To all, Has anyone, aside from the piping people within the Washington Group, had bad experience with ASTM A193-GrB7 studs ? It seems that the defective fasteners were discovered by the fitters when they tried to torque up 3/4 inch stud bolts. They sheared at only%7E45 ft-lbs (!!??) A group of the studs were examined and cross sectioned. Large (.0625") regularly spaced voids were found within. The ends of the studs were marked "B7" and SUN (is this a foreign manufacturer ?) Anyone else have experiences to share about this recent problem ? -MJC

MJCronin ASTM A 193- B 7 - studs - with large inclusions (at the ingot stage or billet forming stages of manufacture) and with coarse threads can fail with little torque loads. If it is re-rolled product manufacture problem would compound with inclusions and with coarse thread in studs / bolts. Some classic case of failures experienced in the manufacture of HSLA steels in UK and in Germany and also a part of the same in Japan in early 1970's - with large inclusions are well known pointers to this problem to the industry (in general). Failure at such low torque load - 45 ft lbs is too low- indicates a high possibiility of the manufacture from re-rolled manufcture with high probability of large inclusions (from whichever country the studs were supplied.)and if the studs were coarse threaded, Failure happens mostly at the neck of stud to first or second coarse thread in such studs. Trust this helps you to further investigate from this angle. C.V.Srinivasan Nishi Engineers Pvt Ltd India Nov 10, 2006 E-mail: nishi@vsnl.com >To all, > >Has anyone, aside from the piping people within the >Washington Group, had bad experience with ASTM A193-GrB7 >studs ? > >It seems that the defective fasteners were discovered by the >fitters when they tried to torque up 3/4 inch stud bolts. >They sheared at only%7E45 ft-lbs (!!??) > >A group of the studs were examined and cross sectioned. >Large (.0625") regularly spaced voids were found within. > >The ends of the studs were marked "B7" and SUN (is this a >foreign manufacturer ?) > >Anyone else have experiences to share about this recent >problem ? > >-MJC

Attached is a portion of a warning my company received 4 November regarding same topic and same manufacturer. I also have a power point presentation on the same topic but I don't know how to attach it. I can forward to you if you provide your email address. "Please be aware of a failure with PTFE coated B7 Studs. Bolts broke while tightening at a Dow Chemical plant at Sarnia, Ontario, Canada. Other similar failures have occurred at a Valero refinery, Lake Charles, La. Manufacturer is reported to be Sun Fasteners located in Ningbo, China."