Pressure surge in gas pipe line

[CRG]

Hello,

Have any of you seen calculations for predicting pressure surges in gas pipelines. Known are operating pressure, temp, flow coefficient of valve, time it takes to close valve, etc. What I need to know is what pressure spike is probable with sudden closure of valve (2-8 seconds.

 

[TD2K]

Yes, you can do similar calculations for surge pressures in gas pipelines but they are much, much less than for liquid pipelines.

I've not heard of surge relief facilities on gas pipelines similar to those provided at times for liquid pipelines.

The company I know who does gas analyses is Stoner Associates out of Houston (they may be using another name, not sure) but it was used primarily by gas pipeline companies to manage line pack during increases/decreases in supply/demand.

 

[SooCS]

I have never heard of gas pipeline surge either. But I have heard such a thing a gas pipeline packing,especially if the demand for gas at the downstream end of the pipeline fluctuate from day to night, while the operators prefer to produce at a constant flowrate. Instead of producing at fluctated rates, the operator set the production at some average constant flowrates of the day and night so that during the night when the demand drops, the pipeline is packed with gas to it max allowable operating. As the demand pick up during the day, the additional demand is supply from the packed gas.

 

[davefitz]

The problem is probably similar to "steam hammer" in high pressure power plants. In those cases, steam at 2800 psig in a long ( 200' lg x 20" NPS) pipeline is decelerated due to closure of the steam turbine stop valve, in a closure period of 0.2 sec. The original steam velocity was about 280 fps, and the deceleration of the entire mass of steam in the pipeline ( to zero fpx) causes a large momentum transfer to the piping elbows etc.

A similar problem may exist for long ( 50 mile) compressed natural gas pipelines ( at 900-1200 psig) if a check valve or overpressure stop valve closes ( codes require closure in less than 1 sec)

 

[CRG]

Thanks davefitz,

It is the same problem with different gas properties. Do you know what equations the power generation industry uses to calculate this surge pressure? Is it in B31.1? Any source you can point me towards will be appreciate.

Thanks