How to rapidly depressurise and oil pipeline?

[mch22112]

Hello all,
I am dealing with a long distance, large diameter oil pipeline. It has two pump station (at the start and mid-point), and typical block valve stations along the route. What is the fastest way to depressurise the section between the start of the pipeline and the mid-point pump station? I'm suggesting isolating the pipeline from the station at the start of the line and then runing the mid-point station pumps until they trip on low suction pressure. Following this a pump suitable for low suction pressure operation could be used to bring the pipeline to atmospheric pressure.
Thanks

 

[BigInch]

Depending on elevation profile you might only accomplish draining a very limited portion of the pipeline near station 2. It may be that any further segments past a significant high point might not be drained at all, or only partial draining will be accomplished as can be driven by higher elevation hydraulic heads. You'd better take a hard look at this before suggesting it.

you must get smarter than the software you're using.

 

[mch22112]

Thanks BigInch,
Yes, I had thought about elevation issues and there will be sections of the line that cannot be depressurised to atmospheric. This is something that cannot be avoided. The rapid depressurisation is to be carried out in the event of a leak (most likely caused by theft attempt). Rapid depressurisation followed by block valve closure will be carried out. Does anyone have any better ideas?

 

[BigInch]

Better ideas for what?

you must get smarter than the software you're using.

 

[mch22112]

Any better ideas for getting pressure out of the line quickly and isolating the leak. In the event of a large leak I guess the block valves would be closed first and the leak itself would do the depressurising! For small leaks (e.g. drill holes), I'm not sure about the best approach. Thanks

 

[dcasto]

Open a line at the origin end and put oil in a tank. How much oil do you think it takes to de pressure a line? It isn't that much!!!

 

[mch22112]

Thanks dcasto. Yes, it's not that much. For the pipeline in question it's less than 1000 m3.

 

[dcasto]

you said depressure, not empty. for a 1000 m^3 line de-pressured from 100 atm to 1 atm would require the removal of 18 m^3