What is Sendzimir Method?

The Sendzimir method is mainly a word appearing on galvanized steel pipes and is also the development of galvanized steel pipes. It combines the annealing process with the gi pipe zinc process. The in-line annealing mainly consists of an oxidation furnace and a reduction furnace. The strip steel is directly heated to about 450 degrees in the oxidation furnace, and the rolling oil remaining on the strip surface is burned off to purify the surface. After that, the strip is heated to 700-800 degrees to complete the recrystallization annealing. After the cooling section is controlled to the temperature of the zinc pot, the temperature is about 480 degrees. Finally, the zinc pot is galvanized without contact with the air. This is the Sendzimir method. Due to the high yield and good galvanizing quality of the Sendzimir method, this method has been widely used.
Also known as the direct heating method of flame; firstly, the strip is eluted with alkali by alkali, and then the scale of the surface is removed with hydrochloric acid, washed with water, dried, and then passed into a vertical in-line annealing furnace directly heated by a gas flame, and the furnace is strictly controlled. The ratio of the gas to the air is so that the incomplete flame is burned in the case of excess gas and insufficient oxygen, thereby causing a reducing atmosphere in the furnace. The steel tube is rapidly heated to a recrystallization temperature and cooled under a low hydrogen protective atmosphere, and finally immersed in a zinc liquid in a sealed state to carry out hot-dip galvanizing steel pipe zinc. The method is compact, with low investment costs and high output (up to 50/hour). However, the production process is complicated, especially when the unit is stopped, in order to avoid burning the strip, it is necessary to use the method of traversing the steel strip away from the steel strip. This has many operational problems. Therefore, the hot-dip galvanized steel pipe zinc industry adopts this method very little.
Galvanized strip is a variant of the Sendzimir method. It simply replaces the degreasing of the oxidizer with an alkaline electrolytic degreasing tank. The rest of the process is basically the same as the Sendzimir method. After the original board enters the working line, it is first electrolytically degreased, then washed, dried, and then recrystallized and annealed by a reducing furnace with a protective gas, and finally into the zinc pot hot-dip galvanized steel tube zinc in the case of sealing. In this method, since the strip steel is not heated by the oxidation furnace, the oxide film on the surface is thin, and the hydrogen content of the shielding gas in the reduction furnace can be appropriately reduced. This is beneficial to furnace safety and reduced production costs. However, since the strip steel is not preheated, it enters the reduction furnace, which undoubtedly increases the heat load of the reduction furnace and affects the life of the furnace. Therefore, this method has not been widely used.

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