1.1 This specification2 covers electric-fusion-welded austenitic chromium-nickel stainless steel pipe suitable for corrosive or high-temperature service, or both, or for general applications.
Note 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”
1.2 This specification covers the grades of alloy and stainless steel listed in Table 1. The selection of the proper grade and requirements for heat treatment shall be at the discretion of the purchaser, dependent on the service conditions to be encountered.
1.3 Five classes of pipe are covered as follows:
1.3.1 Class 1—Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed.
1.3.2 Class 2—Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required.
1.3.3 Class 3—Pipe shall be single welded by processes employing filler metal in all passes and shall be completely radiographed.
1.3.4 Class 4—Same as Class 3 except that the weld pass exposed to the inside pipe surface may be made without the addition of filler metal (see