Joint Efficiency in Finite Element analysis (Asme Sec VIII Div 2)

[dali13]

Dear All,

I am working on the calculation of a Pressure Vessel according to the ASME 2011 Sec VIII Division 2.
I am modelling the Pressure Vessel using the Finite Element Methods and the Elastic Stress Analysis Method (Part 5 - Asme 2011 Div 2).

The Vessel I am working on has a weld joint efficiency of 0.7
The part 4 of Asme 2011 (Div 2) says that "The weld joint efficiency of a welded joint (..) is used in the design of a joint as a multiplier of the appropriate allowable stress value..". (4-2-4)

Should I consider this even in a finite element analysis according to part 5.
Should I multiply the allowable stress value by 0.7 in my case.

Besides, if I should apply the 0.7 factor, should I apply it also for the pressure test loading?

Last point, could I use the allowable stress defined in Part 4 (4.1.6.2) for the test condition.
Could I multiply the allowable stress for test by a factor of 1.5 to validate a local stress in the finite element method.

Thank you all
Ali

 

[TGS4]

Joint efficiency factors and FEA is complicated and there is no universal approach. For your local stress analysis, does the local region cross one of the weld joints that has this efficiency?

Regarding the test condition, the code acommittees are working on a resolution. It is highly unlikely that there will be any limits on Pl at the test condition. However, the requirements of 4.1.6.2 will need to be achieved exactly as written. Otherwise, the stress limits for the design load case combinations are considered sufficient to provide a suitable margin at the test condition.