Pressure plant and equipment such as boilers, compressed air receivers, pressure piping and other pressure vessels can be hazardous, particularly in an industrial environment where they can seriously injure or kill workers. They are considered to be High Risk Plant.

PCBUs must ensure that regular maintenance, inspection and testing of the pressure equipment be conducted by a competent person.

Types of pressure vessels

A pressure vessel is a vessel subject to internal or external pressure which includes any interconnected parts and components, valves, gauges and other fittings up to the first point of connection to connecting piping. These vessels can be fired heaters and gas cylinders.


Boilers are classified as a vessel, or an arrangement of vessels and interconnecting parts, in which:

  • steam or vapour is generated or
  • water or other liquid is heated at a pressure above that of the atmosphere.

Boilers can be operated through the application of fire, the products of combustion, electrical power or similar high temperature means. Boilers include all parts and equipment directly associated with that vessel such as:

  • superheaters and reheaters
  • economisers
  • boiler piping
  • supports, mountings
  • valves, gauges and controls
  • fittings and boiler settings.

To achieve compliance for boiler operation you must have:

  • a current plant registration number
  • an operator with a high risk work licence or is trained by an RTO to safely operate the plant without supervision
  • a current boiler inspection certificate stating that the boiler is 'safe to operate'
  • an independent assessment for certificate for attendance category
  • a logbook in place and up to date
  • a procedure for safe operation, testing, cleaning and maintenance displayed
  • completed a hazard and risk assessment.

Pressure piping

Pressure piping is an assembly of pipes, pipe fittings, valves and pipe accessories subject to internal or external pressure and used to contain or convey fluid or to transmit fluid pressure. This includes:

  • distribution headers
  • bolting
  • gaskets
  • pipe supports
  • pressure containing accessories.

Air receivers / Compressed air

An air receiver is a pressure vessel that acts as a reservoir or storage vessel within a compressed air system. Air receivers can explode and cause serious injuries or death if they are not adequately maintained and inspected, or if they have been operated above the design pressure. Compressed air can also cause injuries.

General safety requirements

  • Consider PPE when using compressed air; goggles, face shield and other eye protection when used for cleaning purposes.
  • Assess the hazards and risks and put controls in place to minimise the risk of injury to people and equipment before using compressed air.
  • Do not point air tools or cleaning tools at people as this can result in injuries. Common injuries include eye and skin damage. They are further exacerbated when broken skin injuries exist.

Air supply

  • Maximum rated pressure must be marked on pipes, hoses and fittings. The pressure rating must be greater than the design pressure for the system for intended use. Air lines should be marked and colour-coded to identify for use with compressed air only.
  • Position air supply isolation valves as close as possible to the point of operation to allow immediate shut off in the event of an emergency.
  • Before disconnecting hand tools, turn off the air. Except where quick disconnect devices are used.


  • Keep hoses free of oil and grease to minimise deterioration.
  • Secure air hoses so that the risk of hose end whipping does not occur. Hose end whipping can lead to accidents and serious injuries.
  • Avoid trailing hoses across floors to prevent trips and falls in the workplace. Suspend hoses overhead to allow efficient access and protection from damage.

Static electricity

  • When using air tools, static electricity can generate. Equipment should be grounded where using such equipment in the vicinity of fuels, flammable vapours or explosive atmospheres.


  • Air should never be used to clean dust off clothing or person’s skin.
  • For bench cleaning, the pressure should be reduced to 100kPa unless equipped with a diffuser nozzle to provide a lesser pressure. Alternatively, consider using a vacuum cleaner as this is safer and cleans away debris for safe disposal. Cleaning with air only moves the debris from one area to another.

Hazard levels

Pressure vessels are rated from A through to E, with A being the most hazardous and E the least hazardous. These hazard levels are calculated using Australian Standard AS 4343:2005.

There are a number of factors that contribute to a pressure vessels hazard level, which include:

  • volume
  • pressure
  • temperature
  • location
  • usage
  • contents type.

Pressure equipment is required to be registered according to the identified hazard level A, B and C and regularly inspected by a competent person in accordance with the Australian Standard AS/NZS 3788 to ensure it is safe to operate.

Licence requirements

You will need a high risk work licence to operate specific pressure equipment in South Australia including:

  • standard boilers above 150 kw (unless certified compliant to AS 2593 for unattended operation)
  • advanced boilers above 150 kw (unless certified compliant to AS 2593 for unattended operation)
  • steam turbines over 500KW
  • reciprocating steam engines with piston diameter of 250mm and above.

Registration requirements

Design registration

You must register new designs and alterations to designs of boilers, pressure vessels and gas cylinders which have a calculated Hazard Level of A, B, C or D when assessed in accordance with Australian Standard AS 4343:2005.

The equipment Hazard Level assessment is normally the responsibility of the designer, manufacturer, importer, or supplier.

Once a pressure vessel design is registered, you must permanently mark the design registration number on each pressure equipment item manufactured to that registered design.

You must hold a copy of the design registration certificate for item of plant registration of boilers and pressure vessels. A supplier must share a copy of the design registration certificate with the purchaser.

Plant registration

You must assess each boiler or pressure vessel for item of plant registration, particularly where they have required the prerequisite design registration.

The equipment Hazard Level is assessed in accordance with the Australian Standard AS4343:2005. Any item of plant with a Hazard Level of either A, B or C requires registration before it can be operated for normal use.

Gas cylinders do not require item of plant registration.

Importing pressure vessels to South Australia

All pressure equipment coming into South Australia regardless of where it was designed and manufactured is required to be assessed for design registration.

If the design of the equipment has not been registered by the designer or manufacturer, then the responsibility to register is with the person who imported the equipment, or the person with management or control of the item of plant in the workplace.

The importer must:

  • conduct a hazard level identification and risk assessment as if they were the designer and manufacturer of the plant. Any risks must be eliminated or minimised
  • provide relevant information relating to the design and safe use of the plant to the end user.

Design registration must be obtained prior to supply or use of the equipment in South Australia. It is an offence to operate or allow someone to operate pressure equipment that is required to be design registered and has not received registration.


You must have a competent person (inspector) regularly inspect pressure equipment to ensure it is safe to operate. A competent person is someone who has education and training in the inspection of pressure equipment. Before engaging an inspector, you should ask them to provide evidence of their qualifications and training records in pressure equipment inspection. An inspector may be a member of an organisation that recognise their qualifications and training such as Engineers Australia, the Australasian Institute of Engineer Surveyors or the Australian Institute for the Certification of Inspection Personnel.

The inspection must be in accordance with Australian Standard AS/NZS 3788:2006 In-service inspection of pressure equipment. The Standard outlines the responsibilities for both the inspector and you as the owner of pressure equipment. The Standard incorporates a table that details the periods between routine inspections as well as information that leads the inspector through the inspection process for the various types of pressure equipment.

On completion of the inspection, the inspector will provide you with a Certificate of Inspection and a Report. The certificate must include a statement from the inspector indicating that they have conducted the inspection in accordance with Standard AS/NZS 3788 and that the equipment is 'Safe to operate' (where this is found to be the case).

Further information

Information sheet – compressed air - Safe Work Australia

Guidance material for the safe design, manufacture, import and supply of plant - Safe Work Australia

AS/NZS 1200 Pressure Equipment

AS 2593 Boilers – Safety management and supervision systems

AS/NZS 3788 In-service inspection of pressure equipment

AS 4343 Pressure equipment – hazard levels

WHS Regulations 224 and 739