Hydrostatic Test Meaning: What Is a Hydrostatic Test?

Confused about hydrostatic test meaning? Need compressed air cylinders tested but not sure how to go about it? You’re not alone.

At Newcastle Safety Servicing, we inspect compressed air cylinders of all classifications and sizes daily. The hydrostatic pressure test procedure is essential for ensuring the functionality of a compressed air cylinder and the safety of those who rely on its operation.  However, there are still plenty of our customers that do not quite understand what a hydrostatic test is, and what it means for cylinders to undergo regular testing.

Hydrostatic Test Meaning

Hydrostatic testing is a common type of testing often used in re-qualifying low-pressure cylinders. The test identifies any leaks that may be present within the cylinder and assess its overall integrity. Examples of equipment that undergo hydrostatic testing would be fire extinguishing cylinders, storage tanks, gas cylinders and chemical pipelines.

To define hydrostatic testing, it is a procedure in which the internal and external condition of the cylinder is inspected and then taken above its working pressure to test for any leaks or damaged seals.

Why Is Hydrostatic Testing Necessary?

When considering the hydrostatic test meaning, it is essential to consider why it is carried out. The testing procedure certifies a new piece of equipment or one that has been rebuilt or repaired before use. This test is also carried out annually on scuba tanks as per Australian requirements.

The tests are carried out per industry and national guidelines and conducted by certified technicians. These tests are logged, and the equipment is tagged to demonstrate that it is safe for use. Testing guarantees the correct function of the cylinder and prevents accidents or injuries from occurring due to inadequate maintenance.

An example of what could occur if the cylinder had any flaws includes a seal rupture. At high pressure, the slightest rupture could result in an explosive reaction. Identifying such issues in a controlled testing environment is significantly safer than if they occur during operation.

For example, in Australia, all scuba cylinders are required to undergo hydro-testing annually. Scuba testing is completed under Australian Standard 2030.1 at a certified test station. Australian standards are quite stringent compared to other parts of the world. In New Zealand, only visual inspections are an annual requirement, and hydrostatic testing is conducted every two years. In the USA, testing is required every five years.

Now we have covered the hydrostatic test meaning, let’s look at what the testing procedure involves.

Hydrostatic Pressure Test Procedure

The hydrostatic pressure test procedure begins with an external inspection of the cylinder, looking for physical damage, gouges, dents, and corrosion. Particular attention is paid to repainted cylinders as they could have been heat-treated or had dents filled in. Dents, corrosion, and heat-treating can all negatively affect the integrity of the compressed air cylinder and lead to a failed result—most tanks that fail inspections before pressure testing is due to poor external condition.

Following the initial external inspection, the cylinder is drained, and the valve is removed. The technician will then assess the neck thread and internal spaces for corrosion and deterioration using telescopic mirrors. Meticulous inspection is vital as steel cylinders are susceptible to rust and some more so depending on how they were manufactured. The rust within the cylinder also provides the technician with a gauge of how well the cylinder has been maintained, as internal often occurs due to inadequate care.

After the inspection is complete and the cylinder has been emptied, it is connected to a pressure testing panel. The cylinder is pressurised and filled with a liquid, often water. It is filled to the desired pressure, known as the test pressure. The working pressure and test pressures used and signed off for the procedure are set by the cylinder manufacturer and found on the cylinder’s neck.

The cylinder is held at the test pressure for a period; the time varies depending on the cylinder being tested. The pressure is then slowly released, and the expansion measured on a manometer tube. The recorded expansion is measured against Australian standards to see if the cylinder has passed the hydrostatic test and is fit for use.

The cylinder is then disconnected from the test panel and inverted to drain and dry. To finish the procedure, the “o” ring is replaced, and the valve is re-installed. The cylinder is stamped, filled, leak tested, and the test certificate is completed. This process is usually completed and the cylinder ready for pick up within 48 hours.

The Benefits of Hydrostatic Testing

To define hydrostatic testing and outline its procedure is one thing, but it is vital to understand its benefits as well. The benefit of annual testing, especially at the same testing site, is that technicians can build up a test data log. Over time, this shows the health record of the cylinder and can be used to determine whether degradation is occurring or the cylinder is in good condition. Having a clear idea about the condition of the cylinder can prevent any accidents and injuries as the cylinder comes to the end of its working life.

Contact the Hydrostatic Testing Experts

Newcastle Safety Servicing provides hydrostatic testing for all compressed air cylinders from personal SCUBA cylinders to G size storage cylinders. We pride ourselves on excellent service and meticulous testing procedures. We are an SAI Global Certified Test Station and can test and repair all types of compressed air cylinders.

For more information about our services and testing, get in touch with our team today.