Re: Pipe Pressure

>Is this pressure valid only for the pressure acting from internal only ?
Yes. External pressure involves potential stiffening rings and buckling response. The pressure that is designed for is the pressure difference across the pipe wall. If you had 250 psig inside and 100psig outside, the design pressure would be 150 psi internal pressure. Note that if you ever had the 250 psi acting alone, with only atmospheric pressure on the outside, you'd have to design the pipe for 250 psi.

You'd do well to study up on this stuff if you're going to be doing piping calculations or reviewing them. This is a basic principle.

Christopher Wright P.E.    |"They couldn't hit an elephant at
chrisw@skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)