Wall thickness or Design pressure for the gas pipeline

P = Design Pressure, psig

S = Specified Minimum Yiled Strength, psi

t  =  Nominal Wall thickness, inch

D = Nominal Outside diameter, inch

F = Design factor

E = Longitudinal joint factor

T = Temperature derating factor,

When considering wall thickness for offshore pipelines, the pipe must be thick enough to prevent hydrostatic collapse under external pressure but also contain the internal pressure, and consequently the minimum wall thickness tmin is calculated as follows:

where CA is Corrosion Allowed dan P int and P ext are internal and external pressure.

A location class 1 is any 1 mile (1.6 km) section that has 10 or fewer buildings intended for human occupancy (such us  wasteland, desert, mountains,grazing land, farmland, and sparcely populated area), a location class 2 has 10-46 building (such us fringe areas around cities and towns, industrial areas, ranch or country estate), a location class 3 has 46 or more building (such us suburban housing developments, shopping centers, residential areas, industrial areas and other populated), and location class 4 included areas where multistory buildings are prevalent, where traffic is heavy or dense and where there may be numerous other utilities underground. Multistory means four or more floors above ground.