Metallics JG8HC2334 Bolts 3/8-16 X 3/4 G8 Hxbt St-zn (Jar 100)

It is a 3/8-16 bolt, so 16 threads per inch on a 3/8 inch diameter shank (measured outside diameter 0.3690 to 0.3750 inch). That is the standard UNC coarse thread for 3/8, so it mates with any 3/8-16 hex nut; for a Grade 8 bolt at full load you want a matching Grade 8 (or Grade C) nut rather than a plain commercial nut, since the nut is what usually fails first.

Grade 8 buys you tensile capacity. This bolt is medium carbon steel, heat treated, with a minimum tensile strength of 150,000 psi and minimum yield of 130,000 psi, hardness Rockwell C33-39. A Grade 5 tops out meaningfully lower, which is exactly why automotive and fleet work specifies Grade 8 where the joint load is higher. For light sheet metal or strut hanging where the load is low, a Grade 5 or a Grade 2 is usually all the drawing calls for.

No. These Grade 8 hex bolts are not Buy American compliant and are not ARRA compliant, and country of origin is listed as multiple. On a federally funded job with domestic sourcing requirements you need a domestically produced fastener instead.

Head width across flats measures 0.551 to 0.562 inch, which is a 9/16 inch wrench or socket. That is the standard hex size for a 3/8 inch bolt, so your existing 9/16 sockets and impact fit without hunting for an odd size.

The finish is zinc over steel, which handles indoor, damp mechanical room, and sheltered exterior service. It is not stainless. For direct weather exposure, coastal air, or anywhere standing water sits on the head, zinc plating will eventually give up, and heat treated Grade 8 steel is also more sensitive to hydrogen embrittlement concerns than a plain low carbon fastener. Specify hot dip galvanized or stainless for sustained wet exterior work.

These ship as a jar of 100, and 100 jar is the order minimum, so the jar is the unit you buy rather than loose pieces. Metallics does make other sizes and quantities in the G8HC and JG8HC series available by request if 3/4 inch length or a 100 count does not suit the job.

Material conforms to AISI 1021 through 1045, a medium carbon steel, then heat treated to reach Grade 8 properties at Rockwell C33-39. Do not weld to it or heat it during install, since that undoes the heat treatment the strength depends on.

Metallics lists the field application as the electrical, plumbing, heating and air conditioning industries, and the Grade 8 heat treat came out of automotive and fleet work where higher tensile capacity than a Grade 5 is needed. In practice that means equipment and compressor mounting, machine base anchoring, and high load bracket work rather than general strut and sheet metal hanging.