Industrial components need to undergo pressure testing to determine their structural integrity before use.

Components like pipes and pipelines undergo pressure-mediated checks to ensure they meet the relevant industrial safety standards.

One way to test these pipelines is through hydrostatic testing.

The article below will discuss hydrostatic testing and why it's essential.

Table Of Contents


What's Hydrostatic Testing?

Hydrostatic testing plays an essential role in quality control.

Hydrostatic tests are administered to check the strength and usefulness of items like gas cylinders, storage tanks, pipes, and chemical pipelines.

Hydrostatic testing works by filling objects with water.

Following that, the water is pressurized inside the pipeline or vessel to make sure it can handle the pressures of everyday usage.

Typically, water is used for the liquid in the hydrostatic pressure testing process unless it could damage the pipe or vessel.

This guarantees that it can withstand pressure without splitting at its seams or letting any leaks occur in its structure.

Following ASME hydrostatic test regulations, vents must be placed on the pipe or vessel's high points before starting the test to remove any trapped air as water is added.

The test cannot be completed until the air is cleared.

The name comes from when engineers used compressed air as their hydraulic fluid instead of water.

“Hydro” means water in Greek and “statikos,” means solid, as in static.

Through hydrostatic testing, we can gain confidence that the object won't rupture or leak when exposed to pressure or corrosive conditions.


Common Hydrostatic Testing Methods

Three common hydrostatic testing techniques are used to test vessels and cylinders.

Those tests are the water jacket method, the direct expansion method, and the proof pressure testing method.


Water Jacket Method

The water jacket method requires placing the vessel in a closed chamber, referred to as the test jacket, and filling it with water.

The test jacket is also filled with water.

The vessel is pressurized inside the test jacket for a pre-determined amount of time.

The vessel is expanded within the test jacket, causing water to flow into a glass tube so it can be measured for total expansion.

The total expansion is recorded, and the vessel is depressurized so it can return to its original size.

Sometimes the vessel won't return to its original size.

When that happens, it's called permanent expansion.

The serviceability of the vessel is determined by comparing total expansion to permanent expansion.

The larger the percentage increase, the more likely the vessel will be retired.


Direct Expansion Method

The direct expansion method involves filling a vessel or cylinder with a specified amount of water.

Once filled with water, the system is pressurized and you measure the water level to see how much water was expelled when the pressure is released.

The permanent and total expansions are determined by calculating the amount of water forced into the vessel, the test pressure, and how much water was expelled from the vessel.


Proof Pressure Method

The proof pressure test applies internal pressure to discover any weak points or leaks due to wall thinning that might result in the failure of the vessel.

This method is only permitted in the U.S. when the U.S. Code of Federal Regulations doesn't require permanent and total expansion values to be recorded.


Why Is Hydrostatic Testing Important?

Hydrostatic testing services can determine if a vessel can hold the amount of pressure it’s rated for safely.

This process guarantees that weld joints and flanges on industrial equipment are installed correctly, and the material will be able to handle the pressure.

These testing requirements are especially important in industrial applications involving the storage and transportation of fuel, chemicals, and other hazardous materials.

These materials can explode if they fail under pressure, and in pipelines a weakness in the structural integrity of a pipe could dramatically impact both the environment and economy.



For hydrostatic testing to work in any form, you need quality equipment.

It's very important to use quality equipment for your testing and have it installed by an experienced company.

STEVENS has complete hydrostatic testing and documentation in place, as well as in-house chemical cleaning and flushing and protective coating capabilities.

If you need professionally installed hydrostatic testing equipment, don't hesitate to contact STEVENS.




About The Author


I'm Ben Sparhawk, the Content Writer and Marketing Account Manager for the esteemed STEVENS company. As someone passionate about crafting captivating content, I take great pride in creating pieces that highlight STEVENS' capabilities and communicate the depth and breadth of their outstanding work.

In my role, I'm constantly striving to develop messaging that resonates with our clients and effectively showcases the exceptional work that we do here at STEVENS. I believe that communication is the key to success, and I work tirelessly to ensure our marketing efforts are engaging and informative.

When I'm not working, I often spend time with my three wonderful children. Becoming a dad is one of the best things that has happened to me, and I love every moment I get to spend with my wife and kids. You can also find me in the gym, trying to better myself, and I also enjoy spending time outdoors hiking or checking out local parks.