**Exhibit4.20**EXECUTION COPY          AMENDMENT NO. 18, LIMITED WAIVER AND CONSENT (this ***“Amendment”****)*datedas of March 29, 2007, to the Second Lien Credit Agreement dated as of July29, 2004, among THERMADYNE INDUSTRIES, INC., a Delaware corporation*(****“Industries”****),*THERMAL DYNAMICS CORPORATION, a Delaware corporation*(****“Dynamics”****),*TWECO PRODUCTS, INC., a Delaware corporation *(“****Tweco”)****,*VICTOREQUIPMENT COMPANY, a Delaware corporation *(****“Victor”****),*C & G SYSTEMS, INC.,an Illinois corporation *(****“C& G”****),*STOODY COMPANY, a Delaware corporation*(****“Stoody”****),*THERMAL ARC, INC., a Delaware corporation *(“****Thermal Arc****”),*PROTIP CORPORATION, a Missouri corporation *(****“ProTip”****),*THERMADYNEINTERNATIONAL CORP., a Delaware corporation *(“****International****”*and, togetherwith ProTip, Thermal Arc, Stoody, C & G, Victor, Tweco, Dynamics andIndustries, the *“****Borrowers****”),*the Guarantors party thereto, the Lenders fromtime to time party thereto and CREDIT SUISSE, as administrative agent (insuch capacity, the *“****Administrative Agent****”)*and as collateral agent (in suchcapacity, the ***“Collateral Agent”)***(as amended by Amendment No. 1 andAgreement effective as of September 30, 2004, by Amendment No. 2 and JoinderAgreement dated as of November 22, 2004, by Amendment No. 3 and Consentdated as of January 3, 2005, by Amendment No. 4 dated as of March 16, 2005,by Amendment No. 5 dated as of March 30, 2005, by Amendment No. 6 dated asof March 31, 2005, by Amendment No. 7 dated as of July 1, 2005, by AmendmentNo. 8 dated as of August 8, 2005, by Amendment No. 9 dated as of October 7,2005, by Amendment No. 10 and Agreement dated as of November 7, 2005, byAmendment No, 11 and Agreement dated as of December 29, 2005, by AmendmentNo. 12, Waiver and Consent dated as of March 9, 2006, by Amendment No. 13and Agreement dated as of April 5, 2006, by Amendment No. 14 and Consentdated as of May 9, 2006, by Amendment No. 15 dated as of June20, 2006, by Amendment No. 16, Waiver and Agreement dated as of July21, 2006, by Amendment No. 17 and Agreement dated as of January 30,2007 and as further amended, supplemented or modified, the ***“CreditAgreement”).***          A.Pursuant to the Credit Agreement, the Lenders have extended credit to the Borrowers.          B. The Borrowers and the other Credit Parties have requested that theAdministrative Agent and the Lenders amend the Credit Agreement and provide a limited waiverand consent as set forth herein.          D. Capitalized terms used but not defined herein shall have the meanings assigned tothem in the Credit Agreement.
 

 
2          Accordingly, in consideration of the mutual agreements herein contained and other good andvaluable consideration, the sufficiency and receipt of which are hereby acknowledged, the partieshereto agree as follows:          SECTION 1. ***Limited Waiver****.*The Administrative Agent and the Lenders hereby waive any Defaultor Event of Default solely to the extent that the Credit Parties breached (a) Section 6.02(i) ofthe Credit Agreement as a result of funding investments in Foreign Subsidiaries in excess of theaggregate limit of $6,000,000 by an amount no greater than $700,000 and (b) Section 5.11 of theCredit Agreement with respect to any credit card collection accountslocated at Arvest Bank.          SECTION 2. ***Limited Consent.***Pursuant to Section 6.02(n) of the Credit Agreement, theAdministrative Agent hereby consents to the making of a capital contribution by Industries inThermadyne Victor Ltda in an amount not to exceed $300,000.          SECTION3. ***Amendments.***(a) Section 6.02 of the Credit Agreement is hereby amended by deletingthe number “$6,000,000” in clause (i) thereof and inserting “$6,700,000” in its place.          (b) Section 6.02(n) of the Credit Agreement is hereby amended and restated in its entirety asfollows:“(n) other investments by Credit Parties and Foreign Subsidiaries not exceeding$2,000,000 in the aggregate (net of cash received by any Borrower from any ForeignSubsidiary as a result of a sale of assets or Stock, in whole or in part, of suchForeign Subsidiary) with the Administrative Agent’s prior written consent;”          SECTION 4. ***Representations and Warranties****.*To induce the other parties hereto to enter intothis Amendment, the Credit Parties represent and warrant to each of the Lenders, theAdministrative Agent and the Collateral Agent, that, after giving effect to this Amendment, (a)the representations and warranties set forth in Article III of the Credit Agreement are true andcorrect in all material respects on and as of the date hereof, except to the extent suchrepresentations and warranties expressly relate to an earlier date, and (b) no Default or Event ofDefault has occurred and is continuing.          SECTION 5**.*****Effectiveness.***This Amendment shall become effective as of the date set forthabove on the date that the Administrative Agent (or, in the case of clauses (a) and (b) below, itscounsel) shall have received:          (a) counterparts of this Amendment that, when taken together, bear the signaturesof the Credit Parties and the Required Lenders;          (b) acopy of a fully executed and delivered amendment, in form and substancereasonably satisfactory to the Administrative Agent, to the First Lien Credit Agreement; and          (c) payment in full of all fees and other amounts due and payable on or prior tosuch date hereunder or under any other Loan Document.
 

 
3          SECTION 6. ***Effect of Amendment****.*Except as expressly set forth herein, this Amendment shall notby implication or otherwise limit, impair, constitute a waiver of, or otherwise affect the rightsand remedies of the Lenders, the Administrative Agent or the Collateral Agent under the CreditAgreement or any other Loan Document, and shall not alter, modify, amend or in any way affect anyof the terms, conditions, obligations, covenants or agreements contained in the Credit Agreement orany other Loan Document, all of which are ratified and affirmed in all respects and shall continuein full force and effect. Nothing herein shall be deemed to entitle any Credit Party to a consentto, or a waiver, amendment, modification or other change of, any of the terms, conditions,obligations, covenants or agreements contained in the Credit Agreement or any other Loan Documentin similar or different circumstances. This Amendment shall apply and be effective only withrespect to the provisions of the Credit Agreement specifically referred to herein. After the datehereof, any reference to the Credit Agreement shall mean the Credit Agreement, as modified hereby.This Amendment shall constitute a “Loan Document” for all purposes of the Credit Agreement and theother Loan Documents.          SECTION 7. ***Counterparts****.*This Amendment may be executed in any number of counterparts and bydifferent parties hereto in separate counterparts, each of which when so executed and deliveredshall be deemed an original, but all such counterparts together shall constitute but one and thesame contract. Delivery of an executed counterpart of a signature page of this Amendment byfacsimile transmission shall be as effective as delivery of a manually executed counterpart hereof.          SECTION 8. ***Applicable Law.***THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCEWITH, THE LAWS OF THE STATE OF NEW YORK.          SECTION 9. ***Headings.***The headings of this Amendment are for purposes of reference only andshall not limit or otherwise affect the meaning hereof.          SECTION 10. ***Expenses.***The Borrowers agree to reimburse the Administrative Agent for allout-of-pocket expenses in connection with this Amendment, including the reasonable fees, chargesand disbursements of Cravath, Swaine & Moore LLP, counsel forthe Administrative Agent.          SECTION 11. ***Reaffirmation****.*Each of the Guarantors hereby acknowledges receipt and notice of,and consents to the terms of, this Amendment, and affirms and confirms its guarantee of theObligations and, if applicable, the pledge of and/or grant of a security interest in its assets asCollateral to secure the Obligations, all as provided in the Collateral Documents as originallyexecuted, and acknowledges and agrees that such guarantee, pledge and/or grant of securityinterest continue in full force and effect in respect of, and to secure, the Obligations under theCredit Agreement, as amended hereby, and the other Loan Documents.[Remainder of this page intentionally left blank]
 

 
     **IN WITNESS WHEREOF**, each of the parties hereto has caused this Amendment to beexecuted and delivered by its duly authorized officer as of the date first set forthabove.       THERMADYNE INDUSTRIES, INC.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       THERMAL DYNAMICS CORPORATION,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       TWECO PRODUCTS, INC.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       VICTOR EQUIPMENTCOMPANY,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       C & G SYSTEMS, INC.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       STOODY COMPANY,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.
 

 
       THERMAL ARC, INC.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       PROTIP CORPORATION,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       THERMADYNEINTERNATIONAL CORP.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       THERMADYNE HOLDINGS CORPORATION,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       MECO HOLDING COMPANY,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       C&G SYSTEMS HOLDING, INC.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.
 

 
       CIGWELD PTY LTD.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       DUXTECH PTY LTD.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       QUETACK PTY, LTD.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       QUETALA PTY, LTD.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       THERMADYNE AUSTRALIA PTY LTD.,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.       THERMADYNE INDUSTRIES LIMITED,       by /s/ Patricia S. Williams         Name: PATRICIA S. WILLIAMS    Title: V.P. SECTY & G.C.
 

 
       THERMADYNE WELDING PRODUCTS