ASTM A358/A358M-19 | ATIS Document Center
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 6.2.2.1 and 6.2.2.2). 1.3.5 Class 5- Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed.