A thick-wall underwater pipe is placed at 20 m below sea level. The pipe is carrying compressed natural gas with pressure of 50 MPa. The pipe has 115 mm outer diameter and made of stainless steel with yield strength of 205 MPa. The density of sea water is 1029 kg/m. (a) Determine the resultant outer pressure acting on the underwater pipe. (1 mark) (b) What is the minimum inner diameter to ensure the pipe does not yield? (6 mark) (c) Sketch the stress distribution of hoop and radial stresses across the pipe wall, complete with stress labelling. (2 mark) (d) What is the resultant longitudinal stress of the pipe? (1 mark)