To deal with valve corrosion of pump and valve fittings, we can add corrosion inhibitor.
When it comes to corrosion control, the mechanism of corrosion is that it promotes the polarization of the battery. Corrosion inhibitors are mainly used for medium and filler. When it comes to the anti corrosion of the valve accessories, we should also pay attention to the addition of corrosion inhibitor in the medium, at this time, the corrosion of the equipment and the accessories of the pump valve can be slowed down, such as chromium nickel stainless steel in the oxygen free sulfuric acid, the high degree of solubility becomes cremated and the corrosion is serious, but the addition of a small amount of oxidant such as copper sulfate or nitric acid can make it possible. The stainless steel changes to blunt state, and a protective film is formed on the surface to prevent the corrosion of the medium. If a small amount of oxidant is added into the hydrochloric acid, the corrosion of titanium can be reduced.
The test pressure of the valve parts in the pump valve parts is often used as the medium of pressure test. It is easy to cause the corrosion of the valve. In the water, it is necessary to pay attention to the need to add a small amount of sodium nitrite to prevent the corrosion of the water to the valve. The asbestos filler contains chloride, which is very corrosive to the stem. If the method of distilling water washing can reduce the content of chloride, this method is difficult to be carried out in a lot of difficulties and can not be popularized. The ester is suitable for special needs.
In order to protect the stem of the pump valve fittings and prevent the corrosion of asbestos packing, the corrosion inhibitor and sacrificial metal are coated on the stem of asbestos packing. Corrosion inhibitor from sodium nitrite and sodium chromate will create a passive film on the stem surface to improve the corrosion resistance of the stem.
This solvent can dissolve slowly and can be lubricated; zinc is added to the asbestos as a sacrificial metal. In fact, zinc is also a kind of corrosion inhibitor. It can first combine with chlorides in asbestos to reduce the chance of chloride with the valve parts of the pump valve parts to reduce the chance of corrosion.
If the corrosion inhibitor such as red lead and calcium lead acid is added to the coating, spraying on the surface of the valve can prevent atmospheric corrosion. After that, the corrosion protection of pump and valve parts can also be carried out by electrochemical protection. There are two kinds of protection for such protection, anode protection and cathodic protection. The cathodic protection method for large valves and important valves is an economical, simple and effective method.http://www.pump-casting.com/