Swing check valve with outside lever & counterweight 2

[JimmyLu]

I will purchase the 42" 150# swing check valve which based on API 6D standard . And the valve need additional outside lever & counterweight .
The question is if API 6D standard allow the outside lever and counterweight on it ??? or another standard or specification can allow it ?

Thanks for the reply and appreciate .

 

[gustorf]

JimmyLu, why don't you look for non-slam nozzle check valves?
They are made to API 6D by for example Mokveld or Noreva without the need for lever & counterweight.
What is the service and purpose of the valve?

 

[stanier]

Counterweighted swing check valves are not really the best if there is a possibility of transients in your system. At 42" the energy dissipated could be disastrous.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[JimmyLu]

Thanks for your reply .

The check valve avoid the oil return when the oil vessel pump the oil to the onshore station .
The operation unit tell me the swing check valve(include counterweight) which is used over 30
years . And the counterweight can be used for confirming the opening angle and reinforcing the seal.

Based on above their requirement .

 

[stanier]

JimmyLu,

Ship's pumps are normally driven by hydraulic pumps that stop almost instantaneously. Unless the ship or shore facilities have surge mitigation measures such as a gas acumulator you could be asking for trouble.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[stanier]

Check out the attached

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[gerhardl]

Stanier: one of the best presentations I have seen regarding check-valves.

JimmyLu: what is the age of the original system? If somewhat old, the valve as originally supplied may not be available today!

Based on what is mentioned in other postings and my personal experience: a swingcheck valve with load could maybe be a sensible choice, but following points (and probably more) should be considered:

a) Price will increase if not commercially ready available. Could be more difficult to get today.
b) Should be avoided if not found as standard item and documented.(Eg if new construction is necessary for added lever and weight, and hence not tested before)
c) Will only work properly if dimensioned correct according to flow. If original works properly, replacement should be identical equal in construction of all properties ( Cv, arm and weightload etc. etc)
d) Dampened start and stop of pumps, and varying load could give problems (swinging) with this type of valve.
b) Loss (here: only used for shorter periodes at a time).
c) If available double eccentric BFL swingcheck could be considered. (Depending on difference to original type)
d) .. and as said: non-slam, nozzle checkvalve is the technical best choice, especially if flow varies.

 

[stanier]

JimmyLu,

I often costed check valves for projects up to DN3000. My realisation is that a swing check valve, with hydraulic dampener to prevent check valve slam, guard to protect operators from the swinging counter weight and counter weight and arm cost more than a reasonable non slam valve such as by Noreva.

http://www.noreva.de.

On top of this there is the risk that the hydraulic dampener will not be maintained and a catastrophe could occur due to waterhammer. Nineteen people died in a pump room in Canada due to a failure caused by waterhammer. The pipe burst and the pump room flooded. Unfortunately the pumps were being inspected at the time. Would you like that on your conscience or a lawyer standing outside your house demanding the deeds?

If you want to read more on check valves get hold of papers by Delft laboratories or Utah University. Also look into the nuclear regulatory approved check valve lists. Some dual plate check valves were banned because of failures. I do not know of swing check valves being used in that industry.

Also ARD Thorley's book Fluid Transients in Pipeline Systems or Ellis's Pressure Transients in Water Engineering covers their dynamic performance quite well. Professor Thorley describes swing check valves as "agricututral at best". Take heed.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[JimmyLu]

To gerhardl : The old system has used over 30 years .As you say , the old design had not
existed. And API 6D appears not to include with counterweight of swing check valve.
I will communicate with operation unit about the standard applicability of the \
valve.
Thanks for your good suggestions .

To stanier : Thanks for your great help and the good presentation.
Based on your practical suggestion , I will estimate the applicability of the swing
check valve with counterweight . And consider the other check valve you suggest.

 

[hsbcn]

Whilst you're at it, have a look at Crane's Compac Nozzle Check valves; not the cheapest in the market, but they don't work with (or need counterweights).

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.

 

[siavash1111]

lever & counterweight are part of the locking device for the check valve API 6D mentioned that “Locking devices for check valves shall be designed to lock the valve in the open position only” . I have seen some valve manufacture products like TOM WHEATLEY, VITS , GROVE… which install in pipeline . the lever or gear operator use to open the check valve for reverse flow or reverse pigging operation . I have attached TOM WHEATLEY swing type check valve, you can see the application of the locking device in page 12 .

 

[stanier]

siavash111,

Using a locking lever for maintenance purposes might be useful but if the adoption of a swing check valve causes waterhammer what is the benefit? A more professiona approach would be to have an isolate=ion valve in line that is shut. An isolated bypass would contain the non slam check valve. The check valve would be in the normally open stream. This would be isolated should the pipeline need to be pigged or the check valve mainatined.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/