Rationale

ASTM A860 was designed to be an "ASTM equivalent" to MSS-SP-75. Section 12 of A860 puts tighter requirements of wall thicknesses on fittings of all sizes (93.5% of nominal) whereas MSS-SP-75's thickness tolerance applies to fittings NPS16 and larger. This revision would harmonize the wall thickness requirements to make them in-line with A960 and MSS-SP-75.