UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

(Address of principal executive offices, including zip code)

(Registrant's telephone number, including area code)

The accompanying notes are an integral part of these consolidated financial statements.

The accompanying notes are an integral part of these consolidated financial statements.

Distribution Per Common Unit

Distributions per common unit for the three and nine months ended March 31,September 30, 2019 and 2018 were as follows:

On October 4, 2018, the Partnership and Westlake GP, 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. No common units had been issued under this program as of March 31,September 30, 2019.

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. ProceedsNet proceeds to the Partnership from the sale of the units were approximately $62,934.$62,661. 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.

The Partnership and OpCo regularly enter into related party transactions with Westlake. See below for a description of transactions with related parties.

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 each charges Westlake a fee.

Sales to related parties were as follows:

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.

Charges from related parties in cost of sales were as follows:

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:

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.

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 a term 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 $34$716 and $496 was included in the receivable under the Investment Management Agreement balance at March 31,September 30, 2019 and December 31, 2018, respectively. Total interest earned related to the Investment Management Agreement was $818$716 and $540$703 for the three months ended March 31,September 30, 2019 and 2018, respectively, and $2,688 and $1,861 for the nine months ended September 30, 2019 and 2018, respectively.

The Partnership's receivable under the Investment Management Agreement was as follows:

Accounts Receivables

The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake under the Ethylene Sales Agreement.

The Partnership's accounts receivable from Westlake were as follows:

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 related party accounts payable balances were as follows:

Related Party Leases

OpCo is obligated to Westlake under various rail cars leases. Operating lease rentals paid to Westlake for such leases were $514$597 and $318$687 for the three months ended March 31,September 30, 2019 and 2018, respectively, and $1,673 and $1,705 for nine months ended September 30, 2019 and 2018, respectively, and reflected in other charges from Westlake that are included in cost of sales.

OpCo has two2 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.

Debt Payable to Related Parties

See Note 9 for a description of related party debt payable balances. Interest on related party debt payable balances for the three months ended March 31,September 30, 2019 and 2018 was $5,900$4,411 and $4,866,$5,639, respectively, and for the nine months ended September 30, 2019 and 2018 was $15,436 and $16,052, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. Interest capitalized as a component of property, plant and equipment on related party debt was zero$0 and $15$63 for the three months ended March 31,September 30, 2019 and 2018, respectively, and for the nine months ended September 30, 2019 and 2018 was 0 and $109, respectively. At March 31,September 30, 2019 and December 31, 2018, accrued interest on related party debt was $5,852$4,411 and $5,448, respectively, and is reflected as a component of accrued liabilities in the consolidated balance sheets.

Debt payable to related parties was as follows:

Major Customer and Concentration of Credit Risk

During the three months ended March 31,September 30, 2019 and 2018, Westlake accounted for approximately 86.7% and 86.2%, respectively, of the Partnership's net sales. During the nine months ended September 30, 2019 and 2018, Westlake accounted for approximately 85.9% and 82.7%84.4%, respectively, of the Partnership's net sales.

Other

See Note 7 above for an additional related party transaction.

Long-term debt payable to Westlake consists of the following:

On March 29, 2019, the Partnership borrowed $123,512$123,511 under the MLP Revolver to partially fund the purchase of the additional 4.5% interest in OpCo.

The weighted average interest rate on all long-term debt was 4.8%4.3% and 4.4%, respectively, at March 31,September 30, 2019 and December 31, 2018.

The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include 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 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 March 31,September 30, 2019 and December 31, 2018 are summarized in the table below. The Partnership's long-term debt includes the OpCo Revolver and the MLP Revolver at March 31,September 30, 2019. The fair value of 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.

Accrued Liabilities

Accrued liabilities were $20,433$22,964 and $16,250 at March 31,September 30, 2019 and December 31, 2018, respectively. Accrued interest,Commodity derivative related accrual, accrued maintenance, capital expenditurestaxes and accrued taxes,interest, which are components of accrued liabilities, were $5,852, $3,850, $2,827$7,160, $4,918, and $2,931,$4,411, respectively, at March 31,September 30, 2019, and $5,448, $2,688, $2,818$315, $1,564, and $1,564,$5,448, respectively, at December 31, 2018. No other component of accrued liabilities was more than five percent of total current liabilities.

Non-cash Investing Activity

The change in capital expenditure accrual resulted in an increase in additions to property, plant and equipment by $52$1,213 for the threenine months ended March 31,September 30, 2019. The change in capital expenditure accrual resulted in a decrease in additions to property, plant and equipment by $117$1,380 for the threenine months ended March 31,September 30, 2018.

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 ("RCRA"), 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. Westlake will indemnify the Partnership for liabilities that occurred or existed prior to August 4, 2014.

This Management's Discussion and Analysis of Financial Condition and Results of Operations section should be read in conjunction with the accompanying consolidated financial statements and the notes thereto and the consolidated financial statements and notes thereto included in Westlake Chemical Partners LP's annual report on Form 10-K for the fiscal year ended December 31, 2018 (the "2018 Form 10-K"), as filed with the SEC on March 1, 2019. Unless otherwise indicated, references in this report to "we," "our," "us" or like terms, refer to Westlake Chemical Partners LP (the "Partnership"), Westlake Chemical OpCo LP ("OpCo") and Westlake Chemical OpCo GP LLC ("OpCo GP"). References to "Westlake" refer to Westlake Chemical Corporation and its consolidated subsidiaries other than the Partnership, OpCo GP and OpCo. The following discussion contains forward-looking statements. Please read "Forward-Looking Statements" for a discussion of limitations inherent in such statements.

We are a Delaware limited partnership formed by Westlake to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, we closed our initial public offering (the "IPO") of 12,937,500 common units. In connection with the IPO, we acquired a 10.6% interest in OpCo and a 100% interest in OpCo GP, which is the general partner of OpCo. On April 29, 2015, we purchased an additional 2.7% newly-issued limited partner interest in OpCo, resulting in an aggregate 13.3% limited partner interest in OpCo, effective April 1, 2015. The 12,686,115 subordinated units of the Partnership, all of which were previously owned by Westlake, were converted into common units of the Partnership on August 30, 2017. On September 29, 2017, we completed a secondary public offering of 5,175,000 common units and purchased an additional 5.0% newly-issued limited partner interest in OpCo, resulting in an aggregate 18.3% limited partner interest in OpCo, effective July 1, 2017. On March 29, 2019, we completed a private placement of 2,940,818 common units and used the net proceeds to purchase an additional 4.5% interest in OpCo, effective January 1, 2019, resulting in us owning an aggregate 22.8% limited partner interest in OpCo.

Currently, our sole revenue generating asset is our 22.8% limited partner interest in OpCo, a limited partnership formed by Westlake and us in anticipation of the IPO to own and operate an ethylene production business. We control OpCo through our ownership of its general partner. Westlake retains the remaining 77.2% limited partner interest in OpCo as well as a significant interest in us through its ownership of our general partner, 40.1% of our limited partner units (consisting of 14,122,230 common units) and our incentive distribution rights. OpCo's assets include (1) two ethylene production facilities ("Petro 1" and "Petro 2" and, collectively, "Lake Charles Olefins") at Westlake's Lake Charles, Louisiana site; (2) one ethylene production facility ("Calvert City Olefins") at Westlake's Calvert City, Kentucky site; and (3) a 200-mile common carrier ethylene pipeline (the "Longview Pipeline") that runs from Mont Belvieu, Texas to Westlake's Longview, Texas facility.

The body of accounting principles generally accepted in the United States is commonly referred to as "GAAP." For this purpose, a non-GAAP financial measure is generally defined by the Securities and Exchange Commission ("SEC") as a numerical measure of a registrant's historical or future financial performance, financial position or cash flows that (1) excludes amounts, or is subject to adjustments that have the effect of excluding amounts, that are included in the most directly comparable measure calculated and presented in accordance with GAAP in the statement of income, balance sheet or statement of cash flows (or equivalent statements) of the registrant; or (2) includes amounts, or is subject to adjustments that have the effect of including amounts, that are excluded from the most directly comparable measure so calculated and presented. The non-GAAP financial measures described in this Form 10-Q are not substitutes for the GAAP measures of earnings and cash flows. We use each of MLP distributable cash flow and EBITDA to analyze our performance. We define distributable cash flow as net income plus depreciation, amortization and disposition of property, plant and equipment, less contributions for turnaround reserves, maintenance capital expenditures and mark-to-market adjustment on derivative contracts. We define MLP distributable cash flow as distributable cash flow less distributable cash flow attributable to Westlake's noncontrolling interest in OpCo and distributions attributable to the incentive distribution rights holder. MLP distributable cash flow does not reflect changes in working capital balances. We define EBITDA as net income before interest expense, income taxes, depreciation and amortization. The non-GAAP financial measures described in this Form 10-Q are not substitutes for the GAAP measures of earnings and cash flows. We use each of MLP distributable cash flow and EBITDA to analyze our performance. MLP distributable cash flow and EBITDA are non-GAAP supplemental financial measures that management and external users of our consolidated financial statements, such as industry analysts, investors, lenders and rating agencies, may use to assess:

The following table presents reconciliations of MLP distributable cash flow to net income and net cash provided by operating activities, the most directly comparable GAAP financial measures, for each of the periods indicated.