Metallics TXV144D 1/4-28 x 4 in. 5/16 Hex Head Heavy Duty Drill Screws - #5 Drill Point - All-Weather - Each

The TXV144D carries a #5 drill point, which is the heaviest point in the common self-drill range and is what you use for thick steel-to-steel work such as structural angle, heavy strut backing, and beam flanges. Metallics calls it out specifically for heavy duty steel-to-steel application. The point drills its own hole, so no pilot is needed, but the steel stack has to be thin enough that the drill flutes clear before the threads engage.

It is a 1/4-28 machine thread, 28 threads per inch, made to SAE J78-2013 for self-drilling tapping screws. That is standard 1/4-28 UNF pitch, so a 1/4-28 nut threads on. On a drilled hole in steel the screw forms its own mating thread, so a nut is only needed if you are through-bolting.

A 5/16 inch hex socket. The hex head measures 0.367 to 0.375 in. across the flats and 0.409 across the corners, with head height of 0.172 to 0.19 in. Run it with a nut setter in an impact or screw gun; there is no slotted or Phillips drive on this head.

It is finished with a zinc all-weather coating, which is what Metallics puts on fasteners intended for exposed and exterior steel work. That covers rooftop equipment, exterior strut, and canopy framing. It is a coated carbon steel screw, not stainless, so for constant salt spray or submerged conditions you want a stainless fastener instead.

Country of origin is the United States, and the product is described as made in the USA. However, it is not flagged Buy American compliant and not ARRA compliant in the manufacturer data, so on a federally funded job that carries those clauses do not submit it as compliant.

The 4 inch length is for stacking through spacers, insulation, or layered steel where the point still has to reach live metal at the far end. Only the threaded shank does the holding, so measure your total grip and make sure the drill point fully exits the last layer of steel before the threads start cutting, otherwise the point burns off and never taps. For plain steel-to-steel with no standoff, a shorter TXV screw is the better call.

Yes, it is a hex washer head. The integral washer runs 0.480 to 0.520 in. outside diameter and 0.030 to 0.050 in. thick, so it spreads the clamp load over roughly a half inch of bearing surface. No separate flat washer is needed for steel-to-steel.

They ship in a jar, with an order minimum of 50 each. Metallics notes other sizes and quantities are available by request if 4 inch is longer or shorter than you need.

Head geometry follows ASME B18.6.3-2010 and the threads follow SAE J78-2013. If your spec sheet calls for a tapping screw to those two standards in a 1/4-28 x 4 in. size, the TXV144D meets the callout.