HESUPIPE
Construction characteristics of HDPE gas pipelines
1. Easy installation, maintenance and operation
There are two ways to connect PE pipes.
One is electric fusion connection, which is generally applicable to pipes with a diameter less than De110;
the other is hot melt connection, which is generally applicable to pipes with a diameter not less than De110, and no sleeve fittings are required in the docking. The above two connection operation methods can be mastered in a short-term training, the welding quality can be guaranteed, and the construction progress is fast. In addition, in the gas pipeline network that has been in operation, the three-way operation can be carried out with gas. This process cannot be achieved by using steel pipes as gas pipelines.
PE pipes themselves are light in weight and do not require lifting equipment. It is convenient to transport and lower the pipe into the trench. PE pipe welding only requires an electric hot melt welding machine. The equipment is light, the degree of automation is high, no manual welding is required, the installation and construction are convenient, the strength is small, and the efficiency is high. The buried PE pipeline for gas is mainly connected by hot melt or electric fusion, and its interface strength is generally higher than the strength of the pipe itself. Therefore, compared with rubber ring joints or other mechanical joints, there is no risk of leakage due to joint distortion. PE pipes have excellent flexibility, which greatly enhances the value of this material to pipeline projects. Due to the flexibility of polyethylene, polyethylene gas pipelines with smaller diameters (generally not more than D100) can be supplied in coils, which saves a lot of pipe fittings during construction and avoids the possibility of interface leakage; for non-grooving construction, the direction of the polyethylene gas pipeline can be easily changed according to the requirements of the construction method, so that the shape of the pipe can be changed before construction, and its original size and dimensions can be restored after the old pipe is inserted. PE pipes are easy to maintain, and holes can be opened or repaired on the pipeline without stopping the gas. There are very mature technologies in this regard. Polyethylene pipes are conducive to future accident repairs and maintenance. Since polyethylene pipes have good flexibility, in actual projects, gas pipelines with operating pressures below 0.1MPa are blocked by clamping equipment. In the process of repairing and connecting new pipelines, there is no open flame, which reduces the danger of gas system gas-carrying operations; since the clamping operation is used for repairs or connecting new pipelines, this operation does not last long. Therefore, the polyethylene pipe is flattened in a short time, and when the stress is removed, the polyethylene gas pipe itself should be able to basically restore its original shape. PE pipe has great advantages in trenchless pipeline construction. There are many cases of crossing roads and buildings when constructing gas pipelines in urban areas. When using trenchless technology, PE pipes have relatively large disturbance, fast welding speed and convenient construction.
2 Anti-corrosion treatment
PE pipe is a high molecular polymer of polyethylene, with stable chemical properties, little corrosion by chemical substances and stray currents in the soil, and good acid and alkali resistance. Therefore, polyethylene gas pipes do not need to be anti-corrosion treated when laid, and their service life is up to 50 years. It is particularly pointed out that there are many kinds of buried steel pipe anti-corrosion technical methods that use PE materials as anti-corrosion layers. According to relevant literature, foreign PE was buried and used for 60 years, and then dug out and re-welded. The welding and body quality can also meet the quality index requirements specified for PE pipes; PE pipes do not need to be anti-corrosion treated. The general design life of steel pipes is 20 years.
3 Strong engineering adaptability
There are many professional pipelines in municipal engineering and residential courtyards, and the pipe positions are tight. In this complex construction environment, PE pipes have good flexibility and flexibility: when the pipe base sinks slightly, it is not easy to break; the flexibility of PE pipes can be used to lay them in a winding shape or with the terrain. The turning angle is large during construction, and it is easy to bypass obstacles within the allowable bending radius, reducing the number of joints and reducing the difficulty of construction.
4 Low investment cost
The urban gas transmission and distribution network is an important part of the urban gas project. The cost of the gas pipeline network accounts for a large proportion of the total cost of the gas project (about 40%). Therefore, it is of great significance to study the economic cost and economic operation of the gas pipeline network. The economic performance comparison between PE gas pipeline and steel pipe is as follows: (1) The price advantage of the pipe over the currently commonly used gas steel pipe is well known. For pipes below DN200, PE pipe is cheaper than steel pipe; small-diameter PE pipes generally use electric fusion connection, and the price of PE pipe fittings is high; for large-diameter PE pipes, due to the thicker wall thickness, their price is higher than that of steel pipes, but they can be connected by hot melt, saving the cost of pipe fittings, and have a long service life (the service life of PE pipes is 50 years, and the service life of steel pipes is limited to 18 years according to the depreciation period of gas facilities of the National Planning Commission), and no anti-corrosion is required. The comprehensive price is still lower than the investment of steel pipes. (2) Because PE pipes are highly flexible, they can be prefabricated on the ground and then placed in the trench without the need for a working pit. Therefore, the earthwork volume of the PE pipe construction trench is smaller than that of the steel pipe construction trench. (3) The medium-pressure steel gas pipeline must undergo non-destructive testing during the installation and welding process, which is a valuable expense, and the inspection procedure is also relatively complicated; while the inspection procedure, inspection methods and means of PE gas pipes are simple and effective, and the inspection fee is very low. In short, the material and installation cost of gas PE pipes have obvious advantages over steel pipes, and the comprehensive economic performance of PE gas pipes is far better than that of steel pipes.