The material composition of the ASTM A193 Grade B7M Standard Stud Bolt is similar to that of B7. But the B7 is lower strength and requires tightening of all fasteners (eg Stud bolts, bolts) manufactured (not sampling). Grade B7M can withstand chlorine, sulfide and hydrogen environments. For stud bolts or B7M bolts, use a 2HM nut. Baut Tanam