NAT FORM CLASS 2 Thread

[pneveu]

I am looking for information on NPSM straight pipe threads. The drawing I am using is from 1953 and is referencing straight pipe threads for mechanical joints ASA, B2-1, table 13, page 25. Does anyone have a reference chart or refernce book that may be available to shed light on this? We are contracted to make a 9.5"-8N and 10"-8NPS straight thread for hydraulic tubing.

 

[BillPSU]

The Machinery Handbook 28th edition gives a chart for NPSM threads based on ANSI/ASME B1.20.1-1983(R2006). The problem with this chart is that it only goes up to 6" nominal pipe size. You may have to get a copy of the ANSI/ASME standard for your larger size threads.

I would suggest you talk with your customer about this thread and get an understanding of his expectation. There really isn't a 9.5 inch pipe being made so it is a calculated size. Checking this size of thread will be a problem unless you have a quantity of parts to make as a thread gage will be very expensive and you will probably have to gage this thread with measurement over wires. If you are making an internal thread you will either have to purchase a thread plug gage or get approval to make it based on a supplied threaded tube or one you make to be a gage.

Good Luck on this project.