Long-Term Debt

Long-term debt consists of the following:



	December 31,
	2017		2016
August 2013 Promissory Notes (variable interest rate of prime plus 1.5%, original scheduled maturity of August 1, 2023)	$	—	$	31,775
OpCo Revolver (variable interest rate of London Interbank Offered Rate ("LIBOR") plus 3.0%, original scheduled maturity of August 4, 2019)	220,416		427,513
MLP Revolver (variable interest rate of LIBOR plus 2.0%, original scheduled maturity of April 29, 2021)	253,544		135,341
Long-term debt payable to Westlake	$	473,960	$	594,629

In 2013, the August 2013 Promissory Notes were issued for capital expenditures incurred by Westlake. In connection with the IPO, OpCo assumed the August 2013 Promissory Notes and used proceeds from the IPO to repay a portion of the balance it assumed. On September 29, 2017, the Partnership repaid the remaining balance of the August 2013 Promissory Notes.

In connection with the IPO on August 4, 2014, OpCo entered into a $600,000 senior unsecured revolving credit facility agreement with Westlake (the "OpCo Revolver"). The OpCo Revolver accrues interest quarterly at a rate of LIBOR plus 3.0%, which may be paid-in-kind as an addition to the principal at OpCo's option. Proceeds drawn under the OpCo Revolver during 2016 were used to fund capital expenditures at OpCo's ethylene plants and to fund the working capital requirements.

On April 29, 2015, the Partnership entered into a $300,000 revolving credit facility agreement with Westlake (the "MLP Revolver") to fund the Partnership's purchase of an additional 2.7% newly-issued, limited partner interest in OpCo for $135,341. On August 1, 2017, the Partnership entered into an amendment to the MLP Revolver agreement, extending the maturity date from April 29, 2018 to April 29, 2021. On December 5, 2017, the Partnership entered into an amendment to the MLP Revolver credit agreement, increasing borrowing capacity from $300,000 to $600,000. Borrowings under the MLP Revolver bear interest at LIBOR plus a spread ranging from 2.0% to 3.0% (depending on the Partnership's consolidated leverage ratio), payable quarterly. 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. During August 2015, the Partnership entered into an interest rate contract with Westlake to fix the LIBOR component of the interest rate for a portion of the MLP Revolver balance. The interest rate contract terminates on the earlier of the MLP Revolver maturity date or in August 2018.

As of December 31, 2017, 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 3.76% and 3.72% at December 31, 2017 and 2016, respectively.

As of December 31, 2017, the Partnership had no scheduled maturities of long-term debt until 2019. The OpCo Revolver is scheduled to mature on August 4, 2019 and the MLP Revolver is scheduled to mature on April 29, 2021.