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                                                                   EXHIBIT 99.12

                                    GUARANTY

                  For value received, the sufficiency of which is hereby
acknowledged, WEDGE Group Incorporated, a Delaware corporation ("Guarantor"),
does hereby guaranty, unconditionally (except as expressly set forth below) and
absolutely, the full and timely payment and performance of all of the
obligations of Farinvest, Ltd. ("WEDGE") to Pitts-Des Moines, Inc. ("PDM") under
Article I of the Standby Funding Agreement among Chicago Bridge & Iron Company,
N.V. ("CB&I"), PDM and Farinvest dated as of the date hereof (the "Agreement")
and waives any and all defenses in connection therewith (other than failure by
PDM to perform its obligations thereunder). PDM may only call upon this Guaranty
by delivery of a notice to Guarantor at the address and in the manner set forth
below stating that WEDGE has not performed its obligations under the terms of
Article I of the Agreement and that three or more days have elapsed since
performance was due. Within one (i) business day following the delivery of such
notice, Guarantor shall pay to PDM the Funded Amount by wire transfer of
immediately available funds to such account as PDM shall specify in such notice.

                  Guarantor consents and agrees that: WEDGE may be granted
indulgences or forbearances generally, including, but not limited to, extensions
of time for payment or may be released; that any of the provisions of the
Agreement may be modified or waived; that any party liable for payment on the
Agreement (including, but not limited to WEDGE or Guarantor) may be granted
indulgences, forbearances or may be released; that neither the insolvency,
bankruptcy, reorganization, arrangement, readjustment, composition, dissolution
nor liquidation of WEDGE or Guarantor shall affect the obligations hereunder of
Guarantor; that no claim need be asserted against the trustee in bankruptcy or
receiver of WEDGE; and that the obligations of Guarantor hereunder shall remain
in full force and effect and shall not be released, discharged or in any way
modified or otherwise affected, notwithstanding any indulgence, forbearance,
change, compromise, surrender, extension, renewal, acceleration, modification,
waiver, release or other action, all of which may be effected without notice to
or further assent by Guarantor, and without in any way waiving or otherwise
affecting any obligations of Guarantor hereunder or any rights that PDM may have
hereunder or by virtue of any law.

                  Except as expressly set forth above, Guarantor waives notice
of acceptance of this Guaranty, presentment, demand, notice of dishonor,
protest, notice of protest, nonpayment or default to WEDGE or Guarantor, and all
other notices to which WEDGE or Guarantor may otherwise be entitled, and all
suretyship and any and all other defenses to which Guarantor may otherwise be
entitled including, without limitation, the legality, binding effect or
enforceability of the Agreement in whole or in part. Guarantor further waives
all exemptions to which Guarantor may now or hereafter be entitled under any
law.

                  This is a guaranty of payment and performance and not of
collection. Except as expressly set forth above, the liability of Guarantor
under this Guaranty shall be direct and immediate and not conditional or
contingent upon the pursuit of any remedies against WEDGE or any other person or
entity. Guarantor waives any claim to require that an action be brought against
WEDGE or any other person or entity prior to action against Guarantor hereunder.
If the



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obligations under the Agreement are partially paid or performed through the
election of PDM to pursue any of the remedies mentioned therein or if any
obligation is otherwise partially paid or performed, Guarantor shall remain
unconditionally (except as expressly set forth above) and absolutely liable for
the entire unpaid or unperformed amount of any such obligations.

                  The obligations of Guarantor under this Guaranty shall remain
in full force and effect without regard to, and shall not be released,
discharged or in any way modified or otherwise affected by, any circumstance or
condition (whether or not Guarantor shall have any knowledge or notice thereof),
including, but not limited to, any bankruptcy, insolvency, reorganization,
arrangement, readjustment, composition, dissolution, liquidation or similar
proceeding with respect to WEDGE or WEDGE's properties or WEDGE's creditors, or
any action taken by any trustee or receiver or by any court in any such
proceeding. Guarantor agrees to pay PDM's reasonable attorney fees incurred in
enforcing its rights under this Guaranty.

                  In the event that any one or more provisions contained herein
shall for any reason be held to be invalid, illegal or unenforceable in any
respect, such invalidity, illegality or unenforceability shall not affect any
other provision hereof and this Guaranty shall be construed as if such invalid,
illegal or unenforceable provision had never been contained herein.

                  THIS GUARANTY SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED
IN ACCORDANCE WITH THE SUBSTANTIVE LAWS OF THE COMMONWEALTH OF PENNSYLVANIA.
GUARANTOR HEREBY IRREVOCABLY AND UNCONDITIONALLY SUBMITS, FOR ITSELF AND ITS
PROPERTY, TO THE NONEXCLUSIVE JURISDICTION OF ANY PENNSYLVANIA STATE OR FEDERAL
COURT OF THE UNITED STATES OF AMERICA SITTING IN PITTSBURGH, PENNSYLVANIA, AND
ANY APPELLATE COURT FROM ANY THEREOF, AND GUARANTOR HEREBY IRREVOCABLY AND
UNCONDITIONALLY (i) AGREES THAT ANY CLAIM IN RESPECT OF ANY ACTION OR PROCEEDING
MAY BE HEARD AND DETERMINED IN SUCH PENNSYLVANIA STATE COURT (OR, TO THE EXTENT
PERMITTED BY LAW, IN SUCH FEDERAL COURT), (ii) WAIVES, TO THE FULLEST EXTENT IT
MAY LEGALLY AND EFFECTIVELY DO SO, ANY OBJECTION WHICH IT MAY NOW OR HEREAFTER
HAVE TO THE LAYING OF VENUE OF ANY SUCH ACTION OR PROCEEDING IN ANY SUCH
PENNSYLVANIA STATE OR FEDERAL COURT, AND (iii) WAIVES, TO THE FULLEST EXTENT
PERMITTED BY LAW, THE DEFENSE OF AN INCONVENIENT FORUM TO THE MAINTENANCE OF
SUCH ACTION OR PROCEEDING IN ANY SUCH PENNSYLVANIA STATE OR FEDERAL COURT. EACH
OF THE PARTIES HERETO AGREES THAT A FINAL JUDGMENT IN ANY SUCH ACTION OR
PROCEEDING SHALL BE CONCLUSIVE AND MAY BE ENFORCED IN OTHER JURISDICTIONS BY
SUIT ON THE JUDGMENT OR IN ANY OTHER MANNER PROVIDED BY LAW. GUARANTOR
IRREVOCABLY CONSENTS TO SERVICE OF PROCESS AND NOTICE ADDRESSED TO GUARANTOR AT
1415 LOUISIANA, SUITE 3000, HOUSTON, TEXAS, 77002, ATTN: GENERAL COUNSEL (FAX:
(713) 524-3586)



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AND SENT IN THE MANNER PROVIDED FOR NOTICES IN SECTION 6.03 OF THE AGREEMENT.

                  This is a continuing Guaranty until all covenants and
obligations of WEDGE to PDM under Article I of the Agreement have been
extinguished. The provisions of this Guaranty shall be binding upon Guarantor
and its successors and assigns, and shall inure to the benefit of PDM and its
respective successors and assigns.

                  Guarantor hereby represents and warrants to PDM that it is a
corporation duly incorporated and validly existing under the laws of Delaware;
that it has full corporate power and authority to enter into this Guaranty and
to perform its obligations hereunder; the execution and delivery of this
Guaranty and the performance of Guarantor's obligations hereunder have been duly
authorized by all necessary action on the part of Guarantor; this Guaranty
constitutes a legal, valid and binding obligation of Guarantor, enforceable
against it in accordance with its terms, except that enforceability may be
limited by any applicable bankruptcy, insolvency, reorganization, moratorium or
similar law affecting the enforcement of creditor's rights generally; and
neither the execution nor the delivery of the Guaranty, nor the performance by
Guarantor of the terms hereof will (a) violate any provision of any law of any
state or of the United States or any rule or regulation thereunder, or of any
order, writ, injunction or decree applicable to Guarantor, or (b) conflict with,
or result in a breach or default or the creation of any lien under, any note,
indenture, mortgage, credit agreement, license or other material agreement to
which Guarantor is a party, or by which it is bound, or (iii) violate or breach
Guarantor's charter documents or bylaws.

                  Guarantor hereby relinquishes and waives any and all rights of
subrogation or otherwise to the position of WEDGE with respect to the Deed of
Pledge (as defined in the Agreement) and hereby acknowledges and proclaims that
its rights of reimbursement and repayment from CB&I are, and shall remain,
unsecured, and further agrees to use its best efforts to cause WEDGE to release
the Deed of Pledge and its security interest thereunder in the event that this
Guaranty is called.

                  Capitalized terms used herein and not otherwise defined shall
have the meanings ascribed to them in the Agreement.

                  IN WITNESS WHEREOF, Guarantor has executed this Guaranty this
7th day of February, 2001.

                                        WEDGE GROUP INCORPORATED


                                        By: /s/ JAMES M. TIDWELL
                                           -------------------------------------
                                        Its: Vice President
                                            ------------------------------------




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