Non-return Valve Selection

[ddkm]

What are the key criteria for selection of a non-return valve for the use in a high pressure liquid stream (>45 bar)?

---engineering your life---

 

[JimCasey]

Well, that's on the high end of ANSI 300, as long as your unspecified temperature is still moderate.

Then you will wish to select your material to be compatible with the process fluid.

Determine the type of check, or nonreturn, valve you wish to use:
Ball check
Swing check,
Wafer check
Piston check
GLobe nonreturn valve
there are others.

Specify the connection you need: wafer, flanged, socketweld, NPT, etc,

Does the valve need antislam feature (Spring-loaded closed)

Is the valve to be installed in a horizontal pipe (easiest) or a vertical pipe flowing upwards (more difficult) or a vertical pipe flowing downwards (really difficult)

Must the valve have resilient seats for tight shutoff, or are metal-to-metal seats acceptable?

This ought to get you started.

 

[ddkm]

Jim, thanks.

You mentioned on the type of non-return valve to use. What are the advantages of using a piston type?

The application for my plant is in a horizontal pipe. Resilient seats are expected, rather than metal-to-metal.


---engineering your life---

 

[JimCasey]

A piston check causes a little more pressure loss than a swing check, but it is more positively guided and the spring plus the weight of the piston cause the valve to close as soon as the flow goes to zero-instead of requiring reverse flow to close the valve.

I googled piston check valves and hit this page:

http://www.flowserve.com/eim/Products/Valves/Check/Check-Piston

 

[Ashereng]

Jim,

Can you describe a "globe non-return" valve? Thanks.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JimCasey]

A globe-nonreturn valve looks like a globe valve with a manual handwheel. Internally the valve stem is not coupled to the disc: it can push down only. So when the handwheel is backed off to the open position, the globe nonreturn valve acts as a piston check. When the handwheel is screwed in, the disc is prevented from opening.

I also see this type of valve referred to as a stop-check.

 

[Ashereng]

Thanks.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[ddkm]

What is the selection criteria for type and size of an NRV for general flow?

Example: are these required?
Pressure
Fluid type
etc

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[lastone]

Make very sure that you size the check correctly if you go with a piston check. Make very certain there is zero potential for solids in the process line containing the check, and most of all make sure there is enough momentum in the line you are checking to ensure it remains fully open. There is a considerable amount of DP in a piston check compared to a swing check. We spent major $$'s in a Unit I work in replacing piston checks. I'm not saying never use a piston check. I'm sure there are instances where they work well, but the design should be scrutinized. Make sure you read page 2-7 of Crane 410. I quote, "Sizing of check valves in accordance with the specified minimum velocity for full disc lift will often result in valves smaller in size than the pipe in which they are installed; however, the actual pressure drop will be little, if any, higher than that of a full size valve which is used in other than the wide-open position." I have found the hard way that this is a very wise and true statement. And equally important, make sure that if you are putting in this check for safety reasons or to satisfy a PHA/HAZOP that you put in two in series and put them on an inspection cycle. One check is not reliable enough.

 

[ddkm]

last one,

Thanks for the info. We'll keep that in mind for our application.

But I need to clarify my question. I'm now selecting a check valve for another different application. It's no longer for a high-pressure flow, but for normal flows. We have been using disc-check valves for this, but I was wondering if the disc-check was the correct valve to begin with.

Whether it is or not, therefore my question is on the selection criteria of a check valve. What are the considerations that you would take to decide which type of non-return valves to be used: examples disc-check valve, swing check valves, piston check valves, dual-plate check valves etc.

Also, is there a comprehensive online resource that I can refer regarding this topic?

---engineering your life---