MIL-B-8831B, MILITARY SPECIFICATION: BOLT, 180 KSI FTU AND 180 KSI FSU, 450 DEGREES F PROTRUDING AND FLUSH HEAD, GENERAL SPECIFICATION FOR (23 AUG 1982) [S/S BY NASM8831]., This specification is for bolts used where temperatures are not greater than 450 deg. F and ultimate tensile strength is 180 KSI Ftu (ultimate tensile stress) and 108 KSI Fsu.