Joint efficiency for dished end thickness calculation

[Bmechz]

ASME sec Viii Div 1 vessel has a dished end formed from a single piece of plate(without any long seam) and the complete vessel is spot radio graphed (joint eff. is 0.85).Kindly let me know whether we can use the joint efficiency 100% for dished end thickness calculation as it seamless.

Baijuz

Baiju Eapen
Static Equipment Design Engineer

 

[gr2vessels]

Yes.
Cheers,
gr2vessels

 

[brkmech1234]

gr2vessels,

This is can be used for non Hemisphercial heads only. Incase of Hemi sphercial heads 0.85 joint efficiency to be used; I just referred the code.

 

[Karloss12]

If the head is seamless or 100% X-Rayed:

If the Shell-Head circ seam is 100% X-Ray or Modified Spot in accordance with UW-11(a)(5)(b) then the head can have a weld efficiency of 1.00.

If the shell-head seam has Normal Spot X-Ray or no Radiography at all then the head can have a weld efficiency of 0.85.

Modified Spot and Normal Spot are different. I understand if you invoke modified spot you have to X-Ray the T-Section between the Shell logitudinal seam and Shell-Head Circ seam. Do some research. There are are other threads relating to getting a weld efficiency of 1.00 by invoking UW-11(a)(5)(b).

If you decide to have Normal Spot and Modified Spot, then the Modified Spot X-Rays are seperate and in addition to Normal Spot Requirements.

Seamless and 100% X-Rayed heads are treated the same way.

 

[gr2vessels]

brkmech, you are right. I stand corrected.
Cheers,
gr2vessels