Industrial gases are used in confined spaces throughout the world yet site accidents still occur far too often with potentially fatal consequences, warns Afrox’s Manufacturing Industries Business Manager, Johan Pieterse.
“Working in confined spaces for maintenance, repair or statutory inspections is a common activity in industrial plants,” says Pieterse. “Employers and their personnel must be fully informed about the serious hazards associated with working in these situations. Accidents happen because people are either insufficiently trained or have become over-confident as a result of the repetitiveness of the task.”
Leading gases and welding products group Afrox has a dedicated risk assessment team that offer a specific focus on working safely with gases in confined areas. These assessments result in recommendations to increase safety levels.
“Industrial sites differ and that’s why individual risk assessments are critical to ensure the safety of workers and to protect employers from legal action in the event of a serious accident,” says Pieterse. “These assessments identify, for instance, the properties of the gases being used, to determine if they could potentially combine to form an explosive mixture, enrich the environment with oxygen or act as an asphyxiant.”
Gases can accumulate in places such as boilers, pressure vessels, drains, pits and underground work areas and these areas usually have limited or restricted access and have vessels or structures that require ladders, stairs or other means to get in and out.
Typically, storage vessels which have contained hydrocarbon fuels and oils, present a very real hazard. For workers in pits, sewers and other below-surface locations, methane is an ever-present danger.
The type of work carried out in these areas usually requires generating heat and electric current for activities such as cutting and welding, which is potentially hazardous in the presence of flammable gases.
“Enclosed environments also have the potential for atmospheric hazards such as asphyxiation, which can occur where there is less than 19.5 % oxygen present in the atmosphere,” says Pieterse. “Oxygen depletion is usually caused by hot work that uses up the oxygen present in the area, or by an inert gas leak that displaces oxygen in the atmosphere. Recently, this led to the death of two people when argon gas leaked into the pit where they were working.”
Pieterse says oxygen enrichment is another hazard to watch out for where oxygen levels greater than 23% are exposed to open flame or other source of ignition. This will result in a very explosive condition.
Toxic industrial gases can also infiltrate confined areas in the form of vapour, mist or fumes and can cause breathing difficulties, irritation to the skin, eyes, and mucous membranes and, depending on the substance, can lead to death.
“Companies are required by law to evaluate the risks these workplaces pose to their employees and then take steps to prevent them,” Pieterse says. “Where work in confined spaces is unavoidable, the onus is on the employer to ensure that it is as safe as possible.”
An often-repeated Afrox recommendation is that where fuel gases are used in confined spaces for any pre-heating, cutting, brazing or soldering applications, only fuel gases with a density less then air, such as acetylene, should be used. This is because acetylene is about 10% lighter than air and, if it escapes, would rise and deplete safely into the atmosphere. Acetylene is also safer for pre-heating processes, with lower potential for flashbacks.
Where fuel gases are heavier than air, leakages will sink to the lowest level, posing a serious hazard.
Proper procedures and guidelines should be strictly followed when implementing hot work procedures in confined spaces. Employers must understand the Hazardous Work Permit System, which governs responsibilities and processes, stresses Pieterse.
“As part of the global Linde Group, we have conducted extensive research into developing oxyfuel processes that create safer working environments and the latest technology arising from these studies is available to our customers,” he says.