SS316L, AL6XN, or Aluminum in Chloride Atmosphere 3

[smarts]

We need to replace vent on large steel tank used for chlorination and water storage (2 mg/l Cl). About 6 months ago, we installed vent made of bare SS304 and it already shows significant corrosion (rust and pitting). We want to avoid paint finishes. We are considering SS316L, AL6XN, or Aluminum. How should we decide? A 12-month field test is not OK. Thanks in advance

 

[mcguire]

It's unlikely that 316 would work if 304 did that badly. You should be considering at least the alloy level of 2205.
Al6XN is better, but quite expensive. 29-4C would be another alternative. Aluminum would fail quicker than 304.

 

[EdStainless]

2205 sounds like a good option.
Don't use AL29-4C or Sea-Cure (superferritics) if there will be much field welding or if you need structural strength. They are both only available in light gages.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[mcguire]

EdStainless is quite right about those superferritics. I should have included Seacure, which is every bit as good as 29-4C.
Along the same lines, 2507 is one more step up from 2205, but not as available, I think. EdStainless would know better than I since he's still in the game.

 

[joeswoes]

An obvious application for a fiberglass tank, no reason to sweat the various metallics

 

[stanweld]

As an alternate to the materials, I would look at 904L SS for the vent.

 

[EdStainless]

With todays Ni and Mo prices I have to agree with Joe and suggest that composite is a good option.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm