Ductile iron pipe is one of the materials for modern urban water supply, property fire control and natural gas transportation. In practical application, in order to improve the corrosion resistance and extend the service life of the product, galvanizing is very important for it. Through galvanizing, the protective layer can be added for the ductile iron pipe. After years of repeated experiments with several materials, a kind of anticorrosive material with low price and good quality, which is zinc, has been found for ductile iron pipes.
The zinc spraying layer of ductile iron pipe can play an active role in the maintenance of the pipe through the electrochemical effect of zinc and iron, forming a safe and stable maintenance layer. In the process of touching the soil, The metal zinc on the surface of the ductile iron pipe gradually Turns Into a tight, adherent and continuous zinc salt layer, and the asphalt paint on the outer layer looks like the same film, so that the zinc turns into an insoluble zinc salt instead of a soluble zinc hydroxide. One of the primary characteristics of the zinc spraying layer is that it can actively repair the maintenance layer at the damaged place, so as to maintain the integrity of the maintenance layer zinc Ions migrate to the damaged area through the sealed pores to repair the wound and turn into a stable insoluble spray.
In fact, in addition to galvanizing, there are many ways of anti-corrosion treatment for ductile iron pipes, such as asphalt paint coating, cement mortar lining + special custom coating, epoxy coal asphalt coating, epoxy ceramic lining, aluminate cement coating, sulfate cement coating, polyurethane coating, etc. different anti-corrosion treatment methods are suitable for ductile iron pipes in different occasions. For example, asphalt paint coating is used to transport gas pipes. Preheating the pipes before painting can improve the adhesion of asphalt paint and accelerate the dryness. And cement mortar lining + special coating is suitable for the pipeline of sewage transportation, which can improve the anti-corrosion ability of the lining. Epoxy coal tar pitch coating is suitable for both gas pipeline and sewage pipeline.
It is a two-component coating, which has high adhesion and very lubricating appearance; the epoxy ceramic is only used when the ductile iron pipe is used for sewage pipe and gas pipe, but because the manufacturing technology is difficult and the cost is high, it has certain limitations in the application. If aluminate cement coating and sulfate cement coating are used on the surface of ductile iron pipes, they are both suitable for internal corrosion protection of ductile iron pipes for sewage pipes, and improve the ability to resist the corrosion of acid and alkali components in sewage. Polyurethane coating is also a special coating, with the same anti-corrosion effect.