This document is the TN 5.07 Post-Installation Testing for HDPE Pipe. It explains testing requirements before and after installation for HP pipe products.

HDPE pipe is often tested after or during installation to ensure a sound installation was accomplished. Types of post installation field testing include deflection testing and joint testing. Specific testing required for the project will be found in the project specifications.

For Deflection Testing, an important feature of any flexible pipe is its ability to deflect, or oval, under load without structural distress. Flexible pipe must deflect in order to mobilize the strength of the surrounding backfill. Deflection allows the load to be transferred from the pipe to the surrounding backfill. As a result, flexible pipe can withstand very high loads as a relatively light structure. A table for base inside diameters for HDPE pipe supports the recommendations.

It is important to understand that mandrel testing is a go/no-go test. If any line were to not pass a mandrel, it is important to determine the cause. Obstructions in the line, not associated with deflection, may influence the test. Visual inspection is recommended in the event of a no-go result.

Joint testing is an important part of any gravity sewer system, both in testing for infiltration and exfiltration. Infiltration aids to estimate the amount of sewer water that will be conveyed to, and ultimately treated by, the waste water treatment plant.

Exfiltration aids to estimate the loss of sewage water into the surrounding soil. The two primary ways of testing sewer pipe joints for infiltration and/or exfiltration is using air or water to create a constant pressure within the system. A table with values for time to pressure drop for HDPE is provided.

Infiltration and exfiltration with water is explained with allowable leakage defined.

HDPE pipe is intended for gravity flow drainage applications and may be tested for deflection and joint tightness as discussed in this technical document. It is important to note that the testing procedures are no different than for other gravity flow drainage products currently being used in the market. This document does not purport to address the safety concerns associated with testing HDPE pipe.