Engenharia mecanica

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Welding processes

The welding processes that may be used in the construction of vessels under this parto f these divisions are restricted as follows:
1- arc welding processes: atomic hydrogen, electro gas, gas metal arc, gas tungsten arc, plasma arc, shielded metal arc, stub, and submerged arc;
2- other than arc welding processes: electron beam, flash, electroslag, explosive*,induction, inertia and continuous drive friction, laser beam, oxyfuel gas, resistance, and thermit.
B – other than pressure inherent to the welding processes, no mechanical pressure or blows shall be applied except as permitted for peening in UW-39.
C – Defitions are given in section IX which include variations of these processes.
D – Arc stub welding and resistance stub welding may be usedonly for nonpressure-bearing attachments, having a load or nonload-carrying function, except for material listed in Table UHT-23 provided that, in the case of ferrous 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. (25mm) diameter maximum for roundstuds and an equivalent cross-sectional area for studs with other shapes.
E – The electros lag welding process may be used for butt welds only in ferritc steels and austenitic stainless steels of types listed in UW-5 (D), provided the requirements of UW-11(a)(6) and UW-44-(d) are satisfied.
F – the electrogas welding process may be used for butt welds only in ferritic steels and austeniticstainless steels of types listed in UW-5 (d), provided the requirements of UW-11 (a) (6) are satisfied. When a single pass is greater that 1 ½ in (38mm) in ferritic materials, the joint shall be given a grain refining (austenitizing) heat treatment.

UW – 28 QUALIFICANTION OF WELDING PROCEDURE

A) Each procedure of welding that is to be followed in construction shall be recorded in detailby the manufacturer.
B) The procedure used in welding pressure parts and in joining load-carrying nonpressure parts, such as all permanent or temporary clips and lugs, to pressure parts shall be qualified in accordance with section IX.
C) The procedure used in welding nonpressure-bearing attachments which have essentially no load-carrying function (such as extended heat transfer surfaces,insulation support pins, etc), to pressure parts shall meet the following 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 nay automatic welding process 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. Alternatively, AWS standard welding procedure specifications that have been accepted by section IX may be used provided they meet all oher requiments of this division. Qualification of a welding procedure specification that have been accepted by section IX may be used providedthey meet all oher requiments of this division. Qualification of a welding procedure by one Manufacturer shall not qualify that procedure for any other Manufacturer except as provided 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) topressure parts hall be qualified in accordance with section IX.
1) The qualification test for welding operators of machine welding equipment shall be performed on a separate test plate prior to the start of welding or on the first workpiece.
2) When stud welding is used to attach load-carrying studs, a production stud weld test of each welder or welding operator shall be performed on a...
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