Esteemed experts,
I need a piece of information, please.
Which is the right allowable to check hoop stress at hydrotest condition per ASME B 31.3?
Minimum yield strength Sy or cold allowable Sc?
Thanks.
Best regards

Alessio

There is no "official" check for hoop stress in B31.3. Hoop stress is managed through the wall thickness "rule".
Also, B31.3 states that the test pressure should be limited so that it does not exceed the lesser of the yield strength or 1.5 times the component rating at test temperature.
I would say your value is Sy.
CAESAR II has a hydro case and, by default, the allowable (Longitudinal & Shear) stress limit is Sy.

Hi,

its true that allowable stress in hydrotest is not clearly stated in B31.3.
It used to be 0.9Sy (by analogy with B31.1 i assume) are you sure it's now Sy ?
do you know when or why the change ?

thanks for the clarification

Alcor,

You are entirely wrong.
Read again and carefully ASME B31.3 Code, Para. 345.2.1(a) / "Testing / General Requirements for Leak Tests / Limitations on Pressure / Reduced Test Pressure":

<< If the test pressure would produce a circumferential or longitudinal stress (based on minimum pipe wall thickness) in excess of yield strength at test temperature or is greater than 1.5 times the component rating at test temperature, the test pressure may be reduced to the maximum pressure that will not exceed the lesser of the yield strength or 1.5 times a component rating at test temperature.>>

B31.3 and B31.1 have different requirements for pipe stress limitation under Hydrotest Conditions. Caesar II stress compliance checks are set accordingly. Just follow them (if you do not have direct access to B31 Codes) and avoid speculations.

Dorin,

thxs for your answer.
my understanding is that allowable stress in hydrotest is Sy, as per B31.3 section 345.2.1(a)
althought the formulation of that paragraph could have been clearer.