Jul.10, 2018Keywords:Steel Silo corrosion resistant, steel silo life span, steel silo material
Salt spray test is an environmental test which mainly USES the artificial simulated environment conditions created by salt spray test equipment to assess the corrosion resistance of products or metal materials. It is divided into two categories, one is natural environment exposure test, the other is artificial acceleration simulation salt fog environment test. Artificial simulated conditions of salt spray test is to use a certain volume of space test equipment, salt spray test chamber, in his capacity space, using the method of artificial salt fog environment to the salt fog corrosion resistance properties of the product quality evaluation. Compared with the natural environment, its salt fog environment of chloride salt concentration, content of general natural environment can be salt fog several times or more, make the corrosion speed is greatly increased, salt fog test was carried out on the product, the results of time also greatly reduced. For example, in a natural exposure environment to a product sample
In the test, the corrosion may take a year, while in the artificial simulated salt spray environment, the results can be similar within 24 hours. The artificial simulated salt spray test also includes neutral salt mist test, acetate mist test, copper salt accelerated acetate mist test, and alternating salt fog test.
(1) neutral salt spray test (NSS test) is the earliest and most widely used accelerated corrosion test method. It USES 5% sodium chloride brine solution, the PH of the solution is adjusted in the neutral range (6 ~ 7) as the spray solution. Salt spray test temperature 35 ℃, requirements of sedimentation rate in between 1 ~ 2 ml / 80 cm & sup2.
(2) the ASS test was developed on the basis of neutral salt fog test. It is to add some glacial acetic acid to 5% sodium chloride solution, so that the PH value of the solution is reduced to about 3, the solution becomes acidic, and the salt fog formed eventually becomes acidic from the neutral salt fog. Its corrosion rate is about three times faster than the NSS test.
(3) copper salt accelerated acetic acid salt spray test (CASS) is a newly developed a kind of foreign fast salt-fog corrosion test, the test temperature is 50 ℃, salt solution to add a small amount of copper salt, copper chloride, strongly induced corrosion. Its corrosion rate is about eight times that of the NSS test.
The specific time is converted into:
Neutral salt spray test for 24h-- natural environment for 1 year
Salt spray test of acetic acid for 24h-- natural environment for 3 years,
Copper salt accelerated acetic acid salt fog test for 24h- natural environment for 8 years
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