Sealed Polypropylene Pipe Fittings PP Flanges Mechanical Component

In construction and decoration, PP flanges act as critical "transition connectors" between PP pipe systems and equipment, pipelines of different materials, or large-diameter pipe segments, realizing stable and detachable connections through standardized assembly steps. The core connection process mainly includes three stages: preparation of matching components, sealing structure installation, and mechanical fastening.

In specific construction and decoration applications, PP flanges are widely used in key pipeline nodes that require stability and maintainability. In residential water supply and drainage systems, they are mainly used to connect PP water supply pipes to water heaters, water pumps, or indoor water tanks—for example, in high-rise residential buildings, a PP flange is installed at the interface between the household water supply pipe and the community main pipe, which facilitates later inspection and maintenance of the household pipeline without affecting the entire building's water supply. In public building equipment connections, large-diameter PP flanges are used in the main drainage system to connect horizontal main pipes and vertical risers, or to connect PP pipes to sewage treatment equipment—the detachable structure allows for regular cleaning of the grease separator without cutting the pipeline. In building rainwater and sewage treatment systems, PP flanges are applied to the connection between roof rainwater collection pipes and ground drainage wells, or between underground PP sewage pipes and inspection wells—their corrosion resistance ensures long-term use in outdoor or underground humid environments, and the flange connection enables quick disassembly of the inspection well cover for pipeline dredging. Additionally, in renovation of old buildings, PP flanges play a key role in "material transition"—when replacing old cast iron drainage pipes with PP pipes, a PP flange can be matched with a metal flange to realize the docking of new and old pipelines, avoiding the need for overall pipeline replacement and reducing renovation costs and construction time.​

First, it is necessary to select PP flanges that match the pipe diameter and connection type—common types include flat welding flanges (suitable for low-pressure pipelines) and socket welding flanges (for medium-pressure scenarios). Before connection, the end of the PP pipe is inserted into the flange socket (for socket welding flanges) or welded to the flange sealing surface (for flat welding flanges) using a hot-melt machine, ensuring the pipe and flange form an integrated structure without gaps. Next, a sealing element is placed between the two mating flanges. Common sealing materials include EPDM gaskets and PTFE gaskets, which are placed in the flange's sealing groove to prevent fluid leakage. Finally, bolts and nuts are used to fasten the two flanges—bolts are inserted through the flange holes in a diagonal sequence, and then tightened gradually with a wrench to ensure uniform pressure on the sealing gasket, avoiding local over-tightening that damages the flange or under-tightening that causes leakage. This connection method not only adapts to the connection between PP pipes and different equipment but also enables the docking of PP pipelines with metal pipelines by matching flanges of different materials.​

PP flanges have unique advantages in construction and decoration, which make them irreplaceable in many scenarios. First, strong detachable performance is their core advantage—unlike one-time hot-melt connections of PP elbows, flanged connections can be disassembled by removing bolts, which is convenient for later maintenance or equipment replacement, reducing the need for large-scale pipeline demolition and saving renovation costs. Second, excellent sealing and pressure-bearing capacity—the combination of standardized flange structure and high-quality gaskets can withstand medium pressure (usually 0.6-1.0 MPa) in building pipelines, meeting the pressure requirements of domestic water supply and large-flow drainage systems, and effectively avoiding leakage problems caused by unstable interfaces. Third, corrosion resistance and compatibility—PP flanges have the same chemical stability as PP pipes, which are not eroded by domestic wastewater or slightly acidic rainwater, and can be used with non-metallic gaskets to avoid electrochemical corrosion, extending the service life of the entire pipeline system. In addition, their lightweight characteristic reduces the load on building structures, especially for overhead pipeline installations, and simplifies on-site transportation and hoisting operations.​