I'm trying to source a valve for a hydropower station, with 700m head and 5cms flow (1000psi, 80,000gpm) and the water is fairly silty. The original was a trunion mounted ball valve, and the supplier was bought out by another manufacturer, who I've requested a quote from already.

The plant manager's preferred vendor, who I normally trust, has given him a quote for a fairly inexpensive chinese ball valve, made to API 6D, also trunion mounted, with retractable seats.  On paper looks ok, not great, and the company seems to have very minimal experience in hydropower.

Can anyone recommend another source for a DN800/PN100 ball valve, or tell me if they have experience using API-6D valves in water service?

Roughly 80% of API-6D certified ball valve suppliers are in China or India.  Its where you will find the least expensive unit.  However, if there is a problem, good luck in getting it fixed unless they have strong local support.

If you contact some of the big names in the valve business (Cameron, Tyco, Velan, Flowserve, etc.) you should get both the product you need with proven experience as well as service after the sale in case you need it.

You're talking about an ANSI Class 600 equivalent valve (1440 psi rated pressure [1014m]).

FWIW, a Class 400 is rated for 960 psi [676m].  There is no Class 500, and actually Class 400 is rarely seen.  A lot of companies offer 150, 300, 600, 900, etc.

But back to the point . . . I wouldn't worry about getting an API 6D conforming valve.  There are plenty of water valves out there, and you don't want to pay for meeting oilfield requirements unnecessarily.  If you don't want to use a Chinese or Indian made valve (and I don't blame you), you might have a hard time finding a low-priced, general service water valve.

There is a company in Italy that makes large diameter ball valves, but it was bought by an Indian company (Virgo) several years ago, so they might have discontinued the Italian manufacturing.  There used to be a manufacturer in Brazil, but that was quite a few years ago.  ViNtrol in Oklahoma City sells the Virgo valves under their name, or you could contact Virgo Engineers in Houston directly, but they're amateurish to deal with.  Maybe a search for "Virgo Italy" will get you the name of the Italian operation.

I can't recall any other valve company names in the US, Canada, or England which might actually make the valves themselves.  A lot of them import parts from China or India and just do final assembly, at best.  On one that large, they probably import the complete unit.

It's the design requirements that make this one expensive.  It has to have retractable seats, hydraulically operated with water pressure to seat and retract.  It has to close under full flow.  It has to be certified dead-end service.  It has to fit into the same envelope the other one was in.  It's the main valve into the plant power system, so it has a pretty important job.  The temp and pressure ratings are not all that unique.  But they are combined with the size!

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