Acceptance criteria when considering UG-22(j)

[mg75]

Hi everyone,

Since 2008, ASMEVIIIdiv1 requires that "test pressure and coincident static head acting during the test" is considered in designing a vessel.
I hope I was not the only one to keep an eye on this before code eventually asked for it.
However, div1 does not mention specific acceptance criteria when this case is considered (or I failed to find them out). I mean criteria like those of UG-23(d) when considering a combination including wind or earthquake, or like those of div2 in §4.1.6.2 a)

I am reluctant to believe that Code div1 expects its users to design vessel considering the test case as if it was a mere additional design situation, using the same allowable stresses.

Would anyone complain if we keep, when considering the test case, our own criteria which are S < 90%.Sy, and all joint efficiencies set back to 1 ?

Indeed, we never had any trouble during the hydrotests we performed so far with these criteria. So I am just trying to find some backup literature that would help to keep sceptical queries or obsessive perfectionism at bay, that would require to stick to current limits of UG-23 considering (wrongly ?) that test case falls into one of the "combination(s) of loadings listed in UG-22 that induce primary membrane stress and are expected to occur simultaneously during normal operation of the vessel" (UG-23(c)).

Thanks in advance for your thoughts.

 

[SnTMan]

mg75, I am not aware of any specific allowable stresses for Code hydro, and your 90% yield is widely used. I'm not so sure about setting the efficiencies to one. You might see UG-99(d), which applies the limit of "visible distortion".

Obviously, if back calculating the applied stress at given thickness and hydro pressure, the allowable will need to be increased above the values used for design.

Regards,

Mike