The production of plastic-coated steel pipes involves several steps that can lead to various defects affecting both the appearance and performance of the final product. These issues can reduce the quality and durability of the pipes if not properly addressed. Below are some common problems encountered during production.
Weld Defects
Weld defects are a significant concern, often requiring manual mechanical grinding to address. However, the grinding process can leave uneven surfaces and affect the appearance of the pipe. Additionally, the pickling and passivation process used to treat the welds can also result in surface unevenness.
Difficulty Removing Scratches
Scratches produced during processing are difficult to remove through overall pickling and passivation. These scratches, along with impurities such as carbon steel and welding splashes, can cause chemical or electrochemical corrosion, leading to rust when exposed to corrosive environments.
Uneven Polishing and Passivation
After manual polishing, pickling and passivation treatment may not achieve uniform results, especially on larger workpieces. This inconsistency in treatment can leave surfaces uneven, impacting the aesthetics and corrosion resistance. Additionally, the process can be labor-intensive and costly due to high labor and material expenses.
Limited Pickling Capacity
Pickling and passivation pastes have limitations and are not effective in removing black oxide scale, especially those created by plasma cutting and flame cutting. These scales can interfere with the coating process and compromise the quality of the finished pipe.
Scratches Caused by Human Factors
Scratches caused by human errors during hoisting, transportation, and structural processing are common. These scratches make surface treatment more challenging and are often the primary cause of rusting after treatment, as they expose the metal beneath the coating.
Equipment-Related Issues
Scratches and creases are also prevalent during the bending and folding of profiles and plates. These imperfections can lead to rust after surface treatment, compromising the overall performance of the plastic-coated steel pipe.
Other Contributing Factors
During the procurement and storage of raw materials for plastic-coated steel pipes, handling issues such as bumps and scratches during hoisting and transportation can also contribute to rust formation. These factors can significantly affect the appearance and longevity of the pipes.
Conclusion
The production of plastic-coated steel pipes involves several challenges related to surface treatment and handling. These issues, including weld defects, scratches, and inconsistent surface treatment, must be carefully addressed to ensure high-quality, durable pipes. Proper handling, improved manufacturing processes, and advanced equipment can help mitigate these common problems and improve the overall performance of the pipes.