316L in swimming pool environment

[stanny123]

When we make pool equipment like pool ladders other types of things we use 316L bright polished tube. Then after a time it looks like it's going rusty we think it's the chlorine that's causing the problem is there anyway of stopping it with something. We clean them down but it seems to happen around welds or slight mucky areas rough places. It would be nice if there is a simple solution.

 

[EdStainless]

Are you pickling after fabrication?
I suspect that a lot or this is related to small imbedded particles of iron.
These could come from being touched by a wrench or set down on a steel surface.

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Plymouth Tube

 

[weldstan]

There are number of weak acid (generally phosphoric or citric) solutions that will remove iron contaminants from the surface.
Be sure to only use stainless steel wire brushes that have never been in contact with carbon & low alloy steels to clean welded areas. Abrasive polishing with appropriate abrasives (also never used on carbon & low alloy steels are also effective.
What is the heat tint color after welding? You may need to pickle depending on color.

 

[EdStainless]

Any weld heat tint, even a light straw color should be pickled.
If you use a wire brush or abrasive (as described above) you must passivate afterwards.
There are citric and/or phosphoric acid passivation treatments.
They must be done warm and they take hours.
A room temp dip in 25% Nitric acid will do the same in 5 min.

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Plymouth Tube

 

[stanny123]

Thanks for the replys we don't use wire brushes to clean the surfaces they get cleaned using polishing equipment like mops polishing compounds. Then wipe down with rags and stainless cleaners.

 

[EdStainless]

But without passivation the microscopic particles from the polishing that have been imbedded in the surface will be a source for corrosion initiation.

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Plymouth Tube

 

[Guest102023]

Tell the kids to stop spalshing around so much, it increases the dissolved oxygen in the water.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[EdStainless]

Parts that are regularly wetted should never rust.
There is a reason why you are not allowed to use SS hardware overhead in pools.
Because it will fail and things will fall down.
Where it can't get rinsed the chloramines collect and eventually CSCC will cause failures, even at room temp.

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Plymouth Tube