What are pressure vessels?
A pressure vessel is a container or vessel that holds a pressurising fluid, either a gas or liquid, which is subject to internal or external pressure. Pressure vessels also include the interconnected parts such as valves, gauges and other fittings up to the first point of connection to the pipework.
Every pressure vessel has a Hazard Level ranging from a Hazard Level A, being the most hazardous to a Hazard Level E being the least hazardous. Hazard Levels are determined by using the formula outlined in AS4343-Pressure Equipment-Hazard Levels.
Factors that influence a pressure vessels Hazard Level include:
- Design Pressure (P)
- Volume (V)
- Design Temperature
To comply with the current laws, legislation and Australian Standards, you need to know the Hazard Level of your pressure equipment, as certain hazard levels require registration.
What are the inspection requirements for Pressure Vessels?
Failing to inspect pressure equipment in accordance with the applicable Australian standards may result in a fine. It’s the pressure vessel owner’s responsibility to ensure all pressure equipment in use is certified as “Safe to Operate” and registered with the appropriate regulatory authority within your state.
A “competent person” needs to regularly inspect and assess pressure vessels categorised as Hazard Level A, B, C & D in accordance with AS3788-Pressure Equipment- In- Service Inspection.
You are breaking the law if you operate pressure equipment that has not been assessed as “Safe to Operate” by a competent person.
Inspection requirements of pressure equipment is clearly identified in AS3788:2006 R2017 and occurs –
- During commission and / or recommissioning;
- During service – Periodic in-service inspection is completed as per Table 4.1 in AS3788. In-service inspections consist of both internal and external inspections;
- Following repairs (Pressure vessels have to be hydrostatically tested following weld repairs);
- Pressure relief and safety valves are subject to regular inspection and overhaul / bench testing to ensure they are in a safe working condition.
The design code for pressure vessels, AS1210:2010 requires every pressure vessel to be protected by a safety relief device that prevents the vessel pressure from rising more than 110% of the vessel’s design pressure.
This pressure relief device must be inspected annually and recalibrated at the same time as the internal inspection frequency of the pressure vessel or five years, whichever is the lessor.