COATING - 3

In case of fire-stops,a melting burning plastic pipe must be squeezed together and shut so that there would be no opening for fire to propagate to an otherwise rated wall or floor assembly while the intumescent application is used to achieve passive fire protection for such application as fire stopping,proofing,gasketing,and window casing.But it is important to note that some intumescent are substable to environmental influences such as humanity which reduce or negate their ability to function.protection casing also has some method of evaluating the life prediction of coating and their ability to predict service life real environment and are discussed in the contest of degradation process of coating systems. other experimentation that are conducted to determined the following includes:
1.The ingress of reactants into the steel and coating surface.
2,Accelerated test for performance evaluation ASTM B117 standard practice for operating salt    spray(fog) apparatus.ISO 7253,Testing standard ASTM B117-1939 and B117-1997.
3.Accelerated test for performance evaluation ASTM. G85,standard practice for modified salt spray(fog), testing which includes the following:
-Continuous acetic and acid salt spray test
-Cyclic acidified salt spray test.
-Cyclic sea water acidified test.
-Cyclic So2 salt spray test.
-Dilute electrolyte cyclic fog dry test.
The last item of the modification,the dilute electrolyte cyclic fog dry test was reported to give best correlation without door exposure test and uses a much diluted electrolyte (0-0.5%sodium chloride)
with small amount (0.35%)of ammonium sulphate to represent industrial atmosphere.The test cycle alternate between one hour of fog and one hour of dry off and in each fog drying cycle the fog will gradually increased thus exposing the samples to a water range of salt concentration ASTM D9894 - 96 practice for cyclic salt fog/uv exposure of painted metal.