Also known as Pressure Class 150 flanges, these flanges have thick, strong walls to handle heavy duty industrial plumbing and water supply applications, such as water processing, waste water treatment, and irrigation. They meet NSF/ANSI 61 for drinking water. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. All are PVC, which has good corrosion resistance. Some are also glass filled for extra durability. They meet ASTM D1784 specifications and testing requirements for material quality.

To prevent leaks in threaded connections, apply a sealant to the male threads. Threaded connections can be taken apart as needed for maintenance and repair. For metal threads, use PTFE tape. For plastic threads, apply a non-hardening, plastic-compatible sealant. Tape or sealants with PTFE are not recommended for plastic-to-plastic connections. When making a threaded connection be careful not to overtighten the threads. To prevent cracks and leaks, finger tighten the fitting, then wrench-tighten one to two turns.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.