3PE anti-corrosion steel pipe in the course of the precautions, three-layer structure of polyethylene (3PE) anti-corrosion coating with its good corrosion resistance, moisture resistance and mechanical properties, in the oil pipeline industry has been widely used. This kind of anti-corrosion pipe pipe end easily due to corrosion and the emergence of the Alice problem. Analysis: 3PE coating steel pipe in the polished section of the polyethylene layer groove, the tube end of the weld is not grinding or grinding is not smooth, will lead to protruding parts of the polyethylene at the bottom of the epoxy powder was worn off , In the anti-corrosion tube open time for a long time, the weld surface metal will be first corrosion, resulting in 3PE anti-corrosion layer of Alice phenomenon. To avoid 3PE anti-corrosion tube side of the side of the measures are:
1, Without affecting the case of nozzle welding, should be appropriate to increase the end of the polyethylene layer epoxy powder length of the reservation, can prevent the steel pipe for a long time, pipe metal corrosion caused by a serious 3PE corrosion Alice.
2, Anti-corrosion pipe open for a long time, should be covered in the pipe end to prevent rain erosion, resulting in serious corrosion pipe end. The following are the same as the "
3, If the pipeline site construction period is longer, you can brush in the pipe side of the metal can be welded to install anti-rust paint to prevent the corrosion tube during storage due to corrosion caused by 3PE anti-corrosion layer Alice.
4, Strict control of the end of the pipe at the end of the weld grinding quality. In the weld at the polyethylene groove outside the body and other parts of the same, so that the epoxy powder to retain the length of> 20mm, to prevent the bottom of the epoxy powder at the weld first corrosion caused by 3PE anti-corrosion layer Alice. Pipe end weld grinding should pay attention to: 1) from the beginning of the weld to the polyethylene chamfer should be 10-20mm no weld height and the same body of the same layer of polyethylene, to ensure that the tube end Polyethylene groove at the extrusion bonding quality. 2) weld after grinding the height should be done with the body flush, do not have a clear extra height, in order to prevent polished in the polished layer of polyethylene, the epoxy powder together with the polished.
