` Hydrostatic testing methods | Wildon (UK) LTD

0800 998 1374

Skip to content

0800 998 1374

Head Office 01889 529 234 / 01782 606 706

KSB logo Lowara logo ITT logo Constructionline logo British Water logo Klargester logo TT Pumps logo EBara logo
Water tank

Hydrostatic testing methods

Posted on February 13, 2018

Hydrostatic testing is a vital process for verifying the performance and integrity of a variety of vessels, including boilers, water tanks and pipework. A hydrostatic pressure testing allows you to see whether your equipment is working safely and if it is free from problematic leaks. Whether your equipment is new, it’s undergoing scheduled servicing or a problem has developed which is in need of troubleshooting, hydrostatic testing can prove a valuable tool. Let’s take a look at what this test involves and the different methods for carrying it out.

What is hydrostatic testing?

A hydrostatic pressure test is a way in which to examine whether your equipment in question is watertight/airtight, in good shape, and will be able to handle working conditions. The test generally involves filling the equipment – whether its a tank, pipework, or other such vessel – with pressurised water, set at a greater pressure than would be expected during normal operation, just to be on the safe side. Sometimes, dye is added to the water to aid detection of any potential leakages.

Water is used due to being practically incompressible, meaning that should the equipment break or fail during testing, the risk of damage or injury from the sudden release of pressure would be much reduced compared to other substances, such as gases.


There are a variety of different methods for carrying out a hydrostatic pressure test, and the particular method selected will be chosen according to the type of equipment being tested.

Water jacket

In this test, the vessel is placed in a ‘water jacket’ – a larger container which is filled with water and envelops the vessel. The vessel is then pressurised, maintained for around 30 seconds and then depressurised, and any changes in water level in the water jacket are measured. If the vessel leaks or becomes slightly warped by the pressurisation, water level changes will be measured.  

Direct expansion

This method involves filling a vessel with water, pressurising the vessel to testing level, and then measuring the amount of water which is expelled when there is a release of pressure. The expansion – both permanent and total values – can then be calculated to determine how the vessel coped.

Proof pressure

This is a basic form of pressure testing. It merely involves pressurising a vessel to the appropriate testing level, and then carrying out a thorough inspection of the vessel. Signs of leakages, deformation, wall thinning, and other such weaknesses would result in a failure to pass.

Ultrasonic testing

Ultrasonic testing is a more unusual, lesser used form of pressure testing. It is, however, an innovative, accurate and versatile method. Ultrasonic pulses of energy are emitted and spread through the vessel being tested in waves. The pulses are sensitive to imperfections in the vessel – such as cracks, warping or thinning walls – and can relay this information back to be reviewed and judgements can then be made about the integrity and safety of the vessel.  


Wildon UK can offer hydrostatic pressure testing to customers throughout Stoke on Trent, Staffordshire, and further afield across the UK. Our team of dedicated experts will work to make sure your equipment is safe, ensuring the most appropriate testing method is selected for your requirements. If you have any queries, or for more information regarding any of our services, simply get in touch.

Go back to

Speak to our friendly consultants today, call: 0800 998 1374

Farm Slurry Systems

Learning to manage animal waste efficiently forms part of helping your business to grow and flourish, as you draw on resources that are readily available, and farm slurry systems provides the ideal way to achieve this. Read More »

  • Design
    As wastewater specialists, we can design a system that is tailored around your individual needs.

  • Supply
    Once a design has been created we will supply and install it safely at your premises.

  • Maintenance
    We are on hand to carry out any maintenance duties to avoid unwanted problems in the future.

  • Repairs
    Our wastewater engineers are highly trained to perform any repairs necessary to keep your system working efficiently.

Wildon (UK) Ltd is a registered company in England. Registered Number 5759940 VAT Number 217 95 81 80