Shell Thickness Calculation Formulae of ASME Sec-VIII Div-1

[661660]

Shell Thickness Calculation Formulae of ASME Sec-VIII Div-1, At bottom it's used 0.6 factor.
Dear Expert please explain how this factor has taken... I mean how it is arrived ?
If any reference documents please share.

Regards
Aakash

 

[pravin143]

Hello
The factor .6 is come from various study and after iteration for more information you need to ref PTB part where commentary are given.

 

[661660]

Thanks Pravin ji,
I have checked ptb 4 . There is no xommentry available for this...
Anyone having any further idea on this question..
Regards
Akash

 

[Geoff13]

The simple t = PR/S for a cylinder is based on thin shell theory, where the shell will be in pure hoop tension.

However as the thickness increases there are additional stresses in the shell plate. The 0.6P term is a simple correction (though not a perfect correction) to account for these. At sufficiently high pressures or shell thicknesses the Appendix 1-2 formula must be used to more completely account for this effect. Division 2 Part 4 uses this more accurate formula for all pressures and thicknesses.

 

[prex]

By using the Tresca criterion for a thin shell, that factor would be 0.5 instead of 0.6, as the average through thickness stress is 0.5P compressive. I think that the exact factor used is based onto historical reasons, other national codes use slightly different factors.

prex
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