In the process of producing electric heating pipe, blackening treatment is sometimes used. Heat treatment is a process of heat treatment of metal objects such as stainless steel. After treatment, there will be an oxide film on the surface to achieve the purpose of anti-corrosion and rust prevention. After heat treatment, the wear resistance of heating pipe surface will be improved, the hardness of the surface will be improved, and the components inside the heating pipe will not be affected.

Under the normal working conditions, the following steps are simple and convenient for blackening treatment of the surface of the electric heating pipe:

1. Firstly, clean the surface of the metal tube to keep it clean;

2. The second is to degrease the surface, which can completely place the metal pipe in the degreasing liquid. The pH value of degreasing liquid is about 13, and the time is not less than half an hour. After degreasing, wash with clean water.

3. Next, acid cleaning can be carried out. The pH value of pickling solution is about 3, and the treatment time is no longer than 10 minutes. After pickling, clean with water;

4. Blackening treatment: the pH value of the pool liquid concentration is between 2-4, the treatment time is 10 minutes up and down, and it is extremely clean after blackening;

5. Dry and oil;

According to the above five points, it is a very effective way to blacken the electric heating tube.