PE pipe is divided into four kinds according to the material: low density, medium density, high density and ultra-high molecular weight. Different kinds of welding methods and heating temperatures are different. Large caliber requires the use of a special hot melt machine, hot melt butt connection (that is, the tube and tube directly melting connection) can also be connected through the electric fusion parts.
So, what are the factors that affect PE pipe welding?
China HDPE parts factory says that the factors affecting PE pipe welding are: temperature, time, pressure and so on.
First, the influence of temperature shift on PE pipe welding
The influence of different climate and temperature on the welding quality of PE water pipe
With the shift of the four seasons, the temperature will be different, which will also affect the welding and installation of PE pipes. When the temperature is elevated in summer, the temperature is set to about 200°C, and the PE water supply pipe will be deformed when the temperature is too steep. When the temperature is low in winter, the temperature can be properly increased to about 220°C, and the PE water supply pipe will appear incomplete welding and virtual welding phenomenon.
Taking the most common ambient temperature of 20°C as an example, the normal welding temperature of pe pipe should be 220 degrees, and the heating time is the thickness of pipe wall x10 seconds. However, depending on the temperature, the welding temperature can be set to 230 degrees below 0℃, and the heating time is the thickness of the tube wall x12 seconds.
1. Below 0 degrees, the welding temperature can be set to 230 degrees, and the heating time is the tube wall thickness x12 seconds.
2. When the temperature is 0° C-10 °C, the welding temperature can be set to 225 degrees, and the heating time is the tube wall thickness x11 seconds.
3. When the temperature is between 10°C and 20°C, the welding temperature can be set to 220 degrees, and the heating time is the thickness of the tube wall x10 seconds.
4, the temperature is 20° C-30 °C, the welding temperature can be set to 210 degrees, the heating time is the thickness of the tube wall x 10 seconds. Above 30°C, welding temperature can be set to 205 degrees, heating time is tube wall thickness x 9 seconds.
We can get the reference index of pe pipe welding work: welding temperature: 220 degrees ±10 degrees, heating time: tube wall thickness x 9~12 seconds.
Second, the influence of time and pressure on PE pipe welding
Welding temperature, time, pressure and welding surface cleanliness affect hot melt quality.
Welding temperature, time, pressure, welding surface cleanliness; the temperature is determined according to the raw material grade, PE100 is 215-235°C, PE80 is 200-220°C, time and pressure are determined according to PE pipe specifications and welder parameters, PE pipe welding surface must be sterile. The weld is mainly controlled by program, and the appearance is determined by judgment: flanging edge is uniform and symmetrical, and the height is moderate; smooth surface without scaling; no impact marks, the lowest point of the weld is higher than the surface of PE pipe, no crack in the test weld.
The hot melt of PE pipe is normally carried out by the hot melt machine, which should be executed according to the temperature of the weather, the heating parameters of the hot melt machine and the applied pressure.
The best hot melt temperature and time for PE water pipe welding:
Heating plate temperature 200~230°C, large diameter, wall thickness of PE water pipe, slightly longer welding time.
Hot melt welding of PE pipe should accurately master the heating time. If the heating time is overly short, uneven heating is easy to occur, which leads to difficulties in matching. Heating time is too lengthy, easy to melt, gelatinous substances and loss. Set the heating plate temperature at 200 ~ 230℃. The best hot melt temperature time can be selected by referring to the following table:
Conditions not suitable for welding:
(1) The construction in winter is affected by low temperatures. The relevant national regulations obviously point out that the construction of PE pipeline below -5℃ should be stopped or the welding process should be adjusted. If the temperature is very low, the PE pipe will be unevenly heated. If the cutting time is overly short, there will be particles inside the weld, which will lead to easy fracture of the pipe. Without insulation measures, welding is not recommended.
(2) Secondly, under the influence of strong winds, strong winds will make PE pipe welding joints cool quickly, and the temperature inside and outside the welding joints is not uniform, resulting in a decrease in the bearing capacity of the welding joints. There are no windproof measures, so welding is not recommended.
(3) At present, the codes do not have reasonable suggestions for seasonal construction measures. Through exploration practice and some previous experience, the treatment method of gale weather is typically the construction measures of temporary public workshops in mining areas, and attention should also be paid to the sealing of both sides of the pipeline to prevent the risk of wind when cooling down.
(4) For the influence of low temperature, the current measures in the general mining area are to use tiny sun or other heating measures to keep warm the welding orifice of PE pipe, or to use electric heating. However, it is necessary to pay attention not to be too close to the welding office and heat up in advance. When the temperature reaches 5°C or higher, welding operation is not to be carried out.
(5) In the wind season, welding construction should not be carried out in the absence of wind insulation.