What are malleable steel pipe fittings?

Malleable steel pipe fittings are widely used in automatic sprinkler systems in fire engineering, but there are many types, how to know them?

Malleable iron pipe fittings, galvanized pipe fittings, and threaded pipe fittings are generally aliases for malleable iron pipe fittings. But they are different from each other. The following will give a brief explanation in terms of naming.

Malleable steel pipe fittings are pipe fittings made of malleable steel. The English translation of Magang is malleable iron (malleable translates into Chinese as forgeable and tough. Iron means steel). Because the first syllable of English pronunciation is ma, we translate it into Magang in Chinese, but strictly speaking, the Chinese translation should be malleable iron (maleable cast iron).

It should be noted that although malleable cast iron has certain toughness, it cannot be used for forging. Malleable iron pipe fittings and malleable iron pipe fittings are named according to the material of the pipe fittings, while galvanized pipe fittings are named according to the surface treatment of the pipe fittings (it can also be said that they are used for the connection of galvanized pipes).

Since the malleable steel pipe fittings are made of iron, they are prone to rust when exposed to the air. In particular, our malleable steel pipe fittings are mainly used for fire protection and water supply projects. The pipe fittings are exposed to humid environment for a long time and are more prone to rust. Therefore, the malleable steel pipe fittings need to be treated with anti-rust treatment on its surface. The surface anti-rust treatment of malleable steel pipe fittings is generally divided into two types: hot-dip galvanizing and cold-dip galvanizing. Hot-dip galvanizing refers to a galvanizing treatment method in which the pipe fittings are immersed in a zinc solution melted at a high temperature of 700-800 degrees, so that the surface of the pipe fittings is covered with a layer of zinc. Cold galvanizing is also called electro-galvanizing. Its principle is to rely on electrophoresis to transfer and attach the zinc hanging on the anode to the surface of the pipe hanging on the cathode, thereby forming a thin and uniform zinc layer.

(Hot-dip galvanizing (galvanizing) is also called hot-dip galvanizing and hot-dip galvanizing: it is an effective metal anti-corrosion method, mainly used in metal structure facilities in various industries. It is to immerse the rust-removed steel parts at 500°C In the molten zinc solution left and right, the surface of the steel member is attached with a zinc layer, so as to achieve the purpose of anticorrosion. Hot-dip galvanizing process: finished product pickling-water washing plus plating solution drying rack-plating-cooling-chemical cleaning and polishing hot-dip galvanizing Zinc finish. Hot-dip galvanizing is developed from the older hot-dip galvanizing method. Since France applied hot-dip galvanizing to industry in 1836, it has a history of more than 170 years. In the past 30 years, with With the rapid development of cold-rolled strip steel, the hot-dip galvanizing industry has been able to develop on a large scale.)

The cost of hot-dip galvanizing is higher than that of cold-dip galvanizing, but because the hot-dip galvanizing layer is relatively thick, and the surface zinc layer reacts with the iron matrix at high temperature, there is a mutual penetration between the zinc layer and the iron matrix. The transition layer, so the combination of the zinc layer and the pipe fitting matrix is particularly firm, and it is not easy to fall off. Although the cost of the cold galvanized layer is relatively low, the zinc layer is even and attractive, but because the electroplating is only to cover a layer of zinc metal film on the surface of the pipe fitting substrate, the galvanized layer is thin and easy to fall off. In addition, a large amount of toxic waste liquid will be produced in the production process of electro-galvanizing.

Because the malleable steel pipe fittings are connected by thread, it can also be called threaded pipe fittings (thread pipe fittings). However, it should be noted that although most of the galvanized pipe fittings refer to malleable steel pipe fittings, some welded pipe fittings or other iron pipe fittings The surface is also galvanized, so strictly speaking, galvanized pipe fittings are not equal to malleable steel pipe fittings.

The same is true for threaded pipe fittings. Some iron pipes and even plastic pipes are also connected by threaded pipes, but the material is not malleable steel. Similarly, strictly speaking, threaded pipe fittings are not equivalent to malleable steel pipe fittings.