Do you offer merchant couplings with NPT tapered pipe threads?

Boshart supplies merchant couplings in accordance with the ASTM A865: Standard Specification for Threaded Couplings, Steel, Black or Zinc Coated (Galvanized) Welded or Seamless, for Use in Steel Pipe Joints.

Steel 1/2” to 2” Sizes – No!

We do not carry NPT taper threaded merchant couplings in the sizes up to and including 2”. The industry standard practice for 2” and smaller merchant couplings is to furnish straight-tapped couplings (NPS) as per ASTM S865 Section #9 - Threading.

Steel 2” and Larger Sizes – Yes!

All merchant couplings 2” and larger are taper tapped. The industry standard practice for 2” and larger merchant couplings is to furnish taper-tapped couplings (NPT) as per ASTM S865 Section #9 - Threading.

NPT (National Pipe Thread) and NPS (National Pipe Straight) have the same 60° thread angle, shape with flat crest and root profiles, and threads per inch (pitch). However, NPT threads are tapered, while the NPS threads are parallel (straight).

Option: Steel “Drive Couplings” with NPT Tapered Thread

In applications where a positive seal is critical, we do offer three sizes of steel couplings with NPT tapered threads. These are sold as “Drive Couplings” which are a heavy-duty steel coupling with FNPT threads specially designed for driving well points. They have custom NPT threads that are threaded deeper than the standard NPT thread to provide additional thread engagement for a super strong connection.

The tapered thread with increased engagement makes this product a great option for submersible pump installation on galvanized steel drop pipes. These couplings may be a desirable alternative for your application.

304 & 316 Stainless Steel 1/2” to 2” Sizes – YES!

Our stainless steel merchant couplings are all supplied with NPT tapered threads. We offer sizes up to and including 2”.

This is an upgrade as it is not the industry standard practice for 2” and smaller merchant couplings to be furnished with taper-tapped couplings (NPT) as per ASTM S865 Section #9 – Threading.

The taper tapping of the stainless steel merchant couplings makes the Boshart stainless steel merchant couplings a premium product. They are ideal for applications where a watertight connection is required.

Additional Resources:

https://support.boshart.com/why-are-steel-merchant-couplings-up-to-2-threaded-nps-vs.-npt

https://support.boshart.com/are-merchant-couplings-the-same-as-wrought-steel-couplings

https://support.boshart.com/what-is-the-pressure-temperature-rating-for-your-series-gmc-blmc-blhmc-merchant-couplings