Metallics TXV148D 1/4-28 x 8 in. 5/16 Hex Head Heavy Duty Drill Screws - #5 Drill Point - All-Weather - Each

The Metallics TXV148D 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 drill points and is what you use when you are fastening into thick structural steel rather than light gauge deck or stud. The screw drills and taps its own hole in one pass, so no pilot hole is needed.

It is a 1/4-28 fine thread, 28 threads per inch, made to SAE J78 - 2013 for self-drilling tapping screws. 1/4-28 is the UNF fine series, so the thread form matches a standard 1/4-28 UNF nut or tapped hole. Note this is the fine pitch, not 1/4-20 coarse, so a 1/4-20 nut will not thread on.

Yes. The finish is a zinc all-weather coating, which is what the "All-Weather" designation in the part description refers to. That makes it suitable for exterior steel-to-steel fastening and damp or exposed locations where a plain zinc screw would start showing rust early.

8 inches of overall screw length. With the #5 drill point consuming the first part of that, an 8 inch drill screw is specified when you are driving through a deep assembly or standing off through insulation, sheathing, or stacked members into steel. For thinner steel-to-steel joints a shorter length in the same TXV series is the better call.

Country of origin is the United States, but the product data lists it as not Buy American compliant and not ARRA compliant. On a federally funded project where those clauses apply, treat this part as not qualifying and have the specifier confirm an alternate before you buy.

There is a washer feature under the head, with an outside diameter of 0.480 to 0.520 inch and a thickness of 0.030 to 0.050 inch. That gives you about a half inch of bearing surface to spread load against the fastened material. The spec data covers the washer dimensions only, so if your detail calls for an EPDM bonded sealing washer for weather tightness, verify that separately rather than assuming it.

Case hardened to Rockwell C32-40 from AISI 1016 to 1024 low carbon steel. That combination is standard for a self-drilling screw: a hard enough case for the point to cut steel, with a core ductile enough that the shank does not shear off under drive torque. Torsional strength is 150 lb-in minimum.

They ship in a box, with a minimum order of 25 each. So the smallest purchase is a 25 piece quantity of the TXV148D rather than a single screw. Other sizes and quantities in the TXV series are available by request.

Head and body dimensions follow ASME B18.6.3-2010, with the thread to SAE J78 - 2013. If your submittal or spec section calls out a tapping screw to ASME B18.6.3, the TXV148D meets that dimensional standard, which is the usual way an engineer specifies hex washer head self-drillers.