Wellhead Choke Valves

[Johnrem]

Good morning;

I'm about to design piping system inside oil production wellhead. Around 5 meters from Xmass tree I'll arrange a choke valve. My concerns is dealing with supporting this choke valve. I'd like to know if choke valve behavior is same as PSV.
PSV need its connected pipe to be rigidly fixed to balance the reaction force generated when PSV spits.
Is reaction force generated when we operate a choke valve? Is vibration an intinsic problem of choke valves?

Thank every body

 

[BigInch]

Vibrations are not intrinsic, but certainly possible enough to prepare for it. They can be avoided by proper sizing and keeping velocities low and away from resonant pipe frequencies.

Partially open or closed valves can cause increased pipe stresses. In a poor configuration, the pipe can deflect with those added stresses. Those stresses plus weight of the valve may require support. 5 meters is usually a pretty long way without any support in any case. Do yourself and your boss a favor and put a support near the valve. Let somebody else take it out.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/

 

[Johnrem]

We provide support just before the choke valve, but the question is dealin with type of support to provide: anchor? guides? Stopper?...etc.

 

[BigInch]

Theoretically it shouldn't be acting like a relief valve or vent with a high dynamic thrust, so unless you're going to operate the chokes very fast, doubtful, just a vertical support is all that is usually needed. Forces due to changing flow direction, or forces generated by slowly opening/closing valves can typically be handled by the pipe steel alone.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/

 

[Johnrem]

BigInch;

Many thanks.
Yes, this is generally the practice of supporting the choke valve (vertical support only). But in some cases, vibrations occurs at the vicinity of choke valve and may need a fixation.
Vibrations are may be caused by slug flow. What do you think?

 

[BigInch]

If vibrations are more or less constant, I'd first think its a high velocity through the valve plus perhaps a pipe resonant frequency problem. If they are intermitant and tend towards the violent side, slugging seems more probable.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/

 

[C2it]

The nature of a wellhead choke valve is to regulate flow, and thus velocity, with a small variable port, and usually a needle. Consequently there will always be the potential for flow induced noise and vibration where high pressures and pressure drops are involved. Also there is the risk of two phase flow and flashing at the valve. The difficulty of dealing with this in service makes it worthwhile taking preventative action in design. Best practice is to support, stop and guide, or 'anchor' the pipe local to the valve. To reduce structure-borne noise, an acoustic insert may be used.