﻿ Cylindrical Shell Under Internal Pressure | Oil & Gas Industry Technology Updates

## Cylindrical Shell Under Internal Pressure

ASME Code, Section VIII, Division 1, uses an approximate equation for determining the required thickness of a cylinder subjected to internal pressure:

where:
t = Required thickness of shell, in
P = Internal design pressure, psi
S = Allowable stress, psi
R = Inside radius of cylinder, in
E = Joint efficiency factor, dimensionless

Consider a vessel with an inside diameter D = 96 inches. The design pressure P = 100 psig.

Material: SA 515-70 plate

Design Temperature: 100°F

Corrosion Allowance (c.a.): 0.125 inch (corroded I.D. = 96.250 inches.)

All circumferential and longitudinal seams are double-welded butt joints and are spot radiographed. The vessel is to be built per ASME Code, Section VIII, Division 1.
From Table UCS-23 of the Code, for SA 515-70 at temperatures up to 650°F, S = 17,500 psi. For spot radiographed joints, from Table UW-12, E = 0.85.

Use 0.5 inch plate.