Pressure Vessel Inspection
What Are Pressure Vessels?
A pressure vessel is a container designed to hold gases and liquids and different pressures. These vessels are used in various industries such as mining, storage, transportation, oil and gas. These systems also include associated components, such as:
- Valves
- Gauges
- Safety fittings
- Connected piping up to the first point of connection
Since these vessels are under pressure, their failure can be hazardous. For this reason, they are under special design, maintenance, and inspection requirements.
Hazard Levels Explained
In Australia, every pressure vessel is classified by a Hazard Level under AS 4343 – Pressure Equipment – Hazard Levels. This classification helps determine how dangerous a vessel is if it fails.
Hazard levels range from:
- Level A – the highest risk
- to Level E – the lowest
Knowing the level of hazard is critical in understanding what regulatory requirements are applicable, such as whether your equipment needs to be registered with a state or territory authority.
Pressure Vessel Inspection Requirements
Term “Classified Plant “is no longer used, The Work Health and Safety (WHS) Regulations lists the plant that require registration as “Registrable Plant” which includes Pressure Equipment.
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.
The owner has a legal obligation to ensure the pressure equipment is:
- Registered with the relevant state or territory regulator
- Examined and certified as “Safe to Operate”
- Regularly examined by a “competent person”
A “competent person” for pressure vessel inspections must have the relevant engineering qualifications or knowledge of the technical standards. Source: Work Health and Safety (WHS) Regulations.
It is a violation of safety standards to operate unregistered or uncertified pressure equipment and can result in penalties or prosecution.
When Must Pressure Vessels Be Inspected?
In accordance with AS 3788:2006 (R2017), pressure equipment needs to be inspected at critical stages during its life cycle:
Commissioning or Recommissioning
Prior to a vessel being placed into service—or returned to service following a period of inactivity—it needs to be examined to verify its safety and functionality.
In-Service Inspections
- In-service inspections are required when the vessel is in service. These inspections are typically:
- External inspections – to reveal damage, corrosion, or leaks
- Internal inspections – to reveal internal wear, corrosion, or cracking (wherever possible)
The frequency of these inspections is determined by the vessel hazard level, service conditions, and inspection history. Refer to Table 4.1 of AS 3788 for further information.
Post-Repair Inspections
If a vessel has welded repairs or alterations, it will need to be hydrostatically tested—that is, pressurised with water—to ensure structural integrity before it can be put back into service.
Who Can Conduct the Inspection?
All inspections will need to be conducted by a “competent person”, as described in AS 3788. That is, someone who:
- Is suitably qualified and experienced in pressure equipment
- Is familiar with the appropriate Australian Standards
- Able to recognize safety issues and decide if the equipment is safe to use