J-T Valve

[dungun]

Hi
In upstream and downtream of 2" JT valves designed with velocities 148ft/sec and 98ft/sec respectively.i.e velocities achieve sub-sonic during full open and sonic while trottling. I think this velocities exceed the vapor velocity limit(acceptable). Anybody can comments??

 

[mucour]

You are right. The velocity exceeds acceptable limit. It shows that the line is undersized carrying more than acceptable. The JT valves trim could also be damaged by the high velocity and turbulence.

 

[dungun]

Mucour
Any article? for reference. Manufacture recomend the size but after installation i suspect the size not correct. Manufacture say its okey!.

 

[mucour]

Let me ask some more questions. Is this the gas velocity in the line? What is the material of the pipe (CS or SS)?. You know the principle of the JT is pressure drop in order for liquid to separate.

The overiding factors to be concerned about in this case are:
1) Noise level
2) Vibration
3) Erosion

The gas velocity will be an issue if we are talking of line velocity (max. 20m/s or 66ft/s). But in the case of pressure drop across a valve, the factors mentioned above shall be the issue to be concerned with.

 

[dungun]

Can be considered as vapor velocity. The line made from SS.

 

[MortenA]

you are not clear if the line is 2" or if its just the valve (and may a short section up/down the valve).

API14E states that velocities above 60 ft/sec should only be considered following through investigation (noise and other subject).

Best regards

Morten