Natural gas pipeline velocity

[RGME]

Hello all,

I have a situation where the mainline block valve in a 36" natural gas pipeline is closed for a period of time. During this time, the pressures on either side of the valve drift apart. e.g. Upstream pressure = 800psig. Downstream = 600psig. If the mainline valve is now opened what is the maximum gas flow rate across the valve? What would be the best equation to use to estimate this?

Also, what is a good rule of thumb to use for maximum allowable gas velocities in the pipeline? I have read in many cases that 100ft/sec should not be exceeded, but I believe this is to avoid excessive noise. Is this true?

Thanks

 

[BigInch]

Velocity limits depend on where you are. Usually there is nothing wrong with high velocities over small distances in a station, its just that they add up to unmanageable pressure drops if you try to do the same thing out on a long pipeline, or if your line is dirty, you might increase sand abbrasion on the interior. Limiting velocities to not "strip corrosion inhibitor" doesn't ring as I have always found higher velocities are good for anti-corrosion work as,
1.they keep the line clean
2. they keep the inhibitor well distributed on all interior surfaces of the pipe and not just running along the bottom,
3. they keep any water and other crud moving and from collecting at pipeline low spots.