Structure and Design Principles of Electrofusion Fittings
Time:
2022-08-26 17:03
Structure and Design Principles of Electrofusion Fittings
Design Principles:
Electrofusion Fittings It is a specially developed product featuring a vector-based structural system, offering robust capabilities such as plastic load-bearing, variable deflection, reliable electrofusion welding, and spigot-and-socket alignment, making it ideal for connection piping systems using PE-RT and PE pipes.
1. External Structure:
Electrofusion fittings feature a large-radius arc, which effectively reduces water pressure. Under conditions of thermal expansion and contraction, the axial expansion and displacement of the pipe can be naturally accommodated by the fitting’s unique curved deformation. The pipe’s thermal expansion and contraction provide axial displacement space and confer the material’s inherent characteristics of load-bearing capacity, variable deflection, and self-adaptability.
2. Internal Structure:
2.1 Electrofusion Fittings Pure copper wire is used as the heating element, with a diameter of 0.6 mm to 0.8 mm. Specifically, DN63–90 fittings are heated using 0.6-mm-diameter copper wire, while DN110–250 fittings use 0.8-mm-diameter copper wire. Due to its inherent properties—such as high-temperature resistance, stable electrical resistance, consistent and sustained heat generation, excellent aging resistance, oxidation resistance, and non-corrosiveness—during electric fusion welding, pipe fittings of the same specification exhibit uniform heating, ensuring reliable and stable quality and safety of the electrofusion process. Moreover, the connection remains securely intact throughout the process.
2.2 The electrofusion fittings feature symmetric inspection ports on their exterior. The inner bore of each inspection port extends into the pipe to a depth of 3 mm ± 0.1 mm. The basic operating principle of the inspection port is that, during the electrofusion heating process, the fitting and the pipe undergo surface thermal expansion. When the material reaches the plasticization temperature and the plasticization depth attains 3 mm, the degree of softening of the plastic at the inspection port is assessed. As the pressure at the joint continuously increases, the inspection port gradually protrudes from the inner bore. Once the plasticization depth of the pipe material reaches the design value of 6–7 mm—experimentally confirmed as the typical plasticization depth for this type of pipe material—the inspection port will automatically cease extending and eventually come to a complete stop, signaling the end of the process. Throughout the entire electrofusion procedure, the inspection port provides a visual basis for evaluating the effectiveness of the electrofusion bonding.
2.3 Electrofusion Fittings A cooling zone of 10–20 mm is provided between the copper leads at both ends and the pipe-end region; this distance may be increased as the nominal maximum outer diameter of the electrofusion fitting increases. The purpose of the cooling zone is to maintain its temperature within the range of 30–50°C throughout the heating process, preventing the material from softening like a plug, thereby inhibiting the extrusion of molten plastic beyond the fusion zone and ensuring that all plastic remains within the fitting port. At the same time, the cooling zone helps sustain a certain level of pressure at the joint, resulting in a tighter connection. This is why a slight convex deformation appears on the inner bore of the pipe after electrofusion joining.
2.4 The electric fusion welding machine features automatic temperature-sensing control, enabling it to automatically adjust the current and fusion time in response to varying ambient temperatures. When the temperature deviates by more than 5°C, the machine automatically adjusts the parameters within the following nine temperature ranges: 0–5°C, 6–10°C, 11–15°C, 16–20°C, 21–25°C, 26–30°C, 31–35°C, and 36–40°C; additionally, there are two further ranges: 41–45°C. Under both hot and cold environmental conditions, the fusion performance remains consistent.
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On January 15, 2018, Zhejiang Qingfa Pipe Fittings Technology Co., Ltd. conducted a completion environmental protection acceptance monitoring in strict accordance with relevant national laws and regulations and the Technical Specifications for Completion Environmental Protection Acceptance of Construction Projects, based on the “Completion Environmental Protection Acceptance Monitoring Report for the Technological Transformation Project of Zhejiang Qingfa Pipe Fittings Technology Co., Ltd.’s Annual Production of 5 Million PE Pipe Fittings,” prepared by Zhejiang Hongbo Environmental Monitoring Co., Ltd.
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