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Carbon steel pipe - Is corrosion an issue?

Carbon steel pipe - Is corrosion an issue?

Carbon steel pipe - Is corrosion an issue?


I have designed CLOSED cooling system using carbon steel pipes. The water used is treated and clean.
A corrosion allowance of 1 mm have been added. In addition the pH is controlled (to 9-10) using Natrium hydroxide.

My colleague has used stainless pipes before, but I insist on carbon steel.

Should I be worried about corrosion?

Thank you in advance!

RE: Carbon steel pipe - Is corrosion an issue?

"Treated" with what?

If you add some corrosion inhibitor then in a closed system without access to a re supply of Oxygen Carbon steel should be OK.

You should probably introduce a magnetic filter to pick up the black gunge which might develop.

You always need to be concerned about corrosion, but not overly worried.

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

RE: Carbon steel pipe - Is corrosion an issue?

Water treatment and a strainer are a good idea.
In my house, we have carbon steel piping from a thermosyphoning water system that's 115 years old and it is fine.

RE: Carbon steel pipe - Is corrosion an issue?

Add de-aerators to get most air out. I prefer the ones combined into a dirt-separator.
Hopefully you don't have leaks, but you typically have fill valves that add new water with oxygen.

Typically you have annual testing and pH buffer and corrosion inhibitors are added in a pot-feeder

RE: Carbon steel pipe - Is corrosion an issue?

Almost every HVAC closed chilled water system out there is carbon steel. Most open ones are too, at least on larger piping where copper or other material is not practical. Get a water treatment company on board. You'll be fine.

RE: Carbon steel pipe - Is corrosion an issue?

Thanks for the replies.

I will add corrosion inhibitor.

RE: Carbon steel pipe - Is corrosion an issue?

The German engineering council has produced a set of guidances (e.g. VDI2035) for chemical free treatment of closed water systems for heating, cooling and district networks made of carbon steel pipes. Worth a read!

RE: Carbon steel pipe - Is corrosion an issue?

Stainless steel is a poor choice. Internally, there is no benefit over carbon steel with properly treated water. Externally, insulation prevents the stainless steel from forming its passive oxide layer and will accelerate corrosion. Copper alloys would be a superior choice IF corrosion resistance is required.

RE: Carbon steel pipe - Is corrosion an issue?

The vast bulk of any corrosion issue in these systems is directly related to make-up water. The dissolved oxygen carried by that water is the killer. Keep the system tight and the make-up water supply manually valved out. That way you know exactly when any make-up is added. Fix any leaks promptly.

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