Metallics JNYN168 Nuts 3/4-10 Hx Ny-Ins Locknut St-zn (Jar 25)

It's a 3/4-10 nut, so 3/4 inch nominal with 10 threads per inch, cut to ANSI/ASME B1.1. That's the UNC coarse pitch for 3/4 inch, so it mates with standard 3/4-10 coarse-thread bolts, rod, and all-thread. It will not run onto 3/4-16 fine thread.

Yes. The nut is built to ASME B18.16.6 for prevailing-torque nuts, with threads to ANSI/ASME B1.1. Those two standards are what a spec reviewer wants to see for a nylon insert hex locknut, and the part number to cite is Metallics JNYN168.

No. Metallics lists the JNYN168 as not Buy American compliant and not ARRA compliant, with multiple countries of origin. If your contract carries a domestic-sourcing clause, you need a documented domestic-origin fastener instead.

Across the flats the nut measures 1.052 to 1.064 inches, so a 1-1/16 inch wrench or socket is the fit. Height across the hex runs 0.860 to 0.890 inches.

Treat them as single-use. The nylon collar takes a thread impression the first time it's run on, and once that impression is cut the prevailing torque drops off. On vibration-prone mounting, which is what the JNYN series is intended for, install a fresh nut rather than re-running one you backed off.

Keep them off high-heat work. The locking element is nylon, not metal, so sustained heat softens it and the prevailing torque goes away. The body is zinc-plated steel, which handles heat fine, but the insert is the limit. For hot locations use an all-metal prevailing-torque locknut or a jam nut instead.

Zinc-plated steel is a dry to mildly damp indoor finish. It handles normal interior mechanical rooms and indoor strut or hanger work, but in wet, washdown, coastal, or buried locations zinc plating will eventually corrode through. Specify stainless or hot-dip galvanized hardware for those openings.

They ship 25 to a jar, and 25 each is the order minimum, so one jar is the smallest buy. The jar weighs 3.1 lbs and measures 5.75 by 3.5 by 3.5 inches, which matters if you're stocking a van shelf or a bin. Metallics lists other sizes and quantities in the JNYN series on request.

It will, as long as the rod is 3/4-10 coarse thread. These are called out for electrical, plumbing, and HVAC service and specifically for high-vibration areas, which covers rooftop units, pumps, and equipment hangers where a plain nut walks loose. One caution: because the nylon sits at the top of the nut, you need the rod to run fully through the insert for the lock to engage, so don't leave the nut short-threaded.