What are the special requirements for the application of electrofusion branch saddle in high pressure pipeline system- Ningbo Lianda Plastic Pipe Co., Ltd.

Higher material performance requirements
Electrofusion branch saddle used in high-voltage systems must be made of high-density polyethylene raw materials that meet standards such as ISO 4437, EN 1555 or GB/T 15558. The material grade should reach PE100 and above, with higher tensile strength, internal pressure resistance, stress cracking resistance and low-temperature impact resistance. The raw materials should have clear batch numbers and quality traceability records, and the melt mass flow rate (MFR) should be controlled within a reasonable range to ensure that no thermal degradation or performance degradation occurs during welding and service. In special applications such as gas high-pressure systems, the slow crack growth (SCG) and rapid crack propagation (RCP) properties of the material must also be considered.

Reinforced structural design ensures pressure-bearing stability
In order to cope with the stress concentration and interface deformation risks caused by high internal pressure, the electrofusion branch saddle joint needs to strengthen the base thickness, branch pipe outer wall strength and resistance wire layout density in structural design. The joint base usually adopts a multi-layer composite reinforcement structure to improve the contact area with the main pipe and the uniformity of load distribution. The branch pipe part needs to be thickened or prefabricated with reinforcement ribs to prevent expansion deformation or shearing and shearing during high-voltage operation. The laying density of the resistance wire should be increased and the distribution should be more uniform to ensure that the welding heat field is fully covered, the interface is fully melted, and there is no empty welding or false welding.

High-voltage dedicated welding parameter control system
The electric fusion welding system needs to be equipped with a high-precision control module with functions such as constant pressure, constant current, and automatic identification of parameters. The welding machine should support automatic barcode identification to ensure that the actual welding parameters are completely consistent with the manufacturer's recommended values. The controller must have safety mechanisms such as overload protection, power-off welding, and temperature compensation to avoid welding failures due to unstable power supply or ambient temperature differences. For application scenarios with pressure levels of PN10 and above, it is recommended to use an intelligent welding machine with data recording and remote export functions to achieve digital quality tracking of the entire process.

Strict pre-welding pipeline pretreatment process
The high-pressure pipeline network has extremely high requirements for the welding interface, and more stringent pipe pretreatment must be carried out. Including mechanical scraping, double cleaning, degreasing and static removal and other operating steps. The scraping depth needs to be precisely controlled between 0.2 and 0.4 mm to ensure that the fresh PE matrix is exposed at the welding interface and to prevent the oxide layer from interfering with molecular fusion. Before welding, it is necessary to stand in a dry environment for a certain period of time to prevent condensation or moisture absorption on the surface of the pipe, which will affect the hot melt effect. All tools need to be calibrated and maintained regularly to ensure uniform scraping and thorough cleaning.

Strong control during welding and cooling stages
High-voltage system welding is particularly sensitive to the cooling process. After welding, the fixture must be cooled naturally in a completely locked state, and no loosening, displacement or external force intervention is allowed in advance. The cooling time should be reasonably extended according to the ambient temperature and pipe specifications, usually not less than 30 minutes. When constructing in winter or plateau areas, it is also necessary to equip insulation sleeves or mobile insulation sheds to prevent excessive cooling rate from causing internal stress concentration or brittle cracking in the welding area. The fixture can be removed after cooling to perform branch pipe opening or subsequent operations.

Precision and sealing maintenance of opening operations
Some saddle joints are designed as post-weld opening structures. In high-pressure pipeline systems, the hole opening operation must be carried out using original special tools to ensure that the hole position, diameter, and depth are consistent with the saddle channel. During the operation, it is forbidden to twist or push the branch pipe to prevent affecting the main weld structure. The chips generated by the hole opening must be cleaned up and prevented from entering the main pipe. Some manufacturers will provide pre-sealed diaphragms or mechanical limit structures to improve the sealing reliability and operational safety after the hole is opened.