three pieces valves 2

[emadelmahdy]

three pieces valves (bolts b7) at design temperature 410°c has been rejected by our client due to ASME b16.5 which confirm that the maximum temperature can be used in bolted joints are 400°c, there is any code allow us to use this three pieces valves

 

[LittleInch]

Where has 400c come from? The only reference I can find in 16.5 is a guidance note in 2.5.2, but it is not a maximum.

A similar warning note appears in B 16.34 (2.3.1) which is more relevant, which has no upper number.

Both specs depend on the material used, but go up to 538C

using a bolted valve for this temperature would seem to be problematic, as external load capacity is reduced and leakage could more easily occur. However the 400c limit is a guide only as afar as I can see so therefore ASME B 16.5 and 16.34 are valid up to 538C

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[emadelmahdy]

as per ASME B16.5 item 2.5.2 that at temperature above 400°c for class above 150 flanged joints may develop leakage.

 

[emadelmahdy]

ASME B16.5 item 2.5.2 confirm that for class above 150 the flanged joints may develop leakage at temperature above 400°c

 

[LittleInch]

I know that - the point is the wording is "may". It then goes onto say "unless care is taken to avoid imposing severe external loads, severe thermal gradients, or both."

Hence there is no prohibition and in any case limits like this make no real sense. Why would it be ok at 399 C and not Ok at 401 C. However we engineers like strict limits, but in this case the "limit" is for guidance only and so long as the vendor can demonstrate that the valve will be good at 410C, then there is noting to prevent the valve from being used.

Personally I would insist on an all welded valve at that temperature as the possibility of leakage from bolted joints would increase to a level I wouldn't personally like, but this is not my decision. You can't though hang any rejection of the valve on the ASME code.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.