Electric Fusion Pipe Fittings

Electric fusion pipe fittings refer to a type of plastic (polyethylene) pipe fittings that can be melted by the temperature generated by electric current to achieve connection. Capacity (that is, ampere) is the main parameter. In some low-voltage circuits, the voltage requirement is not high, and only the ampere is marked.

Construction supporting tools

PE pipes: pipe cutting machine; grinder (polishing sheet), marker; electric fusion welding machine (in accordance with ISO12176-2)

Remarks: Installation of PSP pipes: pipe cutting machine; trimming knife, grinder (polishing sheet), marker; electric fusion welding machine (in accordance with ISO12176-2)

PE electric fusion pipe fittings

1. Development of PE pipeline system

PE (polyethylene) is a series of resins that can be produced by various process methods, with various structures, characteristics and multiple uses. It has accounted for one-third of the world's synthetic resin production, ranking first. The application of PE pipes began in the 1940s, and was originally used as telephone line conduits and mine pressureless drainage (low-density PE pipes). In the mid-1950s, PE pipes were used for water supply (high-density PE pipes). In the mid-1960s, PE pipes were used to transport and distribute natural gas (medium and high density PE pipes were used). PE pipe systems have become the second largest plastic pipe variety in the world after PVC-U pipes. They are widely used in gas transmission, water supply, sewage discharge, agricultural irrigation, oil fields, mines, chemicals, post and telecommunications, and other fields.

2. Characteristics of PE electrofusion pipe fittings

In the sales and applications of polyethylene pipe systems, about 15% to 20% of the sales belong to pipe fittings. The pipe fittings of polyethylene pipe systems are mainly divided into hot melt pipe fittings and electric fusion pipe fittings. Due to the price, the amount of hot melt pipe fittings used in engineering applications is more than that of electric fusion pipe fittings, but electric fusion pipe fittings have an important and irreplaceable role in engineering and maintenance. In particular, electric fusion pipe fittings are less affected by the external environment and human factors during construction, so they are more reliable and more popular with users. In particular, electric fusion pipe fittings are increasingly used in gas pipe projects. At the same time, due to the complex production technology, high cost and high sales price of electric fusion pipe fittings, the profit margin of electric fusion pipe fittings manufacturers is also high, making them a hot spot for investment.

At the same time, since the base of the electrofusion fittings is PE material, the PE pipeline system composed of PE pipes solves the two major problems of traditional pipelines: corrosion and leakage at the joints. Its advantages are mainly reflected in the following:

(1) Corrosion resistance: long service life

(2) No leakage at the joints: The use of electrofusion fittings to connect essentially ensures the identity of the interface material, structure and pipe body of the PE pipeline system, and realizes the integration of the joints and pipes 

(3) It can effectively resist underground movement and end loads: After the PE pipeline system is connected by welding, the joints based on this method are resistant to end loads and will not leak at the joints. At the same time, the stress relaxation characteristics of PE can effectively consume stress through deformation. Therefore, in most cases, expensive anchoring is not required at the joints and bends. In addition, due to its high toughness, the elongation at break generally exceeds 500%, and the PE pipeline system has a very strong adaptability to uneven settlement of the pipe base.

Installation and use steps

1. Cut the pipe vertically and use a scraper to remove the surface oxide layer at the position of the pipe socket to the electrofusion fitting.

2. Use a marker pen to mark the surface of the pipe according to the socket depth of the electric fusion pipe fitting.

3. Insert the pipe into the electric fusion pipe fitting to the depth of the marking line. After installation, the axis of the pipe coincides with the electric fusion pipe fitting.

4. Fix the pipe and the pipe fitting with a clamp to prevent dislocation and loosening during welding.

Precautions

1. During installation, the inner wall of the electric fusion pipe fitting 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 welding pipe fittings until the welding is completed and cooled for 30S before you can approach.

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 the matching power supply according to the requirements of the electric fusion welding machine. The farther the power supply is from the electric fusion welding machine, the larger the power line diameter is required to avoid undervoltage affecting the welding quality.

5. When installing the pipeline, the elbow and tee pipe fittings must be well reinforced with piers or fixed with brackets and properly compensated for the pipeline.

6. Pipes must be buried below the frozen soil layer, and water must not soak the pipes in the trench during installation and welding.

7. When the temperature is low, the welding of electric fusion pipe fittings must be well insulated.

8. When working in an environment with a large temperature difference between day and night, it is necessary to use a straightener and other tools to fix the pipes on both sides of the electric fusion pipe fittings to prevent thermal expansion and contraction from affecting the welding quality.

9. During the cooling process, the pipes and pipe fittings cannot be moved.

Issues that need to be noted when installing electric fusion 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 below the 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 with large temperature differences between day and night, it is necessary to promptly select a centralizer 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, insulation measures should be taken to avoid unnecessary losses;

4. Finally, the pipe cannot be moved at will during the cooling process.

Detection method

Detection method of PE electric fusion pipe fittings

The detection method of PE electric fusion pipe fittings is elongation at break: elongation at break is one of the manifestations of good flexibility of the pipe. By measuring 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 settlement of the foundation, and meeting the needs of seismic performance.

Weather resistance: After the pipe is exposed to the combined factors of natural climatic conditions such as sunlight, cold and heat, wind and rain, oxygen, its strength, thermal stability and elongation at break will all be reduced. By measuring the weather resistance of bamboo, it is confirmed that the pipe retains the performance 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 to slow crack growth of the pipe, it is confirmed that the pipe retains the resistance to slow crack growth of the raw materials to ensure the basic load capacity and long-term service life of the pipe.

Thermal stability: By measuring the thermal stability of the pipe, it is confirmed that the pipe retains the original performance of the raw materials and ensures that the material can still meet the use requirements during construction, welding and 50a of service life.

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%, confirming that the pipe basically retains the original performance of the raw material to ensure the reprocessing process and welding performance of the pipe.