what is the factor of safety of ASME SECTION VIII div. 1 and div. 2 of Edition 2007 and EDITION 2004.

How factor of safety is considered in design equations?

please give example if u can...

thanks in advance.

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Paresh Gujarati
M.TECH (Industrial Process Equipment Design)

Hello Paresh,

There is no "safety factor" in the ASME Code, since the safety depends on a lot of different variables. I think what you are asking for is the basis of the stress allowables.

Basis for Stress Allowables
- 2/3 of yield strength (general req., not only in the ASME Code)
- min. specified ultimate tensile strength divided by DF (design factor)

The history of the design factor (as far as I remember) is:
1914: Division 1 started with a DF of 5.0
1942: the DF was reduced to 4.0
1963: the first edition of Division 2 started with a DF of 3.0
1999: for Division 1 the DF was dropped to 3.5
2007: new Division 2 starts with a DF of 2.4

In general: the more you know about your vessel, the closer you are allowed to get to the UTS.

Michael