This specification covers wrought stainless steel fittings for pressure piping applications.
Several grades of austenitic stainless steel alloys are included in this specification, Grades are designated with a prefix, WP or CR, based on the applicable ANSI or MSS dimensional and rating standards, respectively.
For each of the WP stainless grades, several classes of fittings are covered, to indicate whether seamless or welded construction was utilized. Class designations are also utilized to indicate the nondestructive test method and extent of nondestructive examination (NDE). Table 1 is a general summary of the fitting classes applicable to all WP grades of stainless steel covered by this specification. There are no classes for the CR grades. Specific requirements are covered elsewhere.
This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.
The values stated in either inch-pound units or SI units are to be regarded separately as standard.
Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
This specification does not apply to cast steel fittings. Austenitic stainless steel castings are covered 730 in Specifications A 351/A 351M, A 743/A 743M, and A 744/A 744M.
