Coupling Nuts

Coupling nuts are a hexagonally-shaped threaded fastener known for joining two external threads. They are also known as a rod coupling, rod coupler nut, coupling nut, or extension nut. Wrench tightening is allowed via the hex shape.

Frequently Asked Questions About Coupling Nuts

What are coupling nuts used for? 

Coupling nuts are commonly used in applications where a long threaded connection is needed, such as construction, structural frameworks/support, HVAC and suspended piping, and other industrial equipment.

What is a reducing coupling nut?

A reducing coupling nut is a variant design that allows the joining of rods of differing thread sizes.

Can coupling nuts connect two threaded rods? 

Yes, coupling nuts are used to join two male threads, and a very common example of this is two threaded rods. However, they can also be used to join other externally threaded rods and studs. 

What sizes do coupling nuts come in?

AFT offers coupling nuts in both metric and SAE sizes. Diameter-thread sizes range from #2-56 to 2”-4 1/2 or M5-0.80 to M30-3.50.

What materials and finishes do coupling nuts come in?

Coupling nuts are made of either stainless steel, steel, or brass, and have either a hot dipped galvanized, plain, or zinc Cr+3 finish. Choosing a stainless steel coupling nut or adding a zinc finish can add additional corrosion resistance.