1. Groove connection.
Cut off the pipeline according to the pipe diameter required by the design and the length of the pipe section after on-site review. Check the nozzle, if it is found that the nozzle is burr, uneven or the end face is not perpendicular to the axis of the pipe, it should be corrected.
1) Use a special scraper to bevel the inner layer of polyethylene at the nozzle, with a slope angle of 20-30° and a depth of 10-1.5mm, and the groove should be wiped clean with clean paper or cloth.
2) Round the nozzle with a rounder.
3) Put the locking nut and C-type clamping ring on the tube, and insert the core into the tube to reach the root of the core at the mouth of the pipe; Move the C-clamp ring to 0 percent from the nozzle5-1.At 5mm, tighten the lock nut and the pipe fitting body.
1. Welding connection.
According to the design requirements, the working pressure is 0Steam pipes above 1MPa, heating pipes with a general pipe diameter of more than 32mm, and fire pipes in high-rise buildings can be connected by electric and gas welding.
1) There should be windproof, rainproof and snowproof measures when the pipeline is welded, the ambient temperature of the welding area is lower than -20, the weld should be preheated, the preheating temperature is 100-200, and the preheating length is 200-250mm.
2) Generally, pipeline welding is in the form of counterpart and assembly.
3) Before welding, the axis of the two pipes should be centered, and the ends of the two pipes should be spot welded firmly, and the pipe diameter should be spot welded at three points below 100mm, and the pipe diameter should be spot welded at four points above 150mm.
4) If the wall thickness of the pipe is more than 5mm, the groove should be shoveled at the weld part of the pipe end, such as the pipe groove processed by gas welding, the oxide scale on the surface of the groove must be removed, and the uneven part that affects the welding quality must be polished flat.
5) The pipe should be welded with the flange, the pipe should be inserted into the flange first, spot welded 2-3 points first, and then used the angle ruler to align and level before welding, the flange should be welded on both sides, and the inner weld should not protrude from the flange sealing surface.
1. Flange connection method (need to disassemble, connect with equipment valves, etc.).
1) Where the pipe section and the pipe section are connected by flange or the pipe section is connected with the flange valve, the standard flange must be selected according to the design requirements and working pressure.
2) The diameter and length of the connecting bolts of the flange should meet the requirements of the specification, and the flange bolts should be tightened symmetrically, and the exposed thread buckle of the fastened bolt should be 2-3 buckles, which should not be greater than half of the diameter of the bolt.
3) Flange connection liner, generally water supply (cold water) with a thickness of 3mm rubber pad, heating, steam, domestic hot water pipes should use asbestos rubber pad with a thickness of 3mm. The gasket should be concentric with the pipe diameter and should not be deviated.
1. Threaded connection method (galvanized steel pipe, plastic-lined galvanized steel pipe).
1) Pipe breaking: According to the on-site surveying and mapping sketch, draw a line on the selected pipe and break the pipe according to the line.
2) Threading: The broken pipe should be set up according to the diameter of the pipe, and the general diameter of 15 32mm threading is 2 times, 40 50mm threading 3 times, and 70mm or more threading 3 4 times is appropriate.