This specification covers wrought welding fittings for pressure piping , factory – made from nickel alloys . Threaded fittings as covered in ASME B16.11 are also covered by this specification . The term welding applies to butt – welding or socket – welding parts such as 45 and 90° elbows , 180° bends , caps , tees , reducers , lap-joint stub ends , and others types , as covered by ASME B16.9 , ASME B16.11 , MSS-SP-43 , MSS-SP-95 , and MSS-SP-97 .

Several grades of nickel and nickel alloys are included in this specification . Grades are designated with a prefix , WP or CR , based on the applicable ASME or MSS dimensional and rating standard .

Class WP fittings are those manufactured to the requirements of ASME B16.9 , B16.11

For each of the WP nickel and nickel alloy grades , several classes of fittings are covered to indicate whether seamless or welded construction was utilized / Class designations are also utilized to indicate the non-destructive test method and extent of non-destructive examination (NDE). Table 1 is general summary of the fitting classes applicable to all WP grades of nickel and nickel alloys covered by this specification . There are no classes for the CR grades . Specified requirements are covered elsewhere .