Choosing a coating testing regimen

A. For this sort of use, you may have to devise a test.

Considering it's for off-shore drilling, salt spray isn't entirely inappropriate. Mechanically abuse to the point of multiple breaks in the powder coat, followed by salt spray is somewhere near real life.

Observe how severe the mechanical abuse is expected to be then bang it with a hammer, or drag behind a truck as seems appropriate. Control the number of hammer blows or miles dragged. ;-)

Certainly hot dip-powder coat will prove far superior.

A. Geoff,
I have been in this game long enough to know that none of us are experts. At best, we are avid learners and sharers of experience.
There is no doubt that standard Salt spray test techniques unfairly disadvantage HDG's actual performance in real world situations.
Surely then, the answer is to actually duplicate real world worst conditions as a real test?
Confronted with this same dilemma years ago I subjected samples to "real world" testing by immersing specimens at half tide mark and leaving them for 6 months.
I can assure you that a properly powdercoated, HDG substrate won out most convincingly.
Some times you just have to take the bull by the horns and demonstrate the superiority of your process in real terms.
Put your samples in the Atlantic or the North Sea preferably near a Marina where they will be disturbed by boat wake.

The Academics usually catch up a decade or two later.

It is possible to fudge Salt Spray results but as your process is genuinely superior why bother?

Regards,
Bill
And hurry up with the degassing problem solution.

A. Good day Geoff.
I am by no means well versed in the "proven testing" of materials. We do know all test matrixes indicate process qualification.
Here are my thoughts;
Prepare test panels as A) current coating, B) proposed coating.
On half of the surfaces perform adhesion tests as per:
BATS 4860 TY I /TY II CL 2
FED-STD-141 Method 6301.
Since the components are subject to wear and tear in the real world, why not try to simulate conditions?
After the adhesion tests maybe a heat cycle followed by a cold cycle, and then exposure to salt spray.
Again, these are only my thoughts on the matter.
I am curious as to other thoughts, as it relates to testing in controlled conditions as compared to real time.
Regards,

A. Hi Geoff,

Considering your situation, I would suggest that salt spray would be a suitable test, especially as it is a direct comparison of performance and the environmental conditions that the parts are seeing in-service.

A simple salt spray may take a long time to produce results, so the panels need to simulate the damage likely to be seen in use. The standard way to do this is simply to scribe a cross on the panel to the base material before placing in the salt spray cabinet. We have used this method of coating evaluation for a number of years and as a direct comparison method it is a good indicator of comparative performance.

Obviously the only real test would be natural weathering, but as these tests typically run for years rather than weeks it is rarely practical. Accelerated weathering tests suffer from the same arguments than salt spray often suffers from in that they are not a good indicator of in-service performance and their true use is in comparative testing.

Certainly for initial trials I would stick to salt spray, as a friend often says to me "keep it simple stupid".