Metallics JSFN1213 Nuts 1/2-13 Serr Flange Locknut St-zn (Jar 100)

No. The flange on the JSFN1213 acts as the bearing surface, with an outside diameter of 1.000 to 1.031 inch, which is about what a 1/2 inch flat washer covers. That footprint spreads the clamp load and lets the nut span an oversized or badly aligned hole, so you save a part and an assembly step.

No. The JSFN1213 is listed as not Buy American compliant and not ARRA compliant, with multiple countries of origin. If your contract carries a domestic sourcing clause, specify a domestically produced flange nut instead.

Across the hex flats the JSFN1213 measures 0.736 to 0.750 inch, so a 3/4 inch wrench or socket fits it. Overall width across the hex corners runs 0.840 to 0.866 inch, and the nut stands 0.437 to 0.458 inch tall with 0.31 inch of wrenching height, so a standard socket gets full purchase on the hex above the flange.

They resist loosening by different means. The JSFN1213 is all steel with serrations on the flange face that bite into the mating surface as you wrench it down, so it takes more torque to back it off than to run it on, and there is no plastic element to soften in heat. A nylon insert nut does its locking in the threads instead and is reusable more readily, but the insert has a temperature ceiling. For hot or outdoor mechanical work, the all steel serrated flange nut is the safer pick, with the caveat that the serrations mark the surface they clamp.

No. The locking action on the JSFN1213 happens at the flange face, not in the threads, so it does not gall screw threads the way a distorted thread or all metal prevailing torque nut can. Bolts and rod come apart clean for reuse.

It is built to ASME B18.16.4-2008, the standard for prevailing torque metric and inch series flange lock nuts, so the hex, flange, and height dimensions are interchangeable with any other nut made to that spec. Hardness is Rockwell HR15N 78 to 90. If your drawing calls out B18.16.4, this answers it.

Treat them as one time use on the clamped surface. The locking function on the JSFN1213 comes from serrations that displace material on the mating face when wrenched down, so once the serrations have cut their seat, a second installation on the same surface does not develop the same resistance. Threads are fine, since the nut does not gall them, but plan on fresh nuts when you reassemble a joint that matters.

They ship in a jar of 100, and 100 count is the order minimum, so the jar is the buying unit. Metallics lists other sizes and quantities in the JSFN series by request if you need a different thread size or a bulk count for a standing MRO stock.

The JSFN1213 is steel with a zinc plated finish, which handles indoor and normally dry exterior service. Zinc is a sacrificial coating, so for continuously wet, coastal, or chemically aggressive locations, step up to a stainless flange nut instead.