EXHIBIT 3.31

                          CERTIFICATE OF INCORPORATION

                                       OF

                      WESTLAKE CHEMICAL MANUFACTURING, INC.

                                   ARTICLE I

         The name of the corporation is WESTLAKE CHEMICAL MANUFACTURING, INC.

                                   ARTICLE II

         The registered agent of the corporation is The Corporation Trust
Company. The address of such registered office in the State of Delaware is The
Corporation Trust Center, 1209 Orange Street in the City of Wilmington, County
of New Castle, Delaware 19801.

                                  ARTICLE III

         The nature of the business or purposes to be conducted or promoted by
the corporation is to engage in any lawful act or activity for which
corporations may be organized under the General Corporation Law of the State of
Delaware.

                                   ARTICLE IV

         The total number of shares of stock which the corporation shall have
authority to issue is one thousand (1,000) shares of common stock at a par value
of One and No/100 Dollars ($1.00) each.

                                   ARTICLE V

         The name and mailing address of the incorporator are as follows:

         Stephen LeSatz, Jr.        2801 Post Oak Boulevard, Suite 600
                                    Houston, Texas  77056

                                   ARTICLE VI

         The name and mailing address of the person who is to serve as the
director of the corporation until the first annual meeting of the stockholders
of the corporation or until a successor is elected and qualified is as follows:

         Stephen LeSatz, Jr.        2801 Post Oak Boulevard, Suite 600
                                    Houston, Texas  77056



                                   ARTICLE VII

         In furtherance and not in limitation of the powers conferred by
statute, the Board of Directors is expressly authorized to adopt, amend or
repeal the by-laws of the corporation.

                                  ARTICLE VIII

         Elections of directors need not be by written ballot unless the by-laws
of the corporation shall so provide.

         All action required to be taken or which may be taken at any annual or
special meeting of stockholders of the corporation may be taken without a
meeting, and the power of stockholders to consent in writing, without a meeting,
to the taking of any action is specifically granted.

         Meetings of stockholders may be held within or without the State of
Delaware, as the by-laws may provide. The books of the corporation may be kept
(subject to any provision contained in the statutes of the State of Delaware)
outside the State of Delaware at such place or places as may be designated from
time to time by the Board of Directors or in the by-laws of the corporation.

                                   ARTICLE IX

         A director of this corporation shall not be liable to the corporation
or its stockholders for monetary damages for breach of fiduciary duty as a
director, except to the extent such exemption from liability or limitation
thereof is not permitted under the Delaware General Corporation Law as the same
exists or may hereafter be amended. Any repeal or modification of the foregoing
sentence shall not adversely affect any right or protection of a director of the
corporation existing hereunder with respect to any act or omission occurring
prior to such repeal or modification.

                                   ARTICLE X

         The corporation reserves the right to amend, alter or repeal any
provision contained in this Certificate of Incorporation, in the manner now or
hereafter prescribed by the laws of the State of Delaware, and to add additional
provisions authorized by such laws as are then in force. All rights conferred on
the directors or stockholders of the corporation herein or in any amendment
hereof are granted subject to this reservation.

                                   ARTICLE XI

         The corporation shall indemnify its directors and officers, and may
indemnify its employees and agents, to the extent permitted by the General
Corporation Law of the State of Delaware.

         I, THE UNDERSIGNED, being the incorporator hereinabove named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, do make this Certificate, hereby declaring and certifying
that this is my act and deed and the facts

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herein stated are true, and accordingly have hereunto set my hand this 13th day
of December 2000.

                                                    /s/ Stephen LeSatz, Jr.
                                                    ----------------------------
                                                        Stephen LeSatz, Jr.

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