What Is Pressure Vessel Inspection and When Is It Required?

Pressure vessel inspection is a type of non-destructive evaluation conducted on already installed or a new pressure vessel. When pressure vessels were first developed and used, there were not many stringent regulations to oversee the vessel and workers’ safety. Many times, over-pressurized vessels would explode, causing monetary and environmental damage. To combat the issue, the American Society of Mechanical Engineers (ASME) was formed. The ASME is responsible for outlining specifications for the pressure vessels’ manufacturing and maintenance in the USA. While testing the pressure vessels, tank testing companies offering worldwide inspection services follow the guidelines laid down by the ASME.

If you are a pressure vessel manufacturer or use them at your facility, here are two pressure vessel standards you should know.

API 510: API 510 is an inspection code laid down by the API or American Petroleum Institute. API 510 standard governs aspects like repair, alterations, and inspection of the pressure vessels.

ASME Section VIII: The ASME Section VIII standard guides how fired, and unfired pressure vessels will be designed and fabricated. The code also outlines what certifications and qualifications tank inspection companies should inspect and test the pressure vessels.

Besides the code mentioned above and standards, federal agencies and industries can form their standards to regulate the manufacturing and inspection of pressure vessels.

The pressure vessel manufacturers’ responsibility is to ensure all the standards are being followed when designing and building the vessels. However, this is not all. Proper upkeep and maintenance of the pressure vessels are also essential for the safety of the tank, facility, people, and environment.

Methods of Pressure Vessel Testing 

Pressure vessels and containers must be appropriately manufactured and structurally sound to hold its content. It should also be useful in keeping the vessel’s pressure and robust enough to avoid leakage. When conducting a pressure vessel test, the inspector looks for traces of cracks, punctures, and other such flaws. If these flaws are not fixed in time, they can result in catastrophic damage.

Hydrostatic and pneumatic pressure vessel testing methods are some of the most common NDT used by inspection companies.

In Hydrostatic testing, water is used as a testing medium. On the other hand, pneumatic testing involves the use of non-toxic gas as the medium.

How Hydrostatic and Pneumatic Tests different? 

While both hydrostatic and pneumatic are some of the most effective NDT methods, they require a different setup.

Pneumatic testing uses non-toxic gas like nitrogen or oxygen. The use of gas as a testing medium makes pneumatic testing relatively unsafe. If the test is not done correctly or any crack appears on the tank while performing the test, it can lead to an explosion.

Hydrostatic testing is a reliable and safer testing option. In hydrostatic testing, the vessel is filled with water. Once the vessel is entirely filled with water, it’s pressurized up to 1.5 times of its limit. The inspector then checks for any sign of possible leakage or design flaws.