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MHI Risk Engineers - Approved Inspection Body - SANAS - MHI Regulations






Do you know if your installation, plant or storage is an MHI?

Do you have a major hazard installation?

If so, have you performed a valid MHI Risk Assessment according to SANS 1461?

If a company deals with more than a 1000 kg of a hazardous product it could be classified as an MHI. To determine is your facility is an MHI, it is the responsibility of the owners/employers to commission a MHI Risk Assessment. The purpose of the MHI Risk Assessment is to reduce the risk of a major accident or incident, hence reducing the risk to employees and members of the public. The MHI Risk Assessment will also determine if the plant should be classified as an MHI. The MHI regulations are here to protect people and your businesses.


Major Hazard Risk Assessment 

MHI Risk Engineers Pty (Ltd) is accredited and is an Approved Inspection Authority for the Department of Labour  

 to perform major hazard risk assessment according to the SANS 1461 method for the following :

  • Toxic gas / liquid chemicals
  • Flammable Gas / Liquid releases
  • Explosion of materials
  • Oxidizing Agents

Major Hazard Installation is any installation which can result in an event which can lead to the death of its employees or members of the public. A gas release can result in injury due to exposure , if the gas is toxic can result in death. If the gas is flammable and ignites it can cause fatal levels of thermal radiation which will cause serve burns. The gas released can also result in an explosion. MHI Risk Assessments determine the risk to people within the installation and people around the installation. MHI Risk Assessment is done according to SANS 1461 Standard.  The scenarios which are modeled are  :

  • Toxic gas release
  • Flammable liquid - pool fire
  • Flammable gas - jet fire / flash fire
  • Overpressure - blast shockwave 

You may ask what is jet fire , pool fire, toxic gas effects or over pressure effects. I have include videos which will explain this in detail. Like our page when done 


The video below shows the impact of a toxic gas release on the employees, the community around the facility and the costs incurred to the establishment as a result of the loss of primary containment. What could cause a gas release from your plant ? What do you think you can do to prevent such an incident? Type your comments on our blog.


BLEVE - Boiling Liquid Expanding Vapour Explosion / Jet Fire / Pool Fire

The video below shows the effects of a ruptured LPG bullet. The tank is rupture, liquid is lost  to ground which is set alight , the pool fire heats up the tank causing the liquid in the tank to vaporize. The pressure relief valve lifts to release material to the atmosphere, the material ignites resulting in a jet fire.  The heat around the tank causes the tank steel to weaken which results in a catastrophic failure of the tank. This is know as a BLEVE. Do you have an LPG Bullet at your plant? Can you think of possible reasons for a rupture? How would you prevent this? Leave your comments on our blog.


The video below shows what happens during a chemical explosion. A shock wave will destroy anything in its path. If a human is in the path , the persons internal organs will rupture resulting in death. The shock wave will also send buildings crashing to the ground and debris flying in all directions. Have you experienced a situation like this? leave your comments on our blog.


A toxic gas release can be see in the picture below. The red zone is where exposure will be fatal, where as in the green envelop people will have e.g 30 minutes to evacuate, the yellow zone is  where people may experience some form of discomfort during exposure.  

Toxic concentrations - Thermal radiation - Pressure Contours are plotted on the map:

The picture below shows the dispersion of gas with wind direction. Red Zones are fatalities may occur. 

The MHI Risk Assessment will result in risk curves been generated for all scenarios which will determine if the risk to employees or society is acceptable or not. An example of the risk curves are shown below:

Risk Curves Plotted - Risk to employees and society



AFTER THE EXPLOSION - This is whats left of the homes surrounding the plant