Weld joint coefficient for fixed tube sheets
Thread Content
It is stated in 151 that for the shell side cylinder of fixed-plate heat exchangers where non-destructive testing is not possible, the welding joint coefficient should be set at 0.6. Is it necessary to use this value of 0.6?
The standard uses the word ‘should’, and personally I think 0.6 should be taken
I just can’t figure out how to handle this
Using 0.6 does not affect the calculation results.
When using SW6 software for calculations, the coefficient of the circumferential joint must be entered in the shell side cylinder input
It is the Class A joint coefficient, and it has no impact on strength calculations.
The title “Weld joint coefficient for fixed tube sheets” does not match the content.
0.6 must be used; it is the circumferential stress that needs to be entered when performing calculations for sw6. This value is not related to the strength calculation of the shell, but it affects the verification of the axial stress in the shell-side cylinder.
A value of 0.6 shall be used, as it is related to the allowable axial stress value for the shell-side cylinder (the same requirement applies to towers as well). The reviewers need to pay special attention, as they cannot see this value on the printed calculation sheet.
The final circumferential weld often cannot be inspected, but it remains a weak point that needs to be considered during the assessment of axial stress in heat exchangers; therefore, a welding joint factor of 0.6 was adopted. This is also in line with the principles governing the selection of welding joint factors as per ASME standards.