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Cleaning stainless pipe

I'm in the humidification business and we use a lot of stainless steel pipe. I use those pipe for reverse osmosis water. We do some welding on them and drill some holes. We notice that the product that we were using wasn't as good as we thought. We use hydrofluoric acid for 4 min and water for 20 min then air to dry. What is the best for cleaning stainless pipe.

Thanks,

Guillaume Cavanagh-Morin
Engineer - Québec, QC, Canada
2004

I have never heard of that acid, possibly a typo? What to use for cleaning is totally dependent on what the soil to be removed is and are you etching the pipe for weld prep or what? Plain cleaning would normally be done with an organic solvent or an alkaline cleaner formulated for the specific type of soil.

James Watts
- Navarre, Florida
2004

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Hydrofluoric acid (I assume this is what you mean) is an etchant for stainless steel (and most everything else, of course- even glass). It will not give you a good passive layer on the stainless steel. To do this you need to use nitric acid or citric acid formulations per ASTM A967. I am not sure if you are trying to CLEAN the pipe or make it corrosion resistant. Please clarify.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2004