LAC 55:V.5022
D. The maximum allowable working pressure on the shell of a boiler or drum shall be determined by the strength of the weakest course computed from the thickness of the plate, the tensile strength of the plate, the efficiency of the longitudinal joint, the inside diameter of the course, and the factor of safety allowed by these rules and regulations in accordance with the following formula.
TStE = maximum allowable working pressure, psig
RFS
where:
TS = specified minimum tensile strength of shell plate material, psi. When the tensile strength of steel or wrought-iron shell plate is not known, it shall be taken as 55,000 psi for steel and 45,000 psi for wrought iron.
t = minimum thickness of shell plate, in weakest course, inches.
E = efficiency of longitudinal joint, method of determining which is given in Paragraph PG-27 of Section I of the ASME Code.
R = inside radius of the weakest course of the shell of drum, inches.
FS = factor of safety which shall be at least 5.
AUTHORITY NOTE: Promulgated in accordance with R.S. 23:531 and R.S. 51:1424.
HISTORICAL NOTE: Promulgated by the Department of Public Safety, Office of State Fire Marshal, LR 33:1356 (July 2007).