API 6A (pressure rating design)

[mustafa2014]

Dear all,

good day, i am working now in a subsea project our requirement were gate valves 2 & 4" gate valves with pressure class rating 10000 psi as per ISO 10423. Our vender proposed valves as per API 6A with expectations on pressure rating which is 7500ps. THE API 6A is not stated in API 6A , there are 10000 & 5000 psi.

My question is , is the different pressure rating influence the design variables: or the temperature ,the material selection and the stress limit calculations for materials are obtained independently from the design pressure (e.g .:fora 5k psi or a 10k psi the temperature
rating ,the material selection and the allowable stresses does not change ,as the related
formulas to calculate them ).

this task is quit urgent please

 

[yudhichen]

API Spec 6A (20th Ed) clause 4.2.1.1 clearly mention working pressure at 2k, 3k, 5k, 10k, 15k, & 20k.
Any working pressure other than those mention regarded as non-API monogram.
Vendor might supply API 6A valve with pressure rating other than above mention provided their valve in non-API monogram & tested to be qualify at those unique pressure rating.

Based on API 6A Table 5 & 6, different (working) pressure rating shall determine allowed material designation with certain material property requirement. Hence, it will affect stress limit calculation.

Pressure & temperature rating are independent variable. Both parameter with environment consideration (material class) shall define material selection with certain property requirement.