MS pipes for chilled water

which type is cost effective

PVC

Thanks, but I mean which type is cost effective MS steel or SS.

Why Are you replacing them,Are you putting in a new system and are we talking AC units? If Its AC units I would stay with PVC,MS steel will rust and stainless is very Expensive.

Thanks, we are replacing PVC due to many break downs in the piping system. it is industrial chilled water system for printing machines. the working pressure is 5 bars, the pipes can take up to 13 bar, still it fails on frequently. we have alot of leaks, pipes burst, elbow-pipe join breaks.

Have you considered PEX? It's flexible, can take some pressure and is easy to plumb with "shark bites"

Hello, I would recommend that you use mild steel, either welded or with victaulic connections from 2.5" and above and use threaded connections below 2" diameter, It will last you many years and would be way more cost effective than stainless steel. The trick to using mild steel for chilled water is to have a vapor barrier between it and the insulation. If you do not have this the pipe will constantly drip and make the pipe rust from the outside. I currently have about 12 miles of mild steel piped chilled water in the paper mill that has been in service for 12-15 years and we have had no problems with it. Be very careful using galvanized pipe for chilled water as it can react unfavorable to certain chemicals in chillers and actually cause problems with the tubes.

pipewelder

Thanks for the info.

Why does the PVC pipe failed? Frozen pipe? External damage? Sudden pressure surge in system? Improper installation?

Nothing confirmed, but most properly due to teh follwoing;

1. bad installation
2. Sudden change in pressure as we used fixed speed pump, while consumption flow of chilled water is variable.
3. weak pipe supports.

T add comment of your original post:

As a qualifying of "cost effectiveness" thoroughly consider the re-installation of PVC but maybe up grade to a stronger schedule #80 for instance. Strengthen the supports and install a pressure regulator.