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Common problems in the production and processing of plastic coated steel pipes

1. Weld defect

Welding defects are more serious, which are compensated by manual mechanical grinding treatment methods. The resulting grinding marks cause uneven surfaces and affect the appearance. Only pickling and passivating the welding seam also causes uneven surface.


2. Scratches are difficult to remove

The overall pickling and passivation can not remove various scratches generated during the processing, and can not remove carbon steel, splashes and other impurities that adhere to the surface of the plastic-coated steel pipe due to scratches and welding splashes, resulting in chemical or electro-chemical corrosion and rust in the presence of corrosive media.


3. Uneven grinding and polishing passivation

After manual polishing, pickling and passivation treatment. It is difficult to achieve a uniform and uniform treatment effect for a workpiece with a large area, and an ideal uniform surface cannot be obtained. And the cost of working hours and the cost of auxiliary materials are also higher.


4. Limited pickling capacity

Pickling passivation paste is not omnipotent, it is difficult to remove the black oxide scale produced by plasma cutting and flame cutting.


5. Scratches caused by human factors are more serious

In the process of hoisting, transportation and structural processing, scratches caused by human factors such as bumps, dragging, and hammering are more serious, making the surface treatment more difficult, and it is also the main cause of corrosion after treatment.


6. Equipment factors

In the process of bending profiles and plates, scratches and creases are also the main reason for rust after treatment.


7. Other factors

During the procurement and storage of raw materials of plastic-coated steel pipes, bumps and scratches due to lifting and transportation are also serious, which is also one of the causes of rust.