Hdpe electro fusion fittings

Characteristics of PE electrofusion pipe fittings

Electric fusion pipe fittings play an important and irreplaceable role in engineering and maintenance. In construction, electric fusion pipe fittings are less affected by the external environment and human factors, so they are more reliable and more popular with users. Especially in gas pipe projects, electric fusion pipe fittings are increasingly used.

Since the base of the electrofusion pipe fittings is PE material, together with the pipeline system composed of PE pipes and wire mesh skeleton pipes , it solves the two major problems of traditional pipelines: corrosion and leakage at the joints. Its advantages are mainly reflected as follows:

( 1 ) Corrosion resistance: long service life;

( 2 ) No leakage at the joints: The use of electrofusion pipe fittings for connection essentially ensures the identity of the interface material and structure of the PE pipeline system and the pipe body itself, achieving the integration of joints and pipes;

( 3 ) Effective resistance to underground movement and end loads: When PE pipe systems are connected by welding, the joints based on this method are resistant to end loads and will not leak. At the same time, PE ‘s stress relaxation properties can effectively dissipate stress through deformation. Therefore, in most cases, expensive anchoring is not required at joints and bends. In addition, due to its high toughness, the elongation at break is generally more than 500% , and the PE pipe system has a strong ability to adapt to uneven settlement of the pipe foundation .  [1]

Installation and usage steps

1. Cut the pipe vertically, and use a scraper to remove the surface oxide layer at the position where the socket is inserted into the electrofusion pipe fitting.
2. Use a marker pen to mark the surface of the pipe according to the socket depth of the electric fusion fitting.
3. Insert the pipe into the electrofusion pipe fitting until the depth of the marking line. After installation, the axis line of the pipe coincides with the electrofusion pipe fitting.
4. Fix the pipes and fittings with clamps to prevent dislocation and loosening during the welding process. [1]

Precautions

1. During installation, the inner wall of the electrofusion pipe fittings and the pipe welding area are strictly prohibited from being contaminated by organic matter and other substances.
2. When welding pipe fittings, you must stay away from the welded pipe fittings and wait until the welding is completed and cooledfor 30 seconds before approaching.
3. According to the temperature and working voltage changes of the on-site environment, the welding time can be appropriately compensated during welding.
4. Input a matching power supply according to the requirements of the electrofusion welding machine. The farther the power source is from the electrofusion welding machine, the larger the diameter of the power cord is required to avoid undervoltage that affects the welding quality.
5. When installing pipelines, elbows and tee fittings must be reinforced with buttresses or fixed with brackets and properly compensated for the pipelines.
6. The pipes must be buried below the permafrost layer, and water must not soak the pipes in the trench during installation and welding.
7. When the temperature is low, good insulation work must be done when welding electric fusion pipe fittings.
8. When working in an environment with a large temperature difference between day and night, it is necessary to use a centralizer and other toolsto fix the pipes on both sides of the electric fusion fittings to prevent thermal expansion and contraction from affecting the welding quality.
9. During the cooling process, pipes and fittings cannot be moved.

Issues that need to be paid attention to when installing electrofusion pipe fittings:

1. First of all, during the installation process, no organic matter or pollutants should appear on the inner wall and welding area of ​​the electric fusion pipe fittings. At the same time, a certain distance should be maintained during the welding process to avoid unnecessary damage;
2. The landfill area of ​​electric fusion pipe fittings needs to be located belowthe frozen soil layer . It should be noted that during the installation and welding process, the pipes cannot be soaked in water;
3. In harsh environments where the temperature difference between day and night is relatively large, it is necessary to promptly select centralizers and other methods to fix the pipes to avoid affecting the final welding quality due to the principle of thermal expansion and contraction; at the same time, if the temperature is particularly low, it is necessary to Take insulation measures to avoid unnecessary losses;
4. Finally, the pipe cannot be moved at will during the cooling process. [2]

Welding machine wiring reference

Welding machine model Power supply requirements Power cord requirements (according to national standards) Remarks

3KW welding machine single phase 220V 4 mm *74 cable connects two wires into one line and divides them into two groups

5KW welding machine single-phase 220V 6 ㎜ *4 cables combine the two wires into one line and connect them in two groups

11KW welding machine two-phase 380V 6 mm * 4 cable connects two wires into one line and divides them into two groups

9KW welding machine three-phase 380V 4 ㎜ *3 cable

15KW welding machine three-phase 380V 6 mm *3 cable

Detection method

Detection methods of PE electrofusion pipe fittings:

The testing methods of PE electric fusion pipe fittings include elongation at break: elongation at break is one of the manifestations of good flexibility of the pipe. By determining the elongation at break of the pipe, it is confirmed that the pipe retains the performance of the raw materials, ensuring the convenience and economy of construction, ensuring the adaptability of the pipe to uneven foundation settlement, and meeting the needs of seismic performance.

Weather resistance: When the pipe is exposed to the combined effects of natural climate conditions such as sunlight, heat and cold, wind and rain, oxygen , etc., its strength, thermal stability, elongation at break and other properties will all be reduced. By measuring the weather resistance of bamboo, it is confirmed that the pipe retains the properties of the raw materials and ensures that the pipe can still meet the use requirements after receiving a certain amount of energy .

Resistance to slow crack growth: By measuring the resistance of the pipe to slow crack growth, it is confirmed that the pipe retains the slow crack growth resistance of the raw material to ensure the load capacity and long-term service life of the pipe.

Thermal Qualification : Through the determination of the thermal stability of the pipe, it is confirmed that the pipe retains the original properties of the raw material and ensures that the raw material can still meet the usage requirements during construction, welding and 50 years of use.

Melt mass flow rate: By measuring the melt mass flow rate of the pipe and comparing it with the MFR of the raw material, the difference is required to be no more than 20% . It is confirmed that the pipe basically retains the original performance of the raw material to ensure the reprocessing process of the pipe and the quality of the pipe. Welding performance.