Pe hot melt hydraulic butt welding machine operation method
The PE pipeline has the characteristics of easy construction, high speed, corrosion resistance, no pollution and long service life. There are two main methods of PE pipe connection: hot melt connection and fused connection. At present, the main pipeline is mainly made of hot melt connections. The principle of hot melt connection is to close the mating surface of the two PE pipes on the heating tool to heat the flat end surface until it melts. After removing the heating tool, the two molten end surfaces are held together and kept under pressure. Cool the joints to make it a whole.
First, welding preparation. Hot melt welding construction preparations are as follows:
1. Load the slips in line with the specifications of the pipe;
2. Prepare enough support to ensure that the pipe to be welded can be at the same height as the centerline of the rack and can be easily moved;
3. set the heating plate temperature 200 ~ 230 °C (this data to Hangzhou Welding Electromechanical Co., Ltd. supply of welding machine for reference, the specific temperature is based on the data provided by the manufacturer);
4. Turn on the welder power, turn on the heating plate, cutter, and oil pump switch and test run.
Second, welding. The welding process is as follows: Inspect the pipe and clean the pipe ends → Fasten the pipes → Milling cutters Milling pipe ends → Check the pipe end misalignment and clearance → Heat the pipe and observe the minimum height of the flange → Pipe welding and cooling to the specified time → Remove the pipe. In the welding process, the operator should refer to the parameters of the welding process card and, if necessary, adjust it according to changes in weather, ambient temperature, etc.:
(1)Check whether the pipe to be welded is of the correct specification and pressure level. Check if there are any flaws, bumps or scratches on the surface. If the depth of the flaw exceeds 10% of the wall thickness of the pipe, it shall be used after partial resection.
(2) Use soft paper or alcohol to remove oil or foreign matter from both ends;
(3)Place the pipe to be welded in the rack slip so that the length of both ends of the pipe is the same (it is as short as possible without affecting the milling and heating, and should be kept 20~30mm). The part outside the pipe rack is used Hold up the support so that the axis of the tube is at the same height as the centerline of the rack, then fasten with the slips;
(4) Insert the milling cutter, first open the power switch of the milling cutter, then close both ends of the tube and apply proper pressure until continuous chips appear at both ends (the thickness of the chip is 0.5 to 10mm, by adjusting the height of the milling cutter Adjustable chip thickness), remove the pressure, wait a moment, then retract the movable frame and turn off the power of the milling cutter;
(5)Take out the milling cutter, close both ends and check the alignment of both ends (the misalignment between the two ends of the pipe cannot exceed 10% of the wall thickness. It can be improved by adjusting the straightness of the pipe and loosening the slip; the gap between the two ends of the pipe cannot exceed 0.3mm (de225mm or less), 0.5mm (de225mm ~ 400mm), 1mm (de400mm or more), if not meet the requirements, should be milled here until it meets the requirements.
(6) After the temperature of the heating plate reaches the set value, it is placed in the frame and the specified pressure is applied until the minimum crimping on both sides reaches the specified height, the pressure is reduced to the specified value (the two sides of the pipe end just keep in contact with the heating plate, Endotherm) After the time is up, loosen the movable frame, quickly remove the heating plate, and then close the two pipe ends. The switching time is as short as possible. After cooling to the specified time, the pressure is released, the slip is released, and the connected pipes are taken out.
Fourth, the welding inspection practice proves that the polyethylene gas pipeline is the most vulnerable to damage and leakage, which is the pipeline interface. The key to the success and failure of the project is the quality of the pipe connection. Therefore, strict interface quality inspection is very important for underground gas pipeline engineering. Destructive testing of polyethylene pipe connections is required to check internal quality.
(1) After the polyethylene pipe is connected, the construction self-checking and third-party acceptance shall be strengthened, and a certain percentage of interfaces shall be taken out for internal inspection.
(2) Check welder welding data records for all welds
(3) Appearance quality inspection should be conducted 100%. Supervision and other acceptance units shall draw a certain percentage of welding seams for visual inspection according to construction quality. The number shall not be less than 10% of the number of welds, and the number of welds per welder shall not be less than 5.
(4) The destructive test of the interface shall be done for each project. For the interface of the hot melt connection, 3% welds shall be taken and no less than one is recommended. The destructive test can be cut into 4 welds, check the internal fusion conditions, not fully regarded as unqualified, can also do tensile test to see if the tensile strength meets the design and specification requirements. For the unqualified interface, the interface of the welder should be doubled, and if the re-discovery fails, all the interfaces for the welder's construction will be reworked.
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