Metallics JSBH300 Bolts 5/16-24 x 3/4 HXBT SS (Jar 100)

Fine thread. The JSBH300 is 5/16-24, so 24 threads per inch, not the 18 TPI coarse 5/16-18 you see more often in general construction. It will not thread into a 5/16-18 nut or tapped hole, so match your nuts, couplings and tapped enclosures to 24 TPI before ordering.

They are 18-8 stainless, an austenitic alloy suited to general atmospheric corrosion resistance, which is why they show up on chemical and food-processing equipment. For heavy chloride exposure, coastal salt spray or aggressive chemicals, 316 stainless is the better choice; some chemical environments need special corrosion-resistant materials and precautions.

The hex head measures 0.489 to 0.500 inch across the flats, so a 1/2 inch wrench or socket is the fit. Head height is 13/64 inch, which matters if you are torquing in a tight recess or under a cover plate.

The 18-8 stainless spec here is 100,000 to 150,000 psi minimum tensile and 65,000 psi minimum yield, with hardness Rockwell B95-C32. That lands below a grade 5 plated steel bolt on yield, so stainless is chosen for corrosion resistance rather than maximum clamp load. For a structural connection carrying real load, size up or use a graded steel fastener.

Both the ARRA and Buy American fields on the JSBH300 are flagged compliant. Country of origin is listed as multiple, so if your specification requires documentation of a single origin, request the mill paperwork for the lot you receive.

Outside diameter runs 0.3065 to 0.3125 inch, so a nominal 5/16 inch (0.3125) drilled hole is a line-to-line fit at best. Drill 11/32 inch for a clean slip fit through sheet metal or a bracket.

They ship 100 to a jar, and the order minimum is 100 count, so one jar is the smallest buy. The jar packaging keeps loose stainless hardware together on a service truck or in an MRO crib rather than loose in a bag.