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What does CASS test results mean relative to durability in years

What does passing a CASS test mean relative to life of the finish?

Joe Joseph
inspector - Los Angeles
March 24, 2010

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First of three simultaneous responses --

It would be very convenient if there were, but there is no direct correlation between the time spent in any accelerated corrosion test and real-world corrosion time. CASS results are basically just relative to other CASS results. There is just too much variation in the world that the parts will be used in for there to be a general relationship.

Jon Barrows, MSF, EHSSC
GOAD Company

Independence, Missouri

March 26, 2010

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Second of three simultaneous responses -- March 26, 2010

Accelerated corrosion tests like CASS, salt spray, etc are almost impossible to relate to service life. It is probably safe to say that longer time to failure in CASS equates to longer service life, but no more than that. There is no direct relationship.

Service life is undefined as to conditions, and the corrosion mechanisms are different, service life vs accelerated test.

The only appropriate use of accelerated testing is for quality control purposes - ie, "is our process under sufficient control that our accelerated test results are consistent?"

Real life testing, unfortunately, can only be done in real life.

Jeffrey Holmes, CEF
Spartanburg, South Carolina

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Third of three simultaneous responses -- March 29, 2010

Joe,

Good question, and if you search this site for answers about the validity of salt spray tests generally you will find one overwhelming opinion...that they do not relate to real time situations, that their use is purely a quality control tool and that it bears no relation to true weathering conditions.

So the short answer is, no I can't tell you how it relates.

Brian Terry
Aerospace - Yeovil, Somerset, UK

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March 30, 2010

Dear Joe Joseph,
In any of the salt spray test methods, we are not able to say the life of the coating.
But we are not able to measure the plating thickness in all the location, for ex, in thread, edges, etc........
If the part is failing in edges, threads, etc.......... we may consider that location plating thickness is very low. we may focus more on that failure location to increase the thickness. that area also will withstand more life in service condition.

Kannan Boopathi
- Salem, Tamil Nadu, India