River Crossing Pipeline Leak Repair

[faisman]

Hi All,

Anybody had an experience in river crossing pipeline leak repair? We are dealing with crude Export pipeline of API 5L X60 PSL2 material of 18" size. We are currently in design stage and would like to consider a proper provision for this repair in case of future leak occasion. We are dealing with high H2S heavy crude oil.

 

[brimmer]

Would suggest an HDD bore if possible as opposed to an open cut. Use heavier wall pipe. Block valves on either side of the river. Not sure how you would design a provision to make a repair in a river.

 

[faisman]

Dear Brimmer,

Thanks. We did specified for HDD bore for the installation with block valve on both side. And with a 3mm CA on the pipe as well. By having all these, it is no guarantee that we can avoid the failure. Plus, this is a critical export pipeline that we need to ensure minimal shut down within its operational life. If there is any new technology that can repair a river crossing pipeline online and insitu, we would want to consider to provide necessary provision during this design stage. Providing a bypass line is our last resort.

 

[MiketheEngineer]

Probably a stupid and expensive answer - put in two. One breaks - switch to the other. Figure a way to fix the broken one and switch back??

But if it is truly that critical - redundancy is cheap!! And you might not piss off the EPA so much!!

 

[brimmer]

If the line is very critcal, I would go with a spare river crossing. I am not aware of any technology that exists to do a repair insitu, short of pulling a liner through, but then you are liquid hydrocarbon sour service, which would not be the best for a liner.

 

[cvg]

I would not cross a river, highway or other such difficult crossing without using a casing. And if possible, above ground bridged crossing.

 

[DLite30]

--Use abrasive resistant coating (ARO).
--Use heavy wall pipe as stated above, in addition to your corrossion allowance.
--X-ray welds instead of testing by ultrasound.
--consider internal coating
--consider automated SMAW welding versus manual welding.
--jeep the piss out of the coating.

 

[BigInch]

It isn't going to be enough probability of failure of a HDD to cost-justify two crossings. If you have used a HDD crossing, you will not likely have a failure due to scour, as the depth below the mud line is probably quite great. It is also likely that you are not close enough to the bank to lose the embankment cover, even if the river moves out on the bends... I do hope you have set back away from any river bends.

Automatic welding isn't likely to be economical just to do a river crossing.

The highest risk of failure of an HDD crossing, assuming the installed profile is sufficiently low stress and the exterior of the pipeline was not scratched in the process, is from internal corrosion. Setting a good corrosion allowance and perhaps leaving provisions for corrosion monitoring coupons and future corrosion inhibitor injection is your best option.

If you ever did fail an HDD crossing due to some cause other than corrosion, you would likely NOT want to even think about installing a new HDD in the same place, never mind repairing a damaged one. HDD failure would more likely be good evidence that you had chosen a very inappropriate location to cross that river. It would be better to cut your losses and move to another spot.



Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[SJones]

Good corrosion control; good corrosion monitoring; good maintenance pigging and good use of intelligent pigging. Get those right, and you won't need a repair for a corrosion failure.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04