What is acceptable thread breathing (radial expansion)?

jerich1000

How much breathing of a threaded joint is acceptable? Is there a rule of thumb?

The specific application is a stainless steel cylinder with a threaded end. The cylinder is pressurized and an axial load is applied to the threaded end. Under FEA the threaded end bell-mouths away from the thread.

With seals (AS4716), an acceptable level of breathing is defined: .0015 in/in radial breathing for every inch of bore.

But, is there such a rule for threads?

Thanks