Enclosures Question

Well... if PVC enclosures are no good, then NEMA 4X is the way to go. Even NEMA 4X units can rust and corrode. I have seen 4X enclosures rotted out from salt.

In the food industry, which is where I spent the better part of my career, there is a process used on sanitary grade stainless, normally 304 or 316L alloys, called "passivation". This involves the use of a "pickling acid" on the stainless skin to help build up the oxide layer on stainless that protects it. Passivating the outside of a NEMA 4X enclosure will help it resist salt corrosion even more. Contact a "sanitary stainless welding outfit", they will know about what I am referring to and will be able to help you.

Rick...

Normally I specify NEMA 4X SS for stainless although to be honest after a year or two of exposure to marine environments the SS doesn't live up to its reputation. I have been using NEMA 4X AL lately and based on the local ships (Alaska coast) AL may be the way to go - you will have to be careful with what you use to connect to it - galvanized steel will be a problem ...

Have you ever considered Aluminum with a double thick coating of Industrial Powder coating... We use this is a VERY corrosive environment, and NO Problems

DR

Perhaps the best way is to specify a corrosion protection coating when you order the enclosures. There are two good protections against salt spray corrosion. One is water based polyurathane coating and the other is cold application zinc also known as cold galvanization. Sometimes, zinc coatings are not accpeted due to static electricity related problems eventhough they are excellent protection against corrosion. Polyurathane coatings are superior protection against salt spray corrosion due to the absence of pinholes normally one gets due to solvents used in conventional paints. Inside the enclosures, you can use vapour phase inhibitors which protect the contacts etc., from corrosion. Make sure that the rubber gaskets are well maintained to prevent ingress of salt corrosin into the enclosures

I would consider non-metallic enclosures. Same NEMA grades are available molded from glass-reinforced composites. Check Hoffman or other major manufacturers.

I would specify a NEMA 4X (NON-METALLIC). I have runned into that in many occasions designing with treatment facilities.