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Some experience in pipe welding
Jan 24, 2018

Using hot-melt butt welding, hot-melt socket, fused socket, flange connection and other connection methods.

I. Material

The PPH tube is made of high density polypropylene (PPH) as the main body plus antioxidants, anti-ultraviolet and color materials. PPH Tube has the characteristics of good heat-setting, high temperature resistance, good chemical resistance, creep, tension, insulation, insoluble in organic solvents, dry and non-toxic. Applicable to chemical plants, electronic semiconductor plants, pharmaceutical plants, sewage treatment plants and other industries. It has been widely used in high acid and alkali chemical products conveying system, pure water conveying system, drink delivery system, sewage conveying system, environmental engineering and general piping system, telecommunication cable transmission and distribution piping system.

Ii. Welding Machines

PPH Pipeline welding for hot-melt welding, the use of various specifications of hydraulic or manual plastic pipe hot-melt machine. Taking the hydraulic plastic pipe hot-melt machine as an example, the welding is mainly divided into three parts: Welding machine control platform, weld operation Platform, tool placement frame.

Iii. Welding Preparation

matching tube type of tube cutter (pipe cutter), acetone, clean cloth, the surrounding environment to keep clean, no dust, to maintain ambient temperature, not less than 0 ℃.

Iv. Hot-melt welding

A total of 7 steps for welding are mainly divided, preheating, counterpart, heating, welding, cooling and inspection.

1. Cut the pipe with special cutting knife according to the requirement. Cut the pipe should be careful not to run the line and slowly into the blade, not too radical, will damage the blade. When the cutter is difficult to rotate, it should rotate the knife in reverse, remove the blade, and run the line again.

2, preheating with the hydraulic control valve will preheat pressure adjustment to the welding requirements pressure. Regulation method: Locking the heating pressure relief valve, the hydraulic lever pushes forward to watch the stress gauge display. When the required pressure is not reached, loosen the heating pressure relief valve, make the gauge show to zero, adjust the hydraulic control valve, and then lock the heat relief valve until the pressure is expressed to the requirement. Use the temperature setting panel on the welder control platform to set the temperature of the hot melt welding and control the temperature of the heating plate to fit the weld surface. Red shows the set temperature, green display is the current temperature, the face of the red light on the board to jump on the green, hot melt welding can be carried out. The hot melt temperature of PPH is generally set between 195℃~205℃.

3, counterpart

The ① chooses the appropriate mold, and uses the wrench to fix the weld pipe segment on the operating platform;

Note: Fixed at the end of the fixture to tighten the screws at both ends, to avoid the level of pipe segments; When the two pipe sections in the hydraulic lever back to a larger distance should not be less than the thickness of the electric cutting machine, the welding surface of each pipe should be highlighted fixture 40~50mm pipe length, should pay attention to

The ② hydraulic lever pushes to the larger, the two pipe sections counterpart. Visually weld the wrong side of the surface, for the lower half of the hand touch, to make two seam level. When the requirements are not met, the screws are adjusted at both ends to make the weld without the wrong mouth and reach the level.

③ visually two welded surface seams, to reach the seam without obvious gaps, if so, the use of electric cutting machine grinding mouth. The cutting machine is placed on the operating frame, the cutting machine is started, and another person manipulates the hydraulic propulsion lever, the pipe segment is set to the pressure cutting machine, and the welding surface is cut until the welding surface is flush. Step back the hydraulic clamp, remove the cutting machine, put back the tool to place the rack;

Note: Step back after the hydraulic clamp, do not rush to stop the cutter, let the cutter turn a few laps before removing. can make the welding surface more flat, prevent the appearance of section.

④ Clean the welding surface, with a clean cloth dip a small amount of acetone to clean the welding surface.

4, Heating

Remove the heating plate from the tool placement rack that has reached the required temperature. On the operating rack, one side of the welding surface, pushing the hydraulic clamp, so that the pressure to meet the required weld pressure. When the weld surface hot melt flanging reaches 1mm, loosen the heating pressure relief valve, unload the heating force, wait for a period of time, reach the requirement of welding surface hot melt butt.

Note: the heating plate must be placed vertically.

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