A thick-wall underwater pipe is placed at 20m below sea level. The pipe is carrying compressed natural gas with pressure of 50 MPa. The pipe has 115mm outer diameter and made of 316 stainless steel...

A thick-wall underwater pipe is placed at 20m below sea level. The pipe is carrying
compressed natural gas with pressure of 50 MPa. The pipe has 115mm outer diameter and
made of 316 stainless steel with yield strength of 205 MPa. The density of sea water could be
taken as 1029 kg/m3. Find out:
a) What is the resultant outer pressure acting on the underwater pipe?

b) What is the minimum inner diameter to ensure the pipe does not yield?
c) Sketch the variation of hoop and radial stress across the pipe wall, completed with stress
labelling.

d) What is the resultant longitudinal stress of the pipe?