Part 1 of 2 @ Chris C Venicario Buttering (metallurgy) Coating the faces of a weld joint prior to welding to prevent cross contamination of the weld metal and base metal. Experts, can you send acceptance for buttering? TiA..... Hmmmm.....You did not mention what is your project code and standard!!! Anyway here goes your reply: Answer: Excerpts from ASME IX: buttering: the addition of material, by welding, on one or both faces of a joint, prior to the preparation of the joint for final welding, for the purpose of providing a suitable transition weld deposit for the subsequent completion of the joint. In Buttering either fillet or butt, the Approved WPS intended for the welding joint or welding seam shall be also used as the WPS for Buttering-Welding repair. If the essential variables of the Approved WPS is different from the essential variables of the Buttering procedure that you will apply, then you have to requalify your Approved WPS.(e.g. from E-6011 to E-6012 / F3 to F2) How?, you will make a mock up, your test coupon shall also have a big gap, you will do buttering welding until you reached your desired root gap, grind to have a smooth surface profile and proceed to the normal welding sequence or passes.Have your buttering test coupon subject to all the test same as normal WPS. Objective reference: As per ASME IX, QW-283 WELDS WITH BUTTERING QW-283.1 Scope. This paragraph only applies when the essential variables for the buttering process are different than the essential variables for the process used for subsequent completion of the joint. Common examples are (a) the buttered member is heat treated and the completed weld is not heat treated after welding (b) the filler metal used for buttering has a different F‐Number from that used for the subsequent completion of the weld QW-283.2 Tests Required. The procedure shall be qualified by buttering the test coupon (including heat treating of the buttered member when this will be done in production welding) and then making the subsequent weld joining the members. The variables for the buttering and for the subsequent weld shall be in accordance with QW-250, except that QW-409.1 shall be an essential variable for the welding process(es) used to complete the weld when the minimum buttering thickness is less than 3/16 in. (5 mm). Mechanical testing of the completed weldment shall be in accordance with QW-202.2(a). If the buttering is done with filler metal of the same composition as the filler metal used to complete the weld, one weld test coupon may be used to qualify the dissimilar metal joint by welding the first member directly to the second member in accordance with Section IX. QW-283.3 Buttering Thickness. The thickness of buttering which shall remain on the production buttered member after all machining and grinding is completed and before subsequent completion of the joint shall be required by the WPS. When this thickness is less than 3/16 in. (5 mm), the thickness of buttering on the test coupon shall be measured before the buttered member is welded to the second member. This thickness shall become the minimum qualified thickness of buttering. QW-283.4 Qualification Alternative. When an essential variable is changed in the portion of the weld to be made after buttering or when a different organization is performing the portion of the weld to be made after buttering, a new qualification shall be performed in accordance with one of the following methods: (a) Qualify in accordance with QW-283.2 and QW-283.3. When the original qualification buttering thickness is less than 3/16 in. (5 mm), the buttering thickness shall not be greater, nor the heat input higher than was used on the original qualification. (b) When the original qualification buttering thickness is 3/16 in. (5 mm) or greater, qualify the portion of the weld to be made after buttering using any P‐Number material that nominally matches the chemical analysis of the buttering weld metal for the buttered base metal of the test coupon. Additional info as per AWS D1.1: Commentary on Structural Welding Code—Steel C2. Design of Welded Connections C2.6.3 Base Metal Through-Thickness Loading. (3) Application of a layer of “buttering” weld passes approximately 1/8 in. to 3/16 in. [3 mm to 5 mm] thick to the face of the base metal to be stressed in the through thickness direction prior to assembly of the joint has been demonstrated in tests and experience to reduce the likelihood of lamellar tearing. Such a “buttered” layer provides tough weld metal with a cast grain structure in lieu of the fibrous anisotropic rolled steel grain structure at the location of the most intense weld shrinkage strains. C5. Fabrication C5.22.4.3 Correction. Root openings wider than those allowed by Table 5.5 may be corrected by building up one or both sides of the groove faces by welding. In correcting root openings, the user is cautioned to obtain the necessary approvals from the Engineer where required. The final weld is to be made only after the joint has been corrected to conform to the specified root opening tolerance, thus keeping shrinkage to a minimum. 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Posted on: Thu, 11 Sep 2014 11:21:44 +0000
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