TECHNICAL FEATURES
Pipeline pressure testing standard sets precedent
Pressure testing equipment from AHS
Regulations for hydrostatic pressure testing have taken a significant step forward with the release of Water UK’s Water Industry Standard for hydrostatic pressure testing of PE pipes, a move that will ensure the safety and reliability of the process, says Tony Kitchen, technical director at AHS Pipeline Innovation.
Water companies and contractors are adjusting to the requirements of the new Water Industry Standard 4-01-03, released in March 2024, which outlines the required standards for the hydrostatic pressure testing of polyethylene (PE) and polyethylene barrier pipes. The standard replaces previous guidelines from Information Guidance Notice 4-01-03.
The transition from an Industry Guidance Notice (IGN) to a Water Industry Standard (WIS) marks a shift towards more stringent and enforceable standards that aim to improve the safety and effectiveness of the pressure testing
22 process.
WIS 4-01-03 specifies detailed procedures for pressure testing below- ground water supply pipelines and sewer rising mains comprised of PE and PE barrier pipes. It includes guidelines for testing entire systems as well as replacement sections and service connections.
The specifications emphasise the importance of considering the viscoelastic properties of PE, which exhibits what is known as creep behaviour – deformation that occurs when subjected to pressure over time.
Understanding the difference
It is important to understand the distinctions between WIS and IGN:
● An Information Guidance Notice serves as a set of recommendations or guidelines that offer advice on best practice but does not mandate specific actions or procedures.
● A Water Industry Standard is a | October 2024 |
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more formal document that sets out mandatory requirements for products, materials or operational procedures. WIS documents are intended to ensure uniformity and compliance across the water industry, leading to more standardised and reliable outcomes.
Improving safety
The new WIS is designed to improve both the accuracy and safety of pressure testing which means there is now a zero- tolerance policy on pre-pressurisation. Key points are:
● The pipe must be at ambient pressure prior to testing
● If a test has failed, the operator must leave the pipe for four times the length of the ramp-up time before reattempting the test
● The operators must wait for two to three hours between filling and pressurising the pipeline. This takes into consideration the effects of thermal conditioning and allows the
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