# Pipe wall thickness and production tolerances

I made a calculation for a pipe that needs to handle 1 MPa pressure. I based my calculation on ASME VIII div1

My calculation says that my pipe needs to be 3 mm thick. But do I also need to account for the tolerances pipe manufactures have on the thickness?

This should be 12,5% according to a colleague of mine (sorry I don't have the source) but I am quite confident he is correct about this.

I can't find a note in the ASME VIII div1 about this maybe I over-read this.

So the question is: do I need to add the pipe wall thickness tolerance to my calculated thickness to be theoretically correct according the ASME VIII div1?

• Generally yes. For structural steel at least, design calculations are based on the actual size of the tube after worst case manufacturing tolerances. You should check the spec that your pipe is being manufactured to to determine the minimum allowable conforming wall thickness. – Ethan48 Dec 16 '16 at 18:23