ASME B&PVC SEC81$U210 05-24-00 12:12:46 pd: sec81 Rev 15.04

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APPENDIX 28ALTERNATIVE CORNER WELD JOINT DETAIL FOR

BOX HEADERS FOR AIR-COOLED HEATEXCHANGERS

28-1 GENERAL

For box headers for air-cooled heat exchangers usinga multipass corner weld joint constructed in accordancewith Fig. 28-1, the rules of UW-13(e)(4) and Fig. UW-13.2 shall be supplemented as described below.

28-2 SUPPLEMENTARYREQUIREMENTS

This Appendix only replaces the requirement, “a +b not less than 2ts” of UW-13(e)(4) and the weld jointgeometry of Fig. UW-13.2. All other rules in the Codepertaining to welded joints shall apply.

In addition, the following shall apply.28-2(a)A sample corner weld joint shall be prepared

to qualify the weld procedure; and a sample cornerweld joint shall be prepared to qualify each welder orwelding operator. The Manufacturer shall prepare thesample corner weld joint with nominal thickness andconfiguration matching that to be employed with thefollowing tolerances:

28-2(a)(1) the sample thinner plate shall matchthe thickness of the production thinner plate within61⁄4 in.;

28-2(a)(2) the sample thicker plate shall be atleast 1.5 times the thickness of the sample thinner plate.

The sample shall be sectioned, polished, and etchedto clearly delineate the line of fusion. Acceptabilityshall be determined by measurements of the line offusion for use in the calculations for compliance withFig. 28-1. The sample shall be free from slag, cracks,and lack of fusion. A sample corner weld shall beprepared for each P-Number, except that a sampleprepared to qualify a joint made from material with agiven value forK [see 28-2(d)] may be used to qualify

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a joint made from material having an equal or highervalue for K but not vice versa.

28-2(b) This sample corner weld joint is an additionto the Welding Procedure Specification Qualificationand the Welder and Welding Operator PerformanceQualification requirements of Section IX. The followingessential variables apply for both the procedure andperformance qualification, in addition to those of Sec-tion IX:

28-2(b)(1) a change in the nominal size of theelectrode or electrodes used and listed in the PQR;

28-2(b)(2) a change in the qualified root gapexceeding61⁄16 in. (61.6 mm);

28-2(b)(3) addition or deletion of nonmetallic re-tainers or nonfusing metal retainers;

28-2(b)(4)a change in the SFA specification fillermetal classification or to a weld metal or filler metalcomposition not covered in the specifications;

28-2(b)(5) the addition of other welding positionsthan those qualified;

28-2(b)(6) for fill passes, a change in amperageexceeding 25 amp, change in voltage exceeding 3 v;

28-2(b)(7)a change in contact tube to work distanceexceeding1⁄4 in. (6 mm);

28-2(b)(8)a change from single electrode to multi-ple electrodes, or vice versa;

28-2(b)(9) a change in the electrode spacing;28-2(b)(10) a change from manual or semiauto-

matic to machine or automatic welding or vice versa.28-2(c) After production welding, the back side of

the weld shall be subjected to a visual examination toassure that complete fusion and penetration have beenachieved in the root, except where visual examinationis locally prevented by an internal member coveringthe weld.

28-2(d) K,the ratio of through-thickness (Z direction)tensile strength to the specified minimum tensile

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ASME B&PVC SEC81$U210 05-24-00 12:12:46 pd: sec81 Rev 15.04

Fig. 28-1 1998 SECTION VIII — DIVISION 1

FIG. 28-1A99

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ASME B&PVC sec81$u210 06-03-99 09:04:11 pd: sec81 Rev 14.04

28-2 APPENDIX 28 — MANDATORY 28-2

strength, shall be taken as 0.6. Higher values forK,but not higher than 1.0, may be used if through-thickness tensile strength is determined in accordancewith Specification SA-770. The test results, includingthe UTS in addition to the reduction in area, shall bereported on the Material Test Report, in addition tothe information required by Specification SA-20 whenthe testing in accordance with Specification SA-770 isperformed by the material manufacturer. If the testingis performed by the vessel Manufacturer, the test resultshall be reported on the Manufacturer’s Data Report.See UG-93(b) and UG-93(c).

28-2(e) The maximum value ofts (see Fig. 28-1)shall be limited to 3 in. (76 mm).

28-2(f) Both members may be beveled as shown inFig. 28-1 sketch (b). When the bevel angle (a) is largeenough to satisfy the UW-13(c)(4) requirements, thealternative rules of this Appendix do not apply. When

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the bevel angle (a) results in weld fusion dimensionsthat do not satisfy the UW-13(e)(4) requirement thata + b is not less than 2ts, the following shall besatisfied.

28-2(f)(1) The angle (a) shall be equal to orgreater than 15 deg.

28-2(f)(2) The dimensiona2 shall be measuredfrom the projected surface of the plate being attachedas shown in Fig. 28-1 sketch (b).

28-2(f)(3) The angle (b) shall be equal to orgreater than 15 deg.

28-2(f)(4)All other requirements of this Appendixshall be applied.

28-2(g) When all the requirements of this Divisionand the supplemental requirements of this Appendixhave been met, the following notation shall be enteredin the Manufacturer’s Data Report under Remarks,“Constructed in conformance with Appendix 28.”

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