Archived Rulemaking: Transportation of Natural and Other Gas and Hazardous Liquids by Pipeline; Temperature Limits on Steel Pipe That Has BeenCold Expanded To Meet the Specified Minimum Yield Strength
These amendments increase the temperature limit to which steel pipe that has been cold expanded to meet the specified minimum yield strength (SMYS) maybe heated without a reduction in design pressure. The limit now is 6000 F and temperatures above 800' F are needed to remove defects called "hard spots." Research shows that a temperature of 9000 F can be withstood for up to 1 hour without reducing the yield strength of the pipe and that the limit can be safely increased to permit the removal of hard spots and to eliminate a potential cause of hydrogen stress cracking (HSC).