OT: welding area cooling system

[geoplc]

We have been fighting for years with severe corrosion buildup in our cooling system which serves all of our spot and MIG welding machines and fixtures. The system is comprised at many areas of brass, aluminum, and steel black pipe fittings. We know that the different metals are inviting corrosion but a good portion cannot be prevented albeit reduced. Currently we have some water tower "expert" who has been "tweaking" our system by adding various chemicals to control the PH,etc. but I have seen no improvement. I even ran an experiment where I took a rod of magnesium on a cord and a combination of a brass fitting connected to an aluminum fitting connected to a steel fitting on a cord, inserted them into the holding tank. A few weeks later the aluminum fittng was reduced to a whit blob and the magnesium was slightly pitted. I figured magnesium being the least noble of metals would have gone first. Anyone have have a system without these problems?
The main piping in the ceiling is all PVC it is mainly the connecting fittings, mainfolds, SCR heatsinks, etc that have the issues.

 

[icky812]

The problem can be from several sources. Galvanic reaction and PH are the two of the most common causes.

With galvanic reaction where multiple metals are present in the system, current can flow from one metal to another causing an electrolytic reaction where the metal is pulled into the solution. In some cases grounding can help. In many cases you may need to install a cathodic or anodic protection system to fix the problem.

With PH, the Acidic or Alkaline balance is disturbed and this causes the metals to also be pulled into the solution. Adding chemical additives as your consultant is doing is the fix for this problem.

Sometimes it is a combination of both problems and a hybrid approach is needed.

 

[geoplc]

Hi icky812,

I was presuming the galvanic reaction myself which is why I thought maybe adding a sacrificial anode of magnesium would at least slow down the effect. What struck me as odd was that the sample of aluminum that I inserted at the same time as the magnesium turned to a unrecognizable blob of white corrosion. (This was the combination of brass/steel/alum that I was speaking of earlier). Any idea of what type of PH/acidity levels I should be trying to attain?

 

[icky812]

Not offhand. An expert in the chemical additive area should be able to have the correct tests done and be able to figure it out if it is PH.

Magnesium is not always the correct protection metal. Various metals can be used depending on what the actual problem is.

Sometimes you need an active system versus a passive system. For example Sulphuric Acid tanks use an active system since a passive system would be consumed in a few days and would corrupt the mixture.

Since your cooling welders, I am guessing that you might have stray current causing or compounding the issue. You might want to talk to a person from a company that specializes in active anodic and cathodic protection systems and see what they have to say in addition to looking at the PH levels.

 

[geoplc]

Thanks for all of your helpful info and insight icky812:beerchug: Now I have a better understanding of how to approach this issue and who to contact.

 

[icky812]

No problem. Hopefully you'll get this solved.

 

[leitmotif]

We have been fighting for years with severe corrosion buildup in our cooling system which serves all of our spot and MIG welding machines and fixtures. The system is comprised at many areas of brass, aluminum, and steel black pipe fittings. We know that the different metals are inviting corrosion but a good portion cannot be prevented albeit reduced. Currently we have some water tower "expert" who has been "tweaking" our system by adding various chemicals to control the PH,etc. but I have seen no improvement. I even ran an experiment where I took a rod of magnesium on a cord and a combination of a brass fitting connected to an aluminum fitting connected to a steel fitting on a cord, inserted them into the holding tank. A few weeks later the aluminum fittng was reduced to a whit blob and the magnesium was slightly pitted. I figured magnesium being the least noble of metals would have gone first. Anyone have have a system without these problems?
The main piping in the ceiling is all PVC it is mainly the connecting fittings, mainfolds, SCR heatsinks, etc that have the issues.

Where I could I would switch all metals to brass.
Not too sure what to do about aluminum heat sinks.

Wonder about dielectric fittings?

I do not believe you want this system to run acidic pH <7.0

Thinking way back diesels used chromate for cooling
see
http://www.tpub.com/engine3/en32-32.htm

My first inclination would be to use automotove anti freeze OR use automotive coolant filters only with the additive pack in them. Automotive coolant systems have multiple metals in them ie iron, copper, brass aluminum.

Dan Bentler

 

[shooter]

You will have to make two different water systems.
One inside system with a closed loop and lots of inhibitors and clean water without salt, etc.
and a cooling tower with a heatexchanger to cool your internal loop, as this water will evaporate do not use any additivs to this water.