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How many hours salt spray equals 30 years life?

I need information about how much exposure time in hours, to make salt spray test with zinc coated cable for use in overhead lines structures for a expected period of life about 30 years.

Dante Sagula Filho
Lautec Empreend. Com. Ltda. - Sao Paulo, SP - Brasil
2000

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2000

First of all, you should know that nobody can directly correlate salt spray hours to real service life. Specifications for a fixed number of salt spray hours exist, and these specifications do have a years-of-service target, but there is no definitive correlation between salt spray hours to years of life.

I would say that for 30 years of service, your cable should be able to last at least 2000 hours of salt spray before the first sign of red rust. I do not think a plain coating of zinc can give this sort of performance. You may be able to get this from a good zinc-alloy plating with a big, thick, hex chrome passivate, possibly with an additional post-treatment.

30 years is a very long time for most electroplating and hot-dip processes. You need something with high-quality performance. I work in the automotive industry which targets 10 years, and plain zinc is usually not good enough for us.

Tim Neveau
Rochester Hills, Michigan