pipe material for instrument air

[lakshmi]

I have recently been given the responseabilty of the air system. Problem is they have installed Galvanized pipe. I am from the old school, carbon steel, brass, or copper. My question is Galvanized pipe for instrument air headers a new trend or will it still flake off and cause problems.
thanks
lakshmi

 

[mduplessis]

The use of galvanized pipes for pneumatic or compressed air is quite common in my experience. If you are worried of flaking and rust problems just make sure that there is adequate drying, draining and trapping of moist in the air, which is good practice in any case. Personally I do not know of any problems experience from the use of galvanized pipes. It is a good idea to cover the pipes exposed to the outside environment with a good protective paint.

 

[peterpom]

The use of galvanised pipe for instrument as opposed to plant air is not good practise. If the air is dried to a pressure dew point well below the lowest possible ambient, which it should be for instrument use, there should be no problems. Even so, it is good practise to install good quality particle filters at each user point.

It is usual to use copper or stainless steel for instrument air. There are also some high quality plastic pipes and plastic coated aluminium tubes which are excellent for this application.

A properly installed instrument air system would include an air filtration and dehydration package, with non-corrosive piping and tubing. Then no point of use particle filters are required.

 

[ctolbert]

Lakshmi:

I've been through the same situation at a large steel mill. The instrument air was pre 1970's and I had no budget to do a full retro-fit.

We can all agree that stainless is better, and If one had the choice and the money...then certainly one would replace it all.

My only solution was to choose the worst areas and start replacing, cleaning, and recalibrating the equipment. A calibration program is your best resource. I moved the periodicity up from annually to semi-annually. This allowed more inspection and analysis of the instruments being affected. It also gave me a better target to focus on.

I hope you have an easier time than I did.

Carl