Hi, as per my knowledge the effective length for secondary equivalent stress is
2.5x sqrt (Rt) which when i read ASME section VIII division 2. I dont remember the exact clause number saying this. Can anybody tell me which clause number??
Why I am asking afterall?? Reason is, I have one element on which loading is Pm+Pb+Q
so I taken allowable stress as 3SE as per div 2. One designer asking me i have to take it section VIII div 1 which only accounts for internal pressure. I am talking for small cylindrical shell to which there is flat plate welded on top & bottom. Basic thinking is we must go for internal pressure as per div 2. But i think as the effect of secondary stress (Q) is limited to 2.5xsqrt (Rt), therefore for cylindrical vessels are generally designed as per UG27 of div. 1 as effect of secondary stress id limited to only short distance. But in my case as the shell length is too much within this effective length of secondary stress, I can take allowable stress as 3SE as per div 2.
Hope to hear from you people.
Intention of doing all this is to decrease minimum thickness of shell. Somebody can advice to give stiffeners to decrease thickness of shell. But this shell is inside other shell (vessel), so I cant use stiffeners.
Please advice ASAP & if anybody can tell me which clause gives that 2.5sqrt(Rt) formula then many thanks.
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