What are the main connection methods of pe pipes?

Taking the construction of PE φ 200 as an example, the average truck can load 200 m φ 200 PE pipes and unload them in the trench of1000 mm. We use a fleet of two butt welding machines to connect the pipes in pairs, and after reaching a certain number, lay pipes beside the trench. Then connect the PE pipe with a welding machine and put it into the groove.

Two welders and a team can make full use of the cooling time of the first joint to operate the second joint. This construction method is efficient. For example, 1998 Dadukou New Town site in our city, the project includes 3958mφ 200 PE pipeline, φ250 PE pipeline and two φ200 PE valves, all of which are butt welded, and the whole project only takes 40 days.

If the project uses steel pipes with the same caliber, and a welder in a fleet welds six joints every day, it will take three months to complete. If the construction team adopts the best collocation, the effect will be more ideal. Taking 200PE pipe as an example, the best personnel combination is two welders (one full-time and one part-time monitor), four auxiliary workers and half an electrician. Half an electrician only has basic electrician knowledge and is responsible for the wiring of equipment power supply. If there is such a welder or workman candidate, you can save half an electrician.

The working time of electric welding machine should be arranged skillfully. Working 8 hours a day, two welding machines are used for butt joint in pipe piles, which can weld 12 ~ 14 joints. When the pipeline is scattered along the ditch, one welder is usually used to weld on the ditch, so that six welded joints can be welded in 8 hours, and another welder can rest. If six people in this fleet cooperate tacitly for a long time, two welding machines can be used at the same time, so that 8 ~ 10 welding joints can be welded.

(2) simple construction

(1) the trench of steel pipe construction requires the trench bottom to be flat, the trench is straight, the corner points are clear, and the trench of pe pipe is flat. The trench is not straight, but it also meets the requirements of snake-shaped installation of PE pipes. When turning, the trench does not need to be dug into a broken line, so the flexibility of PE pipes can be fully utilized to pass smoothly.

(2) Steel pipe construction needs arc welding machine, covered electrode oven, covered electrode incubator, oxygen cutting tools, welding materials, covered electrode, oxygen and acetylene gas, ultrasonic flaw detector, X-ray machine, darkroom for film development, electric spark instrument for checking anticorrosion coating, pig balls for purging, and even cranes for transporting pipelines. The welding equipment of PE pipe is simple. A hydraulic pump station, a hot plate, a milling cutter and a fixture form a butt welding machine, and welding materials are not needed. For professional installation companies that need to install pipelines with different pressure grades, these devices must be equipped. However, it is very important for companies that only install pressure pipes below 0.4MPa to compare and let them make the best choice.

③ It is more prominent in emergency construction. In April and May of this year, the hotel suffered a serious landslide due to heavy rain, resulting in multiple fractures of the 200-meter-long φ 2 19 natural gas steel pipe. Our company used 200PE tube electric fusion welding, and the gas supply was restored in only 8 hours.

(4) The insulation and anticorrosion process is omitted.

According to the emergency rescue statistics of natural gas pipeline leakage of Chongqing Gas Group, most of them are damaged anticorrosive coatings, resulting in electrochemical corrosion, corrosion and gas leakage. Most of the air leakage points are distributed in the pipe network below 0.3MPa, so our company uses pe pipes in the pipe network below 0.4MPa, which not only solves the problem of electrochemical corrosion, but also reduces the cost. According to the root calculation, the comprehensive construction price of PE pipe below 200mm is lower than that of steel pipe with the same caliber.

2 PE pipe construction management countermeasures

Due to the characteristics of PE pipe itself, there are also shortcomings, which need to strengthen management. We mainly take the following five measures:

(1) The PE pipe can't be applied with electrical signals by equipment, so the exact position of the buried PE pipe can't be detected. We take the following measures to solve this problem: burying pipeline corner piles, combining with burying tracer lines and warning tape, and making full use of the position of valve wells for positioning. The most important thing is to draw accurate as-built drawings. When signing a contract with a survey company, it is particularly emphasized to conduct survey before backfilling the trench.

(2) The quality of welding equipment is very critical. We use 1996 welding machine produced by a factory in northeast China, and the pressure, temperature and heating time are not indicated at all. We operate according to the experience and feelings of construction workers. The accident occurred in the construction of binjiang road PE 160 pipeline project of Caiyuanba, and the joint burst one week after the pipeline was put into production. Later, we eliminated this welding equipment and chose another domestic butt welding machine with reliable quality. It is cheaper than imported welding machines, but it also has many faults. Some of them are man-made, such as burning the motor with the milling cutter too hard, and on the other hand, the quality of the parts of the equipment itself is unstable.

We should regularly maintain the equipment and check whether it works properly. At the same time, strengthening the inspection of weld appearance quality can also find the working state of welding machine. For example, in the appearance quality inspection project. By checking the width of one side, the working condition of the heating plate can be found in time.