Metallics SBH943 Bolts 5/8-11 x 2-3/4 HXBT SS (Box 25)

The SBH943 is 316 stainless steel, not 18-8. The molybdenum in 316 gives it greater corrosion resistance than 18-8 and better strength at elevated temperatures, which is why it gets specified for coastal, wastewater, pool chemical and roof-top mechanical work. Both alloys are austenitic, so neither is magnetic in the annealed condition and neither is heat treatable.

The SBH943 runs 100,000 to 150,000 psi minimum tensile with 65,000 psi minimum yield and a hardness of Rockwell B95 to C32. That puts it between a Grade 2 and a Grade 5 carbon bolt in strength, so you trade some tensile capacity for corrosion resistance. For high load structural connections where rust is not the problem, a carbon steel Grade 5 or Grade 8 is the stronger choice; where moisture, chlorides or chemical exposure is the problem, the 316 is the one that lasts.

Across flats the hex head measures 0.922 to 0.938 inch, which is a 15/16 inch wrench or socket. Head height is 25/64 inch, with a wrenching height of 0.269 inch, so a standard depth socket seats fine in a flush installation.

The SBH943 is flagged compliant for both Buy American and ARRA, which is what a government, healthcare or education procurement office needs on the submittal. Country of origin is listed as multiple, so if your spec requires a single named origin on the certification, state that at the time you order.

You can, but stainless against galvanized or plain carbon steel in a wet location sets up galvanic action and the carbon steel side corrodes first. Keep the mix for dry interior work, or use the 316 bolt with stainless nuts and washers where the connection sees weather or chemicals, which is where its molybdenum-bearing alloy earns its place. Use an anti-seize on stainless to stainless threads; austenitic fasteners gall when run down dry under load.

Metallics lists the SBHC and JSBHC hex bolts for electrical, plumbing, heating and air conditioning work: hanging strut and channel, anchoring equipment pads, bolting duct and pipe supports, and panel and enclosure mounting. For a property manager or MRO buyer, the practical reason to stock the 316 version in 5/8-11 is rooftop and mechanical room work where a plated bolt streaks and seizes within a few seasons.