scope:

Purpose of Field Testing:

Hydrostatic testing is universally known and accepted as the primary means of demonstrating the fitness for service of a pressurized component. It is the responsibility of the owner, through its agents (engineer, contractor, or hydro-test company) to develop its own safe and appropriate hydro-test plan, taking into consideration all the elements presented in this and other reference documents, in order to access and accept the installed pipeline from the contractor. After hydrotest, a pipeline or pressure vessel component may usually be expected to safely contain its intended operating pressure. However, even after a successful hydro-test, leakage or forced ruptures may occur later, for a variety of other reasons. The precommissioning hydro-test is simply one tool for evaluating a pipeline. The purposes of hydrostatic field testing of polyethylene pressure pipes using water are several, including:

To access the installed structural integrity of the pipeline for acceptability.

To try to reveal the occurrence of faults or defects in the pipe laying procedures, as exemplified by damaged pipe or fusion joints non-conforming to the qualified fusion procedures.

To try to reveal the occurrence of faults in the assembly procedures for pipeline components, as exemplified by tapping bands or saddles, flange sets, or Mechanical Joint assemblies.

To try to validate that the pipeline will sustain an acceptable level of over- pressure slightly greater than its design pressure, without leakage.

Note: Field testing is not intended to supplement or replace product standard test requirements.

The factors which affect the hydro-testing of HDPE pipe during commissioning procedures are: the creep characteristics of the PE pipe, the percentage volume of trapped air in the pipeline, and temperature variations. The self-limiting creep expansion of HDPE pipe is normal behavior for plastic materials when an internal pressure is applied, and is not an indication of a leak.