Reciprocating Compressor Valves Reliability

Several keys to valve reliability:

1) Measure and understand the pulsation characteristics of the machine and design the valve appropriately to eliminate over travel and flutter.

2) Select the proper lift and spring K for the conditions (and if conditions change over time retrofit lift and spring K).

3) Understand the service, if there are contaminants that go through the valve, use a poppet or a moppet. If the service is clean a plate valve is fine.

4) Lubrication rate is important. Spend some time and effort to optimize lube rates.

5) Monitoring valve temps is ok to get early indication of a failure, but won't improve reliability much. Regular PV analysis will give you the proper data to optimize valve design.

6) Liquids kill valves, make sure you have proper KO and heat tracing on the suction, and proper alarms on KO drum level to prevent carry over.

7) Contaminants in the gas do too. If contamination damage is occurring consider cyclone filters or other devices to clean up the gas.

8) Keep your cylinders cool, dry, and well lubricated...

First thanks for comments. I like to add more information about the compressors in discution:

1.No problem with pulsation.

2.The VDA for valves is done and the valves are proposed by compressor manufacturer.

3.The service is not so clean, in present we are using poppet and intend to change to moppet.

4. The compressor are lube oil free lubrication.

5. Each discharge valve has temperature monitor sensor with indication in DCS.

6. Suction drum of each compressor has liquid level protection with alarm and trip action.

7. Suction drums have demisters installed, and more the temporary strainers for start-up stage are kept on the position.

8. Cooling system are operating at 5-6 deg. C more than suction gas temperature to avoid liquid producing from handled gas, and as I stated before is lube oil free.

Using this key words you may find searching by google a very interesting document about reciprocating valves reliability: <<Compressor Optimisation Conference CO 2007 Organizer: ESD Simulation Aberdeen 30-31 January 2007 >>.

Filters are always a help but can cause problems if the gas is dirty. The composition of your gas looks like most H2 process gas.

What is your current valve MTBF and what would you like to extend it to.

Is there any pattern to your failures. Has there always been a valve problem from start up or is this a new problem. Has the process changed in any.

Do the suction or delivery valves show most failures. Describe the failures. Do the inboard or outboard valves fail more often.

What unloading do you use.

What startup gas do you use and for how long.

What valve spring and plate materials are in use.

If you are currently using plate valves and it is process gas dirt/liquid that is causing breakage then the Moppet valve may give you an improved MTBF but get a guarantee, no cure no pay.

Standard radius disc valves have a proven track record when it comes to being capable of working well in dirty gas. Supply of this type of valve is from Cook Manley in the US or CPI in UK.

If the supplier is sure he can fix your problem, he should be prepaired to to offer you a guarantee. Its a buyers market!

There was mention of heat tracing on the compressor suction. Is this necessary?

Also, how critical is it to keep the water temperature warmer than the inlet gas temperature?

I understand what API 618 states. However, if I have a cylinder full of gas, could I actually fail a piston simply due to too cold a jacketwater (i.e. my process simulator indicates that will minimal cooling I will get droplets of water but not a cylinder full)?

I do have valve life issues (valves last about 6 months in clean gas). Valves are standard plate valves.

My gas is 0.68 gravity natural gas in the North Sea. I am troubleshooting some rod and piston failures (repeated) and researching.

Hello

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