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                                                                     EXHIBIT 3a1

                          CERTIFICATE OF INCORPORATION

                                       OF

                                HI MERGER, INC.



                 FIRST:  The name of the Company is HI Merger, Inc.
(hereinafter the "Company").

                 SECOND:  The address of the registered office of the Company
in the State of Delaware is Corporation Trust Center, 1209 Orange Street, City
of Wilmington, County of New Castle, Zip Code 19801, and the name of the
registered agent of the Company at such address is The Corporation Trust
Company.

                 THIRD:  The purpose of the Company 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 as set forth in Title 8 of the
Delaware Code (the "DGCL").

                 FOURTH:  The total number of shares of all classes of stock
which the Company shall have authority to issue is 1,000 shares of common
stock, par value $0.01 per share ("Common Stock").  Except as otherwise
provided by law, the shares of Common Stock may be issued for such
consideration and for such corporate purposes as the Board of Directors of the
Company (the "Board of Directors") may from time to time determine.

                 In the event of voluntary or involuntary liquidation,
distribution or sale of assets, dissolution or winding-up of the Company, the
holders of the Common Stock shall be entitled to receive all the assets of the
Company, tangible and intangible, of whatever kind available for distribution
to stockholders, ratably in proportion to the number of shares of Common Stock
held by each.

                 Each holder of Common Stock shall have one vote in respect of
each share of Common Stock held by such holder on each matter voted upon by the
stockholders.

                 FIFTH:  The name and address of the incorporator is

                                  Timothy S. Taylor
                                  3000 One Shell Plaza
                                  910 Louisiana
                                  Houston, Texas  77002.





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                 SIXTH:  The powers of the incorporator are to terminate upon
the filing of the Certificate of Incorporation with the office of the Secretary
of State of the State of Delaware.  The person whose name and mailing address
are set out immediately below is to serve as the sole director of the Company
until the first annual meeting of stockholders or until his successor is
elected and qualify:

<TABLE>
<CAPTION>
                  Name                              Address
                  ----                              -------
                  <S>                               <C>
                  Stephen W. Naeve                  1111 Louisiana Street
                                                    Houston, Texas 77002
</TABLE>

                 SEVENTH:  The following provisions are inserted for the
management of the business and the conduct of the affairs of the Company, and
for further definition, limitation and regulation of the powers of the Company
and of its directors and stockholders:

                 (a)      The business and affairs of the Company shall be
         managed by or under the direction of the Board of Directors except as
         otherwise provided by law.

                 (b)      The Board of Directors shall have concurrent power
         with the stockholders to make, alter, amend, change, add to or repeal
         the Bylaws of the Company (the "Bylaws").

                 (c)      The number of directors of the Company shall be as
         from time to time fixed by, or in the manner provided in, the Bylaws.
         Election of directors need not be by written ballot unless the Bylaws
         so provide.

                 (d)      In addition to the powers and authority hereinbefore
         or by statute expressly conferred upon them, the directors are hereby
         authorized to exercise all such powers and do all such acts and things
         as may be exercised or done by the Company, subject, nevertheless, to
         the provisions of the statutes of Delaware, this Certificate of
         Incorporation and any Bylaws adopted by the stockholders; provided,
         however, that no Bylaws thereafter adopted by the stockholders shall
         invalidate any prior act of the directors which would have been valid
         if such Bylaws had not been adopted.

                 EIGHTH:  Meetings of the stockholders may be held within or
without the State of Delaware, as the Bylaws may provide.  The books of the
Company may be kept (subject to any provision contained in the statutes)
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 Bylaws.

                 NINTH:  A director of the Company shall not be personally
liable to the Company or its stockholders for monetary damages for breach of
fiduciary duty as a director, except for liability (a) for any breach of the
director's duty of loyalty to the Company or its stockholder or stockholders,
(b) for acts or omissions not in good faith or which involve intentional
misconduct





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or a knowing violation of law, (c) under Section 174 of the DGCL, as the same
exists or hereafter may be amended, or (d) for any transaction from which the
director derived an improper personal benefit.  If the DGCL is amended after
the date of filing of this Certificate of Incorporation to authorize the
further elimination or limitation of the liability of directors, then the
liability of a director of the Company, in addition to the limitation on
personal liability provided herein, shall be limited to the fullest extent
permitted by the amended DGCL.  Any repeal or modification of this Article
NINTH by the stockholders of the Company shall be prospective only, and shall
not adversely affect any limitation on the personal liability of a director of
the Company existing at the time of such repeal or modification.

                 TENTH:  The Company reserves the right to amend, alter, change
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.  All
rights herein conferred are granted subject to this reservation.

                 I, the undersigned, being the incorporator hereinbefore named,
for the purpose of forming a corporation under the laws of the State of
Delaware, do make, file and record this Certificate of Incorporation, do
certify that the facts herein stated are true and accordingly, have hereunto
set my hand this 9th day of August, 1996.



                                              /s/ TIMOTHY S. TAYLOR
                                              -------------------------
                                              Timothy S. Taylor





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