3/8" NPT Tap Depth

[adchampion]

Does anyone have a definitive reference for the required tap depth for a 3/8" NPT port. I understand from reading on here the tap depth is not usually called out, but if anybody has a standard or a guide that I could check our test parts against, I would much appreciate it.

I have a bonnet with 4 measurable ports. On three of them the depth of full thredas range from .330 to .350 and the 4th one is .470. This variation of almost 3 threads seem excessive. All the ports gaged within 1/2 turn of each other and the drill diameters are all within .003, so i ar struggling to figure out how these port differ so much in the threading.

Thanks,

Ben

 

[Graybags]

See spec ASME B1.20.1 for NPT info.

Regards

 

[gvc99]

Try

http://www.sizes.com/materls/pipeThrd.htm.

Hand tight plus wrench make up is 7 1/2 turns which is 7.5/18 = .417. The table in the website says .408

Regards,

George Chapek

Cambridge Valley Machining, Inc.
28 Perry Lane, PO Box 160
Cambridge, NY 12816