Need corrosion resistant coating on AL explosion proof enclosures

[MichaelGK]

Gentlemen,

I'm new to the forum and hoping for a bit of guidance on a project for one of our customers.

We've been asked to supply AL explosion proof enclosures for electrical components, mounted on the decks of barges. In the past, one step epoxy coatings have been applied without success (3-6 months). I'd like to assume the manufacturer had prepped the units properly before coating.

My thoughts were to look at products similar to Alodine EC2. We also use 316 SS bolts to secure the door on the unit. I'd also like to use a application shop in the Seattle area, but a recommendation may be against the forum rules.

The objective is to apply a coating that may last 2-3 years, if possible.

Thanks in advance for your help.

Sincerely,
Mike K.

 

[micalbrch]

Short question: AL means aluminum?

What happened to the epoxy coating? Did it scale? Then I would guess the surface preparation (degreasing) wasn't done correctly.

 

[MichaelGK]

Thanks for the quick response.

Yes, the "AL" is aluminum. As I've not been out to the site, I'll have to have photo's sent. By the customers description, scaling had occurred.

My thoughts are that if I have the coating done locally, I'd have better control over the process.

Any other comments you may have?

Mike K.

 

[micalbrch]

I'm still sure that a proper coating/painting of the aluminum enclosure is sufficient. Passivating is the other option but more expensive and passivating is not a guarantee against corrosion. It is sometimes just used to get a proper surface for the coating.

 

[RPstress]

The Al alloy used is probably the major element in susceptibility to corrosion. A 5000-series should have very long life marine conditions even if bare (I take it that this is a salt-water environment).

 

[MichaelGK]

Gentlemen,
Thanks for your responses.
The makeup of the enclosure is listed as "copper free cast aluminum". It is 100% exposed to salt water.

The manufacturer lists the finish as "Standard Aluminum lacquer paint".

After reading a bit more, my thoughts are to suggest a hard coat anodizing if they want a durable finish.

Any experience with this HCA finish?

I could also check with a local waste water treatment plant as they use the explosion proof units in some corrosive environments.

I appreciate your input.

Mike K.

 

[micalbrch]

HCA is indeed an option and it increases the corrosion resistance. There are several types of hard coat anodizing and your special aluminum alloy is of importance, too. Make sure that whoever will do the anodizing knows exactly what your requirements are.

 

[MichaelGK]

Mical and RP,

I appreciate your input. You've provided the help I need. I have a request for the type aluminum, 5000 or 6000 series. With that info in hand, I'll then call one of our local shops, such as ASKO Processing.

I do have the option of ordering W/O coating (i.e., natural finish).

Again, thanks for your help. Have a great holiday season.

Cheers !

Mike K.