Metallics JTEKD31 12 x 7/8 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - Steel Zinc - Each

No. The washer is integral to the head on the JTEKD31, with an outside diameter of 0.398 to 0.432 in. and a thickness of 0.022 to 0.039 in. That bearing surface spreads load over the hole, which is what you want through strap, clip, or bracket. It is a bonded metal washer only, so if you need a weather seal on exterior panel you want a separate EPDM sealing washer.

Type BSD means self-drilling and self-tapping: it drills its own hole and forms its own thread in one pass, no pilot and no nut on the back. That is what you want for one-sided access into structural or sheet steel in the 0.110 to 0.210 in. range, such as hanging strut, straps, or box brackets. If you are going into masonry, wood, or hollow drywall, this is the wrong fastener type entirely.

A 5/16 in. hex driver or nutsetter. The indented hex head measures 0.305 to 0.312 in. across the flats and 0.34 in. across the corners, with a head height of 0.139 to 0.155 in. A standard magnetic 5/16 nutsetter in an impact or screw gun drives it.

These are AISI 1016-1024 carbon steel with a zinc finish. Zinc plating handles dry interior and protected exterior work, but it is not a long-term answer for direct weather, coastal air, or anything in standing moisture. For sustained exposure specify a stainless self-drilling screw instead.

It is a #12 diameter screw, 7/8 in. long, with 14 threads per inch to the SAE J78-2013 thread standard. With the drill point and flutes consuming part of that length, plan on fastening material that still leaves full thread engagement in the base steel. On the thickest rated panel, 0.210 in., you have limited remaining thread, so keep the attached part thin or step up in length.

The JTEKD31 is case hardened to Rockwell C32-40 with a minimum torsional strength of 92 lb-in. That is enough for normal gun driving, but an impact set on high torque will twist heads off any self-drill screw once the point seats. Let the drill point cut on steady pressure (about 2.5 seconds through a 1 mm plate) and back off the trigger as the washer pulls down.

Metallics lists the JTEKD31 as ARRA compliant and Buy American compliant, with country of origin China. On federally funded work the governing clause differs by program, so match those flags to the specific clause in your contract before you submit.

Two standards cover it: dimensions to ASME B18.6.3-2010 and threads to SAE J78-2013, with material per AISI 1016-1024. Note that SAE J78 does not include specifications for #7 diameter drill screws, so only diameters it covers (including this #12) can be cited to it.