GRE pipe for chilled water system. 4

[moideen]

I lack prior experience with GRE pipe. For one of our hotel projects, we were considering replacing the ABS pipe with MS (ERW black steel pipe). However, there have been suggestions that GRE pipe may outperform steel pipe in a chilled water system. Does anyone have experience using GRE in chilled water system? Any insights would be greatly appreciated, as our planning is still in the initial stage.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[LittleInch]

I lack prior experience with GRE pipe.

Therein lies the biggest issue. GRE is not a different form of steel or even pipe like PVC or ABS. it is it's own speciality and system design, construction and operation.

It can be great but is often difficult to install correctly, very easy to damage / crack / wear away, requires a LOT of vendor specific fittings, requires installers experienced in its installation and if you want to have constant trouble / leaks / maintenance issues for the next 20 years then use GRE. It is very difficult to QA check joints as you go along until you fill it and then test it.

It is a great material in theory, but the reality of installation and operation is rather more troublesome.

Buried flat firewater main or water system inside a plant room or process plant site - maybe - especially for something like salt water.

Chilled water in a building. Hmmmmmm

To adapt your quote a bit

The problem with the world is that intelligent people (engineers with experience) are full of doubts, while stupid onesGRE salesmen are full of confidence.

IMHO.

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

 

[MortenA]

One disadvantage is that its susceptible to pressure surges - even below design pressure. This often occurs in fire water systems especially if you have elevation differences.

--- Best regards, Morten Andersen

 

[moideen]

Thanks LI and Morten. I'll be meeting the GRE man in person in Dubai in the coming days. When we initially met, he offered a 50-year warranty! He seems to be concentrating on sales. I have requested relevant documents and project references done previously.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[TugboatEng]

Look closely at the terms. Warranty doesn't cover lost revenue. Warranty doesn't cover of gaining access for repair.

 

[LittleInch]

Warranty doesn't cover installation or design errors or leaks, only that the pipe he's selling you won't leak.

The warranty is basically useless.

The references will basically be useless as well as all they did was supply the materials. But try and find the maintenance engineer in any of the properties they mention and talk to them....

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

 

[EdStainless]

Finding an experienced installer is critical. the joints can be a real pain, but when they are right they are great.
This material also has higher thermal expansion than metal, so the design will need to allow for that.
It also has a lower modulus so it will require more support.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[LittleInch]

If you drop it it might not break then but will a few years later (they call it "bruising", like an apple does when you drop it.

And any movement will wear a hole in it.

With chilled water and pressure it will contract quite a lot as the Poisson ratio is quite high - close to 0.6

And it doesn't' like being bent.

All in all it's a really great material, just not really suited to buildings with multiple joints and connections and stresses and supports and an installer that says he knows what he's doing but doesn't. And doing anything after you've fitted it - now that's a world of pain.

You say GRE might "out perform" steel pipe. In what sense exactly? That's a very vague statement if you don't mind me saying so.

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

 

[EngrPaper]

I second the question for what "outperform" means. What are you trying to get the system to do that FRP would be a better option? Long life, more flexibility, inexpensive materials?

 

[georgeverghese]

Why use cheap ERW pipe, can you not afford seamless pipe?

What is this "chilled water" ? Is it made with RO water doped with oxygen scavenger and biocide, and is this a dilute ethylene glycol solution ?

 

[nabeel3]

Dear Moideen

Jointing of GRE piping is expensive compared to other non metallic piping. Why u decide to change ABS piping

 

[moideen]

@EngrPaper
Steel pipe materials deteriorate over time as a result of scale and corrosion, necessitating chemical treatments for protection. This results in higher maintenance expenditures. GRE pipes, on the other hand, do not require such treatments, leading in cost savings and waste reduction. Furthermore, GRE marketers claim that insulation is unneeded because to their decreased conductivity, but I question the feasibility of this claim, especially at ambient temperatures ranging from 45 to 50 °C.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[moideen]

@nabeel3
ABS piping has been causing numerous issues for the past decade. The curing time for chilled water pipe repairs takes hours, making it impractical to perform repairs in an active hotel building without shutting down operations.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[moideen]

@georgeverghese
Switching to seamless piping would significantly escalate costs. Here, we typically use black steel ERW schedule 40 PIPE for projects, ranging from small to large, that involve direct municipal water supply.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[nabeel3]

Moideen

Have u tried CPVC Pipes?

 

[moideen]

I have not seen CPVC in chilled water systems; it is primarily reserved for domestic plumbing applications

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[LittleInch]

Steel pipes only deteriorate if you don't look after them.
A closed system like a chilled water just needs a good dosing with anti corrosion and oxygen scav and then each time if you drain the system.
Then should last for decades.

GRE is in theory great for such purposes, but design and installation need high levels of experience and competence.
there is no way on earth a GRE pipe will insulate sufficiently to stop condensation and heat ingress. The fact that the salesman told you that should create some doubts as to everything else he's telling you.

But the installation is the key. In UAE and Oman there are some good installers, but tend to want more money. It is money well spent. Don't believe anyone when they you they CAN do it, (but haven't done it before).

You need to support the pipes much better than steel or PVC, they expand and move more than steel and are just different. GRE pipes with small supports can wear away the pipe in a few years or months.

Most importantly each vendor is different in terms of the material properties, the fittings available and even the size of the pipe itself. So you're locked into one supplier. if they go bust or stop supplying then you're in big trouble.

If you think repairing PVC is difficult and time consuming you clearly haven't seen GRE. It is an utter shit show.

Also forget doing any modifications once you've designed it and built it.

As for leak testing....

Find another hotel or few where it has been fitted or ask for references and names etc and go ask the poor maintenance man what he thinks of GRE piping in a hotel.

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

 

[pierreick]

Hi,
"Steel pipe materials deteriorate over time as a result of scale and corrosion, necessitating chemical treatments for protection. This results in higher maintenance expenditures."
Where did you get this info? Did you consult a chemical treatment company about the requirement and cost? Always used Steel pipe, Indonesia, China, Thailand.
BTW this is part of operation cost not maintenance.
Pierre

 

[moideen]

@LittleInch : You've been a big help, Little Inch. I now have enough information to start preparing a technical counter report against GRE. Thank you very much.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[moideen]

@pierreick
I agree with you, sir. We have a chilled water system that's been operational for 20 to 40 years, using steel pipes. While some sections are in good condition, others have deteriorated, largely due to variations in the diligence of the individuals responsible for chemical treatment maintenance. Some follow proper treatment protocols, while others do not.

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-