Check Valve Flapper Failure 1

[SV855]

I have come across frequent flapper (disc) failures on swing type check valves. The service in the flow line is oil+water mixture and the pressure is generally in the range of 30-40 psig. I assume the failure is due to pressure variations in the line and the continuous disc movement due to it. This is happening on multiple flow lines and recurring as well. Can someone kindly advise the solution to overcome this? Change the check valve type maybe?

Thanks.

 

[hydtools]

Likely more flow reversals and closure speeds causing failure.

Ted

 

[LittleInch]

Non return or check valves are not really designed to work in transient manner or indeed activate more than a few times. The dynamic forces from a transient revers flow are huge.

If you're getting multiple reverse flows then you need soft closure valves or more pressure dampers. Neither are cheap

Can you describe the operation a bit more?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SV855]

Thanks guys. Looks like corrosion is also a major factor in this. Inspected a flapper that was broken from the hinge pin. Looks like corrosion is affecting the smaller parts like pin causing it to break. These are flow lines from high water cut wells and also only intermittent flow. So this might result in water accumulation in the lines accelerating corrosion. So I guess a combination of flow issue + corrosion is the cause for failure.

Appreciate your inputs. TA.

 

[gerhardl]

Check-valves will often (ref. Littleinch) cause problems with varying flowrates. To low rates will create pulses and slam/chattering effects. Even worse are the water-hammer effect if it occurs. Pins breaking indicates both excessive mechanical forces and corrosion

The quality and type of valves should always depend on cost over expected lifetime. How long do you want the valves/piping system to run without trouble and maintenance cost? Seen this way a non slam (soft closing) valve could be best and cheapest solution.

Other solutions (depending on size) is SS non-return disc valves (no hinge on these) for smaller sizes, or sigel or double flap with or without return spring,or weighted valves in SS,rubber coated or wirh high quality coating.

 

[mk3223]

May need to clearly identify root causes of the damaged valve for a real solution to resolve the issue.
First, if the broken pin caused by the corrosion, it can be solve by replacing it with a right material. Was it the only damage on the failed valve?
Second, are the flow lines occurred related to the failed valve or something else?

 

[SV855]

Thanks guys. Looks like an upgrade in material is the way forward.

 

[gerhardl]

Thank you for your clarification. Without flow detailed and a detailed piping diagram with all data/details it is difficult to comment further.

Two remarks: Ball checkvalves might be easy to inspect and cleaned, but are perhaps even more inclined to give chattering and waterhammer than swingcheck valves, unless very precisely dimensioned and used within the designed limits of flow.

Checkvalves might cause problems unless placed with a free straight line of 3-5 valve lengths before the valve after other pipeline components (bends, pumps, valves etc.)

I assume this is taken care of in the design.

 

[SJones]

There might also be a fatigue element to the failure, so changing the material could address the corrosion, but the fatigue damage mechanism will still be in play.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[SV855]

Yes, we are considering whether to change the type as well. Tilting disc check valve, dual plate type etc.

Thanks.

 

[LittleInch]

SV855,

You're missing the point. Check valve failure like this is due to sudden reverse flow on multiple occasions. Any type of check valve will fail under these conditions unless it is soft close and they are not cheap.

Solve the flow issue or work out how to stop the flow gradually by e.g. closing an isolation valve before turning the pump off or slowly reducing flow using a control valve.

Check valves are there to prevent reverse flow only when the fluid flow is stationary. Rapid changes will just continue to destroy valves and lead to reverse flow when you don't want it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SV855]

Points well noted. Thanks.

 

[Compositepro]

Spring loaded check valves generally close before flow reverses and thus prevent water-hammer. They may also have a greater forward pressure drop.