TESTING OF DUAL CERTIFICATION F316/F316L. 1

[N AHMAD]

Hi,

We have an valve requirement of Dual material grade with CF8M/CF3M, when we do pressure testing for this valve, as per API 598 shell test shall be 1.5 times of maximum allowable pressure at 38 °C (100 °F)and seat test shall be 1.1 times of maximum allowable pressure at 38 °C (100 °F).

When we refer to ASME B16.34, for CF8M material testing pressure is high compare to CF3M,what is the test pressure can be use to test these valves.

 

[EdStainless]

Since dual cert it must be based on the stronger of the two, since that is what you are claiming.

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P.E. Metallurgy, consulting work welcomed

 

[N AHMAD]

Thank you for the response, But i can't able to find it in any standard that for dual grade we have to go for higher test pressure,

Please advise the standard reference if any.

 

[EdStainless]

There are two cases, and it rests on design and intent.
1. The design is based on dual cert and material is deliberately ordered as dual cert. In this case you presume that the higher strength was used in design and therefore must be used in testing. This should be your default assumption unless someone can show you documentation otherwise.
2. The design is based on L grade and the orders call out L grade, you just take dual cert out of convenience. In this case the design is based on the lower strength and the material should only be described (certified) as L grade, and the test pressure should be based on this lower value.

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P.E. Metallurgy, consulting work welcomed

 

[N AHMAD]

Thank you for the response.