Cylinder thick-walled, formulas

This formula is not intended for thick-wall cylinders, and for its limitations the appropriate sections of Code B.31 must be consulted. 

A number of formulas have been developed for calculating the stress in thick walled cylinders due to internal pressure. From Barlow s formula ... 

Table of Formulas 1. Stresses in thick-walled cylinders... 

Usually the pressure-vessel wall is thin in comparison with the inner radius of the ves.sel the "thin-wall formulas for calculating pressure stresses are then applicable [6]. For precise calculations the general equations [7] for vessels with any wall thickness should be used. Thermal stresses are superposed on the pressure stresses and can be approximated by com entional formulas for hollow cylinders and spheres [8]. 

Pipe-Wall Thickness. Once the design pressure and temperature have been established and the pipe material and size selected, the wall thickness is calculated using the appropriate section of the code. In rare cases, a thin pipe must be made thicker to withstand handling. Occasionally the thickness is affected by external loads or vibrations. All codes prescribe essentially the same design formula for metallic hoUow circular cylinders under internal pressure ... 

The structure of this formula can quickly be related to the thin-walled pressure vessel cylinder equation. Using the equation that calculates the stress at the center of the vessel wall, ux = P R + 0.5t)/t, and rearranging to solve for the thickness, results m. t = PR/ ux — 0.5P. The addition of the weld joint efficiency, E, and changing the coefficient before P to 0.6 results in the ASME code formula, t = PR/ SE — 0.6P), which they feel best represents the minimum wall thickness required to contain an internal pressure, P, in a cylindrical vessel having a radius, R, and made of a material with an allowable stress, S. 

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