Early one morning in October 2017, an automatic gas detector alarm went off in an ice rink in Fernie, B.C. It had been triggered by an ammonia leak coming from a small hole in a tube in the rink’s chiller, which helps create ice for a hockey and curling rink. The leak had been detected earlier in the year.
With the refrigeration equipment shut down, three workers started trying to repair it, but there was a large burst of ammonia from the chilling unit. All three men — two city employees and a refrigeration mechanic — were killed.
In 2010, a maintenance contractor had advised replacing the system, but the City of Fernie, after initially scheduling funding to replace the system, eventually deleted the project from its budget.
“Ammonia can be used very safely, but if equipment is not maintained, if end-of-life strategies are not adhered to, then major failures can happen,” says Eric Lalli, leader, incident investigations and provincial safety manager at Vancouver-based Technical Safety B.C.
Combustion systems provide heat for industrial processes that alter the physical and sometimes chemical properties of materials. They are common to a vast array of workplaces. They are also — because they function by the burning of hazardous fuels — very dangerous. When things go wrong, they can lead to serious injuries, fatalities and significant damage to equipment and facilities. Every company using combustion systems must implement a safety program focused on regular maintenance, inspection and training.
HOW COMBUSTION SYSTEMS WORK
Combustion systems are used in almost all manufacturing workplaces, from food processing to the automotive and pulp and paper industries, says Robert Sanderson, director of business development, combustion safety, at Rockford Systems, based in Rockford, Ill. Companies make use of thermal energy processes in many types of metal treating, such as painting, baking, sintering (making a powdered material into a solid mass by heat without melting) and annealing (a heat treatment used to reduce the hardness of a material). They are also used to dry paint, lacquer and enamel on manufactured articles, a process that often involves heating the articles in an industrial drying oven.
“Look around a room. Just about everything you can see has been kissed by the heat of an industrial process, whether it is the paint on the walls; the upholstery that may have been dyed and then baked to dry it on; the plastic which may have been thermally moulded; or the adhesive in the carpeting,” says Sanderson.
Industrial heating equipment includes dryers, furnaces, heaters and ovens. These usually supply heat to a work chamber and use a heat source (electricity or burning fuel). Industrial boilers heat water or generate steam for industrial processes or heating applications. Boilers are used in the chemical, food processing, paper, refining and primary metals industries.
The fuel piping system, or fuel train, is a series of components that feed and control the pressurized fuel to an industrial burner. Valves regulate the pressure and amount of gas flowing through the unit. Key safety features include safety shutoff valves, vent valves, visual-indication mechanisms and proof-of-closure switches.
These key safety features are part of a “valve safety train,” whose main function is to isolate fuel from the oven, furnace or other appliance, adds Sanderson. A valve safety train typically consists of these components plus regulators, in-line strainers, sediment traps, manual valves, throttling valves, pressure switches and test fittings linked to a burner management system.
The primary fuel used by most companies in Canada and the United States is natural gas. Other industrial gases are sometimes chosen: propane may be the second most commonly used and, after that, butane or other specialized atmospheric acids. Fuels such as coal vapours, solids or wood pulp are not used. Some companies use electric heat, which is less economical than gas.
“It all depends on the process. Most users use some type of fuel for their heating. If they are using electrical, it’s often because there’s a specific process need that precludes gas. Gas is almost always less expensive than electricity,” he says. “More and more [users] are shifting to natural gas as coal plants are shuttered in favour of natural gas. There’s a continual increase in the uptick in the use of natural gas, whether it be new industries or shifting of the combustion market.”
RISKS OF COMBUSTION SYSTEMS
Poorly designed and maintained combustion systems can result in serious incidents, such as leaks of hazardous gas from piping systems. One major danger is carbon monoxide, which causes asphyxia. Fires and explosions, which can send burning equipment, debris and pipes flying in all directions, cause severe burns and even death.
“The risk is not just for the workers near the equipment but also for people in the surrounding areas. If you have an explosion, it’s not just the guy who’s working on the boiler; it’s whoever else is working in the area as well who could be injured,” says John Marshall, director of fuels safety at Toronto-based Technical Standards and Safety Authority (TSSA), which registers all contractors handling fuels and certifies trades people who work with fuels.
Moreover, these explosions can inflict terrible damage to workplace equipment and to the buildings themselves, he adds.
“We’ve had explosions and fires that destroy whole buildings.”
MAINTAIN, INSPECT AND TEST
Problems can occur when combustion system equipment is not in good operating condition. Routine maintenance, regular inspection and testing — completed by certified technicians and according to equipment manufacturers’ instructions — are critical to prevent incidents.
First, safety managers need to ensure they are buying equipment from certified suppliers, which means equipment that meets the standards, codes and regulations of the jurisdiction in which they work. For example, valve safety trains, which control the flow of the gas, are designed to meet a variety of international safety standards, including the NFPA (National Fire Protection Association), NEMA (National Electrical Manufacturers Association), CSA (Canadian Standards Association), UL (Underwriters Laboratory) and FM (Factory Mutual Insurers).
The correct installation of the combustion system is essential; mistakes here can cause serious problems. For example, if the venting equipment is not properly installed, the products of combustion can leak into the work area and expose workers to carbon monoxide or other hazardous substances.
The workers who install the system must be certified or licensed by the provincial regulatory authority, such as Technical Safety B.C., which conducts practical testing to ensure a technician’s competence.
“People may not be fully trained on how to install properly. They may take shortcuts because of budget pressures, time pressures or simple lack of knowledge. They’re getting into a business in which they are not fully qualified,” Lalli says.
In jurisdictions with a permit system, such as British Columbia, companies need to apply for an installation permit and for an operating permit for equipment of a certain size. Technical Safety B.C. will then conduct annual inspections of the equipment to determine if it is still being maintained and operated properly.
As well as the venting, other items of equipment can go wrong. One of these is the burner, Sanderson says. If the burner, which is intended to act as a controlled air-fuel mixing device, is not getting the correct air-fuel ratio, it may not mix the fuels correctly.
“As a result, you may get incomplete combustion, which can cause the wrong products of combustion to come off. For example, you may get higher aldehydes or carbon monoxide. If it’s out of tune, you may get more greenhouse gases, such as NOX, which are nitrous oxides.”
Valves also need to be inspected regularly for fuel leakage, he adds. Valves are mechanical devices that have “seats” and “seals” that create barriers to control flow. These seats and seals can wear out.
“With time, debris and throttling, the seats and seals will age, get brittle and eventually leak. All valves leak. It’s a question of what is an acceptable rate of leakage. Is it one drip per year, one drip per day or one drip per second?” Sanderson says.
“So, annually, many of the systems are supposed to be inspected and checked for leakage. By doing an annual inspection, you can document how a seat or seal is leaking: Is it increasing? Is it wearing out? And you can try to be preventive on that.”
An inspection should also include a check of the many safety switches and devices that monitor the valves, he adds. For example, pressure switches should be examined to make sure pressure isn’t too low or too high, which could be indicative of equipment failure. Safety interlock devices, as well, should be checked to make sure they are working properly.
Lack of proper maintenance is a common problem, Marshall says. Boilers should be cleaned regularly and venting systems should be checked. When a venting system becomes blocked, due to debris or squirrel or bird nests, the heating unit may continue to operate, but, instead of sending the fumes up the chimney, it may spill them out into the workplace, exposing workers to carbon monoxide. That could put at risk not just those in the area but all the people in a building or factory.
“The key is regular maintenance and inspection,” he says. “That’s one of the most important things you can do to protect workers. That’s a requirement in the [Occupational Health and Safety] code. Owners and users must maintain their equipment in safe working order. That means you should be following the maintenance requirements recommended by the manufacturer. You should be cleaning the units, and if you see that the piping or venting is starting to rust and deteriorate, then you might want to do some work or look at replacing something.”
GET MANAGEMENT ON BOARD
One common cause of incidents involving combustion systems, Lalli says, is management decision-making and responsibility. In one 2017 incident, in which an explosion in a natural gas-fuelled boiler caused venting to collapse, Technical Safety B.C.’s investigation found the boiler had not been serviced in the three years since its installation, although the manufacturer recommended annual servicing.
A responsible manager recognizes the necessity to follow manufacturers’ instructions and the need to comply with both the provincial OHS code and regulator, he says.
“The manager says, ‘I have to be responsible and comply, despite the fact that it may cost money, downtime or hassle.’”
One critical aspect of managers’ decision-making is asset management, he adds. As the Fernie curling rink incident showed, managers must monitor the age of equipment and be willing to replace those pieces of equipment before they fail, injuring workers and causing damage to facilities.
“We need to make people aware, what is your end-of-life strategy for this equipment? Have you put a budget aside? Have you increased maintenance? Have you increased your inspection frequency? Are you taking into account this is aging equipment and it’s going to become more risky as time goes on?” Lalli says. “It’s surprising to see that a lot of companies, large and small, either are not aware of it or turn a blind eye.”
Everyone who works with or services thermal energy equipment must be trained on that equipment, Marshall says. If a food manufacturing facility, for example, has a malfunctioning oven, a trained worker would know to call in an expert technician, instead of repeatedly trying to light the oven. An untrained worker might not realize the oven is not working.
“If the person hasn’t been properly trained, they may try re-lighting that oven over and over again. At some point, they’ll get a combustible mixture in that oven and it will light, but it will also have an explosion,” Lalli says. “Sometimes, there may be what we call a delayed ignition, which is fairly minor, and the user might get a flash back and a minor burn. But, sometimes, they’re much more critical than that. In a factory, there can be a boiler explosion.”
Training should continue through a technician’s working life, Marshall says. No matter how thorough, the person’s initial training for certification cannot possibly cover the many different scenarios they are likely to encounter. Certainly, re-training is essential where a technician who is experienced working on smaller appliances plans to start working on larger equipment, such as an industrial boiler.
Following the Fernie curling rink tragedy, Technical Safety B.C. issued a province-wide safety order requiring all public facilities with ammonia refrigeration systems to test their equipment. The regulator’s investigation into the incident produced 18 recommendations, some aimed at improving maintenance of ammonia chillers, including regular monitoring of aging systems.
During the investigation, Lalli says, they found a large number of municipal ammonia refrigeration systems were more than 25 and even 30 years old. Yet, as statistics show, systems over 30 years old are bound to fail.
“We did a thorough investigation into that incident and shared our knowledge with the public. We got the message out. Now we’re seeing a lot of municipalities and cities putting a priority on budgets to replace this aging equipment because we’ve made them aware,” he says. “We’ve affected that change we’re hoping to make.”