Help with calculating thread stress and preload

[sadie]

I am working on a design that is basically a pipe that has M45 x 1.25 threads on the end. I will be torqueing a cap onto this at 39 - 49 Nm. I need help trying to calculate the amount of preload this applies and the stress on the threads. I need to make sure it can handle 29.4 kn load in tension. The length of the thread engagement is around 15mm. What formulas do I need or what is a good book to look at to help?

Sadie

[PinkertonD]

Welcome to the forum, it is not so much the preload that will affect strength, it will be the exposed area from the thread-root and the remaining wall thickness of the pipe. That would require standard Strength of Materials calculations. Machinery's Handbook will have all you should need.

[Kelly_Bramble]

http://www.engineersedge.com/thread_...olt_stress.htm

http://www.engineersedge.com/thread_...ed-std-h28.htm

http://www.engineersedge.com/thread_...engagement.htm

http://www.engineersedge.com/fastener_thread_menu.shtml