ASME B16.25-2012 pdf download

ASME B16.25-2012 pdf download.Buttwelding Ends.
1.2 Application
ASME B16.25 applies to any metallic materials for which a welding procedure can be satisfactorily qualified hut does not prescribe specific welding processes or procedures. Unless otherwise specified by the purchaser, it does not apply to welding ends conforming to ASME B16.5, B16.9, or 816.47.
1.3 Relevant Units
ASME B16.25 states values in both SI (Metric) and US. Customary units. These systems of units are to be regarded separately as standard. Within the text, the U.S. Customary units arc shown in parentheses or in a separate table that appears in Mandatory Appendix I. The values stated in each system are not exact equivalents; therefore, it is required that each system of units be used independently of the other. Combining values from the two systems constitutes nonconformance with the Standard.
1.4 Size
Nominal pipe size (NI’S), followed by a dimensionless number, is the designation for nominal fitting size. NI’S is related to the reference nominal diameter (DN) used in international standards. The relationship is typically as follows:
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.
(I’) Components having nominal wall thicknesses over 3 mm (0.12 in.) to 22 mm (0.88 in.) inclusive shall have single angle bevels as illustrated in Fig. 2.
(c) Components having nominal wall thicknesses greater than 22 mm (0.88 in.) shall have compound angle bevels as illustrated in Fig. 3.
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’/2-deg ± 2’4deg bevels or slightly 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.
ed,) 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 applicable component standard or that specified in the purchaser’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 I or Table 1-1 may be used.
4 PREPARATION OF INSIDE DIAMETER OF WELDING END
4.1 General
Preparation of the inside diameter at the end of a component shall be in accordance with one of the following, as specified by the purchaser:
(a) Components to be welded without backing rings shall meet the requirements of the standard or specification for the component.
(‘b) Components to be welded using split or noncontinuous backing rings shall be contoured with a cylindrical surface at the end as shown in Fig. 2, illustration (b) and Fig. 3, illustration (b). If the backing ring contour is other than rectangular, details must be furnished by the purchaser.