Question

A vertical vessel with an internal diameter of 84” has a hemispherical head at the top and an ellipsoidal head of 2:1 at the bottom. The construction material has a maximum allowable stress of 8700 psi at its design temperature. The operating pressure is stated as 48 psig. The overall height of the vessel is 38‟ and a joint efficiency of 1.0 is used.

) Determine the wall thickness of each part of the vessel.

b) If a corrosion allowance of 2 mm is being fixed by the user, determine the wall thicknesses and part MAWPs for each part of the vessel and what is the vessel MAWP?

Answer 1

Data provided in the problem statement

Internal diameter of the vessel = 84 inch

Radius of vessel ( R ) = 84 / 2 = 42 inch

Maximum allowable stress ( S ) = 8700 psi

Operating pressure ( P ) = 48 psi

Height of vessel = 38 inch

Joint efficiency ( E ) = 1

1) Wall thickness of vessel and heads

2)

Corrosion allowance is fixed to 2 mm = 0.07874 inch

New wall thickness of vessel = 0.2324 inch + 0.07874 inch = 0.31114 inch

Thickness of hemispherical head = 0.116 inch + 0.07874 inch = 0.19474 inch

Thickness of ellipsoidal head = 0.232 inch + 0.07874 inch = 0.31074 inch