Stainless steel cable (wire rope) corrosion

[DHHdad33]

I have an installation of a horizontal lifeline in a salt plant where we used all stainless steel anchorages and cable. We inspect it yearly and after the first year in place there were very slight signs of corrosion (apparent rust staining) in the grooves of the cable. In the second year inspection the rust staining is worse. The cable does not appear to be becoming compromised but we were shocked to see it appearing to rust. Has anyone else run into a similar situation where stainless steel cable rusts?

 

[Ron]

Certainly. Stainless steels are not immune to rusting, they just have better corrosion properties than mild steels. Depending on the alloy of stainless steel it will corrode with time. Further, many alloys of stainless steel are attached by chlorides, so I'm not surprised that you have corrosion.

Just keep in mind that your corrosion rate is a lot lower than it would be if you had used a mild steel.

 

[DHHdad33]

Thanks. That's what it was looking like was happening, we just usually use SS shapes and not a lot of wire rope in these plants and the corrosion on them must be imperceptible over time. Do you have a recommendation on an alloy to use for the wire rope for when this eventually needs replaced or for other similar installations?

 

[Ron]

I would suggest a 316L stainless steel alloy cable.

 

[btrueblood]

Not sure even type 316 would do much good in an environment with dried salt depositing into the crevices of a cable. Monel? PVC coated cable?

 

[paddingtongreen]

Texaco used to paint their galvanized handrails in salt spray environments.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[MikeHalloran]

Monel should last indefinitely, but it may be cheaper to just replace the stainless every few years, because Monel contains a _lot_ more nickel, and is tres expensive.

I think at least some of the stainless cable intended for aircraft controls is coated, with (?) nylon or something.

It shouldn't be hard to convince the maintenance crew to wipe down the lifelines with silicone grease on a regular basis. Unfortunately, the only silicone grease that I know to be mostly unaffected by salt water is the heavy vacuum grease sold for stopcocks.



Mike Halloran
Pembroke Pines, FL, USA