Document:

<PAGE>

                                                                    EXHIBIT 4.11

                       AMENDMENT NO. 6 AND WAIVER TO THE
                               CREDIT AGREEMENT

                                                     Dated as of August 5, 2003

   AMENDMENT NO. 6 AND WAIVER TO THE CREDIT AGREEMENT among DRESSER, INC., a
Delaware corporation (the "U.S. Borrower"), and D.I. LUXEMBOURG S.A.R.L., a
corporation organized and existing under the laws of Luxembourg (the "Euro
Borrower", and, collectively with the U.S. Borrower, the "Borrowers"), DEG
ACQUISITIONS, LLC, a limited liability company organized and existing under the
laws of Delaware ("DEG Acquisitions"), DRESSER HOLDINGS, INC., a Delaware
corporation ("Dresser Holdings"), the Subsidiary Guarantors party to the Credit
Agreement referred to below (the "Subsidiary Guarantors"), the banks, financial
institutions and other institutional lenders party to the Credit Agreement
referred to below (collectively, the "Lenders"), WELLS FARGO BANK TEXAS, N.A.,
as the swing line bank, MORGAN STANLEY & CO. INCORPORATED, as collateral agent
(the "Collateral Agent"), MORGAN STANLEY SENIOR FUNDING, INC., as
administrative agent (the "Administrative Agent") for the Lenders and CREDIT
SUISSE FIRST BOSTON, as syndication agent (the "Syndication Agent", and
together with the Collateral Agent and the Administrative Agent, the "Agents").

   PRELIMINARY STATEMENTS:

   (1) The Borrowers, DEG Acquisitions, the Subsidiary Guarantors, the Lenders
and the Agents have entered into a Credit Agreement dated as of April 10, 2001,
as amended by Amendment No. 1 thereto dated as of March 13, 2002, Amendment No.
2 thereto dated as of June 17, 2002, Amendment No. 3 thereto dated as of
December 11, 2002, Amendment No. 4 and Waiver thereto dated as of March 31,
2003 and Amendment No. 5 dated as of June 30, 2003 (such Credit Agreement, as
amended, supplemented or otherwise modified through the date hereof, the
"Credit Agreement"). Dresser Holdings has entered into an Assignment and
Assumption Agreement dated as of July 3, 2002 with DEG Acquisitions whereby
Dresser Holdings assumed the duties and liabilities of DEG Acquisitions under
the Credit Agreement and the Security Agreement. Capitalized terms not
otherwise defined in this Amendment No. 6 and Waiver have the same meanings as
specified in the Credit Agreement.

   (2) The Borrowers have requested that the Lenders amend (i) certain
provisions of the Credit Agreement and (ii) waive certain Defaults and Events
of Default under the Credit Agreement, in each case as provided herein.

   (3) The Lenders party hereto, constituting not less than the Required
Lenders are, on the terms and conditions stated below, willing to grant the
request of the Borrowers as hereinafter set forth.

   NOW, THEREFORE, for good and valuable consideration the sufficiency of which
is hereby acknowledged, and subject to the terms and conditions of this
Amendment No. 6 and Waiver, the parties agree as follows:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                       2

   SECTION 1. The Amendment. Subject to the satisfaction of the conditions
precedent set forth in Section 3, the Credit Agreement is, effective as of the
date hereof, hereby amended as follows:

       (a) The following definitions are hereby added to Section 1.01 of the
   Credit Agreement in correct alphabetical order:

          ""Amendment No. 5 " means Amendment No. 5 to this Agreement dated as
       of June 30, 2003 among the Borrowers, DEG Acquisitions, the Subsidiary
       Guarantors, the Lenders party thereto and the Agents."

          ""Amendment No. 6 and Waiver " means Amendment No. 6 and Waiver to
       this Agreement dated as of August 5, 2003 among the Borrowers, DEG
       Acquisitions, the Subsidiary Guarantors, the Lenders party thereto and
       the Agents."

          ""Amendment No. 6 and Waiver Effective Date" has the meaning set
       forth in Section 3 of Amendment No. 6 and Waiver."

       (b) The definition of "EBITDA" is amended in full to read:

          ""EBITDA" means, in each case of the U.S. Borrower and each of its
       Subsidiaries, for any period, the sum (without duplication) of (a) Net
       Income, (b) to the extent Net Income has been reduced thereby, (i) all
       income taxes and foreign withholding taxes paid or accrued for such
       period, (ii) Interest Expense, (iii) Non-cash Charges less any non-cash
       items increasing Net Income for such period (other than normal accruals
       in the ordinary course of business), (iv) any cash charges resulting
       from the Transactions and the related financings that, in each case, are
       incurred prior to the six month anniversary of the Initial Extension of
       Credit, and (v) any non-capitalized transactions costs incurred in
       connection with actual, proposed or abandoned financings, acquisitions
       or divestitures, including, but not limited to, financing and
       refinancing fees and costs incurred in connection with the Transactions,
       all as determined in accordance with GAAP for such period, (c) an
       allowance for losses (including lost earnings and incremental costs)
       incurred by the U.S. Borrower during the second and third fiscal
       quarters of the Fiscal Year ended December 31, 2003 attributable to a
       labor dispute at the Waukesha plant commencing on or about May 1, 2003,
       as reasonably determined in good faith by the U.S. Borrower, in an
       aggregate amount for all such losses under this clause (c) not to exceed
       $13,000,000, and (d) (1) fees and expenses related to or resulting from
       the re-audit and restatement of financial statements of the U.S.
       Borrower and its Subsidiaries (including the fees of accountants, legal
       counsel and others engaged to perform services in connection therewith),
       (2) fees payable and expenses incurred in connection with Amendment No.
       4 and Waiver, Amendment No. 5 and Amendment No. 6 and Waiver, and (3)
       fees payable in an aggregate amount reasonably approved by the
       Administrative Agent and expenses incurred in connection with a consent
       solicitation relating to Section 4.03 of the Indenture under which the
       Senior Subordinated Debt was issued.

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                       3

       Notwithstanding the foregoing, for purposes of the periods specified
       below, Consolidated EBITDA of the U.S. Borrower and its Subsidiaries
       shall mean the amount specified below:

<TABLE>
<CAPTION>
                 Quarter Ending               Consolidated EBITDA
               ------------------             -------------------
               <S>                            <C>
               December 31, 2000 .........     U.S.$ 58,300,000

               March 31, 2001 ............     U.S.$ 54,900,000
               June 30, 2001 .............     U.S.$ 56,067,000
               September 30, 2001 ........     U.S.$ 58,920,000
               December 31, 2001 .........     U.S.$ 59,652,000

               March 31, 2002 ............     U.S.$ 43,691,000
               June 30, 2002 .............     U.S.$ 47,700,000
               September 30, 2002 ........     U.S.$ 46,900,000
               December 31, 2002 .........     U.S.$ 29,400,000

               March 31, 2003 ............     U.S.$ 38,332,000
</TABLE>

      (c) The definition of "Applicable Margin" is amended by deleting the last
   two sentences in their entirety and substituting therefor the following:

          "Notwithstanding anything herein to the contrary but subject to the
       immediately succeeding sentence, for all purposes of the Agreement, the
       Applicable Margin shall be at Level VI during the period beginning on
       January 1, 2003 and ending on the date that the conditions set forth in
       Section 5.01(p) are met, and thereafter shall be determined in
       accordance with this definition without giving effect to this sentence.
       For all purposes of the Agreement, the Applicable Margin in effect from
       time to time pursuant to any of the foregoing for each of the Eurodollar
       Rate Advances and the Base Rate Advances shall increase by (x) during
       the period of time beginning on the Amendment No. 4 and Waiver Effective
       Date and ending on the date immediately prior to the Amendment No. 6 and
       Waiver Effective Date, 0.50%; and (y) during the period of time
       beginning on the Amendment No. 6 and Waiver Effective Date through the
       end of the Suspension Period, 1.00%."

      (d) The definition of "Suspension Period" is amended in full to read as
   follows:

          ""Suspension Period" means the period of time beginning on the
       Amendment No. 4 and Waiver Effective Date and ending on the earlier of
       (i) December 15, 2003 and (ii) the date on which the Agents receive (x)
       the audited annual financial statements for the U.S. Borrower and its
       Subsidiaries for the Fiscal Year ended in 2002 and (y) the revised,
       audited financial statements for the U.S. Borrower and its Subsidiaries
       for the Fiscal Year ended in 2001, in each case, in accordance with the
       requirements set forth in Section 5.01(p)."

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                       4

      (e) Section 5.01 is amended by adding the following clause (p) at the end
   thereof:

          "(p) Prior to December 15, 2003, the U.S. Borrower shall furnish to
       the Agents and the Lender Parties revised, audited annual financial
       statements for the Fiscal Year ended in 2001 and audited annual
       financial statements for the Fiscal Year ended in 2002, in each case as
       required by Section 5.03(b)."

      (f) Section 5.02(n) of the Credit Agreement is amended by deleting the
   amount "$15,000,000" specified in clause (1) thereof and substituting
   therefor the amount "$35,000,000".

   SECTION 2. Waiver and Standstill. (a) Subject to Section 3 hereof, the
Required Lenders hereby waive any Default or Event of Default in respect of the
provisions of Sections 2.06(b)(ii) (but only in respect of equity proceeds in
an amount not greater than $10,000,000 used to finance an asset acquisition),
2.07(a), 2.08(c), 3.01(a)(vi), 3.01(c), 3.01(e), 3.01(i), 3.02, 4.01(g),
4.01(h), 4.01(i), 4.01(j), 4.01(q)(ii), 5.01(a), 5.01(g), 5.02(b)(ii)(F) and
(G), 5.02(f)(vii), (viii) and (ix), 5.02(g), 5.03(a), 5.03(b), 5.03(c),
5.03(d), 5.04(a) and 5.04(b) of the Credit Agreement and any related or
substantially comparable provision of any Loan Document, in each case
consisting of, resulting from or relating in any respect to (i) the re-audit,
revision or restatement of any financial statement delivered prior to the date
of this Amendment by the U.S. Borrower or any of its Subsidiaries (including,
without limitation, any misstatement therein or in any certificate,
representation or warranty relating thereto and any error, defect or deficiency
in accounting procedures or in the application of accounting principles
reflected thereby or relating thereto or the absence of audited financial
statements for any fiscal period prior to Fiscal Year 2001), (ii) any failure
to deliver any such financial statement when or as required, except as required
by Section 5.01(p), (iii) any failure to comply with any obligation that became
required to be performed or observed under any of such provisions by reason of
the occurrence of any such Default or Event of Default or (iv) any misstatement
as to the absence of any such Default or Event of Default.

   (b) Subject to Section 3 hereof, the Required Lenders waive any Default or
Event of Default now existing or hereafter arising under Section 6.01(e) of the
Credit Agreement resulting from a default under Section 4.03 of the Indenture
under which the Senior Subordinated Debt was issued; provided, however, that
the exercise by the Trustee or the requisite holders of Senior Subordinated
Notes of their right to give a notice of acceleration pursuant to Section 6.02
of such Indenture by reason of the existence of such default under Section 4.03
of the Indenture shall constitute an immediate Event of Default.

   SECTION 3. Conditions of Effectiveness. This Amendment No. 6 and Waiver
shall become effective as of the first date (the "Amendment No. 6 and Waiver
Effective Date") on which each of the following conditions precedents shall
have been satisfied:

      (a) The Administrative Agent shall have received counterparts of this
   Amendment No. 6 and Waiver executed by the Borrowers, DEG Acquisitions,
   Dresser Holdings and the Required Lenders or, as to any of the Lenders,
   advice satisfactory to the Administrative Agent that such Lender has
   executed this Amendment No. 6 and Waiver.

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                       5

      (b) All of the accrued fees and expenses of the Administrative Agent
   (including the accrued fees and expenses of counsel for the Administrative
   Agent) for which invoices shall have been submitted shall have been paid in
   full.

      (c) The Administrative Agent shall have received the consent attached
   hereto duly executed by each Guarantor and each Grantor.

      (d) The U.S. Borrower shall have paid to the Administrative Agent, for
   the benefit of the applicable Lenders, a fee equal to 0.25% of the aggregate
   Commitments of each Lender that has executed and delivered this Amendment
   No. 6 and Waiver on or before August 5, 2003.

   This Amendment No. 6 and Waiver is subject to the provisions of Section 9.01
of the Credit Agreement.

   SECTION 4. Representations and Warranties of the Borrower. Each Borrower
represents and warrants as follows:

      (a) On the date hereof, after giving effect to this Amendment No. 6 and
   Waiver, (i) no event has occurred and is continuing, or would result from
   the effectiveness of this Amendment No. 6 and Waiver, that constitutes a
   Default and (ii) all representations and warranties set forth in the Loan
   Documents shall be true and correct in all material respects.

      (b) No authorization or approval or other action by, and no notice to or
   filing with, any governmental authority or regulatory body or any other
   third party is required for the due execution, delivery or performance by
   the Borrowers of this Amendment No. 6 and Waiver and by the Guarantors and
   the Grantors of the consent attached hereto or other transactions
   contemplated hereby.

      (c) This Amendment No. 6 and Waiver has been duly executed and delivered
   by the Borrowers. The consent attached hereto has been duly executed and
   delivered by each of the Guarantors and the Grantors. This Amendment No. 6
   and Waiver and each of the other Loan Documents, as amended hereby, to which
   each Borrower, each Guarantor and each Grantor is a party are legal, valid
   and binding obligations of such Borrower, such Guarantor and such Grantor,
   as applicable, enforceable against such Borrower, such Guarantor and such
   Grantor, as applicable, in accordance with their respective terms.

   SECTION 5. Reference to and Effect on the Credit Agreement and the Notes.
(a) On and after the effectiveness of this Amendment No. 6 and Waiver, each
reference in the Credit Agreement to "this Agreement", "hereunder", "hereof" or
words of like import referring to the Credit Agreement, and each reference in
the Notes and each of the other Loan Documents to "the Credit Agreement",
"thereunder", "thereof" or words of like import referring to the Credit
Agreement, shall mean and be a reference to the Credit Agreement, as amended by
this Amendment No. 6 and Waiver.

   (b) The Credit Agreement, the Notes and each of the other Loan Documents, as
specifically amended by this Amendment No. 6 and Waiver, are and shall continue
to be in

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                       6

full force and effect and are hereby in all respects ratified and confirmed.
Without limiting the generality of the foregoing, the Collateral Documents and
all of the Collateral described therein do and shall continue to secure the
payment of all Obligations of the Loan Parties under the Loan Documents, in
each case as amended by this Amendment No. 6 and Waiver.

   (c) The execution, delivery and effectiveness of this Amendment No. 6 and
Waiver shall not, except as expressly provided herein, operate as a waiver of
any right, power or remedy of any Lender or the Administrative Agent under any
of the Loan Documents, nor constitute a waiver of any provision of any of the
Loan Documents.

   SECTION 6. Execution in Counterparts. This Amendment No. 6 and Waiver may be
executed in any number of counterparts and by different parties hereto in
separate counterparts, each of which when so executed shall be deemed to be an
original and all of which taken together shall constitute but one and the same
agreement. Delivery of an executed counterpart of a signature page to this
Amendment No. 6 and Waiver by telecopier shall be effective as delivery of a
manually executed counterpart of this Amendment No. 6 and Waiver.

   SECTION 7. Governing Law. This Amendment No. 6 and Waiver shall be governed
by, and construed in accordance with, the laws of the State of New York.

                     [SIGNATURE PAGES IMMEDIATELY FOLLOW]

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

   IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 6 and
Waiver to be executed by their respective officers thereunto duly authorized,
as of the date first above written.

                                              DRESSER, INC., as U.S. Borrower

                                              By
                                                  -----------------------------
                                                  Name:
                                                  Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                            D.I. LUXEMBOURG S.A.R.L., as Euro
                                            Borrower

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                    DEG ACQUISITIONS, LLC

                                    By: FIRST RESERVE FUND VIII, L.P., a
                                        Delaware limited partnership, its
                                        Manager
                                        By: FIRST RESERVE GP VIII, L.P., a
                                            Delaware limited partnership, its
                                            general partner
                                            By: FIRST RESERVE CORPORATION, a
                                                Delaware corporation, its
                                                general partner

                                            By: ______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                            DRESSER HOLDINGS, INC.

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                            MORGAN STANLEY SENIOR FUNDING, INC.,
                                            as Administrative Agent

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                            MORGAN STANLEY & CO. INCORPORATED,
                                            as Collateral Agent

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                            CREDIT SUISSE FIRST BOSTON, as
                                            Syndication Agent

                                            By _______________________________
                                                Name:
                                                Title:

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                            GENERAL ELECTRIC CAPITAL
                                            CORPORATION, as Co-Documentation
                                            Agent

                                            By _______________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                            Dresser Credit Agreement

<PAGE>

                                         REVOLVING CREDIT LENDERS, TRANCHEA
                                         EURO TERM LENDERS AND TRANCHE AU.S.
                                         TERM LENDERS

                                           _____________________________________
                                           [Print Name of Financial Institution]

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         TRANCHE B TERM LENDERS
                                            ____________________________________
                                           [Print Name of Financial Institution]

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         ISSUING BANKS

                                             WELLS FARGO BANK, N.A.

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         CREDIT SUISSE FIRST BOSTON

                                             By ____________________________
                                                Name:
                                                Title:

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         SWING LINE BANK

                                             WELLS FARGO BANK TEXAS, N.A.

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                    CONSENT

                                                      Dated as of August 5, 2003

   Each of the undersigned as a Loan Party under the Credit Agreement referred
to in the foregoing Amendment No. 6 and Waiver and as Grantor under the Security
Agreement dated as of April 10, 2001 (as amended, supplemented or otherwise
modified from time to time, the "Security Agreement") in favor of the Collateral
Agent, for its benefit and the benefit of the Lenders party to the Credit
Agreement referred to in the foregoing Amendment No. 6 and Waiver, hereby
consents to such Amendment No. 6 and Waiver and hereby confirms and agrees that
(a) notwithstanding the effectiveness of such Amendment No. 6 and Waiver, each
Loan Document is, and shall continue to be, in full force and effect and is
hereby ratified and confirmed in all respects, except that, on and after the
effectiveness of such Amendment No. 6 and Waiver, each reference in each Loan
Document to the "Credit Agreement", "thereunder", "thereof" or words of like
import shall mean and be a reference to the Credit Agreement, as amended by such
Amendment No. 6 and Waiver, and (b) the Collateral Documents to which such
Grantor is a party and all of the Collateral described therein do, and shall
continue to, secure the payment of all of the Secured Obligations (in each case,
as defined therein).

                                      DEG ACQUISITIONS, LLC

                                      By: FIRST RESERVE FUND VIII, L.P., a
                                          Delaware limited partnership, its
                                          Manager
                                          By: FIRST RESERVE GP VIII, L.P., a
                                              Delaware limited partnership,
                                              its general partner
                                              By: FIRST RESERVE CORPORATION,
                                                  a Delaware corporation, its
                                                  general partner

                                              By: ____________________________
                                                  Name:
                                                  Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         DRESSER HOLDINGS, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                                         DRESSER INTERNATIONAL, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                                         DRESSER RE, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                                         DRESSER RUSSIA, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                                         LVF HOLDING CORPORATION

                                             By ____________________________
                                                Name:
                                                Title:

                                         MODERN ACQUISITION, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement

<PAGE>

                                         DRESSER ENTECH, INC.

                                             By ____________________________
                                                Name:
                                                Title:

                                         RING-O VALVE, INCORPORATED

                                             By ____________________________
                                                Name:
                                                Title:

                       Amendment No. 6 and Waiver to the
                           Dresser Credit Agreement<PAGE>

                                                                    EXHIBIT 4.12

                          FIRST SUPPLEMENTAL INDENTURE

               THIS FIRST SUPPLEMENTAL INDENTURE (this " First Supplemental
Indenture"), dated as of June 4, 2001, among Dresser Entech, Inc., and Ring-O
Valve, Incorporated (each, a "Guaranteeing Subsidiary" and collectively, the
"Guaranteeing Subsidiaries"), subsidiaries of Dresser, Inc. (or its permitted
successor), a Delaware corporation (the "Company"), the Company, the other
Guarantors (as defined in the Indenture referred to herein) and State Street
Bank and Trust Company, as trustee under the indenture referred to below (the
"Trustee").

                                   WITNESSETH:

               WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of April 10, 2001 providing for
the issuance of an aggregate principal amount of up to $300,000,000 million of 9
3/8% Senior Subordinated Notes due 2011 (the "Notes");

               WHEREAS, the Indenture provides that under certain circumstances
each Guaranteeing Subsidiary shall execute and deliver to the Trustee a
supplemental indenture pursuant to which each Guaranteeing Subsidiary shall
unconditionally guarantee all of the Company's Obligations under the Notes and
the Indenture on the terms and conditions set forth herein (the "Guarantee");
and

               WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee
is authorized to execute and deliver this First Supplemental Indenture.

               NOW THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
each Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

               1.   CAPITALIZED TERMS. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

               2.   AGREEMENT TO GUARANTEE. Each Guaranteeing Subsidiary hereby
agrees as follows:

                    (a)  Along with all Guarantors named in the Indenture, to
                         jointly and severally Guarantee to each Holder of a
                         Note authenticated and delivered by the Trustee and to
                         the Trustee and its successors and assigns,
                         irrespective of the validity and enforceability of the
                         Indenture, the Notes or the obligations of the Company
                         hereunder or thereunder, that:

<PAGE>

                         (i)   the principal of and interest on the Notes will
                    be promptly paid in full when due, whether at maturity, by
                    acceleration, redemption or otherwise, and interest on the
                    overdue principal of and interest on the Notes, if any, if
                    lawful, and all other obligations of the Company to the
                    Holders or the Trustee hereunder or thereunder will be
                    promptly paid in full or performed, all in accordance with
                    the terms hereof and thereof; and

                         (ii)  in case of any extension of time of payment or
                    renewal of any Notes or any of such other obligations, that
                    same will be promptly paid in full when due or performed in
                    accordance with the terms of the extension or renewal,
                    whether at stated maturity, by acceleration or otherwise.
                    Failing payment when due of any amount so guaranteed or any
                    performance so guaranteed for whatever reason, the
                    Guarantors shall be jointly and severally obligated to pay
                    the same immediately.

                    (b)  The obligations hereunder shall be unconditional,
                         irrespective of the validity, regularity or
                         enforceability of the Notes or the Indenture, the
                         absence of any action to enforce the same, any waiver
                         or consent by any Holder of the Notes with respect to
                         any provisions hereof or thereof, the recovery of any
                         judgment against the Company, any action to enforce the
                         same or any other circumstance which might otherwise
                         constitute a legal or equitable discharge or defense of
                         a guarantor.

                    (c)  The following is hereby waived: diligence, presentment,
                         demand of payment, filing of claims with a court in the
                         event of insolvency or bankruptcy of the Company, any
                         right to require a proceeding first against the
                         Company, protest, notice and all demands whatsoever.

                    (d)  This Guarantee shall not be discharged except by
                         complete performance of the obligations contained in
                         the Notes and the Indenture or pursuant to Section 6
                         hereof.

                    (e)  If any Holder or the Trustee is required by any court
                         or otherwise to return to the Company, the Guarantors,
                         or any custodian, Trustee, liquidator or other similar
                         official acting in relation to either the Company or
                         the Guarantors, any amount paid by either to the
                         Trustee or such Holder, this Guarantee, to the extent
                         theretofore discharged, shall be reinstated in full
                         force and effect.

                    (f)  No Guaranteeing Subsidiary shall be entitled to any
                         right of subrogation in relation to the Holders in
                         respect of any obligations guaranteed hereby until
                         payment in full of all obligations guaranteed hereby.

<PAGE>

                    (g)  As between the Guarantors, on the one hand, and the
                         Holders and the Trustee, on the other hand, (x) the
                         maturity of the obligations guaranteed hereby may be
                         accelerated as provided in Article 6 of the Indenture
                         for the purposes of this Guarantee, notwithstanding any
                         stay, injunction or other prohibition preventing such
                         acceleration in respect of the obligations guaranteed
                         hereby, and (y) in the event of any declaration of
                         acceleration of such obligations as provided in Article
                         6 of the Indenture, such obligations (whether or not
                         due and payable) shall forthwith become due and payable
                         by the Guarantors for the purpose of this Guarantee.

                    (h)  The Guarantors shall have the right to seek
                         contribution from any non-paying Guarantor so long as
                         the exercise of such right does not impair the rights
                         of the Holders under the Guarantee.

                    (i)  Pursuant to Section 11.03 of the Indenture, after
                         giving effect to any maximum amount and any other
                         contingent and fixed liabilities that are relevant
                         under any applicable Bankruptcy or fraudulent
                         conveyance laws (including, without limitation, all
                         Senior Debt of such Guarantor), and after giving effect
                         to any collections from, rights to receive contribution
                         from or payments made by or on behalf of any other
                         Guarantor in respect of the obligations of such other
                         Guarantor under Article 11 of the Indenture shall
                         result in the obligations of such Guarantor under its
                         Guarantee not constituting a fraudulent transfer or
                         conveyance.

               3.   SUBORDINATION. The Obligations of each Guaranteeing
Subsidiary under its Guarantee pursuant to this First Supplemental Indenture
shall be junior and subordinated to the Senior Debt of such Guaranteeing
Subsidiary on the same basis as the Notes are junior and subordinated to the
Senior Debt of the Company. For the purposes of the foregoing sentence, the
Trustee and the Holders shall have the right to receive and/or retain payments
by such Guaranteeing Subsidiary only at such time as they may receive and/or
retain payments in respect of the Notes pursuant to the Indenture, including
Article 10 thereof.

               4.   EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees
that the Guarantees shall remain in full force and effect notwithstanding any
failure to endorse on each Note a notation of such Guarantee.

               5.   Guaranteeing Subsidiary May Consolidate, Etc. on Certain
Terms.

                    (a)  No Guaranteeing Subsidiary may consolidate with or
                         merge with or into (whether or not such Guarantor is
                         the surviving Person) another corporation, Person or
                         entity whether or not affiliated with such Guarantor
                         unless:

<PAGE>

                         (i)   subject to Section 11.05 of the Indenture, the
                    Person formed by or surviving any such consolidation or
                    merger (if other than a Guarantor or the Company) shall be a
                    corporation organized and validly existing under the laws of
                    the United States or any state thereof or the District of
                    Columbia, and unconditionally assumes all the obligations of
                    such Guarantor, pursuant to a supplemental indenture in form
                    and substance reasonably satisfactory to the Trustee, under
                    the Notes, the Indenture and the Guarantee on the terms set
                    forth herein or therein;

                         (ii)  immediately after giving effect to such
                    transaction, no Default or Event of Default exists; and

                         (iii) the Company would be permitted, immediately after
                    giving effect to such transaction, to incur at least $1.00
                    of additional Indebtedness (other than Permitted
                    Indebtedness) pursuant to Section 4.09 of the Indenture.

                    (b)  In case of any such consolidation, merger, sale or
                         conveyance and upon the assumption by the successor
                         Person, by supplemental indenture, executed and
                         delivered to the Trustee and satisfactory in form to
                         the Trustee, of the Guarantee endorsed upon the Notes
                         and the due and punctual performance of all of the
                         covenants and conditions of the Indenture to be
                         performed by the Guarantor, such successor Person shall
                         succeed to and be substituted for the Guarantor with
                         the same effect as if it had been named herein as a
                         Guarantor. Such successor Person thereupon may cause to
                         be signed any or all of the Guarantees to be endorsed
                         upon all of the Notes issuable hereunder which
                         theretofore shall not have been signed by the Company
                         and delivered to the Trustee. All the Guarantees so
                         issued shall in all respects have the same legal rank
                         and benefit under the Indenture as the Guarantees
                         theretofore and thereafter issued in accordance with
                         the terms of the Indenture as though all of such
                         Guarantees had been issued at the date of the execution
                         hereof.

                    (c)  Except as set forth in Articles 4 and 5 of the
                         Indenture, and notwithstanding clauses(a)(iii) above,
                         nothing contained in the Indenture or in any of the
                         Notes shall prevent any consolidation or merger of a
                         Guarantor with or into the Company or another
                         Guarantor, or shall prevent any sale or conveyance of
                         the property of a Guarantor as an entirety or
                         substantially as an entirety to the Company or another
                         Guarantor.

               6.   RELEASES. In the event of a sale or other disposition of all
of the assets of any Guarantor, by way of merger, consolidation or otherwise, or
a sale or other disposition of all to the capital stock of any Guarantor, then
such Guarantor (in the event of a sale or other disposition, by way of merger,
consolidation or otherwise, of all of the capital stock of such

<PAGE>

Guarantor) or the corporation acquiring the property (in the event of a sale or
other disposition of all or substantially all of the assets of such Guarantor)
will be released and relieved of any obligations under its Guarantee; provided
that the Net Cash Proceeds of such sale or other disposition are applied in
accordance with the applicable provisions of the Indenture, including without
limitation Section 4.10 of the Indenture. Upon delivery by the Company to the
Trustee of an Officers' Certificate and an Opinion of Counsel to the effect that
such sale or other disposition was made by the Company in accordance with the
applicable provisions of the Indenture, including without limitation Section
4.10 of the Indenture, the Trustee shall execute any documents reasonably
required in order to evidence the release of any Guarantor from its obligations
under its Guarantee.

               Any Guarantor not released from its obligations under its
Guarantee shall remain liable for the full amount of principal of and interest
on the Notes and for the other obligations of any Guarantor under the Indenture
as provided in Article 11 of the Indenture.

               7.   NO RECOURSE AGAINST OTHERS. No past, present or future
director, officer, employee, incorporator, stockholder or agent of any
Guaranteeing Subsidiary, as such, shall have any liability for any obligations
of the Company or any Guaranteeing Subsidiary under the Notes, any Guarantees,
the Indenture or this First Supplemental Indenture or for any claim based on, in
respect of, or by reason of, such obligations or their creation. Each Holder of
the Notes by accepting a Note waives and releases all such liability. The waiver
and release are part of the consideration for issuance of the Notes. Such waiver
may not be effective to waive liabilities under the federal securities laws and
it is the view of the Commission that such a waiver is against public policy.

               8.   NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW
YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS FIRST SUPPLEMENTAL INDENTURE
WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT
THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY.

               9.   COUNTERPARTS. The parties may sign any number of copies of
this First Supplemental Indenture. Each signed copy shall be an original, but
all of them together represent the same agreement.

               10.  EFFECT OF HEADINGS. The Section headings herein are for
convenience only and shall not affect the construction hereof.

               11.  THE TRUSTEE. The Trustee shall not be responsible in any
manner whatsoever for or in respect of the validity or sufficiency of this First
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by each Guaranteeing Subsidiary and the
Company. IN WITNESS WHEREOF, the parties hereto have caused this First
Supplemental Indenture to be duly executed and attested, all as of the date
first above written.

<PAGE>

Dated:  June 4, 2001

                                        DRESSER ENTECH, INC.

                                        By: /s/ Frank P. Pittman
                                           -------------------------------------
                                        Name:   Frank P. Pittman
                                        Title:  Vice President and Asst.
                                        Secretary

                                        RING-O VALVE,  INCORPORATED

                                        By: /s/ Frank P. Pittman
                                           -------------------------------------
                                        Name:   Frank P. Pittman
                                        Title:  Vice President and Asst.
                                        Secretary

                                        STATE STREET BANK AND TRUST COMPANY,
                                        as Trustee

                                        By: /s/ Philip G. Kane Jr.
                                           -------------------------------------
                                        Name:   Philip G. Kane Jr.
                                        Title:  Vice President

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