External Cable Trays: Port Environment

Go for non-metallic types: glassfibre or plastic.

UV and impact issues with Plastic might be a concern?

But a good alternative to consider.

milo

I would stay away from 304, I have seen sea spray conditions do a number on 304 in the past. Many really good alternative materials are becoming more commonplace, as suggested.

316SS would work, but your looking at some $$.

IMHO, 304 is the most cost effective as long as it is exposed to fresh (oxygenated) water. SS316 is best where water becomes stagnant, as in a rudder tube or centerboard trunk on a boat. I'm no chemist here, but boatyard experience tells me you can pay a premium for 316SS you may not need.

That will be 2 cents please.

I will say 316 S.S., since I had designed for a refinery and near shore and all of outdoor material must be 316 S.S. minimum. The owner had tested the 304 and 316 at same time, but 304 won't work.

For most offshore operations, 304SS is banned. Definitely not reccomended.

The issue is sulphur pitting resulting from high sulphur in the alloy and the chlorine ions in the environment. The pits expand and fracture the metal, often with no warning. (supposed to only occur at temps over 60 deg C)

I have had the previous bad experience of diesel valves blowing apart right next to 500 degC turbine exhausts to vouch for this phenomenem. We were very lucky not to have a big kaboosh-kaboom.

Cable tray out in the wind or around conveyors can be subjected to cyclic fatiguing forces that might exacerbate the problem.

Cost aside, the best option by far is 316SS. If mechanical damage is unlikely, fibreglass may be an option, but I would avoid it unless highly corrosive chemicals are present.

My 2.5 cents.....

Where are you?

If in temperate latitudes, fiberglass or similar as suggested earlier would be good.

If in the tropics, dry or wet, UV will rapidly demolish any plastic in the open. (At Mt Isa, Queensland, we had a fiberglass grating become completely unsafe after less than 18 months exposure, despite test from temperate regions which declared it had good resistance to UV).

While 5083 aluminium has good resistance to salt water and spray, bimetallic corrosion is a problem if it is not well insulated from other metals.

304 is prone to pitting corrosion and probably not suitable here. The Mo content of 316 makes it much more resistant to corrosion in a marine /salt spray environment.

Cost of course goes up significantly as you go from fiberglass, aluminium to 304 and 316, but you install once and maintain for far longer, so penny pinching at installation can come back and bite you later.

Just another alternative - have a thought about metal spraying carbon steel instead with zinc or aluminium (the latter more common in coastal environments). This is commonly used on fences, structural steelwork, boats, off-shore oil platforms etc which are all (in some cases obviously) coastal or splash zones.