Butterfly valve downstream of a check valve, will it work.

[NewfieEng]

I am laying out some additons to a existing Natrural Gas compressor station and I am tight on space. To save space I am trying to put a butterfly valve directly downstream of a wheatly swing check valve. Both valves are 20" ANSI 300#. I am worried that when the butterfly vavle is fully open it will interfere with the operation of the swing check.

Does anyone know if there will be interfereance with these types of valve? OR has anyone seen these types of valves in this combination?

 

[JimCasey]

There's mechanical interference, and Dynamic interference. Downstream of a swing-check the flow distribution is going to be both turbulent and distorted. It's really going to beat on the butterfly valve. Even if the pieces do not collide with teach other, I'm thinking this is not a very good application. It would probably be better, if the butterfly valve is used for on-off, to place the butterfly UPSTREAM of the check valve. The check valve parts will move AWAY from the butterfly, and the butterfly vane will act as a straightening vane for the check valve when the BFV is in the wide-open position.

 

[gustorf]

If there is no mechanical interference you may use a nozzle check valve instead of the swing check. They are in operation in compressor stations directly upstream of butterfly valves for decades.
Their streamlined flow pathes prevent turbular flow and do not harm the butterfly.
Additionally they show low pressure losses and non-slamming performance.
Have a look at

http://www.noreva.de

 

[1969grad]

If you have a recip type compressor then a swing type check valve is a bad choice because of the pulsations. A better choice is the piston type like Daniel makes or a nozzle check by Mokveld (spelling ?) as previously suggested.

BTW, I do not think I could sleep at night if I used a butterfly valve for a unit block valve. My choice would be a ball valve with a backup sealant injection system as this valve absolutely, positively has to shutoff.

You should also take into consideration that the unit piping in a compressor station is normally blown down after a period of time after the unit is shutdown.

 

[stewbaby]

From the maintenance point of view I have to agree on Daniels piston check...a swing check, especially downstream of recip machines is a bad idea unless you just love R&M work orders and like hearing clank, clank, clank all day long.

Also agree with 1969grad on isolation choice...although the butterfly will work it is a bad choice for what we know of your application...if positive isolation is needed and differential pressure on closed valve is high I recommned Orbit Valves by Cooper Cameron.

 

[BSQUAREDBUCKEYE]

Tweedie,

Your conbination of swing check valve and then butterfly valve would warrant a call to the manufacturers for more specific dimensions on the check valve outlet and the distance of the BFV disc protuding into the upstream piping.

One thing I didn't see anyone mention is the valve orientation. It would be advised to have the BFV shaft be perpendictular, not parallel to the check valve's hinge. Asymetrical flow patterns generated by the swing check could effect the BFV.

If this is a critical isolation valve I would agree with 1996grad on the ball valve with sealant injection system. WOM has a new valve with DOUBLE seats on both sides. This is new concept in ball valves done in gate valves for years in natural gas ie General Twinseal. To make up the longer face to face than the BFV, use a DFT in-line check valve like the WLC. These guys claim to be "Check Valve Doctors". If you give them the process conditions they will size the valve and install a travel stop that will prevent the valve from beating it self to death.

http://www.womusa.com/

http://www.dft-valves.com/