Metallics JTEKD32SS 12 x 2 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - 410 Stainless Steel - Each

The JTEKD32SS is flagged compliant for both Buy American and ARRA in the manufacturer data, though country of origin is listed as China. On a federally funded project, procurement will want to reconcile those two facts against the specific clause in your contract before you spec it in quantity.

410 stainless is the material used on the JTEKD32SS, which is a hardenable martensitic stainless, the only family that can be heat treated hard enough to drill its own hole. It gives better corrosion resistance than plain carbon steel for exterior or damp work, but it is not 300 series stainless, so in salt spray or chemical exposure it will still show surface rust over time.

92 lb-in minimum torsional strength, with the screw hardened to Rockwell C38-46. That hardness is what lets the point cut steel; it also means the screw is brittle in shear compared with a mild steel bolt, so don't treat it as a structural fastener. Minimum torques are the same as for carbon steel self-drillers, and drill time runs about 2.5 seconds through a 1 mm plate.

The washer is part of the assembly on the JTEKD32SS, with an outside diameter of 0.398 to 0.432 inch and a thickness of 0.022 to 0.039 inch. That bearing surface spreads load on strut, clips, and thin panel so the head doesn't pull through. No separate washer to buy.

A #12 diameter screw, 2 inches long, with 14 threads per inch, made to SAE J78-2013 for the thread form and ASME B18.6.3-2010 for dimensions. Those are the two standards an electrical or mechanical spec will usually call out for a self-drilling tapping screw, so it drops into a drawing that names either.

The 2 inch length on the JTEKD32SS is mostly shank, not drilling depth. The #3 point only needs to clear 0.110 to 0.210 inch of steel, so the extra length is there to pass through whatever you are mounting first, insulation, sheathing, a clamp body, or stacked clips, before it reaches the steel. If your fixture is thin and you only need a few threads of grip, a shorter screw in the same #12 x 14 TPI thread will set faster and leave no protruding tail.

Type BSD describes the point and thread combination: the screw drills its own hole and taps its own thread in one pass, no pilot drill and no nut on the back side. On the Metallics JTEKD32SS that is paired with a #3 drill point for steel in the 0.110 to 0.210 inch range. Use it where you can only reach one face of the steel; where you have access to both sides and need a removable, re-usable joint, a bolt and nut is the better call.

They ship in a jar of 100, which is the order minimum. The packed jar weighs 1.71 lbs. Other sizes and quantities are available by request.