What are the characteristics and testing methods for electric fusion pipe fittings?

　　 Electrofusion Fittings It refers to a plastic (polyethylene) pipe fitting that can be fused by the heat generated through electric current. The rated capacity—i.e., the amperage—is the primary parameter. In certain low-voltage circuits where voltage requirements are not stringent, only the amperage rating is indicated. The following section outlines its characteristics and testing methods:

　　I. Electrofusion Fittings Characteristics

　　Fittings for polyethylene piping systems are mainly categorized into electrofusion fittings and hot-melt fittings. Due to cost considerations, hot-melt fittings are more widely used in engineering applications than electrofusion fittings; however, electrofusion fittings play an important and irreplaceable role in both construction and maintenance. In particular, during installation, electrofusion fittings are less susceptible to human error and adverse external conditions, making them more reliable and thus more favored by users. Notably, electrofusion fittings are increasingly being employed in gas pipeline projects. At the same time, because electrofusion fittings have high manufacturing costs, relatively high sales prices, and a complex production process, manufacturers of these fittings enjoy relatively high profit margins, which has made this segment a popular investment area. Furthermore, since electrofusion fittings are based on PE material, PE piping systems—comprising PE pipes—effectively address two major challenges associated with traditional piping: corrosion and joint leakage. Their advantages are as follows:

　　1. Corrosion resistance: long service life.

　　2. No leaks at the joints: The use of electrofusion fittings ensures, at the fundamental level, that the material and structure of the PE pipe system’s joints are consistent with those of the pipe body itself, thereby achieving seamless integration between the joints and the pipeline.

　　3. Effective resistance to underground lateral and end loads: After fusion-bonded joints are installed in PE piping systems, the joints exhibit excellent performance under end loads and are completely leak-free. Moreover, PE’s stress-relaxation properties enable it to effectively dissipate stresses through deformation. Consequently, in most applications, costly anchoring at joints and bends is unnecessary.

　　II. Electrofusion Fittings Detection method:

　　1. Elongation at Break: Elongation at break is one of the indicators of a pipe’s excellent flexibility. By measuring this property, it can be confirmed that the pipe retains the performance characteristics of the raw materials, thereby ensuring ease and cost-effectiveness of installation, adequate adaptability to uneven foundation settlement, and compliance with seismic performance requirements.

　　2. Weather Resistance: Under the combined effects of natural climatic conditions such as oxygen, rain, temperature fluctuations, and solar radiation, the pipe’s strength, thermal stability, and elongation at break all tend to decline. However, weathering tests on bamboo have demonstrated that this piping material retains the properties of its raw materials and continues to meet service requirements even after receiving positive feedback.

　　3. Resistance to Slow Crack Propagation: By measuring the pipeline’s resistance to slow crack propagation, it is confirmed that the pipeline retains the original material’s inherent resistance to such propagation, thereby ensuring its load-carrying capacity and long service life.

　　4. Thermal Properties: By determining the thermal stability of the pipeline, it is confirmed that the pipeline retains the original properties of the raw materials and that the component materials continue to meet service requirements throughout construction, welding, and the 50-year service life.

　　5. Melt mass flow rate: Measure the melt mass flow rate in the pipeline and compare it with the raw material’s MFR; the deviation shall not exceed 20% to confirm that the pipeline essentially retains the original properties of the raw material, thereby ensuring satisfactory post-processing and welding performance.