partnership entered into the Fourth Amendment (the "MLP Revolver Amendment") to the MLP Revolver. Prior to the MLP Revolver Amendment, the MLP Revolver bore interest at a variable rate of either (a) LIBOR plus 2.0% or, if LIBOR were no longer available, (b) the Alternate Base Rate plus 1.0%. The MLP Revolver Amendment, among other things, extended the maturity date of the MLP Revolver from March 19, 2023 to July 12, 2027 and provided for the replacement of LIBOR with SOFR as the reference rate. Borrowings under the MLP Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the MLP Revolver varies between 1.75% and 2.75%, depending on the Partnership's Consolidated Leverage Ratio. As of December 31, 2024, outstanding borrowings under the MLP Revolver bore interest at SOFR plus the Applicable Margin and credit spread adjustment. The MLP Revolver provides that the Partnership may pay all or a portion of the interest on any borrowings in kind, in which case any such amounts would be added to the principal amount of the loan. The MLP Revolver requires that the Partnership maintain a consolidated leverage ratio of either (1) during any one-year period following certain types of acquisitions (including acquisitions of additional interests in OpCo), 5.50:1.00 or less, or (2) during any other period, 4.50:1.00 or less. The MLP Revolver also contains certain other customary covenants. The repayment of borrowings under the MLP Revolver is subject to acceleration upon the occurrence of an event of default.
As of December 31, 2024, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver.
The weighted average interest rate on all long-term debt was 6.4% and 7.2% at December 31, 2024 and 2023, respectively.
As of December 31, 2024, the Partnership had no scheduled maturities of long-term debt until 2027. The OpCo Revolver and the MLP Revolver are scheduled to mature on July 12, 2027.
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit
12 Months Ended
Dec. 31, 2024
Earnings Per Share [Abstract]  
Distributions and Net Income Per Limited Partner Unit Distributions and Net Income Per Limited Partner Unit
On January 27, 2025, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the period from October 1, 2024 to December 31, 2024 of $0.4714 per common unit. This distribution was paid on February 25, 2025 to unitholders of record as of February 7, 2025.
Distributions are declared subsequent to quarter end; therefore, the table below represents total cash distributions declared from earnings of the related periods pertaining to such distributions.
Year Ended December 31,
202420232022
Net income attributable to the Partnership$62,392 $54,283 $64,173 
Less:
Limited partners' distribution declared on common units66,437 66,421 66,403 
Distribution in excess of net income
$(4,045)$(12,138)$(2,230)
Net income per unit applicable to common limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted-average number of common units outstanding for the period. Because the Partnership has more than one class of participating securities, it uses the two-class method when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units and incentive distribution rights. Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statements of changes in equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. Basic and diluted net income per unit is the same because the Partnership does not have any potentially dilutive units outstanding for the periods presented.
Year Ended December 31, 2024
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,437 $— $66,437 
Distribution in excess of net income(4,045)— (4,045)
Net income $62,392 $— $62,392 
Weighted average units outstanding:
Basic and diluted35,232,870 35,232,870 
Net income per limited partner unit:
Basic and diluted$1.77 
Year Ended December 31, 2023
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,421 $— $66,421 
Distribution in excess of net income
(12,138)— (12,138)
Net income$54,283 $— $54,283 
Weighted average units outstanding:
Basic and diluted35,224,340 35,224,340 
Net income per limited partner unit:
Basic and diluted$1.54 
Year Ended December 31, 2022
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,403 $— $66,403 
Distribution in excess of net income
(2,230)— (2,230)
Net income$64,173 $— $64,173 
Weighted average units outstanding:
Basic and diluted35,217,336 35,217,336 
Net income per limited partner unit:
Basic and diluted$1.82 
The amended Partnership Agreement provides that the Partnership will distribute cash that is deemed to be an appropriate portion of the Partnership's total operating surplus. If cash distributions to the Partnership's unitholders exceed $1.2938 per common unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations:
Marginal Percentage Interest in Distributions
Total Quarterly Distribution Per UnitUnitholdersIDR Holders
Above $1.2938 up to $1.4063
85.0 %15.0 %
Above $1.4063 up to $1.6875
75.0 %25.0 %
Above $1.6875
50.0 %50.0 %
The Partnership's distribution for each quarter in the year ended December 31, 2024 did not exceed the $1.2938 per unit threshold, and, as a result, no distribution was made with respect to the Partnership's incentive distribution rights to Westlake, as the holder of the Partnership's incentive distribution rights.
Distribution Per Common Unit
Distributions per common unit for the years ended December 31, 2024, 2023 and 2022 were as follows:
Year Ended December 31,
202420232022
Distributions per common unit$1.8856 $1.8856 $1.8856 
v3.25.0.1
Partners' Equity
12 Months Ended
Dec. 31, 2024
Partners' Equity [Abstract]  
Partners' Equity Partners' Equity
On October 4, 2018, the Partnership and Westlake Chemical Partners GP LLC, the general partner of the Partnership, entered into an Equity Distribution Agreement with UBS Securities LLC, Barclays Capital Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., RBC Capital Markets, LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated and Wells Fargo Securities, LLC to offer and sell the Partnership's common units, from time to time, up to an aggregate offering amount of $50,000. The Equity Distribution Agreement was amended on February 28, 2020 to reference a new shelf registration and subsequent renewals thereof for utilization under this agreement. To date, no common units have been issued under this program.
On March 29, 2019, the Partnership completed the issuance and sale of 2,940,818 common units at a price of $21.40 per unit through a private placement. TTWF LP, Westlake's principal stockholder and a related party, acquired 1,401,869 common units out of 2,940,818 common units issued in the private placement.
v3.25.0.1
Related Party Transactions
12 Months Ended
Dec. 31, 2024
Related Party Transactions [Abstract]  
Related Party Transactions Related Party Transactions
Related party transactions between the Partnership, OpCo and Westlake are primarily based on agreements such as the Ethylene Sales Agreement, the Feedstock Supply Agreement, the Services and Secondment Agreement, Site Lease Agreements, the Omnibus Agreement, the Investment Management Agreement, the Exchange Agreement, the OpCo Partnership Agreement, the OpCo Revolver and the MLP Revolver. These agreements, discussed in detail in Notes 2 and 8, reflect the pervasive effect of the relationship with Westlake on the Partnership's operations and its consolidated financial statements. Pursuant to these agreements, the Partnership and OpCo regularly enter into transactions with Westlake. See below for descriptions and details of significant related party transactions.
Sales to Related Parties
OpCo sells ethylene to Westlake under the Ethylene Sales Agreement. Additionally, the Partnership and OpCo from time to time provide other services or products for which it charges Westlake a fee.
OpCo sells a significant portion of its ethylene production to Westlake. Sales to related parties were as follows:
Year Ended December 31,
202420232022
Net sales—Westlake$950,801 $1,026,655 $1,342,910 
As a result of the Partnership's decision to postpone the previously announced maintenance turnaround at the Petro 1 facility from the third quarter of 2024 to the first quarter of 2025, OpCo's production resulted in "excess quantities" of ethylene for the contract year ended December 31, 2024. Pursuant to the terms of the Ethylene Sales Agreement, the excess quantities produced by the Partnership during the year ended December 31, 2024 were sold to Westlake at prices that excluded certain non-variable costs of production.
Based on OpCo's 2022 production, the Partnership recognized buyer deficiency fees of $23,835 during the year ended December 31, 2022. The buyer deficiency fee is measured periodically based upon the lower of the actual production deficiency at period end or the estimated annual production deficiency based upon OpCo's annual anticipated production. These periodic estimates are updated at the end of the year based on actual annual production. The buyer deficiency fees are classified as a component of net sales—Westlake. The buyer deficiency fee was received by the Partnership in January 2023.
Cost of Sales from Related Parties
Charges for goods and services purchased by the Partnership and OpCo from Westlake and included in cost of sales relate primarily to feedstock purchased under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement.
A significant portion of the Partnership's inputs included in cost of sales are supplied by Westlake. Charges from related parties for significant inputs included in cost of sales were as follows:
Year Ended December 31,
202420232022
Feedstock purchased from Westlake and included in cost of sales$310,856 $398,700 $764,123 
Other charges from Westlake and included in cost of sales125,702 123,039 172,761 
Services from Related Parties Included in Selling, General and Administrative Expenses
Charges for services purchased by the Partnership from Westlake and included in selling, general and administrative expenses primarily relate to services Westlake performs on behalf of the Partnership under the Omnibus Agreement, including the Partnership's finance, legal, information technology, human resources, communication, ethics and compliance and other administrative functions.
Charges from related parties included within selling, general and administrative expenses were as follows:
Year Ended December 31,
202420232022
Services received from Westlake and included in selling, general and
   administrative expenses
$25,654 $27,085 $26,621 
Goods and Services from Related Parties Capitalized as Assets
Charges for goods and services purchased by the Partnership and OpCo from Westlake which were capitalized as assets relate primarily to the services of Westlake employees under the Services and Secondment Agreement.
Charges from related parties for goods and services capitalized as assets were as follows:
Year Ended December 31,
202420232022
Goods and services purchased from Westlake and capitalized as assets$2,295 $3,660 $2,852 
Receivable under the Investment Management Agreement
On August 1, 2017, the Partnership, OpCo and Westlake executed an investment management agreement (the "Investment Management Agreement") that authorized Westlake to invest the Partnership's and OpCo's excess cash with Westlake for durations of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. Accrued interest of $1,385 and $1,272 was included in the receivable under the Investment Management Agreement balance at December 31, 2024 and 2023, respectively. Total interest earned related to the Investment Management Agreement was $5,364, $4,424 and $1,875 for the years ended December 31, 2024, 2023 and 2022, respectively.
The Partnership's receivable under the Investment Management Agreement was as follows:
December 31,
20242023
Receivable under the Investment Management Agreement$134,557 $94,444 
Accounts Receivable from Related Parties
The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake and any buyer deficiency fee and Shortfall recognized under the Ethylene Sales Agreement.
As of December 31, 2024, accounts receivable includes sales associated with the Excess Production Option which are at a lower sales price as described in Note 2 and under —Sales to Related Parties above.
The Partnership's accounts receivable from Westlake were as follows:
December 31,
20242023
Accounts receivable—Westlake$31,975 $49,565 
Accounts Payable to Related Parties
The Partnership's accounts payable to Westlake result primarily from feedstock purchases under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement and the Omnibus Agreement.
The Partnership's accounts payable to Westlake were as follows:
December 31,
20242023
Accounts payable—Westlake$20,744 $15,166 
Debt Payable to Related Parties
See Note 8 for a description of related party debt payable balances.
Interest on related party debt payable balances, net of capitalized interest, for the years ended December 31, 2024, 2023 and 2022 was $25,701, $26,501 and $13,407, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. At December 31, 2024 and 2023, accrued interest on related party debt was $5,848 and $6,675, respectively, and is reflected as a component of accrued and other liabilities in the consolidated balance sheets.
Debt payable to related parties was as follows:
December 31,
20242023
Long-term debt payable to Westlake$399,674 $399,674 
Related Party Leases
OpCo is obligated to Westlake under various long-term and short-term noncancelable operating leases, primarily related to rail cars and land. Operating lease rentals paid to Westlake for such leases were $1,843, $1,869 and $2,624 for the years ended December 31, 2024, 2023 and 2022, respectively, and are reflected in other charges from Westlake that are included in cost of sales.
OpCo has two site lease agreements with Westlake, each of which has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlake one dollar per site per year.
Major Customer and Concentration of Credit Risk
During the years ended December 31, 2024, 2023 and 2022, Westlake accounted for approximately 83.7%, 86.2% and 84.3%, respectively, of the Partnership's net sales.
General
During the years ended December 31, 2024, 2023 and 2022, the Partnership reimbursed $351, $347 and $243, respectively, to Westlake for certain state tax payments.
Other
See Note 10 above for an additional transaction through which a related party acquired common units in a private placement.
v3.25.0.1
Unit-based Compensation
12 Months Ended
Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Unit-based Compensation Unit-based Compensation
The Westlake Chemical Partners LP Long-Term Incentive Plan (the "Plan") was adopted on July 15, 2014 and provides for grants of unit options, restricted units, phantom units, unit awards, distribution equivalent rights ("DERs") and other unit-based awards. The purpose of the Plan is to attract and retain the services of individuals who are essential for the growth and profitability of the Partnership and to encourage such individuals to devote their best efforts to advancing the business of the Partnership and its affiliates. Awards under the Plan are determined by the board of directors of the Partnership's general partner or a committee thereof (the "Committee"). Under the Plan, DERs may be granted, which represent a contingent right to receive an amount in cash, units, restricted units and/or phantom units, as determined by the Committee at its sole discretion, equal in value to the cash distributions made by the Partnership with respect to a common unit during the period such award is outstanding. The terms and conditions of each award are determined by the Committee. The maximum number of common units of the Partnership that may be delivered with respect to awards under the Plan is 1,270,000. The phantom units along with a corresponding number of DERs were granted to certain non-employee directors of the general partner of the Partnership during the years ended December 31, 2024, 2023 and 2022. These phantom units vest on the first anniversary of the grant date. There were no forfeitures under the Plan during 2024, 2023 and 2022. The total fair value of phantom units that vested during the years ended December 31, 2024, 2023 and 2022 was $423, $278 and $284, respectively.
Non-vested phantom unit awards as of December 31, 2024 and 2023 and changes during the period were as follows:
Number of
Units
Weighted
Average Fair Value
Non-vested balance at December 31, 202318,564 $21.65 
Granted14,646 22.69 
Vested(18,564)22.80 
Non-vested balance at December 31, 202414,646 $23.14 
Each phantom unit represents the right to receive, upon vesting, either a cash payment equal to the fair market value of one Partnership common unit or a Partnership common unit. Each DER has distribution rights only so long as the phantom units to which it relates to has not vested or been settled.
The awards, which are classified as liability awards for financial accounting purposes, are measured at fair value on the grant date of the award and are re-measured at each reporting date until they vest based on the market price of the Partnership's units. The total units available for grant at December 31, 2024 were 1,192,349. The total compensation cost recognized during the years ended December 31, 2024, 2023 and 2022 was $373, $349 and $282, respectively, and is included in selling, general and administrative expenses and the related liability is classified as accrued and other liabilities in the consolidated financial statements of the Partnership. The unrecognized compensation cost associated with all grants under the Plan at December 31, 2024 was $201 and the weighted average remaining term of the units at December 31, 2024 was 0.6 years.
v3.25.0.1
Fair Value Measurements
12 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Fair Value Measurements Fair Value Measurements
The Partnership reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels:
Level 1: Quoted market prices in active markets for identical assets or liabilities.
Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.
Level 3: Unobservable inputs that are not corroborated by market data.
The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Partnership's long-term debt at December 31, 2024 and December 31, 2023 are summarized in the table below. The fair value of long-term debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate.
December 31, 2024December 31, 2023
Carrying
Value
Fair
Value
Carrying
Value
Fair
Value
Long-term debt payable to Westlake
$399,674 $411,489 $399,674 $408,110 
v3.25.0.1
Income Taxes
12 Months Ended
Dec. 31, 2024
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes.
The components of income tax of the Partnership are as follows:
Year Ended December 31,
202420232022
Current
State and local$921 $837 $891 
Deferred
State and local(86)(24)126 
Total provision$835 $813 $1,017 
The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense is as follows:
Year Ended December 31,
202420232022
Provision for federal income tax, at statutory rate$77,699 $70,442 $70,528 
State income tax provision, net of federal income tax effect835 813 1,017 
Partnership income not subject to entity-level federal income tax(77,699)(70,442)(70,528)
Total provision$835 $813 $1,017 
The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows:
December 31,
20242023
Property, plant and equipment$(1,323)$(1,402)
Turnaround costs(223)(230)
Total deferred tax liabilities$(1,546)$(1,632)
Balance sheet classifications
Noncurrent deferred tax liability$(1,546)$(1,632)
Total deferred tax liabilities$(1,546)$(1,632)
v3.25.0.1
Supplemental Information
12 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Supplemental Information Supplemental Information
Accrued and Other Liabilities
Accrued and other liabilities were $16,920 and $24,980 at December 31, 2024 and 2023, respectively. Accrued interest on related party debt, which is a component of accrued and other liabilities, was $5,848 and $6,675 at December 31, 2024 and 2023, respectively. No other component of accrued and other liabilities was more than five percent of total current liabilities.
Insurance Recoveries
During the year ended December 31, 2024, the Partnership recorded business interruption related insurance recoveries of $6,222 as a reduction to cost of sales. All insurance recovery proceeds were collected as of December 31, 2024. These recoveries were related to the settlement of insurance claims for Hurricane Laura, which impacted OpCo's Petro 1 and Petro 2 units in the second half of 2020 and impacted production in the subsequent periods.
Cash Flow Information
Non-cash Investing Activity
Capital expenditure related liabilities, included in accounts payable—third parties and accrued and other liabilities, were $9,863, $7,809, and $6,372 at December 31, 2024, 2023, and 2022, respectively.
Interest and Income Taxes
Interest paid by the Partnership, net of interest capitalized, was $26,528, $24,537 and $10,850 for the years ended December 31, 2024, 2023 and 2022, respectively. Income tax paid by the Partnership was $831, $827 and $683 for the years ended December 31, 2024, 2023 and 2022, respectively, of which $480, $480 and $440 was paid directly to the tax authorities for the years ended December 31, 2024, 2023 and 2022, and $351, $347 and $243 was paid to Westlake as reimbursements for the years ended December 31, 2024, 2023 and 2022.
Operating Leases
Right-of-use assets obtained in exchange for operating lease obligations were $758, $5,079 and $0 for the years ended December 31, 2024, 2023 and 2022, respectively.
v3.25.0.1
Commitments and Contingencies
12 Months Ended
Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies Commitments and Contingencies
The Partnership is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require the Partnership to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. These laws include the federal Clean Air Act, the federal Water Pollution Control Act, the Resource Conservation and Recovery Act, the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Toxic Substances Control Act and various other federal, state and local laws and regulations. Under CERCLA, an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because the Partnership's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Partnership. Pursuant to the Omnibus Agreement, certain subsidiaries of Westlake will indemnify the Partnership for liabilities that occurred or existed prior to August 4, 2014.
The Partnership is also involved in other legal proceedings incidental to the conduct of its business. After considering all relevant facts and circumstances, including applicable insurance and indemnification by Westlake, the Partnership does not believe that any of these legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows.
Other Commitments
The Partnership has various purchase commitments for its capital projects and for materials, supplies and services incident to the ordinary conduct of business.
v3.25.0.1
Segment Information
12 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Segment Information Segment Information
The Partnership has one operating segment, which is the Partnership's reportable segment, OpCo. The operating results of the segment are reviewed by the Partnership's Chief Executive Officer, the chief operating decision maker ("CODM"). The CODM evaluates segment performance based on net income. The CODM reviews the OpCo segment's actual net income trends to allocate resources and assess performance.
The OpCo segment's operations consist of two ethylene production facilities in Lake Charles, Louisiana, one ethylene production facility in Calvert City, Kentucky and a 200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to Longview, Texas. OpCo derives substantially all of its revenue from these production facilities primarily by selling ethylene to Westlake and others, as well as through the sale of co-products of ethylene production, including propylene, crude butadiene, pyrolysis gasoline and hydrogen. All of the OpCo segment's operations are located and conducted in the United States. All of the OpCo segment's sales are attributed to the United States.
Sales to Westlake accounted for more than 10% of sales in the OpCo segment, totaling $950,801, $1,026,655 and $1,342,910 for the years ended December 31, 2024, 2023 and 2022, respectively. Consolidated net sales and provision for income taxes as disclosed in the consolidated statements of operations and depreciation and amortization and additions to property, plant and equipment as disclosed in the consolidated statements of cash flows are fully attributed to the OpCo segment, and as such, separate OpCo segment amounts are not repeated in the tables below.
The accounting policies of the OpCo segment are the same as those described in Note 1.
Year Ended December 31,
202420232022
Significant segment expenses and other segment items
OpCo
Raw material, energy, manufacturing and logistics costs
$605,058 $693,129 $1,094,708 
Depreciation and amortization111,899 110,203 121,074 
Total cost of sales716,957 803,332 1,215,782 
Selling, general and administrative expenses24,699 26,217 26,387 
Other segment items (1)
(3,005)(1,786)494 
Interest expense—Westlake
OpCo$1,410 $1,496 $693 
Corporate24,291 25,005 12,714 
$25,701 $26,501 $13,407 
Net income
OpCo$397,245 $363,028 $350,484 
A reconciliation of total segment net income to consolidated net income is as follows:

Year Ended December 31,
202420232022
Net income from OpCo
$397,245 $363,028 $350,484 
Corporate net loss
(28,086)(28,402)(15,655)
Net income
$369,159 $334,626 $334,829 

December 31,
20242023
Total assets
OpCo
$1,238,420 $1,269,355 
Corporate
49,536 47,487 
$1,287,956 $1,316,842 

_____________________________
(1)Other segment items includes interest expense—Westlake, other income, net and provision for income taxes.
v3.25.0.1
Pay vs Performance Disclosure - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pay vs Performance Disclosure      
Net Income (Loss) Attributable to Parent $ 62,392 $ 54,283 $ 64,173
v3.25.0.1
Insider Trading Arrangements
3 Months Ended
Dec. 31, 2024
Trading Arrangements, by Individual  
Rule 10b5-1 Arrangement Adopted false
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
v3.25.0.1
Insider Trading Policies and Procedures
12 Months Ended
Dec. 31, 2024
Insider Trading Policies and Procedures [Line Items]  
Insider Trading Policies and Procedures Adopted true
v3.25.0.1
Cybersecurity Risk Management and Strategy Disclosure
12 Months Ended
Dec. 31, 2024
Cybersecurity Risk Management, Strategy, and Governance [Line Items]  
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]
OpCo has entered into the Services and Secondment Agreement with Westlake and we, OpCo and Westlake have entered into the Omnibus Agreement. Pursuant to these Agreements, Westlake performs various services for us, including those related to cybersecurity. As such, this disclosure addresses our cybersecurity policies and practices, some of which are executed by Westlake under the Services and Secondment Agreement and the Omnibus Agreement.
With Westlake's support, we maintain a comprehensive approach to cybersecurity and data protection, based on a risk-based, defense-in-depth strategy. Westlake follows industry standard cybersecurity frameworks, including the National Institute of Standards and Technology's Cybersecurity Framework to design, assess and update our cybersecurity strategy, controls and processes. Westlake regularly assesses industry best practices and standards and endeavors to implement them in its efforts to manage cybersecurity risk for us. The focus is on protecting our highest-value information assets, which include manufacturing systems, financial systems, and confidential, personal, and private information.
To safeguard our networks and systems, Westlake has a dedicated cybersecurity organization overseen by its Chief Information Security Officer, which operates within its information technology department overseen by its Chief Information Officer. Westlake's cybersecurity organization employs multiple security controls, such as firewalls, spam protection, web filtering, endpoint detection and response software, controlled access, vulnerability management, redundancies, patching, and regular onsite and offsite backups. Westlake's cybersecurity organization also uses a variety of processes to address cybersecurity threats related to the use of third-party technology and services, including pre-acquisition diligence, imposition of contractual obligations, and risk-based performance monitoring.
Both Westlake's Chief Information Officer and its Chief Information Security Officer have extensive experience in assessing and managing cybersecurity risks, including through decades of collective experience in information technology and cybersecurity roles of increasing responsibility both at Westlake and in prior positions. Westlake prioritizes cybersecurity awareness among employees and contractors through various training exercises, including formal programs and simulated phishing events. Westlake maintains incident response plans, playbooks, and engages third-party cybersecurity firms for simulated cyberattacks and penetration testing to identify potential risks. Westlake also has a third-party cybersecurity firm on retainer for incident assistance and response. Periodic internal self-assessments are conducted by Westlake's cybersecurity organization using the National Institute of Standards and Technology Cybersecurity Framework.
From time to time, we and OpCo experience cybersecurity threats and attempted breaches and other incidents. Westlake classifies and tracks these events based on significance and implements remediation actions that it considers appropriate to address the risks to the Partnership and OpCo relating to such incidents. Although we and OpCo have not experienced material impacts to our business strategy, results of operations or financial condition from any such incidents in the past three years, we cannot guarantee that a material incident will not occur in the future. See "Item 1A. Risk Factors—Failure to adequately protect critical data and technology systems could materially affect our operations."
Cybersecurity Risk Management Processes Integrated [Flag] true
Cybersecurity Risk Management Processes Integrated [Text Block]
With Westlake's support, we maintain a comprehensive approach to cybersecurity and data protection, based on a risk-based, defense-in-depth strategy. Westlake follows industry standard cybersecurity frameworks, including the National Institute of Standards and Technology's Cybersecurity Framework to design, assess and update our cybersecurity strategy, controls and processes. Westlake regularly assesses industry best practices and standards and endeavors to implement them in its efforts to manage cybersecurity risk for us. The focus is on protecting our highest-value information assets, which include manufacturing systems, financial systems, and confidential, personal, and private information.
Cybersecurity Risk Management Third Party Engaged [Flag] true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag] true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag] false
Cybersecurity Risk Board of Directors Oversight [Text Block] The board of directors has authorized and approved our entry into the Services and Secondment Agreement and the Omnibus Agreement with Westlake, and has thereby charged Westlake's Corporate Risk and Sustainability Committee with assisting the board of directors with its oversight of cybersecurity risks, which is a component of our overall enterprise risk management program. As a result, Westlake's Corporate Risk and Sustainability Committee assists with the oversight of our cybersecurity risks. Westlake's Corporate Risk and Sustainability Committee includes directors with cybersecurity experience and expertise, primarily through supervision of information technology departments as executive officers. The board of directors also receives regular updates from Westlake's Chief Information Officer on cybersecurity risks, incidents and trends, and ongoing and planned projects impacting the Partnership and OpCo. Westlake's Chief Information Officer and our senior management receive regular status reports on the Partnership's and OpCo's cybersecurity risks from Westlake's cybersecurity organization. Further, incident updates are reported to our senior management and the board of directors as Westlake's Chief Information Officer and cybersecurity organization consider appropriate, depending on the severity of the incident.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block] As a result, Westlake's Corporate Risk and Sustainability Committee assists with the oversight of our cybersecurity risks. Westlake's Corporate Risk and Sustainability Committee includes directors with cybersecurity experience and expertise, primarily through supervision of information technology departments as executive officers.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block] As a result, Westlake's Corporate Risk and Sustainability Committee assists with the oversight of our cybersecurity risks. Westlake's Corporate Risk and Sustainability Committee includes directors with cybersecurity experience and expertise, primarily through supervision of information technology departments as executive officers. The board of directors also receives regular updates from Westlake's Chief Information Officer on cybersecurity risks, incidents and trends, and ongoing and planned projects impacting the Partnership and OpCo.
Cybersecurity Risk Role of Management [Text Block] The board of directors also receives regular updates from Westlake's Chief Information Officer on cybersecurity risks, incidents and trends, and ongoing and planned projects impacting the Partnership and OpCo. Westlake's Chief Information Officer and our senior management receive regular status reports on the Partnership's and OpCo's cybersecurity risks from Westlake's cybersecurity organization. Further, incident updates are reported to our senior management and the board of directors as Westlake's Chief Information Officer and cybersecurity organization consider appropriate, depending on the severity of the incident.
As part of our incident response planning, Westlake also maintains cross-functional response teams involving personnel outside of its cybersecurity organization, both globally and regionally, in order to be prepared to respond to an incident.
Cybersecurity Risk Management Positions or Committees Responsible [Flag] true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block] To safeguard our networks and systems, Westlake has a dedicated cybersecurity organization overseen by its Chief Information Security Officer, which operates within its information technology department overseen by its Chief Information Officer.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block] Both Westlake's Chief Information Officer and its Chief Information Security Officer have extensive experience in assessing and managing cybersecurity risks, including through decades of collective experience in information technology and cybersecurity roles of increasing responsibility both at Westlake and in prior positions.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block] Westlake's Chief Information Officer and our senior management receive regular status reports on the Partnership's and OpCo's cybersecurity risks from Westlake's cybersecurity organization. Further, incident updates are reported to our senior management and the board of directors as Westlake's Chief Information Officer and cybersecurity organization consider appropriate, depending on the severity of the incident.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag] true
v3.25.0.1
Description of Business and Significant Accounting Policies (Policy)
12 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Description Of Business
Description of Business
Westlake Chemical Partners LP (the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests.
In connection with the IPO, the Partnership acquired a 10.6% limited partner interest in Westlake Chemical OpCo LP ("OpCo") and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and one common carrier ethylene pipeline (collectively, the "Contributed Assets"). Since the IPO, the Partnership has periodically purchased additional limited partner interest in OpCo. Most recently, on March 29, 2019, the Partnership purchased an additional 4.5% newly-issued limited partner interest in OpCo for approximately $201,445, resulting in an aggregate 22.8% limited partner interest in OpCo, effective January 1, 2019. The remaining 77.2% limited partner interest in OpCo is owned by Westlake Corporation. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.
OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. For more information, see Note 2.
The Partnership sells ethylene production in excess of volumes sold to Westlake, as well as all of the co-products resulting from the ethylene production, including propylene, crude butadiene, pyrolysis gasoline and hydrogen, directly to third parties on either a spot or contract basis. Co-products sold to third parties are transported by rail or truck. Net proceeds (after transportation and other costs) from the sales of ethylene co-products that result from the production of ethylene purchased by Westlake are netted against the ethylene price charged to Westlake under the Ethylene Sales Agreement, thereby reducing the Partnership's exposure to fluctuations in the market prices of these co-products.
Basis of Presentation
Basis of Presentation
The accompanying consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States.
The Partnership holds a 22.8% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 77.2% limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. The Partnership's operations consist exclusively of the variable interest entity's operations and, as such, no additional variable interest entity disclosures are considered necessary. Westlake's retained interest of 77.2% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.
Cash And Cash Equivalents
Cash and Cash Equivalents
Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.
Allowance For Doubtful Accounts
Allowance for Credit Losses
The determination of the allowance for credit losses is based on estimation of the amount of accounts receivable that the Partnership believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Partnership's customers, the use of historical experience, the Partnership's accounts receivable aged trial balance, customer specific collectability analysis and an evaluation of economic conditions. The allowance for credit losses is reviewed quarterly. Past due balances over 90 days and high risk accounts, as determined by the analysis of financial strength of customers, are reviewed individually for collectability.
Inventories
Inventories
Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method.
Property, Plant and Equipment
Property, Plant and Equipment
Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects.
Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $197, $164 and $80 for the years ended December 31, 2024, 2023 and 2022, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposal or retirement of property, plant and equipment are reflected in the statement of operations when the assets are sold or retired.
The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.
Impairment Of Long-Lived Assets and Intangible Assets
Impairment of Long-Lived Assets
The accounting guidance for the impairment or disposal of long-lived assets requires that the Partnership assess long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Partnership when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the United States and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped by asset group, the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset group. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell.
Impairment of Goodwill
The accounting guidance requires that goodwill be tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying amount. The impairment test for the recorded goodwill was performed in the fourth quarter of 2024 and did not indicate impairment of the goodwill. As of December 31, 2024, the Partnership's recorded goodwill was $5,814. See Note 6 for more information on the Partnership's annual goodwill impairment test.
Turnaround Costs
Turnaround Costs
The Partnership accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which typically ranges from five to eight years. Deferred turnaround costs are presented as a component of deferred charges and other assets, net. The cash outflows related to these costs are included in operating activities in the consolidated statement of cash flows.
Concentration Of Credit Risk
Concentration of Credit Risk
Financial instruments which potentially subject the Partnership to concentration of risk consist principally of trade receivables from third-party customers who purchase ethylene and ethylene co-products. The Partnership performs periodic credit evaluations, as applicable, of the customers' financial condition and generally does not require collateral. The Partnership maintains allowances for potential losses, as applicable.
Revenue Recognition
Revenue Recognition
Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement.
The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales.
The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (1) have an original expected duration of one year or less or (2) have only variable consideration that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations.
The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement. The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. See Note 2 for a description of the terms of the Ethylene Sales Agreement. The Partnership's direct commodity price risk is limited to the sales to third parties. See the Partnership's consolidated statements of operations for the disaggregation of net sales to Westlake and net sales to third parties.
Transportation and Freight
Transportation and Freight
Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Partnership on outbound shipments are included in cost of sales in the consolidated statements of operations.
Environmental Costs
Environmental Costs
Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Partnership's best estimate of its final pro rata share of the liability.
Income Taxes
Income Taxes
The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized on a separate tax return basis.
Use Of Estimates
Use of Estimates
The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Comprehensive Income
Other Comprehensive Income
The Partnership has not reported consolidated statements of comprehensive income for the years ended December 31, 2024, 2023 and 2022 due to immateriality of the components of other comprehensive income.
Recent Accounting Pronouncements
Recently Issued Accounting Pronouncements
Income Taxes (ASU No. 2023-09)
In December 2023, the Financial Accounting Standards Board ("FASB") issued an accounting standards update to require additional tax disclosures under Topic 740 primarily related to the rate reconciliation and income taxes paid disclosures. The amendments in this update will be effective for fiscal years beginning after December 15, 2024 and are to be applied on a prospective basis. Retrospective application is also permitted. The update is not expected to have a material impact on the Partnership's disclosures.
Disaggregation of Income Statement Expenses (ASU No. 2024-03)
In November 2024, the FASB issued an accounting standards update requiring public entities to disclose on an annual and interim basis detailed information about the types of expenses in relevant expense captions presented on the face of the income statement, including amounts for inventory purchases, employee compensation, depreciation and amortization of intangible assets and a qualitative description for remaining amounts not separately disaggregated. Additionally, the update requires disclosure of total selling expenses, and in annual periods, an entity's definition of selling expenses. The amendments in this update are effective for annual reporting periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027 and are to be applied either prospectively or retrospectively. Early adoption is permitted. The Partnership is currently evaluating the impact of the update on the disclosures in the Partnership's financial statements.
Recently Adopted Accounting Standard
Segment Reporting (ASU No. 2023-07)
In November 2023, the FASB issued an accounting standards update requiring public entities to disclose on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker ("CODM"), the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The update also requires that a public entity that has a single reportable segment provide all disclosures required by the update as well as all existing segment disclosures in Topic 280. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 and are to be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Partnership adopted this accounting standard effective for the annual 2024 financial statements, and the adoption resulted in additional segment disclosures (see Note 17) and will result in additional segment disclosures in the Partnership's interim period financial statements thereafter.
v3.25.0.1
Description of Business and Significant Accounting Policies (Tables)
12 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule Of Estimated Useful Lives Of Assets
Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:
ClassificationYears
Buildings and improvements40
Plant and equipment25
Ethylene pipeline35
Other
3-15
v3.25.0.1
Accounts Receivable—Third Parties (Tables)
12 Months Ended
Dec. 31, 2024
Accounts Receivable, after Allowance for Credit Loss [Abstract]  
Schedule Of Accounts Receivable
Accounts receivable—third parties consist of the following:
December 31,
20242023
Trade customers$11,757 $15,622 
Allowance for credit losses(181)(278)
Other receivables— 3,357 
Accounts receivable, net—third parties$11,576 $18,701 
v3.25.0.1
Inventories (Tables)
12 Months Ended
Dec. 31, 2024
Inventory, Net [Abstract]  
Schedule Of Inventory
Inventories consist of the following:
December 31,
20242023
Finished products$3,748 $4,147 
Feedstock, additives and chemicals310 285 
Inventories$4,058 $4,432 
v3.25.0.1
Property, Plant and Equipment (Tables)
12 Months Ended
Dec. 31, 2024
Property, Plant and Equipment, Net [Abstract]  
Schedule Of Property, Plant And Equipment
Property, plant and equipment consist of the following:
December 31,
20242023
Building and improvements$18,562 $18,623 
Plant and equipment1,950,479 1,936,295 
Other118,870 112,210 
2,087,911 2,067,128 
Less: Accumulated depreciation(1,237,929)(1,161,032)
849,982 906,096 
Construction in progress53,606 37,747 
Property, plant and equipment, net$903,588 $943,843 
v3.25.0.1
Deferred Charges and Other Assets (Tables)
12 Months Ended
Dec. 31, 2024
Other Assets [Abstract]  
Schedule of Other Assets
Deferred charges and other assets, net consist of the following:
December 31,
20242023
Turnaround costs, net$129,565 $133,176 
Other8,063 7,806 
Deferred charges and other assets, net$137,628 $140,982 
v3.25.0.1
Long-Term Debt (Tables)
12 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Schedule Of Long-Term Debt
Long-term debt payable to Westlake consists of the following:
December 31,
20242023
OpCo Revolver$22,619 $22,619 
MLP Revolver377,055 377,055 
Long-term debt payable to Westlake$399,674 $399,674 
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Tables)
12 Months Ended
Dec. 31, 2024
Earnings Per Share [Abstract]  
Schedule of Distributions
Distributions are declared subsequent to quarter end; therefore, the table below represents total cash distributions declared from earnings of the related periods pertaining to such distributions.
Year Ended December 31,
202420232022
Net income attributable to the Partnership$62,392 $54,283 $64,173 
Less:
Limited partners' distribution declared on common units66,437 66,421 66,403 
Distribution in excess of net income
$(4,045)$(12,138)$(2,230)
Schedule of Earnings Per Share, Basic and Diluted
Year Ended December 31, 2024
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,437 $— $66,437 
Distribution in excess of net income(4,045)— (4,045)
Net income $62,392 $— $62,392 
Weighted average units outstanding:
Basic and diluted35,232,870 35,232,870 
Net income per limited partner unit:
Basic and diluted$1.77 
Year Ended December 31, 2023
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,421 $— $66,421 
Distribution in excess of net income
(12,138)— (12,138)
Net income$54,283 $— $54,283 
Weighted average units outstanding:
Basic and diluted35,224,340 35,224,340 
Net income per limited partner unit:
Basic and diluted$1.54 
Year Ended December 31, 2022
Limited Partners' Common UnitsIncentive Distribution RightsTotal
Net income attributable to the Partnership:
Distribution$66,403 $— $66,403 
Distribution in excess of net income
(2,230)— (2,230)
Net income$64,173 $— $64,173 
Weighted average units outstanding:
Basic and diluted35,217,336 35,217,336 
Net income per limited partner unit:
Basic and diluted$1.82 
Distributions Made to Limited Partner, by Distribution
The amended Partnership Agreement provides that the Partnership will distribute cash that is deemed to be an appropriate portion of the Partnership's total operating surplus. If cash distributions to the Partnership's unitholders exceed $1.2938 per common unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations:
Marginal Percentage Interest in Distributions
Total Quarterly Distribution Per UnitUnitholdersIDR Holders
Above $1.2938 up to $1.4063
85.0 %15.0 %
Above $1.4063 up to $1.6875
75.0 %25.0 %
Above $1.6875
50.0 %50.0 %
The Partnership's distribution for each quarter in the year ended December 31, 2024 did not exceed the $1.2938 per unit threshold, and, as a result, no distribution was made with respect to the Partnership's incentive distribution rights to Westlake, as the holder of the Partnership's incentive distribution rights.
Distribution Per Common Unit
Distributions per common unit for the years ended December 31, 2024, 2023 and 2022 were as follows:
Year Ended December 31,
202420232022
Distributions per common unit$1.8856 $1.8856 $1.8856 
v3.25.0.1
Related Party Transactions (Tables)
12 Months Ended
Dec. 31, 2024
Related Party Transactions [Abstract]  
Schedule of Related Party Transactions
OpCo sells a significant portion of its ethylene production to Westlake. Sales to related parties were as follows:
Year Ended December 31,
202420232022
Net sales—Westlake$950,801 $1,026,655 $1,342,910 
A significant portion of the Partnership's inputs included in cost of sales are supplied by Westlake. Charges from related parties for significant inputs included in cost of sales were as follows:
Year Ended December 31,
202420232022
Feedstock purchased from Westlake and included in cost of sales$310,856 $398,700 $764,123 
Other charges from Westlake and included in cost of sales125,702 123,039 172,761 
Charges from related parties included within selling, general and administrative expenses were as follows:
Year Ended December 31,
202420232022
Services received from Westlake and included in selling, general and
   administrative expenses
$25,654 $27,085 $26,621 
Charges from related parties for goods and services capitalized as assets were as follows:
Year Ended December 31,
202420232022
Goods and services purchased from Westlake and capitalized as assets$2,295 $3,660 $2,852 
The Partnership's receivable under the Investment Management Agreement was as follows:
December 31,
20242023
Receivable under the Investment Management Agreement$134,557 $94,444 
The Partnership's accounts receivable from Westlake were as follows:
December 31,
20242023
Accounts receivable—Westlake$31,975 $49,565 
December 31,
20242023
Accounts payable—Westlake$20,744 $15,166 
Debt payable to related parties was as follows:
December 31,
20242023
Long-term debt payable to Westlake$399,674 $399,674 
v3.25.0.1
Unit-based Compensation (Tables)
12 Months Ended
Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Schedule of Nonvested Restricted Stock Units Activity
Non-vested phantom unit awards as of December 31, 2024 and 2023 and changes during the period were as follows:
Number of
Units
Weighted
Average Fair Value
Non-vested balance at December 31, 202318,564 $21.65 
Granted14,646 22.69 
Vested(18,564)22.80 
Non-vested balance at December 31, 202414,646 $23.14 
v3.25.0.1
Fair Value Measurements (Tables)
12 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Schedule Of Carrying And Fair Values Of Long-Term Debt The carrying and fair values of the Partnership's long-term debt at December 31, 2024 and December 31, 2023 are summarized in the table below. The fair value of long-term debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate.
December 31, 2024December 31, 2023
Carrying
Value
Fair
Value
Carrying
Value
Fair
Value
Long-term debt payable to Westlake
$399,674 $411,489 $399,674 $408,110 
v3.25.0.1
Income Taxes (Tables)
12 Months Ended
Dec. 31, 2024
Income Tax Disclosure [Abstract]  
Schedule Of The Provision For (Benefit From) Income Taxes
The components of income tax of the Partnership are as follows:
Year Ended December 31,
202420232022
Current
State and local$921 $837 $891 
Deferred
State and local(86)(24)126 
Total provision$835 $813 $1,017 
Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense
The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense is as follows:
Year Ended December 31,
202420232022
Provision for federal income tax, at statutory rate$77,699 $70,442 $70,528 
State income tax provision, net of federal income tax effect835 813 1,017 
Partnership income not subject to entity-level federal income tax(77,699)(70,442)(70,528)
Total provision$835 $813 $1,017 
Schedule Of Deferred Tax Assets And Liabilities
The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows:
December 31,
20242023
Property, plant and equipment$(1,323)$(1,402)
Turnaround costs(223)(230)
Total deferred tax liabilities$(1,546)$(1,632)
Balance sheet classifications
Noncurrent deferred tax liability$(1,546)$(1,632)
Total deferred tax liabilities$(1,546)$(1,632)
v3.25.0.1
Segment Information (Tables)
12 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment
Year Ended December 31,
202420232022
Significant segment expenses and other segment items
OpCo
Raw material, energy, manufacturing and logistics costs
$605,058 $693,129 $1,094,708 
Depreciation and amortization111,899 110,203 121,074 
Total cost of sales716,957 803,332 1,215,782 
Selling, general and administrative expenses24,699 26,217 26,387 
Other segment items (1)
(3,005)(1,786)494 
Interest expense—Westlake
OpCo$1,410 $1,496 $693 
Corporate24,291 25,005 12,714 
$25,701 $26,501 $13,407 
Net income
OpCo$397,245 $363,028 $350,484 
A reconciliation of total segment net income to consolidated net income is as follows:

Year Ended December 31,
202420232022
Net income from OpCo
$397,245 $363,028 $350,484 
Corporate net loss
(28,086)(28,402)(15,655)
Net income
$369,159 $334,626 $334,829 

December 31,
20242023
Total assets
OpCo
$1,238,420 $1,269,355 
Corporate
49,536 47,487 
$1,287,956 $1,316,842 

_____________________________
(1)Other segment items includes interest expense—Westlake, other income, net and provision for income taxes.
v3.25.0.1
Description of Business and Significant Accounting Policies (Narrative) (Details)
$ in Thousands
12 Months Ended
Mar. 29, 2019
USD ($)
shares
Aug. 04, 2014
shares
Dec. 31, 2024
USD ($)
production_facility
numberOfCommonCarrierPipelines
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Threshold period past due accounts receivable reviewed     90 days    
Capitalized interest     $ 197 $ 164 $ 80
Goodwill     $ 5,814 $ 5,814  
Amortization period, minimum (in years)     5 years    
Amortization period, maximum (in years)     8 years    
Limited Liability Company | Westlake Chemical OpCo GP LLC | Westlake Chemical Partners LP          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Partnership's ownership interest (percent)   100.00%      
Affiliated Entity | Westlake Chemical OpCo LP          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Amount paid to purchase additional limited partner interest $ 201,445        
Affiliated Entity | Westlake Chemical OpCo LP          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Additional ownership interest acquired 4.50%        
Affiliated Entity | Westlake Chemical OpCo LP | Westlake Chemical Partners LP          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Partnership's ownership interest (percent) 22.80% 10.60%      
Westlake | Majority-Owned Subsidiary, Unconsolidated | Westlake Chemical OpCo LP | Westlake Chemical Corporation          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Partnership's ownership interest (percent) 77.20%        
Westlake Chemical OpCo LP          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Number of production facilities | production_facility     3    
Number of common carrier pipelines | numberOfCommonCarrierPipelines     1    
Limited Partner          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Number of units sold in public offering | shares 2,940,818 12,937,500      
v3.25.0.1
Description of Business and Significant Accounting Policies (Schedule Of Estimated Useful Lives Of Assets) (Details)
Dec. 31, 2024
Buildings and improvements  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment, useful life (in years) 40 years
Plant and equipment  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment, useful life (in years) 25 years
Ethylene pipeline  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment, useful life (in years) 35 years
Other | Minimum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment, useful life (in years) 3 years
Other | Maximum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment, useful life (in years) 15 years
v3.25.0.1
Agreements with Westlake and Related Parties (Details)
12 Months Ended
Aug. 04, 2014
USD ($)
lease
lb
$ / lb
Dec. 31, 2024
USD ($)
lb
$ / lb
Dec. 31, 2023
USD ($)
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Term of Investment Management Agreement with Related Party, Maximum   9 months  
IMA, Partnership earned amount added to market rate, basis points   five  
Receivables under Investment Management Agreements with Related Parties, Current | $   $ 134,557,000 $ 94,444,000
Westlake Chemical OpCo LP | Exchange Agreement      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Purchase commitment, fixed margin on variable pricing | $ / lb   0.006  
Exchange agreement amount of purchase agreement | lb   200,000,000  
Westlake Chemical OpCo LP | Westlake | Ethylene Sales Agreement | Investee      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Term of sales agreement 12 years    
Minimum percentage required to be purchased 95.00%    
Maximum mass required to be purchased | lb 3,800,000,000    
Number of years used to calculate average expenses 5 years    
Purchase commitment, fixed margin on variable pricing | $ / lb 0.10    
Long-term Purchase Commitment, Curtail Option Percentage 5.00%    
Long-term Purchase Commitment, Compliance Surcharge Amount | $ $ 500,000    
Purchase commitment, renewal term 12 months    
Long-term Purchase Commitment, Excess Production Percentage 95.00%    
Westlake Chemical OpCo LP | Westlake | Excess Production Option | Investee      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Purchase commitment, fixed margin on variable pricing | $ / lb 0.10    
Westlake Chemical OpCo LP | Westlake | Feedstock Supply Agreement | Investee      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Related party transactions, term of agreements 12 months    
Westlake Chemical OpCo LP | Westlake | Services And Secondment Agreement | Investee      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Related party transactions, term of agreements 12 years    
Period of default in performance that can allow a party to terminate agreement 30 days    
Westlake Chemical OpCo LP | Westlake | Site Lease Agreement | Investee      
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]      
Number of lease agreements | lease 2    
Operating lease, rental amount | $ $ 1    
Term of operating lease 50 years    
v3.25.0.1
Accounts Receivable—Third Parties (Schedule Of Accounts Receivable) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Accounts Receivable, after Allowance for Credit Loss [Abstract]    
Trade customers $ 11,757 $ 15,622
Allowance for credit losses (181) (278)
Other receivables 0 3,357
Accounts receivable, net—third parties $ 11,576 $ 18,701
v3.25.0.1
Inventories (Schedule Of Inventory) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Inventory, Net [Abstract]    
Finished products $ 3,748 $ 4,147
Feedstock, additives and chemicals 310 285
Inventories $ 4,058 $ 4,432
v3.25.0.1
Property, Plant and Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Property, Plant and Equipment, Net [Abstract]      
Building and improvements $ 18,562 $ 18,623  
Plant and equipment 1,950,479 1,936,295  
Other 118,870 112,210  
Property, plant and equipment, gross 2,087,911 2,067,128  
Less: Accumulated depreciation (1,237,929) (1,161,032)  
Property, plant and equipment, net, before construction in progress 849,982 906,096  
Construction in progress 53,606 37,747  
Property, plant and equipment, net 903,588 943,843  
Depreciation expense $ 86,253 $ 84,511 $ 94,744
v3.25.0.1
Goodwill (Narrative) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]    
Goodwill, Gross $ 5,814 $ 5,814
v3.25.0.1
Deferred Charges and Other Assets (Schedule Of Intangible and Other Assets) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Other Assets [Abstract]      
Turnaround costs, net $ 129,565 $ 133,176  
Other 8,063 7,806  
Deferred charges and other assets, net 137,628 140,982  
Deferred Charges and Other Assets [Line Items]      
Amortization $ 25,646 $ 25,692 $ 26,330
Minimum      
Deferred Charges and Other Assets [Line Items]      
Other assets amortization period 3 years    
Maximum      
Deferred Charges and Other Assets [Line Items]      
Other assets amortization period 20 years    
v3.25.0.1
Long-Term Debt (Schedule of Long-term Debt) (Details)
$ in Thousands
12 Months Ended
Jul. 12, 2022
Apr. 29, 2015
USD ($)
Dec. 31, 2024
USD ($)
Rate
Dec. 31, 2023
USD ($)
Rate
Aug. 01, 2017
USD ($)
Aug. 04, 2014
USD ($)
Related Party Transaction [Line Items]            
Weighted average interest rate on all long-term debt | Rate     6.40% 7.20%    
Limited Partner | Senior Unsecured Revolving Credit Facility            
Related Party Transaction [Line Items]            
Long-term debt payable to Westlake     $ 399,674 $ 399,674    
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility            
Related Party Transaction [Line Items]            
Long-term debt payable to Westlake     $ 22,619 22,619    
Basis spread on variable rate, percent     1.75%      
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent     0.10%      
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent     1.00%      
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake            
Related Party Transaction [Line Items]            
Maximum borrowing capacity           $ 600,000
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent 2.00%          
MLP Revolver | Westlake            
Related Party Transaction [Line Items]            
Maximum borrowing capacity   $ 300,000     $ 600,000  
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility            
Related Party Transaction [Line Items]            
Long-term debt payable to Westlake     $ 377,055 $ 377,055    
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Minimum            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent     1.75%      
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Maximum            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent     2.75%      
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent     0.10%      
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent 1.00%   1.00%      
MLP Revolver | Limited Partner | Westlake | Line of Credit            
Related Party Transaction [Line Items]            
Maximum consolidated leverage ratio during one year following acquisitions   5.50        
Leverage capital ratio required during other periods   4.50        
MLP Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit            
Related Party Transaction [Line Items]            
Basis spread on variable rate, percent 2.00%          
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Narrative) (Details) - $ / shares
12 Months Ended
Jan. 27, 2025
Dec. 31, 2024
Above $1.2938 up to $1.4063 | Minimum    
Distributions [Line Items]    
Quarterly distribution per unit threshold (usd per share)   $ 1.2938
Common and Subordinated units | Cash Distribution    
Distributions [Line Items]    
Minimum quarterly distribution per unit (usd per share)   $ 1.2938
Common and Subordinated units | Cash Distribution | Subsequent Event    
Distributions [Line Items]    
Distribution declared per unit (usd per share) $ 0.4714  
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Limited partners' interest in net income subsequent to IPO $ 62,392 $ 54,283 $ 64,173
Limited partners' distribution declared on common units 66,437 66,421 66,403
Distribution in excess of net income (4,045) (12,138) (2,230)
Common units      
Limited partners' interest in net income subsequent to IPO 62,392 54,283 64,173
Limited partners' distribution declared on common units 66,437 66,421 66,403
Distribution in excess of net income $ (4,045) $ (12,138) $ (2,230)
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Basic and Diluted Income Per Limited Partner Unit) (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Limited Partners' Capital Account [Line Items]      
Distribution $ 66,437 $ 66,421 $ 66,403
Distribution in excess of net income (4,045) (12,138) (2,230)
Limited partners' interest in net income subsequent to IPO $ 62,392 $ 54,283 $ 64,173
Weighted average limited partner units outstanding (basic and diluted) 35,232,870 35,224,340 35,217,336
IDR Holders      
Limited Partners' Capital Account [Line Items]      
Distributions declared with respect to the incentive distribution rights $ 0 $ 0 $ 0
Distribution in excess of net income 0 0 0
Limited partners' interest in net income subsequent to IPO 0 0 0
Common units      
Limited Partners' Capital Account [Line Items]      
Distribution 66,437 66,421 66,403
Distribution in excess of net income (4,045) (12,138) (2,230)
Limited partners' interest in net income subsequent to IPO $ 62,392 $ 54,283 $ 64,173
Weighted average limited partner units outstanding (basic and diluted) 35,232,870 35,224,340 35,217,336
Common units $ 1.77 $ 1.54 $ 1.82
Diluted units $ 1.77 $ 1.54 $ 1.82
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Incentive Distribution Rights) (Details)
12 Months Ended
Dec. 31, 2024
$ / shares
Above $1.2938 up to $1.4063 | Unitholders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 85.00%
Above $1.2938 up to $1.4063 | IDR Holders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 15.00%
Above $1.4063 up to $1.6875 | Unitholders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 75.00%
Above $1.4063 up to $1.6875 | IDR Holders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 25.00%
Above $1.6875 | Unitholders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 50.00%
Above $1.6875 | IDR Holders  
Distribution Made to Limited Partner [Line Items]  
Marginal Percentage Interest in Distributions 50.00%
Minimum | Above $1.2938 up to $1.4063  
Distribution Made to Limited Partner [Line Items]  
Quarterly distribution per unit threshold (usd per share) $ 1.2938
Minimum | Above $1.4063 up to $1.6875  
Distribution Made to Limited Partner [Line Items]  
Quarterly distribution per unit threshold (usd per share) 1.4063
Minimum | Above $1.6875  
Distribution Made to Limited Partner [Line Items]  
Quarterly distribution per unit threshold (usd per share) 1.6875
Maximum | Above $1.2938 up to $1.4063  
Distribution Made to Limited Partner [Line Items]  
Quarterly distribution per unit threshold (usd per share) 1.4063
Maximum | Above $1.4063 up to $1.6875  
Distribution Made to Limited Partner [Line Items]  
Quarterly distribution per unit threshold (usd per share) $ 1.6875
v3.25.0.1
Distributions and Net Income Per Limited Partner Unit (Distributions per common unit) (Details) - $ / shares
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Distributions per common unit [Abstract]      
Distributions per common unit $ 1.8856 $ 1.8856 $ 1.8856
v3.25.0.1
Partners' Equity (Incentive Distribution Rights) (Details) - USD ($)
$ / shares in Units, $ in Thousands
Mar. 29, 2019
Oct. 04, 2018
Aug. 04, 2014
Class of Stock [Line Items]      
Partners units, maximum aggregate offering amount, ATM   $ 50,000  
Affiliated Entity      
Class of Stock [Line Items]      
Partners' capital account, units, sold to related party 1,401,869    
Limited Partner      
Class of Stock [Line Items]      
Number of units sold in public offering 2,940,818   12,937,500
Units sold in secondary offering price per unit $ 21.40    
v3.25.0.1
Related Party Transactions (Sales to Related Parties) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Buyer deficiency fee     $ 23,835
Affiliated Entity      
Related Party Transaction [Line Items]      
Net sales $ 950,801 $ 1,026,655 $ 1,342,910
v3.25.0.1
Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity - Westlake - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Feedstock Purchased      
Related Party Transaction [Line Items]      
Related Parties Amount in Cost of Sales $ 310,856 $ 398,700 $ 764,123
Other Service Charges      
Related Party Transaction [Line Items]      
Related Parties Amount in Cost of Sales $ 125,702 $ 123,039 $ 172,761
v3.25.0.1
Related Party Transactions (Services from Related Parties Included in SG&A Expenses) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Services received from Westlake and included in selling, general and administrative expenses $ 28,495 $ 29,751 $ 29,678
Affiliated Entity | Westlake      
Related Party Transaction [Line Items]      
Services received from Westlake and included in selling, general and administrative expenses $ 25,654 $ 27,085 $ 26,621
v3.25.0.1
Related Party Transactions (Goods and Services from Related Parties that have been Capitalized) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Affiliated Entity | Westlake      
Related Party Transaction [Line Items]      
Goods and services purchased from Westlake and capitalized as assets $ 2,295 $ 3,660 $ 2,852
v3.25.0.1
Related Party Transactions (Receivable under the Investment Management Agreement) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
IMA, Partnership earned amount added to market rate, basis points five    
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake") $ 134,557 $ 94,444  
Westlake | Affiliated Entity      
Related Party Transaction [Line Items]      
Interest earned related to the IMA 5,364 4,424 $ 1,875
Westlake | Affiliated Entity | Accounts Receivable      
Related Party Transaction [Line Items]      
Accrued interest included in receivable under IMA $ 1,385 $ 1,272  
v3.25.0.1
Related Party Transactions (Accounts Receivable from and Accounts Payable to Related Parties) (Details) - Affiliated Entity - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Related Party Transaction [Line Items]    
Accounts receivable, net—Westlake $ 31,975 $ 49,565
Accounts payable—third parties $ 20,744 $ 15,166
v3.25.0.1
Related Party Transactions (Debt Payable to Related Parties) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Interest expense—Westlake $ 25,701 $ 26,501 $ 13,407
Affiliated Entity      
Related Party Transaction [Line Items]      
Accrued interest on related party debt 5,848 6,675  
Affiliated Entity | Westlake      
Related Party Transaction [Line Items]      
Interest expense—Westlake 25,701 26,501 $ 13,407
Long-term debt payable to Westlake 399,674 399,674  
Affiliated Entity | Westlake | Accrued Liabilities      
Related Party Transaction [Line Items]      
Accrued interest on related party debt $ 5,848 $ 6,675  
v3.25.0.1
Related Party Transactions (Related Party Leases) (Details)
12 Months Ended
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Aug. 04, 2014
Westlake | Affiliated Entity        
Related Party Transaction [Line Items]        
Operating lease expense $ 1,843,000 $ 1,869,000 $ 2,624,000  
Westlake Chemical OpCo LP | Westlake | Investee | Site Lease Agreement        
Related Party Transaction [Line Items]        
Site lease agreement, number 2      
Term of operating lease       50 years
Site lease expense $ 1      
v3.25.0.1
Related Party Transactions Related Party Transactions (Major Customer and Credit Risk) (Details)
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Revenue Benchmark | Westlake | Customer Concentration Risk | Affiliated Entity      
Related Party Transaction [Line Items]      
Concentration Risk, Percentage 83.70% 86.20% 84.30%
v3.25.0.1
Related Party Transactions (General) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Income taxes paid $ 831 $ 827 $ 683
Affiliated Entity | Reimbursement to Parent for State Tax | Westlake      
Related Party Transaction [Line Items]      
Income taxes paid $ 351 $ 347 $ 243
v3.25.0.1
Unit-based Compensation (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Jul. 15, 2014
Weighted Average Fair Value        
Unrecognized compensation weighted average remaining term 7 months 6 days      
Phantom Share Units (PSUs)        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair value of phantom units vested $ 423 $ 278 $ 284  
Number of Units        
Beginning balance 18,564      
Granted (in shares) 14,646      
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period 18,564      
Ending balance 14,646 18,564    
Weighted Average Fair Value        
Weighted Average Fair Value, beginning balance (usd per share) $ 21.65      
Weighted Average Grant Date Fair Value, Granted (usd per share) 22.69      
Weighted Average Grant Date Fair Value, Vested (usd per share) 22.80      
Weighted Average Fair Value, ending balance (usd per share) $ 23.14 $ 21.65    
Westlake Chemical Partners LP Long-Term Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of units authorized       1,270,000
Weighted Average Fair Value        
Total units available for grant 1,192,349      
Unrecognized compensation cost $ 201      
Westlake Chemical Partners LP Long-Term Incentive Plan | Selling, General and Administrative Expenses        
Weighted Average Fair Value        
Total compensation cost $ 373 $ 349 $ 282  
v3.25.0.1
Fair Value Measurements (Schedule Of Carrying And Fair Values Of Long-Term Debt) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt payable to Westlake, fair value $ 411,489 $ 408,110
Westlake | Affiliated Entity    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt payable to Westlake $ 399,674 $ 399,674
v3.25.0.1
Income Taxes (Schedule Of The Provision For (Benefit From) Income Taxes) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Current      
State and local $ 921 $ 837 $ 891
Deferred      
State and local (86) (24) 126
Total provision $ 835 $ 813 $ 1,017
v3.25.0.1
Income Taxes (Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Tax Disclosure [Abstract]      
Provision for federal income tax, at statutory rate $ 77,699 $ 70,442 $ 70,528
State income tax provision, net of federal income tax effect 835 813 1,017
Partnership income not subject to entity-level federal income tax (77,699) (70,442) (70,528)
Total provision $ 835 $ 813 $ 1,017
v3.25.0.1
Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Income Tax Disclosure [Abstract]    
Property, plant and equipment $ (1,323) $ (1,402)
Turnaround costs (223) (230)
Total deferred tax liabilities (1,546) (1,632)
Noncurrent deferred tax liability $ (1,546) $ (1,632)
v3.25.0.1
Supplemental Information (Accrued Liabilities and Other Income, Net) (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Accrued Liabilities    
Accrued and other liabilities $ 16,920 $ 24,980
Affiliated Entity    
Accrued Liabilities    
Accrued interest $ 5,848 $ 6,675
v3.25.0.1
Supplemental Information (Insurance Recoveries) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2024
USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Insurance Recoveries $ 6,222
v3.25.0.1
Supplemental Information (Cash Flow Information) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Capital expenditures incurred but not yet paid $ 9,863 $ 7,809 $ 6,372
Interest paid 26,528 24,537 10,850
Income taxes paid 831 827 683
Right-of-use assets obtained in exchange for operating lease obligations 758 5,079 0
Reimbursement to Parent for State Tax | Westlake | Affiliated Entity      
Related Party Transaction [Line Items]      
Income taxes paid 351 347 243
State and Local Jurisdiction      
Related Party Transaction [Line Items]      
Income taxes paid $ 480 $ 480 $ 440
v3.25.0.1
Segment Information (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2024
USD ($)
Segment
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Segment Reporting Information [Line Items]      
Number of operating segments | Segment 1    
Depreciation and amortization $ 111,899 $ 110,203 $ 121,074
Cost of sales 716,957 803,332 1,215,782
Selling, general and administrative expenses 28,495 29,751 29,678
Interest expense—Westlake 25,701 26,501 13,407
Net income 369,159 334,626 334,829
Assets 1,287,956 1,316,842  
Operating Segments | OpCo      
Segment Reporting Information [Line Items]      
Raw material, energy, manufacturing and logistics costs 605,058 693,129 1,094,708
Depreciation and amortization 111,899 110,203 121,074
Cost of sales 716,957 803,332 1,215,782
Selling, general and administrative expenses 24,699 26,217 26,387
Other segment items (3,005) (1,786) 494
Interest expense—Westlake 1,410 1,496 693
Net income 397,245 363,028 350,484
Assets 1,238,420 1,269,355  
Corporate      
Segment Reporting Information [Line Items]      
Interest expense—Westlake 24,291 25,005 12,714
Net income (28,086) (28,402) (15,655)
Assets 49,536 47,487  
Affiliated Entity      
Segment Reporting Information [Line Items]      
Net co-products, ethylene and other sales—third parties $ 950,801 $ 1,026,655 $ 1,342,910