Fusion welded method of new polyethylene pipe

In the field of fluid medium transmission, polyethylene (PE) pipe is wide attention in recent years and has been the rapid development of new pressure structure.

Compared with the traditional metal pipe, polyethylene piping systems for light weight, strength and specific rigidity, durability, corrosion resistance, insulation, composite capacity and resistance to fracture. Easy to manufacture and installation, and low cost, the typical service life of up to the metal several times and can save a lot of energy production and use. It is used in the field of urban water supply and drainage and gas transportation and distribution system, agricultural irrigation and drainage systems, factories, mines ventilation system and mud, ore pipeline transportation.

Polyethylene piping systems for manufacturing and laying pipe connection between the impact of an important part of its structural integrity and lasting strength. Since polyethylene molecular chain by a methylene group, and having a high degree of symmetry. Determines its polarity is low, so the connection of the polyethylene pipe can not be used solvent bonding method using only mechanical connection or welding. Practice shows that the welding is a high-quality, high-efficiency plastic pipe connection technology. More mature welding techniques include socket weld, butt welding, fusion welded.

Heating wire which are fused welding molten weld has been the development and promotion of the construction is simple, portable field devices, welding speed, and soon. The basic principle is the high resistance of the wire pre-embedded in the plastic casing wall. Plug, Walter current, electric heating wire to make it around the plastic Division Heating and melting into each other, to form a weld cooling. Its main disadvantage is: (1) when the plastic melts and a small amount of current, closely-spaced heating wire are overlapped with each other to cause a short circuit failure often makes welding; (2) the high cost, the heating wire embedded within the plastic injection molding process and mold complex, will inevitably lead to the high production costs of the welded joints; (3) Upon completion of the welding, electric wire remaining in the weld affect performance, on the one hand, on the other hand, cause unnecessary alloy material waste.

Prepared using the carbon felt polyethylene laminated composite conductive composites as fusion welded materials is feasible during power-up, the resistance of the composite rate of change is very small, can be heated to the melting temperature of polyethylene. Composite molding process parameters temperature of 160 ° C, time 10 min, pressure 10 MPa, the resistance of the composite control in a 100 W. Factors affect the weld strength of the fused heating power, heating time, they impact on the weld strength is mainly attributed to the influence of the temperature of the heating layer, when the temperature of the heating layer is controlled within the range of 140 220 ° C, to obtain satisfactory weld strength. Therefore, the type of input power, it is possible to select an appropriate heating time to achieve the desired welding effect. Electrofusion welding, the presence of a heat affected zone in the vicinity of the heating layer in the melted layer and the heat-affected zone, the degree of crystallinity of the polyethylene, the crystal size will be changed, so that the properties of the material affected.

Weled steel pipe specification, Standard and identification

Welded steel pipe (steel pipe manufactured with a weld) is a tubular product made out of flat plates, known as skelp, that are formed, bent and prepared for welding.