A good pressure vessel is absolutely integral to autoclave operation. If the pressure vessel doesn’t reliably perform as expected, the best case scenario is that the autoclave has a shortened service life, needs more frequent service, or has many failed cycles. The worst case scenario is an extremely serious accident that could injure or kill.

The hydrostatic test procedure for pressure vessels is a crucial tool autoclave manufacturers use to ensure every steam autoclave is safe, effective, and reliable. When performed properly, hydrostatic testing exposes potentially critical structural issues with the autoclave’s pressure chamber.

During a hydrostatic test, the autoclave’s pressure vessel is entirely filled with an incompressible liquid (usually water, sometimes dyed to aid leak detection). The chamber is then sealed and pressurized to a level several times higher than the normal working pressure used during sterilization cycles. Once pressurized, the chamber is checked for leaks and other failures or abnormalities.

At Priorclave, we use a hydrostatic test procedure aligned with the requirements of the European Pressure Equipment Directive (PED). Meeting these stringent requirements helps us maintain production and safety standards and ensure the long-term durability of our autoclaves. Performing this test on each autoclave we manufacture is necessary for compliance with stringent UK regulations (where Priorclaves autoclaves are produced) and industry standards. For those who need supporting documentation, Priorclave can even issue a witnessed pressure test certificate for autoclaves we’ve manufactured, as we are audited by our insurer (Zurich Insurance).

Depending on where you are in the world and use patterns, periodic hydrostatic testing and retesting of your pressure vessel might be an important part of compliance with local laws and your insurers, or simply a good practice to ensure safety and get the most from your investment.

The Hydrostatic Test Procedure

We test each autoclave pressure vessel during production using the following process:

1. Prepare: All chamber outlets are temporarily sealed. That includes removing and blanking off any instrumentation, like pressure gauges. These openings prevent chamber pressure from exceeding normal working levels.
2. Fill: The chamber is completely filled with water.
3. Pressurize: The chamber is pressurized to roughly 3.5 times the normal operating pressure and held for 30 minutes.
4. Inspect: The chamber is closely inspected for any signs of leaks, weeping, or permanent deformation.

We’re often asked whether or not users will need to periodically perform hydrostatic tests on their own. That depends: For many of our customers, hydrostatic tests at the factory during production are sufficient. But that’s not always the case. In you area or industry law may require periodic inspections, including hydrostatic testing. These may be needed as often as once per year. Even in situations where testing is not legally mandated, periodic hydrostatic testing might be a condition set by your insurer, organization, or facility owner.

If you need to get into the nitty gritty of performing a hydrostatic test yourself, Priorclave’s detailed hydrostatic test procedure for pressure vessels PDF is a good place to start.

Are you in the market for a new autoclave? Contact our team. They’ll help you explore your sterilization needs to determine the right configuration of the right autoclave for you.