Design Specification for 1/2" - 11/2" Ball Valves

[piperUK]

Dear Forum,

I'd appreciate others opinion/guidance on the following:

I've been asked to carry out some amendments to a technical specification for ball valves and one of the issues is that the spec calls for DN15 - DN40 Class 900/1500 flanged valves to be in accordance with BS EN ISO 17292 / API 608. However, as BS EN ISO 17292 only covers classes up to 600# & API 608 up to 300# the specification is wrong.

The valves can be trunnion mounted or seat supported, one piece or split body, full or reduced bore.

I'm not sure what to specify - Although API 6D covers the sizes/classes (and has three piece and welded body designs) when I review Vendor catalogs the Vendors do not generally quote the sizes required (usually DN50 and above).

Am I right to just correct the design spec to API 6D or am I creating a problem for future valve procurement? Have I missed a more suitable BS EN ISO / API standard to specify?

Any help would be much appreciated.

 

[gerhardl]

Such 'faults' in specifications as you mention is not uncommon. The result is (if this is a widely or commonly used specification) that there often is a common 'branch understanding' or 'suppliers understanding' of what is actually the 'common practice' or 'allowed or commonly or earlier supplied' to the end user, but without any written exact specification.

In this way it is fairly impossible to amend or correct any specification before the end user actually makes quite clear what he is accepting and expect as norm and specification for the different class and types of valves for different purposes.

The wish is sometimes to select to specify or include certain qualities in certain specifications (but not all), even if the specification is not valid for the pressure class or size. Then it is of course better to state exact what is wished.

At other times a company specification may be outdated in such a way that it excludes newer and better constructions materials or practise.

Conclusion:

A valve specification has to include all necessary specifications to satisfy end user and local authorities in quality, performance and safety aspects. This is actually what should be revised before any specification is revised.

At the same time the specification (or inquiries for procurement) should open for newer constructions, product developments and not exclude alternative bids at higher quality, better materials or longer lifetime than minimum.

Alas, from my experience, you will not be popular if you kick the ball back (excuse me for the pun!) to the upper management. Good luck!

 

[PeterIgg]

I would suggest that you consider ASME B16.34 as the driving specification for this size and class. API 6D is not incorrect, but such small lines hardly qualify as 'Gas Transmission Pipelines'.