Why Hydrostatic Testing is Critical to Employee & Plant Safety

Regardless of the industry, employee and manufacturing plant safety is job number one. For companies that utilize pressurized cylinders, it is critical that these vessels be tested regularly to ensure they can be operated safely. Should a failure occur, the result can be catastrophic for employees of a manufacturing facility.

In this blog, we will look at Hydrostatic Testing, (sometimes known as Hydrotesting), its purposes, how it is performed, as well as the mandated regulations that oversee the use of pressurized vessels.

What is Hydrostatic Testing?

Hydrostatic testing is a highly effective way to evaluate the structural integrity of cylinders that are designed to hold contents under pressure.

The main purpose of the test is to check for leaks. If a pressurized cylinder leaks, a failure could result and cause a very dangerous scenario for both people and property.

The Hydrostatic Testing Process – How it Works

The concept of Hydrostatic Testing is fairly simple, but it must be done only by highly experienced and knowledgeable technicians.

The process involves filling a cylinder with water and then pressuring it. The pressurization gives a technician the ability to look for leaks and also evaluate the structural integrity of the vessel’s weld seams. In addition, all fittings and connectors are evaluated against acceptable performance standards.

It is important to know that Hydrostatic Testing goes well beyond a basic visual inspection, where most structural deficiencies can be missed by the naked eye.

Passing a Hydrostatic Test gives users confidence that a cylinder will perform as intended and hold up to design standards and corrosive environments.

Complying with DOT (Department of Transportation) Specifications

The Department of Transportation mandates that all pressurized cylinders be certified according to strict safety standards. DOT regulations ensure that a pressurized vessel will perform as it should when being filled or emptied.

Any pressurized cylinders that do not meet DOT standards must be taken out of service and no longer used.

How Often Should Hydrostatic Testing be Done?

DOT requires that all pressurized cylinders be tested, however, the time interval can vary based on the type of vessels being used.

In most cases, DOT mandates that tests be conducted every 3, 5, or 10 years. The testing schedule is as follows for all cylinders that have a “DOT” or “ICC” rating. The rating references how much pressure a vessel can hold.

Here are some examples of common ratings and testing periods.

3-Year test:

  • DOT 3HT


  • DOT 3AA
  • ICC 3AA
  • DOT 3A
  • ICC 3A
  • 4BW-240

10-Year test:

  • DOT 3AA – A “star” will follow the most recent hydro test date.

Your Single Source Hydrostatic Testing Solution

Since 1950, Alexander Chemical has been the finest chemical and expert services provider that the industry has to offer. Our unmatched Hydrostatic Testing services are DOT certified and fully comply with all regulations. We provide Hydrostatic Testing on a wide variety of cylinder sizes and configurations.

We also perform comprehensive visual inspections of pressurized vessels, to ensure the safety of our customers and their employees.

Alexander Chemical uses calibrated cylinders to ensure the tests we perform are of the highest quality and in compliance with DOT standards. In addition, we utilize a 14” test head, as well as specially designed test jackets that fit most standard-size cylinders.

Contact Us Today!

If you would like to learn more about our Hydrostatic Testing services, we invite you to contact us today for more information.

For more than 70 years, Alexander Chemical has been the most trusted name in the industry, and we are ready to provide your company with an unmatched level of service and quality.