Then maybe Brad you need to supply more information about what type valve you have and the service it is seeing. Our crystal balls tend to get real hazy when asked vague questions.
Patricia Lougheed
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vpl: Hello Patricia, I have always appreciated your straightforward and good answers. My crystal ball says: Wenever the enduser or (local) authorities require, most often by reason of (high) pressure class or special service and/or consequences if failing, and tested to the appropriate (local) standard.
Eg.: Another way to say what you already have stated.
Testing is essentially unnecessary. All valves bought to an ASME spec have good impact strength at normal temperatures If you need valves with good low-temp impact strength, buy them as such.
Worldwide seen (not only where ASME might be applicable) special services (for instance turbine inlet valves or other applications for hydroelectric powerplants) might be required by local authorities to be tested to prove high enough strength. Different material strength tests may be required.
Same is certainly true for other services or applications.
In general the rule is as Duwe states, but not always!. And yes: buy after application!
If you are asking about impact testing on off-spec valves, you have to make those decisions yourself. If you buy your valves to an ASTM or ISO spec, you can just look in that spec and see what temperature your valve is good for.
Impact testing is typically related to the valve materials not necessarily the valve.So if your making a valve from an ASTM material that requires Impact testing then the parts made from that material will need impact testing.
I have seen some customer cryogenic valve specs that do have requirements for impact testing assembly welds
For impact testing requirement is relative to standards of construction.
If the standards is ASME VIII Division 1 already used for calculation of valves bodies, refer to fig UCS-66M to check if your material shall be impact tested or not.
Maybe, just maybe, your question is being caused by the European Pressure Equipment Directive (PED). This directive does apply to valves nd has statements and requirements for impact testing materials. But my crystal ball is very hazy at the moment as well.
It is not the valve that needs the impact test but the material of the construction that it is made of. The requirement of impact testing of the material is governed by the design code and the material specification.
One needs to ask the reasoning why materials need impact testing. This will lead one to the requirements.
