Thread Root Form - radius or flat - NPSM pipe thread / ASME B1.20.1_2013

[SL_DK]

I have a question regarding thread Root form for NPSM thread i hope someone can help me with.
-I am from Denmark (Europe) and not that familiar with American Pipe Thread.

I have a supplier that claims that it is okay to make a radius at the root on NPSM thread parts (note: External thread)
In ASME B1.20.1 (2013) the thread root profile for NPSM thread is FLAT - NOT radius: ATTACHED Table 6
In chapter 2 "AMERICAN NATIONAL STANDARD PIPE THREAD FORM" there are however accept for radius at the root. Chapter 2.4 Thread Truncation: "a radius form is acceptable, as long as the crests and roots lie within the limits shown in Table 1"
However, the illustration in Table 1 are NPT...

Is chapter 2 a general chapter that also are for NPSM profile despite the NPT illustration?


Best regards

Soeren
(Quality Engineeer)

 

[hydtools]

The NPSM is a straight pipe thread meant for mechanical connections, not for fluid sealing connections. It may have rounded thread root.

The NPT is a tapered pipe thread meant for fluid sealing connection and may have rounded thread root.

The NPTF is the Dryseal tapered pipe thread meant for fluid sealing and will have flat root.

Ted