1.1 This specification covers wrought high-strength ferritic steel butt-welding fittings of seamless and electric fusion-welded construction covered by the latest revisions of ASME B16.9 and MSS-SP-75. Butt-welding fittings differing from This specification covers wrought high-strength low-alloy butt-welding steel fittings of seamless and electric fusion-welded construction for applications in high-pressure gas and oil transmission and distribution systems. Starting materials shall cons