02-041 C.M.R. ch. 76, § 5 - MAWP of Existing Pressure Vessels Not Constructed to Code
1. The MAWP on the shell of a pressure vessel
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 Paragraph A of Section 5, Subsection 1 of this Chapter. The
formula for determining MAWP is as follows:
TStE = MAWP, PSIG
RFS
Where:
TS = Ultimate tensile strength of shell plates, PSI
R = Inside radius of the weakest course of the shell or drum, inches.
T = Minimum thickness of shell plates in weakest course, inches.
E = Efficiency of longitudinal joint, as calculated in the ASME Boiler and Pressure Vessel Code adopted in Chapter 73 of the Program's rules.
FS = Factor of Safety allowed by subsection A.
A.
Factor of Safety. The factor
of safety must be at least five (5).
B.
Tensile Strength. When the
tensile strength of steel or wrought-iron shell plates is not known, it must be
assumed to be 55,000 PSI for steel and 45,000 PSI for wrought iron.
C.
Strength of Rivets.
Calculations concerning riveted joints must be those established by the ASME
Boiler and Pressure Vessel Code as adopted in Chapter 73 of these rules, or as
approved by the director.
Notes
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