Why do malleable steel pipe fittings have sticky mold and succulent defects?

In order to be normal and correct in use, not only the quality of the pipe fittings is required, but also certain operations are required during use. For example, steel pipes must be thoroughly cleaned before entering the tank. In fact, not only is it necessary to clean the steel pipe before entering the storage tank, but it is also not negligible and undesirable to clean the steel pipe before entering the storage tank. This is because there will be a lot of floating ash in the malleable steel pipe fittings, and some floating ash will remain on the pipe fittings. If it is not cleaned, it will enter the barrel plating tank, which will not only pollute the plating solution, but also affect the quality of the coating.

Malleable steel pipe fittings, commonly known as malleable cast iron, are cast into white iron castings and then malleable and annealed. The graphite in the malleable cast iron of malleable steel pipe fittings is in the form of flocculents, which has less splitting effect on the matrix, so its mechanical properties are higher than that of gray cast iron, and its plasticity and toughness are better, but malleable cast iron cannot be forged. The matrix structure of malleable cast iron is different, and its performance is also different. Among them, black heart malleable cast iron has higher plasticity and toughness, while pearlitic malleable cast iron has higher strength, hardness and wear resistance.

As an important fitting used in water pipelines, malleable steel pipe fittings are often exposed to water and air, so their corrosion resistance is very important. Malleable steel pipe fittings are generally galvanized on the surface of the product for anti-rust treatment. Among them, galvanizing is divided into two types: hot galvanizing and cold galvanizing.

Distinguished from the appearance, due to the uniformity of the cold-dip galvanized coating, its surface is close to the rough product, and has the unique surface unevenness of the rough product, which looks smooth and bright. Due to the phenomenon of electric shielding, cold-galvanized parts generally have no galvanized layer inside (except for special galvanized techniques). However, because the hot-dip galvanized layer is relatively late and the fluidity of the zinc solution is poor, the zinc layer on the surface of the hot-dip galvanized pipe fittings is relatively thick, and because the surface of the hot-dip galvanized layer will be oxidized to produce a white protective layer, the color is generally darker. , and the surface smoothness is far less than cold plating products.

There are still some manufacturers who use some ungalvanized black parts to spray a layer of silver powder paint on the surface and sell them as galvanized pipe fittings. The method of distinguishing is also very simple. If two pipe fittings are knocked against each other, the silver powder paint on the surface of the pipe fittings will fall off. In addition, in terms of color, if the silver powder paint pipe fittings do not fall off, the paint layer is very bright, while the cold-galvanized pipe fittings are dark and bright, and there is generally no galvanized layer inside, while the hot-dip galvanized pipe fittings will become dark after a period of time. Ash.