TR FLEX pipe

There have been some recent discussions and posts regarding the pressure ratings for TR FLEX® restrained joint pipe. To ensure the proper information is conveyed, U.S. Pipe is happy to explain in further detail. The confusion lies around AWWA C151 Ductile Iron Pipe, Centrifugally Cast, and the pressure ratings for the pipe versus the joint requirements of the AWWA standard C111.

The C111 standard was developed and established by the American Water Works Association (AWWA) to set minimum performance requirements for Ductile-Iron pipe and fitting joints used in the water-works industry using rubber gaskets.

This standard covers joints such as Flange, Mechanical Joint (non-restrained), Push-on type joint, both non-restrained and restrained. C111 has a Design Qualification for the joint wherein it is stated, at a minimum, the largest size of each group having a common joint design shall be tested. The push-on style joint for testing shall have maximum clearance between the plain end and socket, shall be fully deflected, as allowed by the design tolerances, and subjected to a hydrostatic pressure of 2 times the rated working pressure for 10 seconds without leakage.

The 30 and 36-inch TR FLEX restrained joint, as designed, and manufactured by U. S. Pipe, has always had a Working Pressure rating of 250 psi to comply with design qualifications of C111.

Since U.S. Pipe developed the TR FLEX restrained joint, we have extensive testing, evaluation, and experience with the TR FLEX. The result of this testing and the limitations of TR FLEX guided us in the creation of HP LOK® pipe, and ultimately HDSS® restrained joint pipe. The HDSS joint has a restraint pressure rating that matches the pressure class pipe rating it is used with, making it superior to TR FLEX. This performance led us to discontinue offering TR FLEX pipe.

If you have any questions about this subject, or the standards, please don’t hesitate to reach out to our Technical Resource Team (Click Here).

HDSS Pipe