What are some ways to prevent 3PE-coated steel pipes from curling at the edges?
Release time:
2022-03-19
3PE anti-corrosion steel pipes boast excellent corrosion resistance and water resistance, making them widely used across various industries. However, these anti-corrosion steel pipes are prone to edge warping due to corrosion. This occurs because, when preparing the bevel for the polyethylene layer in the reserved section during grinding, the remaining height of the weld at the pipe end is either left unground or ground unevenly. As a result, the epoxy powder beneath the polyethylene on the protruding portion of the weld gets worn away. Once the pipe is exposed outdoors for an extended period, the metal surface of the weld becomes corroded, leading to edge warping. So, what methods can be employed to prevent the steel pipe from warping?
3PE anti-corrosion steel pipe With excellent corrosion resistance and water resistance, these anti-corrosion steel pipes are widely used across various industries. However, such anti-corrosion steel pipes tend to warp or curl due to corrosion. This occurs because, when preparing the bevel on the polyethylene layer of the reserved section during grinding for 3PE anti-corrosion steel pipes, the remaining height of the weld at the pipe end is either left unground or ground unevenly. As a result, the epoxy powder beneath the polyethylene layer in the protruding portion of the weld gets worn away. Once the pipe is exposed outdoors for an extended period, the metal surface of the weld becomes corroded, leading to edge warping. So, what methods can be employed to prevent the steel pipes from warping?
1. The reserved length of the epoxy powder at the end of the polyethylene layer can be appropriately increased, provided that it does not interfere with the welding of the pipe ends. Extending the reserved length can effectively prevent the edges of 3PE-coated steel pipes from curling due to prolonged storage and severe metal corrosion at the pipe ends.
2. The exposed metal at the pipe ends can be coated with a weldable anti-rust paint. This method is suitable for pipelines in long-span sections. If corrosion-resistant pipes are exposed outdoors for extended periods, the pipe ends should be covered to prevent erosion by rainwater and severe corrosion at the pipe ends.
3. Strictly control the grinding quality of the weld seams reserved at the pipe ends, ensuring they meet high standards.
1) Starting from weld-bead grinding up to the polyethylene chamfer, a smooth polyethylene layer measuring 10–20 mm in length is required, free of any weld seams. The remaining height should be identical to that of the pipe body, ensuring high-quality compression bonding at the polyethylene bevel on the pipe end.
2) The residual height of the weld after grinding should be as flush as possible with the pipe body. The residual height must not be too noticeable, to avoid accidentally grinding away the epoxy powder along with the polyethylene layer when chamfering the polyethylene layer.
4. At the weld seam, the polyethylene bevel must be controlled strictly to ensure that its length is the same as that of other parts of the pipe body, and the retained length of the epoxy powder should exceed 20 mm. This precaution is taken to prevent the edges of the 3PE-coated steel pipe from curling due to premature corrosion at the base of the epoxy powder at the weld seam.
5. The epoxy powder coating on the reserved pipe sections shall cover the entire pipeline to help delay edge warping at the pipe ends caused by corrosion. Whenever possible, replace the wire-wheel grinding method with groove machining. The cutting depth of the tool should be controlled by a stop device located at the base of the cutting edge, thereby preventing damage to the epoxy powder coating during grinding and ensuring the effectiveness of the anti-corrosion protection.
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