API drift test ball valves

[JonGD]

Hi Guys,


I have a question about drift testing for API valves to which I think I know the answer, but would like to check.

From what I understand a drift test is essentially to ensure through any piping/valve system the full bore of the pipe is maintained.

Therefore by the very nature of a control/choke valve, with it's more complex internals and changes of flow direction (e.g.

http://www.severnglocon.com/severn-glocon-products.aspx#ArticleId10),

this test does not - even cannot - apply.

Am I correct in this supposition?


Thanks in advance,


Jon

 

[gerhardl]

It is very common in any technical branch to use a form of 'short hand description' and abbreviation in describing technical matters.

However, any test description for a test to be done in actuality, must be described exactly and in detail. This can be a 'standard' text issued as an official norm or by a certified institution, or by the party requiring the test, with precise description on how this should be done and understood.

It seems to me that the detailed instructions are missing here and that your customer / enduser / the party demanding the test (??????) has not referred to a complete description in writing?

With this in place you should be able to get your exact answer or rephrase your question with reference to the relevant text.