ASME B16.25-2003 pdf download

ASME B16.25-2003 pdf download.Buttwelding Ends.
1 SCOPE 1.1 General This Standard covers the preparation of buttwelding ends of piping components to be joined into a piping system by welding. It includes requirements for welding bevels, for external and internal shaping of heavy-wall components, and for preparation of internal ends (including dimensions and tolerances). Coverage includes preparation for joints with the following: (a) no backing rings (b) split or noncontinuous backing rings (c) solid or continuous backing rings (d) consumable insert rings (e) gas tungsten arc welding (GTAW) of the root pass. Details of preparation for any backing ring must be specified when ordering the component. 1.2 Application This Standard applies to any metallic materials for which a welding procedure can be satisfactorily quali- fied, but does not prescribe specific welding processes or procedures. Unless otherwise specified by the pur- chaser, it does not apply to welding ends conforming to ASME B16.5 or B16.9. 1.3 Standard Units The values stated in either metric or inch units are to be regarded separately as standard. Within the text, the inch units are shown in parentheses. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Com- bining values from the two systems may result in non- conformance with the Standard.
1.5 Referenced Standards Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix II, which is part ofthis Standard. Itis notconsidered practi- cal to identify the specific edition of each standard and specification in the individual references; instead, the specific edition is identified in Mandatory Appendix II. An end preparation made in conformance to this Standard in all other respects will be considered to be in conformance to the Standard even though the edition reference may be changed in a revision of the Standard. 1.6 Quality Systems Nonmandatory requirements relating to the manufac- turer’s quality system program are described in Non- mandatory Appendix A. 1.7 Convention For the purpose of determining conformance with this Standard, the convention for fixing significant digits where limits, maximum or minimum values, are speci- fied shall be ‘‘rounding off’’ as defined in ASTM Practice E 29. This requires that an observed or calculated value shall be rounded off to the nearest unit in the last right- hand digit used for expressing the limit. Decimal values and tolerances do not imply a particular method ofmea- surement. 2 TRANSITION CONTOURS Figure 1 delineates the maximum envelope in which transitions from welding bevel to the outer surface of the componentand fromthe rootface to the innersurface of the component must lie. Except as specified in Note (5) to Fig. 1 and as otherwise specified by the purchaser, the exactcontourwithinthisenvelope is the manufactur- er’s option, providing it maintains the specified mini- mum wall thickness, has no slopes steeper than those indicated for the respective regions, and includes the proper surface for backing rings if specified. 3 WELDING BEVEL DESIGN 3.1 Bevels for Other Than GTAW Root Pass (a) Components having nominal wall thicknesses of 3 mm (0.12 in.) and less shall have ends cut square or slightly chamfered.
3.2 Bevels for GTAW Root Pass (a) Components having nominal wall thicknesses of 3 mm (0.12 in.) and less shall have ends cut square or slightly chamfered. (b) Components having nominal wall thicknesses over 3 mm (0.12 in.) to 10 mm (0.38 in.) inclusive shall have 37 1 ⁄ 2 deg ± 2 1 ⁄ 2 degbevels orslightly concave bevels. See Fig. 4. (c) Components having nominal wall thicknesses over 10 mm (0.38 in.) to 25 mm (1.0 in.) inclusive shall have bevels as shown in Fig. 5. (d) Components having nominal wall thicknesses greater than 25 mm (1.0 in.) shall have bevels as shown in Fig. 6. 3.3 Outside Diameter at Welding Ends Dimension A shall be either that specified in the appli- cable component standard or that specified in the pur- chaser’s component specification. In the absence of a requirement for dimension A in a component standard or a purchaser’s specification, the values for dimension A in Table 1 or Table I-1 may be used. 4 PREPARATION OF INSIDE DIAMETER OF WELDING END 4.1 General Preparation of the inside diameter at the end of a componentshall be inaccordance with one ofthe follow- ing, as specified by the purchaser. (a) Components to be welded without backing rings shall meet the requirements of the standard or specifica- tion for the component. (b) Components to be welded using split or noncon- tinuous backing rings shall be contoured with a cylindri- cal surface at the end as shown in Fig. 2, illustration (b) and Fig. 3, illustation (b). If the backing ring contour is other than rectangular, details must be furnished by the purchaser.