Stationary tanks and process containers
A stationary container system is a tank or a process container together with its associated pipe work and fittings normally located in one place. The requirements for a stationary tank are more specific than for a process container. Stationary container systems can hold flammable, oxidising, toxic and corrosive substances.
Stationary tanks are used for storing or supplying hazardous liquids, and are normally located at specific places. Stationary tanks include:
- all parts and materials that help to maintain the structure and integrity of the tanks
- any means of closing the tanks (for example, a lid or fitted cover)
- any component of the tanks intended to protect the contents of the tank from harm (for example, lightning protection) and
- any other components that are an integral part of the tanks (for example, a liquid height indicator, heating coil, or internal valve).
Stationary tanks do not include packages, intermediate bulk containers (IBC), transportable containers, compressed gas cylinders or tank wagons.
Process containers are stationary containers that hold a hazardous substance during manufacture or use, for example, a mixing container, reaction vessel, distillation column, drier or dip tank.
Stationary container – design and fabrication approval
A stationary tank that is part of a stationary container system must meet certain criteria.
- The tank must be designed to an approved standard.
- The design for the tank must be approved by a compliance certifier.
- The tank must either be built to an approved design by an approved fabricator or treated as a one-off and individually approved.
- The tank must be installed according to the Health and Safety at Work (Hazardous Substances) Regulations 2017.
Read the full requirements for the design and installation of stationary tanks and process containers, as part of a stationary container system, in Part 17 of the Health and Safety at Work (Hazardous Substances) Regulations 2017(external link).
Getting your stationary container system certified
All stationary tanks and process containers must meet legal requirements and when they are above the threshold quantities, they must be certified as detailed in the Health and Safety at Work (Hazardous Substances) Regulations 2017.
This certification is undertaken by a compliance certifier. Contact a compliance certifier(external link)
For further information on compliance certificates for stationary container systems:
Guide for the Certification of Stationary Tanks and Process Containers
The guide for the certification of stationary tanks and process containers, previously published under the Hazardous Substances and New Organisms (HSNO) Act 1996, provides useful information on the design and fabrication of stationary tanks and process containers. This guide is currently being revised to reflect the Health and Safety at Work (Hazardous Substances) Regulations 2017.
Until this revision is complete, the HSNO Guide may still provide useful guidance in how to meet your duties under the Health and Safety at Work Act and the Health and Safety at Work (Hazardous Substances) Regulations 2017.
Fire-fighting equipment and facilities must be installed on stationary containers which contain:
- more than 12,000 litres of liquefied gas or are in a cluster of tanks of more than 12,000 litres
- more than 60,000 litres of a class 3.1 substance or are in a group of tanks of more than 60,000 litres.
You may apply for an exemption from these requirements:
All stationary tanks and process containers which contain liquid hazardous substances must have secondary containment when the tank capacity is above the threshold quantities.
Secondary containment ensures that liquid substances can be contained if they escape from the container in which they are stored.
Guide for refurbishment of above ground tanks used to contain flammable liquids
Stationary tanks used to stored flammable liquids must meet the requirements of Part 17 of the Health and Safety (Hazardous Substances) Regulations 2017(external link) which includes compliance certificates for the design, fabrication and installation of the tank.
When a stationary container system which requires a compliance certificate – stationary tank or process container –is repaired, altered, relocated or replaced the compliance certificate(s) may be invalidated, and new compliance certificates would be required.
For below ground tanks the compliance certificate may become invalid if there is evidence that the tank is leaking.
If there is a change in service of the tank, the compliance certificate may become invalid.
Liquefied Petroleum Gas (LPG) bulk tanks must have a current certificate, issued under the Pressure Equipment, Cranes and Passenger Ropeways Regulations, and must meet certain additional requirements for the location compliance certificate.
Even the most safety conscious organisation can have an emergency, and preparing for one will depend on what hazardous substances you use and store. If you store liquid hazardous substances above the threshold amounts, you will need secondary containment to minimise the extent of the spill and to enable you to recover the spilled substance.
The secondary containment system prevents hazardous liquids, or hazardous substances that may liquefy in a fire, from escalating to a point where staff at the site, the public, or the environment can be harmed. The capacity of your secondary containment system depends on the type of container and the amount of hazardous substance stored.
|Below ground tanks||100% of container capacity|
|Above ground tanks||
110% of capacity of the largest container in the secondary containment system
Applications relating to secondary containment
Certification of sites
Sites that store or use flammable, oxidising, toxic and corrosive substances must have a location compliance certificate if the quantities are over the legal thresholds. Secondary containment is one section checked during this assessment.
Sites needing a stationary container system compliance certificate will also have their secondary containment systems checked.
Stationary container system compliance certificates and location compliance certificates can be issued by approved compliance certifiers.
Disused below-ground tanks
A tank that is stored below the ground and no longer stores hazardous substances is called a 'disused below-ground tank'. They must be removed and disposed of appropriately. Tanks are considered disused if they have been out of service for more than three months.
Removing below-ground tanks
Use the Ministry for the Environment’s checklist(external link) when removing your below-ground tank to help avoid land contamination.
An application to WorkSafe can be made to leave a disused tank in the ground if it is impractical to remove it or if the tank is out of service for only 3 to 12 months, for example when a structure was built over the tank, the tank may be left below the ground, if it is decommissioned appropriately.
It is impractical to remove a disused tank if its removal affects the structural integrity of surrounding structures, for example, the outer edge of the tank is within one metre of a building’s foundations, or the tank is located under a building. Walls may be temporarily supported to allow the removal, but we will consider the practicalities and costs if this is required.
If it is unclear how close the tank is to the building or if the wall is not structurally important, and we cannot determine if it is impracticable to remove the tank, we may request a statement from an accredited structural engineer of the Institution of Professional Engineers New Zealand (IPENZ).
When making the application to WorkSafe, you need to supply supporting evidence to leave the tank in the ground. If a tank is under a foundation wall, then evidence includes photos and support from a compliance certifier or engineer.
Tanks on a farm
A tank located on a farm can be left below ground if it complies with the
If a tank is out of service for between three and 12 months, we may grant temporary approval to allow it to remain in the ground during this time.
To get a temporary abandonment approval:
- the tank must be gas-free (see AS 4976) and filled with water and corrosion inhibitor
- local and regional authorities must be notified so they can update their records, and check that the tank is used again in the future
- evidence of the date of re-commissioning must be sought.
You must provide confirmation that the regional council agrees with leaving the below-ground tank in place. A council may require soil sampling and testing to show the ground is not contaminated.