Uses: Mainly used to connect plastic pipes (such as FRPP/PVDF/PPH and other anti-corrosion plastic pipes or PP pipes) with metal flange valves, equipment or another metal flange. Provides a removable connection point for easy maintenance.
Connection method:
1. Plastic pipe end connection (socket end): Insert the plastic pipe into the plastic socket of the flange.
Hot melt socket welding: Use a special hot melt welding machine to heat the inner wall of the flange socket and the outer wall of the pipe to a molten state at the same time, quickly insert the pipe into the socket, maintain pressure to cool and solidify, and form a firm seal.
Flange head socket welding: First, a separate plastic flange head is hot-melt welded to the pipe end, and then this plastic flange head is bolted to the anti-corrosion/PP flange with a metal ring. The "socket anti-corrosion flange" and "PP socket flange" you describe usually refer to this kind of finished flange with a metal ring, and its plastic socket part has been firmly combined with the metal part.
2. Flange end connection: Align the flange surface with bolt holes on the flange with the butt flange, put a suitable sealing gasket in the middle, insert the bolt, and tighten the nut diagonally, evenly, and in batches to reach the specified torque value.

Installation precautions

1. Cleaning: Ensure that the flange sealing surface, plastic pipe end, and gasket are absolutely clean, free of oil, dust, and scratches. The plastic pipe end needs to scrape off the oxide layer according to the hot melt requirements.
2. Centering: During installation, ensure that the plastic pipe is aligned with the axis of the flange socket to avoid forced insertion causing stress concentration or uneven welding. When the flanges are butt-jointed, the two flanges must be parallel and concentric.
3. Hot melt control: Strictly follow the welding parameters (temperature, heating time, switching time, cooling time) provided by the welding machine manufacturer and the pipe/pipe fitting manufacturer. Too low temperature or too short time will result in cold welding; too high temperature or too long time will result in material degradation, pipe diameter shrinkage, and strength reduction.
4. Insertion depth: The pipe must be inserted into the socket to the specified depth mark line.
5. Cooling: After welding, it must be cooled naturally to ambient temperature in a stress-free state. During this period, it is strictly forbidden to move or be stressed.
6. Bolt tightening: Use appropriate gaskets. Tighten the bolts evenly in diagonal order in batches to finally reach the specified torque value. Avoid over-tightening on one side, which may cause flange deflection, gasket collapse or leakage.
7. Pressure test: After the system is installed, a pressure test must be carried out as required to check whether all connection points are leaking. It is strictly forbidden to tighten the bolts under pressure.
8. Material matching: Ensure that the flange material is compatible with the pipeline medium, temperature and pressure. Anti-corrosion flanges are used in corrosive environments.
9. Stress: The pipeline system should be properly supported and fixed to avoid excessive bending stress or shear force at the flange connection.