How-To Guide: Choosing the Right Type of Pressure Test
Ductile Iron, Stainless Steel & Glass-Reinforced Plastic (GRP)
When dealing with these more rigid pipe materials that do not exhibit creep, a Type I test is most appropriate. A Type I test involves measuring the volumes of water lost during a test period. The pipe is brought back up to the initial test pressure at set intervals during the test by adding water. The volume of water added is accurately measured by our very own Water Added Machine. These volumes are then used to calculate the outcome of the test.
With polyethylene pipes that exhibit creep, there are two options; Type II or a Ten-Minute.
The most common test used for PE is Type II.
A Type II pressure test is known as ‘time critical’. This means the pipe is required to be taken to a specified test pressure and maintained for a set period which is usually around an hour. Pressure readings are then taken at strategic points and a calculation is applied using algorithms that accommodates for creep to determine the outcome of the test.
The Ten-Minute Test was developed for situations where a very short test time is required. It is suitable for testing PE pipes laid with the pipe-busting technique where water supply needs to be reconnected as quickly as possible. A specialist pump with a pre-set regulating valve adds the necessary amount of water to the pipeline to keep it at system test pressure. The amount of water added is used to calculate the pressure changes within the pipeline. The joints are also visually inspected during the test period. This test is somewhat less robust test than a Type II test and it is recommended that it is only used in conjunction with minimal joints (maximum 200m).
For more information on our pressure testing services, visit our website or contact us on 0333 567 3210.
Alternatively, download a copy of our pressure testing best practice guide.