Corrosive gases are classed among Class 2.3 Toxic Gases and have the potential to burn or destroy organic tissue. This blog takes a closer look at the range of hazards presented by corrosive gases stored in cylinders: plus how to segregate them in your cylinder store and handle them safely. Workplaces which hold compressed gases in cylinders must follow the guidelines of AS4332-2004 - The storage and handling of gases in cylinders and we’ll be referring to the relevant sections to help your workplace reach compliance.
Hazards of corrosive gases in cylinders
Corrosive gases are used across a wide range of industries: oil, gas, chemical processing, paper making, and food preservation: corrosive gases like ammonia, hydrogen chloride, chlorine, methylamine, sulfur dioxide are common to these workplaces. Like all compressed gases, corrosive gases present a complex range of hazards because the chemical and toxic properties of the gases are compounded by the physical nature of the cylinders and the fact they are compressed and stored under pressure.
Corrosive gases can create the following hazards at your workplace:
Toxic dangers to people
Corrosive gases and vapours are especially dangerous to people because when these gases are ingested or inhaled they quickly begin attacking, burning and destroying tissue. The eyes and respiratory tract are extremely sensitive and vulnerable to permanent injury. Once the toxins in the gas reach the bloodstream they can penetrate major organs like the the lungs, liver, kidneys, as well as the reproductive and nervous systems.
Exposure to corrosive gases can be fatal and the severity of injuries are impacted by:
- Chemical properties and toxicity levels of the gas
- Length of time the worker is exposed to the gas
- Response times by first aiders, paramedics and hospital staff
- Other chemicals or Dangerous Goods present that may react with the gas
- Overall health of the exposed worker: things like their body weight, whether they were a smoker, if they had allergies
ESSENTIAL: Safety Data Sheets (SDSs) for gases kept or handled on-site, and the appropriate first aid kit, must be kept in a readily accessible location. Section 5.2.1 (c) AS 4332—2004. In the case of toxic and corrosive gases, compliant safety showers and eye wash stations will also be required.
Damage to plant and equipment
Corrosive gases can attack and corrode metals, causing damage to operating plant and equipment while reducing the lifespan of operating machinery. In electrical power systems, the build-up of corrosion creates excess heat which can cause circuit breakers and motor starters to explode. Corroded gas cylinders can cause catastrophic leaks, chemical reactions and explosions.
Toxic hazards to the environment
Corrosive gases can also create environmental hazards. Some corrosive gases represent an acute toxic hazard to aquatic environments, while others can damage fauna, vegetation, and rural properties.
Physiochemical hazards of gas cylinders
The long, slim design of gas bottles (plus the fact they are slippery and heavy) means they are vulnerable to falling or being knocked over. The mechanical energy stored in any gas cylinder is comparable to a car travelling at 180 km/h, and each has the potential to explode if the cylinder is ruptured or overheated. Hazards include:
- Escaping gas - accidental release from mishandling, worn fittings and connections, or corroded cylinders
- Ruptured cylinders - uncontrolled release or explosions from a cylinder being dropped/thrown, or impacted by a falling object, forklift or vehicle.
- Overheated cylinders - explosion after a cylinder is exposed to industrial heat, or dangerous event like a fire or explosion
Leaking cylinders that contain corrosive gas can cause fatalities and dangerous incidents very quickly. All gases under pressure can displace the oxygen in a room or confined space, and corrosive gases that are also flammable become an explosion risk
ESSENTIAL: The Standard requires that all gas cylinders and their fittings be checked regularly for leaks. Section 5.2.1 (j) AS 4332—2004
Locating and segregating toxic and corrosive gases
In your cylinder store it is essential to segregate Class 2.3 Toxic Gases (which include corrosive gases) from incompatible gases and substances, ignition sources and other Dangerous Goods.
- Compressed gases: Class 2.1 Flammable Gases and Class 2.2 (5.1) Non-toxic, Oxidising Gases must be stored at least 3 metres away. If this distance can’t be achieved you can use a screen wall made from non-combustible materials and at least 1 metre higher than the tallest cylinder in either store.
- Combustibles: combustibles, refuse, and vegetation must be kept at least 3 metres away from cylinder stores.
- Buildings: cylinder stores should be located at least 1 metre from building openings: doors, windows, vents, ducting.
- Industrial Heat: make sure cylinders stores are kept clear of plant and equipment that generates heat; furnaces, machinery, radiators, boilers, steam pipes.
- Ignition sources: any potential ignition sources must be kept away from cylinder stores. This includes cigarettes, lighters, personal electronics (and anything could generate static electricity), burners, welders.
Handling and storing corrosive gases
The following represent some of the essential requirements for handling and storing gas cylinders. Remember to always conduct a full risk assessment at your workplace to ensure that all gas cylinder hazards have been identified and properly controlled.
Use Mechanical Lifting Devices
Section 5.3.1 of the Standard requires that mechanical lifting devices, forklifts and cylinder trolleys should be used whenever gas bottles are being received, moved around the worksite, or returned to the supplier. Keep the valves protected and the cylinders upright.
Wear Personal Protective Equipment
Wear suitable PPE that protects all exposed skin surfaces from contact with corrosive gases and vapours. These might include eye guards, face shields, overalls, gloves, and in some cases breathing apparatus.
Ventilate Cylinder Stores
The Standard requires that areas containing toxic and corrosive gases are always well ventilated. Safe exposure levels to the gases must be maintained; gases must remain within explosive ranges, and oxygen levels must be consistently safe. A mechanical ventilation system may be required which incorporates exhaust fans, fumes, ducting, alarms, and monitoring controls.
Use Cylinder Caps and Restraints
Store toxic and corrosive gases upright and keep them restrained using safety straps or a chain — it’s best to keep them in a secure cylinder store. The cylinder valves must be closed when in storage and all Class 2.3 toxic gas cylinders require gas-tight outlet caps or plugs fitted over their valves when not being used.
Install Safety Showers and Eye-wash Stations
A compliant safety shower and eye wash station should be in the work area as well as a first aid kit and emergency PPE. Staff should be well trained in chemical emergencies knowing the location of the safety showers/eye-wash stations and how to use them.
Do you hold toxic, corrosive and other compressed gases at your worksite? We recommend downloading our free eBook Gas Cylinder Storage: Compliance and safety requirements for a detailed look at how to create a safe and compliant workplace. It’s an excellent resource for WHS Managers and supervisors responsible for managing gas cylinders and other Dangerous Goods at the worksite.