14 replies to this topic

[cnpyprojengr]

Has any one encountered the problem given below? Any feed back will be highly appreciated.

There has been many failures on the gate valves and check valves

Gate valve; Gate comes loose from stem
Check Valve; Flappers become dislodged from valve body

Service: Produced water
Operating Temp : 38C
Operating Pressure : 4.5 Kg/Cm2
Design Temperature : 71C
Design Pressure : 8 Kg/Cm2

Valves rating 150 Material Carbon Steel

[joesteam]

You do not have severe service here. I would look first at two potential causes:

Waterhammer - if you have this it could cause lots of problems with valves in the system. Do not look for valves that can withstand water hammer, but rather find the root cause and fix it.

Valves: You may have a particularly bad valve, or a bad run of valves. Are these from different manufacturers or are they various?

[djack77494]

In addition, you should look into the corrosiveness of your produced water. What comes out of the ground in one place may be vastly different from what is produced in another location. This makes it very difficult to generalize. Some produced waters are very corrosive. It should not be very difficult to examine your valves and determine whether your problems were caused by corrosion, erosion, or other causes. Good luck.

[JoeWong]

Where does the produced water come from and where does it goes ?

A few issues could be :

i) Corrosive component i.e CO2, H2S, etc
ii) Erosive component i.e. solid, sand, sludge, etc
iii) Gas and HC condensate passing
iv) High velocity passing

[Qalander (Chem)]

Where does the produced water come from and where does it goes ?

A few issues could be :

i) Corrosive component i.e CO2, H2S, etc
ii) Erosive component i.e. solid, sand, sludge, etc
iii) Gas and HC condensate passing
iv) High velocity passing

Few suggestions;
1) Have any corroded components analyzed? if not they should be analyzed to know the main corrosion products at the worst affected locations.
2) If any of such above identified causes by our JoeWong,Doug are ruled out; then Most probably the material defect/suitabilty for service or Bad batch(as identified by Joesteam) remain probable one's I believe.
Best regards
Qalander

[Rama]

If you rule out all the possible causes mentioned by other members, (I suspect that to be the case), I would suggest that you dismantle the valve and examine where the failure has occurred. Most probably it could be the little pin holding the square nut on the gate – in case it is a rising spindle valve. Or similar part in the case of rising gate type valve.

In most cases we have found the cause to be poor design/ quality of the valve by the manufacturer. This is the case when your purchase department goes for the L1 (lowest) bid. We solved the problem by stringent check of the valve manufacturers’ credentials and listing out ‘preferred manufacturers/ suppliers’. Going for reputed manufacturers, often saves costly down time and ensures that they stand by their guarantee.

[Andrei]

Where I work people are using usually minimum 300# rating. It is something related to what Rama was mentioning, 150# rating is not suitable for industrial use, especially oil&gas.
We, as designers were pushed by the clients to use minimum 300# rating, they had some bad experiences with lower ratings.

[JoeWong]

Andrei,
Some questions...

The Service: Produced water
Operating Temp : 38C
Operating Pressure : 4.5 Kg/Cm2
Design Temperature : 71C
Design Pressure : 8 Kg/Cm2

Valves rating 150 Material Carbon Steel

The design condition demand for 150#. Any specific reason you need to go for 300# ?

[Andrei]

Joe,

There is no process requirement not so ever. It is only from a reliability stand point. Again, it was an operator request, and it's not a rule.
Cost wise is probably cheaper to have all the fittings 300# than keep fixing some failing 150# ones, I never did the math. There were clients that said they've replaced all 150# fittings to get rid of the problems.

[JoeWong]

Andrei,
Ah...OK...That's what i guess...

Thanks for your explanation.

[Rama]

The solution suggested by Andrei is what many follow to increase the reliability of the valves. I have found it reduces down time too.

[cnpyprojengr]

The solution suggested by Andrei is what many follow to increase the reliability of the valves. I have found it reduces down time too.

Discharge flow is 3000 US GPM; valve size is 12" and dicharge line goes to 24" header. These valves are subject to high velocity and causing failure?

[Art Montemayor]

The stated problems are defined as:

Gate valve; Gate comes loose from stem
Check Valve; Flappers become dislodged from valve body

The question was:
Has any one encountered the problem given below? Any feed back will be highly appreciated.

In the course of 48 years, I have had many failures of both gate valves and check valves - each of 150# or 300# service ratings. It is a simple engineering error and overly simplistic explanation to assert or insinuate that 300# valves will function with more robustness or "toughness" than 150# ones. This is a wrong analysis that has no logic.

It is the QUALITY of what you buy (or your purchasing department buys) that has something to do with the quality of what you install and operate. The internal design, casting, forging, machining, and assembly of the valves has ALL to do with the resultant quality of the product - whether it is 150# or 300#.

I would not purchase a gate or check valve designed and fabricated in China at this time unless I had certification that it was totally fabricated AND inspected to the standards and specifications that I am familiar to - not to local Chinese standards that I am unfamiliar with and have no control over. I apply the same purchasing decision to everything I buy - regardless of where it is fabricated.

Quality is the underlying reason for the success of operating equipment and if you don't insist on it and demand it, the results are usually bad.

[Rama]

Dear Friend,

At 3000 US GPM, your velocity (more than 8.5 fps) is rather on the high side. However, if the length of the 12" pipe up to the 24" header is not much, it is quite acceptable. Is the valve close to the 24" header? Is there any gas entrapped in the produced water? Is there a possibility of a two phase flow?

Normally, the gate valve is used in fully closed or fully open position only. It is not recommended for use in controlling the flow. I have, however, come across several instances of gate valves being used to throttle the flow. This can also cause frequent failure of the valve especially when subjected to high velocity flows – more so if the quality is questionable. As I had suggested earlier, could you dismantle the valve for investigating the cause?

If you think I am not inquisitive could you please let me know the manufacturer of the valve, type of valve (rising spindle or rising gate) etc.? I would like to see if I can get a cross section of the valve from the manufacturer’s website. Some details of the industry / country you are working in etc. would help too.

Thanks.

[djack77494]

Essentially reiterating what was said above, check into the possibility of corrosion or erosion related problems. Demand high quality valves. Do not use the valves in ways they were not intended; e.g. throttling with gate valves. 150# or 300# rating only matters at the flanges. Examine the failed valves-much can be found out here.