allowable crude leakage in pipeline

[farhadsh]

Is there any allowable limit of crude that can leak from upstream pipeline facilities? I am trying to specify mechanical seal for PD pump for crude transfer wondering if it needs to be leakage free? or leakage detection to be incorporated. as you know leakage detection / seal plans are costly
please advise

 

[LittleInch]

Not that I am aware of. What type of PD pump are you thinking of?

Any leakage tends simply to get worse over time and creates a hazard, both to personnel, the environment or creates a fire risk.

Design for the odd drop or three, but not for permanent flow of any measurable size.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pennpiper]

Zero leakage is the desirable goal.

Sometimes its possible to do all the right things and still get bad results

 

[bimr]

Zero emissions is also a goal.

 

[1gibson]

Plan 65's aren't too bad, pipe the seal drain to a reservoir with a level switch, address it when it gets full. Easy to record trends in seal leakage that way as well. If it filled up every 2 months when new, and now it fills up once a week, you can plan to refurb the seal soon.

There is no such thing as a "zero leakage" mechanical seal. It leaks out (single seals) at a very slow rate, or you design it to leak into the process (dual seals with barrier fluid/gas systems) so there are zero emissions.

Try to understand what you are doing. Spec a mechanical seal with a low or no allowable leakage. That means a vendor needs to meet this criteria for the duration of the warranty period. You will either get no quotes, expensive quotes to cover risk and a few replacements, or vendors who don't read all the specs. Best case scenario, vendor takes exception to the leakage limits and gives you a regular quote, in that case the only problem is that everyone involved will have wasted time having to deal with it.

 

[georgeverghese]

Things to watch out for when not using plan 53

a) Flash point of the crude cf the temp of the crude as it leaks out - this could be quite hot as it would have picked up heat of friction as it runs past the seals

b) Any other toxic components that would flash out

c) Impact of a and b on the hazardous area classification for equipment around this pump

If the crude is clean and has good lubrication properties, when it leaks past the seal, it would most likely act as a seal barrier fluid. If there are abrasive solids ( there is nothing worse than sand ), would imagine the seal would get torn up in no time, once a minor leak starts. For offshore facilities, you've got sand just about everywhere in liquids handling systems.

Hence, if you go for an unpressurised seal, think it may be a good idea to check what the maintenance crews think, and if their manning and skill levels are up to scratch. The first cost delta of a good seal will be much lower than the total cost of all the chopper flights and boat rides ( and sick bags) for these people to fix these seals over 10years ?

BTW, is this the same pump set where you had a PD pumps in series controls concern posting a few days ago ?