River crossing pipeline

[henrique_]

Hi everybody!

Someone has an experience in river crossing pipeline leak repair? We have some long pipelines installed at Brazil of API 5L X70 PSL2. The pipes has installed by HDD method and some people suggested to install block valves on either side of the river. In my opinion, split the line with block valves could be a big problem because can occur leaks on flange connections and valve gasket. I would like to listen your opionion about this subject. Thanks.

 

[zdas04]

If you are worried about flange leaks, install welded-in block valves. Beyond that, it really depends on the river. If I'm crossing the Amazon, I want block valves. If I'm crossing an ephemeral stream (i.e., one that only flows during the rainy season) then no. Streams in between? Evaluate on a case by case basis, but any river with a chance of an anchor drag by a commercial ship should certainly have block valves.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[LittleInch]

I don't really understand your question.

You ask about "river crossing pipeline leak repair", but then say it's an HDD (basically impossible to repair) and now block valves.

Block valve installation at rivers is commonplace and is required for "major rivers" by ASME B31.4 and many local codes and regulations. I don't know about Brazil, but I would guess that this is normal practice.
Definition of major rivers varies, but commonly it's either one which is used for drinking water or over 25 to 30m wide bank to bank.

Leaks can occur, but many block vales are welded in line and stem seals can be tightened. The amount of leakage would be very small and is normally accepted as a risk because the alternative (no block valves) would risk even more pollution into the river if the pipeline leaks in the river section.

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

 

[bimr]

Agree with LittleInch's comments. Block valve installation at rivers is commonplace and may also be required for environmental protections.

On each side of a water crossing

 

[brimmer]

Block (or check) valves are common practice to have on both sides of a river crossing, to limit the amount of fluid that can leak into the river... Flange connections you can inspect, and if they leak will be seeping a very small amount of fluid. If there are no valves, there could be drain down from the higher sections of the line, into the lower river section, hence the need for valves to stop this from happening. It appears consequence assessment is missing from the design or from your design perspective ignore consequence.

 

[henrique_]

Thanks everybody for all replies.

I'm confused because in iron ore slurry pipelines the block valves isn't used at crossings. Normally is changed the project safety factor (0,65) and the construction methodoly is HDD.

I'll spend more time study about this subject.

Thanks.

 

[DekDee]

henrique,
Some very experienced members have commented above and they may have presumed (as I did) that you were talking about an oil or gas pipeline.
A leak from an iron ore slurry pipeline will have minimal environmental impacts - a leak from an oil or gas pipeline is much more serious.

More facts - better responses
Cheers,
Shane