Why 3PE coating will be thinner in welded seam?
Per steel pipe’s 3PE coating process, there are two reasons why coating will be thinner on welded seam. One is because in the forming process, the other is the cooling process.
First, why forming process will cause coating thinner. In formed weld seam, PE coating, generally speaking, is very good. PE near weld seam, in most case, is better than those away from weld seam. But in forming system, PE coating will have some uneven in surface.
Second is in cooling process. Generally speaking, coating thin position is 2 to 3 meters from pipe end. Under inspection, we know that PE in weld seam is almost the same, but after cooling, PE in weld seam will be different. Let’s have a brief introduction about this point. Before the steel pipe goes into cooling line, PE near pipe end will be cut out. When going into water cooling line, water cooling will have influence on both PE cooling and pipe cooling. Under the influence of inner tube wind, most of the water will be on front of the pipe and some will remain in the end, Cooling form both inside of the tube and outside of the tube can cooling the pipe better. But in the cooling process, PE haven’t been solid then, under water pressure, and as weld seam is not as smooth as the body, much more pressure will be on weld seam, thus PE in weld seam will be thinner than the body.
http://www.xysteelpipe.com/info/Why-3PE-coating-will-be-thinner-in-welded-seam-500-1.htm
First, why forming process will cause coating thinner. In formed weld seam, PE coating, generally speaking, is very good. PE near weld seam, in most case, is better than those away from weld seam. But in forming system, PE coating will have some uneven in surface.
Second is in cooling process. Generally speaking, coating thin position is 2 to 3 meters from pipe end. Under inspection, we know that PE in weld seam is almost the same, but after cooling, PE in weld seam will be different. Let’s have a brief introduction about this point. Before the steel pipe goes into cooling line, PE near pipe end will be cut out. When going into water cooling line, water cooling will have influence on both PE cooling and pipe cooling. Under the influence of inner tube wind, most of the water will be on front of the pipe and some will remain in the end, Cooling form both inside of the tube and outside of the tube can cooling the pipe better. But in the cooling process, PE haven’t been solid then, under water pressure, and as weld seam is not as smooth as the body, much more pressure will be on weld seam, thus PE in weld seam will be thinner than the body.
http://www.xysteelpipe.com/info/Why-3PE-coating-will-be-thinner-in-welded-seam-500-1.htm
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