How to Conduct Hydrostatic Pipeline Pressure Tests

Pipeline pressure testing ensures that new pipelines don’t introduce defects into water and sewer networks, safeguarding water supplies by reducing the incidence of leakage and ensuring pipelines are fully compliant prior to adoption.

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Hydrostatic pressure tests involve extremes of pressure and require a high level of accuracy to ensure confidence in the structural integrity of pipework, so whether it’s a water main pressure test procedure or a smaller diameter section of pipework testing, it’s vital all tests are carried out safely and correctly.

In the UK, the industry standard for hydrostatic pressure testing is set out in Water UK’s IGN 4-01-03 Information & Guidance Note, ‘Guide to pressure testing of pressure pipes and fittings for use by public water suppliers’. In this article we’ll go through the main points of the guide – you can access the full pressure test guidance note here.

Safety during pipeline pressure testing
Due to the extreme pressures involved with pressure testing and the potential for dangerous pipeline failures and even pressurised air explosions, it’s important all tests are carried out safely.

  • Test operatives need to be trained and aware of the risks inherent with pipeline pressure testing. Safety zones must be put in place around any exposed pipelines.
  • Test areas must be cordoned off and warnings given when tests take place.
  • If long sections of pipeline are being tested, all involved should be in mobile phone or radio contact.
  • To minimise the dangers of excess air in the pipeline, swabbing and proper valve operation should be utilised.

Hydrostatic pressure testing equipment
Pipeline pressure tests require the right specification of equipment for the job in hand. All instruments used for recording the test data must also be calibrated and traceable through UKAS.

  • Pump – must be capable of achieving the System Test Pressure (STP) in under 30 minutes
  • Pressure gauge – a digital gauge with a resolution as or more precise than 0.01 bar, or for rigid and semi-rigid pipes, a calibrated conventional circular pressure gauge with at least 200mm diameter.
  • Flow meter – calibrated, with a resolution of 1 litre or better.
  • Data logger system – a pressure transducer with an accuracy of 0.25%, connected to a logger that can record at fixed intervals of 20 seconds or better. GPS and flow capabilities are recommended.
  • Volume container – calibrated and suitable for the expected volume loss, allowing for draw off to be measured during water loss tests.

All of necessary equipment, together with expert support and intervention, is available from Ant Hire Solutions – view our range of accurate and cutting-edge pressure testing equipment here.

Pipeline testing methods
There isn’t a single pipeline pressure test that can be used with all pipes. View the test types below to find the right one for your pipework.

Type 1 Pressure Tests (Hydrostatic)
Designed for testing pipework made from ductile iron, stainless steel and glass-reinforced plastic (GRP), type 1 hydrostatic pressure tests involve the measurement of volumes of water added (type 1a) to maintain the test pressure over a test period, or volumes of water drawn off (type 1b) and measured after the system test pressure has been replaced at the end of a test.

Pipelines are deemed to pass or fail based on the rate of water loss versus the allowed loss as part of the pipeline’s specifications.

Ant Hire Solutions’ type 1 pressure tests use an in-house Water Added Machine (WAM), which can add very small amounts of water to pipelines while logging the amounts added via a data recorder. As well as helping boost accuracy, this data can also be uploaded to the PIPE data management platform to be viewed or analysed remotely in real-time by contractors or utilities.

Type 2 Pressure Tests
Type 2 tests are designed for polyethylene piping but need to consider the possibility of pipe expansion – also known as creep – as the pipe’s pressure is brought up to STP.
Given the dual possibilities of creep or legitimate water loss, polyethylene piping pressure loss can be difficult to identify. This is why Ant Hire Solutions’ type 2 hydrostatic pressure tests involve pipelines being brought up to STP and left for at least an hour, during which the pressure is recorded and filtered through specially developed algorithms that can account for creep. This data is then analysed by our technicians or fed into PIPE where a pass or fail result is given.

10 Minute Test
A quick testing method that aims to minimise disruption to pipeline networks, the 10 minute test utilises a pump with a pre-set regulating valve that adds water to maintain STP. Water is logged as it is added, with the amounts pumped in used to determine the pipeline’s pressure changes, alongside visual inspection of the pipeline during the test.

Learn more about Ant Hire Solutions’ 10 minute hydrostatic pressure test.
Find out more about pipeline pressure testing and the issue of leakages and water scarcity by viewing the other articles in this blog series:

  • Leakage, shortage, stress: the challenges facing UK pipeline networks
  • What is pipeline pressure testing?
  • How to solve problems with pipeline pressure testing and repair
  • Ant Hire Solutions’ ‘9 Steps to Leak Free New Networks’

Discover Ant Hire Solutions’ range of pipeline pressure testing products and services and contact our team of experts today.