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What Is Hydrostatic Testing and Why Is It Important

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  • hydrostatic testing, advice, pressure testing, safe pressure testing
  • Posted date:
  • 01-01-2025
What Is Hydrostatic Testing and Why Is It Important

How Hydrostatic Testing Works

Hydrostatic testing is used to check pipelines, pressure vessels and other systems that hold liquids or gases under pressure for leaks or structural faults.

The process involves filling the system with water or another non-compressible liquid that's typically dyed for visibility. The pressure is then increased to a higher level than the system’s normal operating pressure for a set period while inspectors monitor for pressure drops or visible leaks. If there is any reduction in pressure, it indicates a defect or leak in the structure.

Once the test is complete, the system is then drained and the test fluid is safely disposed of. If any defects are found, the system is repaired, and another round of testing is done to confirm its integrity. Regular hydrostatic testing is essential for preventing leaks and prolonging the lifespan of equipment, making it a critical procedure in many industries. 

The Importance of Hydrostatic Testing for Safety

A hydrostatic test ensures that pipes can withstand pressure without failing or causing property damage, environmental harm or injuries.

One of the main safety benefits of hydrostatic testing is its ability to detect leaks and weaknesses before a system is used. By filling the system with water and applying higher pressure levels, inspectors can identify defects, corrosion, or wear and tear.

Unlike testing with air or gas, hydrostatic testing uses a non-compressible liquid - typically water. This makes it a safer method because, in the event of a failure, water doesn't expand explosively like gas, reducing the risk of dangerous ruptures. This is especially important in industries such as firefighting and plumbing, where pressurised systems are integral.

Hydrostatic Testing vs. Other Pressure Testing Methods

Hydrostatic testing uses water or other non-compressible liquids instead of gas, making it a safer and more reliable option. Pneumatic testing uses air or gas, which is highly compressible. In the event of a failure, the compressed gas can release energy explosively, posing serious risks to workers and the surrounding infrastructure. On the other hand, hydrostatic testing uses water, which doesn't store energy in the same way; therefore, it reduces the risk of ruptures.

Another pressure testing method is ultrasonic testing, which uses sound waves to detect issues without applying actual pressure. While this is useful for non-destructive testing, it doesn't challenge the structure under real-world conditions like hydrostatic testing does, making hydrostatic testing more effective.

Hydrostatic testing is also better at finding small leaks, as the dyed water makes leaks and pressure drops visible. Due to its safety and ability to simulate real-world conditions, hydrostatic testing remains the preferred choice for industries that rely on pressure systems.

Regulations and Standards for Hydrostatic Testing

In the United Kingdom, hydrostatic testing is governed by several standards and regulations to ensure safety and compliance. The main regulation is the Pressure Systems Safety Regulations 2000 (PSSR), which demands that pressure systems undergo thorough examination according to a Written Scheme of Examination (WSE) before use. This process is designed to prevent risks associated with stored energy in pressure systems. 

Following these standards ensures that hydrostatic testing is conducted using the correct procedures, pressures, and safety measures in order to reduce the risk of leaks or structural weaknesses. Compliance with these regulations protects workers, as it minimises their exposure to hazardous conditions, since hydrostatic testing uses high-pressure liquids. 

By following these guidelines, industries can operate with confidence and know that their pressure systems are safe, functional, and fit for purpose under real-world conditions.


We provide professional hydrostatic testing services to ensure the safety and reliability of pressure systems. Anderson Engineering And Welding Services uses industry-approved methods to test pipelines, pressure vessels, and fluid systems to find leaks and weaknesses.