Mjconnol
Mechanical
- Sep 30, 2005
- 6
Hello All
I am having difficulty understanding the proper interpretation of section 319.2.2(d) in cryogenic services.
If there is material variation or a temperature variation within the piping system, the B31.3 code requires (where significant impact to stress is anticipated) the use of the actual modulus of elasticity (Em) at each respective segments operating temperature be used in the displacement stress calculation.
As the values of the global and thus point forces computed in the solution of the global equations (using Em values) would be greater that those had the default modulus (Ea @ 70F) been used, the corresponding “stresses” computed using the calculated forces and code formulas would be at a maximum.
The 31.3 Code then requires the computed stresses be adjusted the by the ratio Ea/Emin for each section which would in effect reduce the point stresses calculated as Em > Ea.
Is this the correct interpretation?????
Comments would be appreciated.