Using 304-H32 for 1

[mswartz]

We've got a lab trailer that is being rebuilt. The mfgr assembled it with a protecting underbelly of 24Ga 5052 aluminum sheet with aluminum rivets into the steel frame.

After six years the frame is rusted and the underbelly has numerous through-holes from corrosion, and is being removed. I'd like to spec stainless sheet to replace the protective bellypan.

I've got enough SS304 in 24ga to do the job, and would isolate the stainless sheet from the (now restored and painted) steel frame using butyl rubber and mount using SS316 rivets.

Will SS304 work in this application, or would I best use 316 sheet? I'm not overly concerned about surface finish, but don't want a recurrence of corrosion. The trailer does get exposed to chlorides from salt spray and road salt, but if isolated, will this be a problem?

 

[BiPolarMoment]

I was just putzing around and looked at this:

http://www.assda.asn.au/asp/index.asp?pgid=17991&cid=34299&id=56951

While your application may not be marine, I'd think the advice would be applicable. Something for you to peruse anyway until the experts arrive.

If it were my personal trailer and I had all that sheet on hand I'd probably just go for it and monitor/rinse on a regular basis, but I understand that's not the case here so I'm not actually endorsing that route.

 

[mcguire]

If salt dries and concentrates on the 304, it will pit and perforate. It can't handle road salt. Isolation won't help.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[mighoser]

I would recommend applying a solid film lubricant. I've found that Sandstrom Products Corporation has the best resistance to salt fog spray (ASTM B117). Do to size of your material probably have to use an air curing formulation. I would use Poxylube 429. If you can bake go for Sandstrom 9A which is almost bullet proof. I would exceed the recommended thickness of .0005-.0007" and go with .0005-.001" or greater. I think .005" would be an upper limit on thickness. Be advised: baking certain alloys of Al for the curing requirements of 9A can reduce their properties.

 

[EdStainless]

I hate to say it, but I don't like the idea of using stainless. If a 5xxx Al didn't hold up I don't give a low alloy stainless much of a chance.
Cevices, mixed metals, salt, mud....
I am not sure that seawater wouldn't be a less severe service.


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