The answer to what is passivation is quiet simple. Passivation is an important step in maximizing the essential corrosion resistance of parts and components machined from stainless steels. It can make the difference between good performance and premature failure. If performed incorrectly, passivation can actually lead to corrosion. Passivation is a post-manufacture method for maximizing the intrinsic corrosion resistance of the stainless steel alloy from which the working part was manufactured. It is not a treatment to remove scales, nor is it like a coat of paint.
The passivation process involves the removal of microscopic iron particles that had been deposited during the manufacturing process. Iron on the surface of stainless steel is also reduced. Removing iron makes the chromium in the steel react with oxygen, forming an invisible and microscopic protective layer. This reduces the possibility that the stainless steel should become stained or rusted with subsequent use. As stainless steel is expensive, passivation is well worth the investment. Nowadays, citric acid is used to passivate steel, which is effective, eco-friendly and safe. Not only does citric acid provide a superior barrier to the surface of steel, it is easy to dispose off after use. Stainless steel parts that are to be passivated must first be cleaned thoroughly. The parts are then placed in a citric acid solution where they remain for a predetermined period of time. Finally, the parts are double-rinsed with clean water and are then dried.
Hydrostatic pressure testing enables leak detection in pressurized vessels, pipelines and plumbing. Newly manufactured pieces are initially certified using hydrostatic testing. They are then periodically re-tested at regular intervals. Using hydrostatic testing helps maintain safety standards and durability of a vessel over time. Testing is done to continually re-certify pressured vessels for safety. The use of hydrostatic testing over gas pressure testing helps to eliminate the possibility of explosions associated with gas pressure testing.
Hydrostatic testing involves filling the vessel or a piping system with a liquid, usually water, and subsequently the pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing if there is a pressure loss. The location of a leak can be better identified if a colorant were mixed with the water. Strength is usually tested by measuring permanent deformation of the container.
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