Repair/Replacement of underground fire water lines 4

[mjpetrag]

We are in the process of scoping for replacement of our underground firewater piping. It is currently an underground network of approximately 20,000 feet of a mix of mostly 6"-10" iron piping installed in the 1950's, and repeated leaks on the system are causing excessive maintenance spend for excavating the leaks, repairing, backfilling, and paving. Due to the massive scope of work and amount of digging involved in the replacement of this piping, we began to think if Horizontal Directional Drilling could be a cost-effective way to replace this pipe. Essentially installing new piping in parallel to the old, and making the connections to the hydrants and high-rise monitors.

We were also evaluating CIPP liners for this piping also.

Most of the piping failures are due to separation of the bell joints. There are some failures where the piping has a hole from rocks rubbing the OD of the pipe, but those are in a minority.

Wanted to get your thoughts on your experiences and recommendations on the most practical path forward

-Mike

 

[1503-44]

Depends on the condition of what you've got. You have to make a judgement if it's worth saving. It sounds like it's really not. In which case a new build would be the only way to go. Newer materials make it easier and more reliable. With a salvage job, you're never sure it all gets repaired. Having doubts about the fire system isn't a good thing.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[LittleInch]

Difficult to say what is "most practical" as we can't see the plant, the access, the locations of the system, number of connection points etc etc

I'm assuming that you want to maintain the existing system whilst replacement works go on?

you need to start looking at what they do the replacement of cast iron gas and water mains.

Basically two methods
Either cut into the pipe and then insert a PE liner, usually with a bit of a gap to the existing pipe. As it's smoother you often don't lose capacity.

Or they use a pipe breaker like this where you break the CI pipe and pull in new PE one instead. I would call these guys as start point and get some options as they do all sorts of stuff.

https://www.tttechnologies.com/products/grundocrack-pneumatic-pipe-bursting/

Or just bite the bullet and go from isolating chamber to isolating chamber and either dig it up or lay alongside and then cap the old one off.

What you need is pipe ramming, not directional drill as you can't really guide these things that shallow underground, but length is limited.

With the size and age of your system I think any sort of internal spray system is limited. Also you will have dozens of tie ins and connections to do.

Not every section will suit the same technique but get down to two or three and then divide the system up according to space, access, other services crossing your line etc.


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

 

[MJCronin]

Please keep us informed about your decision making process, sir and your final choice.

It is only when a complete "case study" is done by the original poster, that eng-tips can come to it's full potential.

Thank you

MJCronin
Sr. Process Engineer

 

[mjpetrag]

This is really great information. I agree, we might be using a combination of different techniques, but that Grundocrack technology is impressive, and exactly what we need on these several hundred foot runs of straight pipe.

I will follow up with what we go with.

-Mike

 

[EdStainless]

I have seen directional drilling used often.
They brough a utility line into a house, 4' below grade, about 150' from the street and hit a 1' target on the wall.
But if you have lots of other buried utilities I would be hesitant.
Sections with minimal branches and a better history would be good options for lining.
Places where you have had issues I would dig it up.

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P.E. Metallurgy, consulting work welcomed

 

[3DDave]

Grundocrack seems like the option least likely to cause unexpected problems. Worst I can see is they price the service appropriately to the benefits of avoiding doing ugly things or taking a lot of time.

 

[LittleInch]

They call it pipe bursting and they are many companies offering it so unlikely to be extortionate.

But you need to talk to the utility contractors not the process plant or oil and gas boys.

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

 

[3DDave]

Not extortionate - but if putting in a cured resin liner would be half the cost but take twice as long then it would be foolish to leave that difference in price. So, up front, it may look more expensive. Even if there are several companies - they are competing against directional drilling and pipe lining to set their prices.

 

[HTURKAK]

In general , i agree with the previous comments and i will try to provide more specific info. for this case;

My points;

- Suggest you to look ( Pipe Bursting Projects ASCE Manuals and Reports on Engineering Practice No. 112 ) and try to see how feasible in this case the pipe renewal with bursting the existing CI pipes.

- AFAIK , CIP is no longer available for use in pressure pipes except some eastern countries. New pipe could be DI, PEH ... CIP , brittle and can be effectively burst and replaced.

- More than ten years ago , my friends did a pipe renewal project the existing pipes were CIP and new ones DIP at a crowded city center.

- I will suggest you to look for experienced contractor on pipe bursting and compare the cost with open excavation and new pipe installation..


My opinion..












Don't underestimate a nail. A nail saves a horseshoe, a horseshoe saves a horse, a horse saves a commander, a commander saves an army, an army saves a whole country.. GENGHIS KHAN

 

[pierreick]

Hi,
I had similar situation in China, and we decided to change for above ground.
You may want to consider this option, easier to maintain but more expensive (rack, winterization plan to prevent freezing).
One issue was the quality of the equipment prone to burst!
My 2 cents.
Pierre

 

[Dhurjati Sen]

Economics would guide you ONLY.

Your piping has lasted for almost 75 years, what else does one ask for?

You can always replace the old piping like by like and keep them underground.

If it's costlier, make it above ground, you save on digging, sleeving and coating, but you need to build structures.

If you have enough funds, go for GRE piping and keep them underground.

DHURJATI SEN
Kolkata, India

 

[LittleInch]

Oh god, not GRE.

Worst material in history for buried pipe. It will leak like a sieve and after 10 years you'll need to rip it out and replace it all again.

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