Metallics TXV148 1/4-20 x 8 in. 5/16 Hex Head Heavy Duty Drill Screws - #5 Drill Point - All-Weather - Each

The Metallics TXV148 is a Type BSD heavy duty drill screw with a #5 drill point, built for steel-to-steel work. The #5 point is the heaviest of the common self-drill points and the screw is hardened to Rockwell C32-40 with a minimum 150 lb-in torsional strength, so it drills and taps structural-gauge steel without a pilot hole. For light 20-gauge decking or thin sheet, a smaller point screw is the better choice since an 8 inch long 1/4-20 is far more fastener than that job needs.

Yes. The TXV148 carries a zinc all-weather coating, which is what makes it suitable for exterior and damp interior steel-to-steel fastening such as rooftop equipment supports, strut, and exposed framing. It is a coated carbon steel screw (AISI 1016-1024), not stainless, so in genuinely corrosive settings like coastal spray or chemical exposure a stainless fastener is the right call.

No. The TXV148 is not Buy American compliant and is not ARRA compliant, with country of origin listed as multiple. If your specification carries a domestic sourcing clause, this part will not satisfy it and you need a fastener certified to that requirement instead.

A 5/16 inch hex socket drives it. The hex head measures 0.367 to 0.375 in. across the flats and 0.409 in. across the corners, with a head height of 0.172 to 0.19 in. Use a magnetic hex driver in a screwgun rather than an impact where you can, since an 8 inch screw needs steady drilling pressure to get the point through steel.

It is a 1/4-20 thread, 20 threads per inch, manufactured to SAE J78-2013, the standard for self-drilling tapping screws. So it cuts its own 1/4-20 thread in the steel as it drills. A standard 1/4-20 nut will run on the threads, but the screw is intended to tap the second layer of steel rather than be used with a nut.

The screw is supplied with a washer: the washer outside diameter runs 0.480 to 0.520 in. with a thickness of 0.030 to 0.050 in. That gives extra bearing surface under the 5/16 hex head on steel. Nothing else is required to install it beyond a 5/16 hex driver.

Length is the whole point here: at 8 inches, the TXV148 reaches through thick assemblies, stacked framing members, or standoff conditions and still taps into the far layer of steel, in a blind connection where you cannot get a wrench on the back side for a nut. A through-bolt needs access to both faces. If you can reach both sides, a bolt and nut is the simpler fastening; where you only have one side, this is the fastener that works.

They ship in a jar, with a minimum order of 25 each. That is a practical count for a single job rather than a bulk case, which suits contractors fastening a limited run of steel-to-steel connections. Other sizes and quantities in the TXV series are available by request.