Precautions for Connecting And Installing Large-diameter Plastic-coated Steel Pipes

1. Cutting of large-diameter plastic-coated steel pipes for water transportation. Metal saws should be used to cut steel pipes. Large-diameter steel pipes should be cut with saws. When cutting with entanglement, the rotation speed should not exceed 800r/min; the cross-section of the steel pipe to be cut should be perpendicular to the axis of the steel pipe;
2. Preparation before connecting large-diameter plastic-coated steel pipes for water delivery.
2.1 The metal burrs of the cut steel pipe port should be smoothed with a fine file;
2.2 A special reamer should be used for plastic-lined steel pipes to chamfer 1/2 of the thickness of the plastic-lined layer, and the chamfering slope should be 10°-15°.
2.3 If the plastic-coated steel coating is intact on the port, it should be chamfered with a sharpener; if the port is damaged, it must be repaired until the coating is completely crack-free;
2.4 After rolling and grooving, the plastic coating on the protruding part of the groove will be damaged and must be repaired until the coating surface is smooth and there are no cracks or damaged points;
2.5 Cleaning processing should use cotton waste and brushes to remove oil, water, and metal cutting at the steel pipe end and inside the steel pipe;
3. Large-diameter plastic-coated steel pipe connection method for water delivery.
3.1 Threaded connection threading should use an automatic threading machine and comply with the current national standard GB/T7306;
3.2 One-time installation method of flange connection: on-site measurement and single-line processing drawing of the steel pipeline can be made, processed, coated, and lined with plastic, and then transported to the site for installation;
Secondary installation method: non-coated and plastic-lined steel pipes and steel pipe fittings can be used on-site, flange welded, and the steel pipes assembled, then disassembled for coating and plastic-lined processing, and then transported to the site for installation.
3.3 Groove connections should give priority to finished grooved plastic-coated steel pipe fittings; the grooves should be grooved using a special rolling groove machine. Note that the groove depth should comply with relevant standards (CJ/T156-2001).