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ASME VIII-2008 pdf download

UW-27 WELDING PROCESSES (a) The welding processes that may be used in the con- struction of vessels under this Part of this Division are restricted as follows: (1) arc welding processes: atomic hydrogen, electro- gas, gas metal arc, gas tungsten arc, plasma arc, shielded metal arc, stud, and submerged arc; (2) other than arc welding processes: electron beam, flash, electroslag, explosive, 6 induction, inertia and contin- uous drive friction, laser beam, oxyfuel gas, resistance, and thermit. (b) Other than pressure inherent to the welding pro- cesses, no mechanical pressure or blows shall be applied except as permitted for peening in UW-39. (c) Definitions are given in Section IX which include variations of these processes. (d) Arc stud welding and resistance stud welding may be used only for nonpressure-bearing attachments, having a load or nonload-carrying function, except for material listed in Table UHT-23 provided that, in the case offerrous materials, the heat treatment requirements of UCS-56 are complied with and the requirements of UW-28(b) and UW-29(a) are met prior to start of production welding. Studs shall be limited to 1 in. (25 mm) diameter maximum for round studs and an equivalent cross-sectional area for studs with other shapes. (e) The electroslag welding process may be used for butt welds only in ferritic steels and austenitic stainless steels oftypes listedinUW-5(d), providedtherequirements of UW-11(a)(6) and UW-11(d) are satisfied. (f) The electrogas welding process may be used for butt welds only in ferritic steels and austenitic stainless steels of types listed in UW-5(d), provided the requirements of UW-11(a)(6) are satisfied. When a single pass is greater than 1 1 ⁄ 2 in. (38 mm) in ferritic materials, the joint shall be given a grain refining (austenitizing) heat treatment.
(c) The procedure used in welding nonpressure-bearing attachments which have essentially no load-carrying func- tion (such as extended heat transfer surfaces, insulation support pins, etc.), to pressure parts shall meet the follow- ing requirements. (1) When the welding process is manual, machine, or semiautomatic, procedure qualification is required in accordance with Section IX. (2) When the welding is any automatic welding pro- cess performed in accordance with a Welding Procedure Specification (in compliance with Section IX as far as applicable), procedure qualification testing is not required. (d) Welding of all test coupons shall be conducted by the Manufacturer. Testing of all test coupons shall be the responsibility of the Manufacturer. Alternatively, AWS Standard Welding Procedure Specifications that have been accepted by Section IX may be used provided they meet all other requirements of this Division. Qualification of a welding procedure by one Manufacturer shall not qualify that procedure for any other Manufacturer except as pro- vided in QW-201 of Section IX. UW-29 TESTS OF WELDERS AND WELDING OPERATORS (a) The welders and welding operators used in welding pressure parts and in joining load-carrying nonpressure parts (attachments) to pressure parts shall be qualified in accordance with Section IX. (1) The qualification test for welding operators of machine welding equipment shall be performed on a sepa- rate test plate prior to the start of welding or on the first workpiece. (2) When stud welding is used to attach load-carrying studs, aproductionstudweldtestofeachwelderorwelding operator shall be performed on a separate test plate or tube prior to the start of welding on each work shift. This weld test shall consist of five studs, welded and tested by the bend or torque stud weld testing procedure described in Section IX.
UW-37 MISCELLANEOUS WELDING REQUIREMENTS (a) The reverse side of double-welded joints shall be prepared by chipping, grinding, or melting out, so as to secure soundmetalatthe base ofweldmetal firstdeposited, before applying weld metal from the reverse side. (b) The requirements in (a) above are not intended to apply to any process of welding by which proper fusion and penetration are otherwise obtained and by which the base of the weld remains free from defects. (c) If the welding is stopped for any reason, extra care shall be taken in restarting to get the required penetration and fusion. For submerged arc welding, chipping out a groove in the crater is recommended. (d) Where single-welded joints are used, particular care shall be taken in aligning and separating the components to be joined so that there will be complete penetration and fusion at the bottom of the joint for its full length. (e) In welding plug welds, a fillet around the bottom of the hole shall be deposited first.

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