The dummy support calculation is based on M.W.Kellogg Design Manual. As per the Kellogg manual, all attachments to the pipe such as trunnion and lugs shall be designed such that the pipe shell bending and pressure stresses do not exceed the allowable.
The bending stress in a cylindrical shell (SB) is a function of pipe diameter, wall thickness and the induced load per linear inch along the edge of attachment and is given by the following formula:
SB = \(\LARGE\frac{1.17f\sqrt[]{R}}{t^{1.5}}\)
where
f = load induced per linear length along the edge of attachment
R = outside radius of pipe shell
t = effective wall thickness of pipe (minimum pipe wall thickness + rpad thickness - corrosion allowance)
The pressure stress in a cylindrical shell is a function of pipe diameter, wall thickness, internal pressure and type of loading. The longitudinal pressure stress (SPL) and circumferential stress (SPC) are calculated using the following formula:
SPL = \(\LARGE\frac{PR}{2t}\)
SPC = \(\LARGE\frac{PR}{t}\)
where
P = Internal design pressure
R = outside radius of pipe shell
t = effective wall thickness of pipe (minimum pipe wall thickness + rpad thickness - corrosion allowance)
