Body Bleed Valve

[gazepdapi]

I was wondering what kind of valve would you guys recommend for body bleeds on large valves (ANSI 600 and 900). Currently we have been using WKM's and Balon but they seem to leak over time, which makes it dangerous for operations to remove bull plugs on the end of these valves. Any valves that you guys have good experience with?

 

[zdas04]

Both WKM and Balon are designed for the price-conscience market. That market only considers purchase price, not life cycle costs. I have had to blow down a half million dollars worth of gas because a "cheep" valve failed and saving that $300 looked a lot less attractive. But the industry keeps on doing it. Over and Over again.

When I specify valves I always specify PBV from Zytec. I've had consistent, very good experience with them. I've probably spent something like $20 million there and only had one valve that didn't perform to specs (for some reason the operating torque on a 16" valve was an order of magnitude higher than the spec). They offered to replace it, but it was already in service and I didn't want to blow the line back down. I replaced the actuator with one that my actuator guy said "sits in one place and it rotates the earth". It passed every ESD test for 10 years. I always wondered what was wrong with it. The station has since been deactivated and the valve (and actuator) are still sitting on the site, but no one at the company I used to work for has much interest in forensics.

There are other good valves, but they are all more expensive than you've been using.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[gazepdapi]

Well the valve that I'm looking for are small size, 1"-2" and will have a high differential across them. (Sometimes as high as 2000 PSIG). I will give them a look.

 

[zdas04]

I've used 2-inch trunion ball valves, but never 1-inch. The 2-inch I've purchased have been PBV. In 1-inch I'd almost prefer to put two threaded floating-ball valves with a bleed between them.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[gazepdapi]

Well this would be a floating ball valve instead of trunion.....although come to think of it trunion might be the way to go to prevent damaging the seat.

 

[zdas04]

How are you going to put a body bleed on a floating ball valve? Are you sure you know what your needs are?

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[gazepdapi]

No the valve (1") will be on the body bleed of a much larger valve.

 

[tr1ntx]

Balon, for some reason, has a high reputation. To say they "all leak" is surely a bit of hyperbole, but only a bit. I've seen hundreds of their small ball valves leak. There is not many more than a handful which, after a decent time in service, I've seen that didn't leak. Their salesmen have managed to convince industry that "all small valves leak eventually".

WKM, well that operation is now full of corporate weenies, with desk jockey geek engineers that don't know jack about manufacturing. They may have a superior, perfectly correct design, but just can't make it correctly. Or the corporate bean counter weenies may have induced design changes to reduced cost.

 

[bcd]

I recommend you understand the reason why these valves are leaking to ensure you find a solution rather than take a "shot on the dark" approach. You want to solve the problem the first attempt?

For example, soft seated floating ball valves are notorious for low pressure leakage after being exposed to high pressure for an extended period of time. Are these valves leaking at high pressure or low pressure? My point is you may be dealing with an issue inherent to soft seated floating ball valves so a switch to trunion or gate valve may be the best choice. But if the valves are leaking because of damaged seats, which is not unusual because body cavities can collect rust and debris which then passes through the drain, then you should be looking for harder seat materials.

Once you know the reason, you can test your options and prove your solution will work and verify the solution is commercially viable.

 

[gerhardl]

bcd just gave you the answer above, and I totally agree.

If you compare your problem to bypass valves used for high pressure water in hydroelectric high- fall plants, used to prefill before main valve opens, you will find quite similar problems to what you and bcd describes.

From old (fifty years or more ago) trunnion mounted ball-valves in small sizes where used, and are still described and required. This has however become an increasing problem as commercial available good constructed small trunnion mounted ballvalves have been more difficult to obtain.

f you are aiming for long-life solution (note. in this area) the obvious replacement, if trunnioin mounted high-qualty is not available is good constructed globevalves allowed for the given delta p conditions, or double eccentric (and trunnion mounted) ball-valves if available in the given dimension (mostly available from 2 inch and up).

 

[gazepdapi]

well these valve see very high differential when opened and they leak at high pressure

 

[hsbcn]

What seat material do you have in the valves?

My focus is on valve stockists in the us and uk who supply duplex and super duplex valves, and inconel and hastelloy valves, plus titanium, alloy 20 and 904L valves.