Explosion in metal shipping container during firefighting

Transcription

1 Explosion in metal shipping container during firefighting Firefighters responded to a fire at a construction business. After approximately one hour, when the fire was almost extinguished, an explosion occurred within a metal shipping container that was located next to a burning structure. Flying debris from the explosion struck one of the fire captains, who sustained fatal injuries. Purpose of this report The purpose of this online incident investigation report is to identify the causes and contributing factors of this incident to help prevent similar incidents and to support preventive actions by industry and WorkSafeBC. This online version is not the official WorkSafeBC report. It has been edited to remove personal identifying information and to focus on the main causes and underlying factors contributing to this incident. Notice of Incident information Number: Outcome: Fatal Core activity: Firefighting Region: Interior Date of incident: December 2011 WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 1 of 17

2 Table of Contents 1 Factual Information Employer Incident site Sequence of events Workday before the incident Responding to the fire Assessing the hazards Fighting the fire The explosion Evidence of the explosion Firefighter training Fire department operations Operational guidelines Incident command Communication Supervision Safety systems Hazard assessment Accountability system Personal protective equipment Explosion elements Analysis Cause of the explosion Failure to recognize the shipping container as a hazard Existing firefighter training Usage of shipping containers Conclusions Cause Ignition of fuel vapours in enclosed metal shipping container Underlying factors Hazard of fuel vapours inside the shipping container not recognized Lack of available training on hazard of fuel vapours in shipping containers Use of shipping container next to combustible structure Limited ventilation in shipping containers Health and Safety Action Taken Office of the Fire Commissioner WorkSafeBC WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 2 of 17

3 1 Factual Information 1.1 Employer The employer is a municipality with a volunteer fire department that provides fire protection and rescue services for the city and surrounding area. Members of the fire department include the officers fire chief, deputy fire chief, and four fire captains and the firefighters. Although all members of the department are volunteers, they are compensated for their time when called out to an incident and are therefore referred to as paid-on-call firefighters. All officers are elected by the members of the department; the chief and deputy fire chief s positions require approval and appointment by City Council. 1.2 Incident site The fire department responded to a call about a fire at a construction business. Three of the buildings or structures at this site were directly affected by the fire: a post-and-beam production building, a modular trailer, and a metal shipping container (sea container). The majority of the construction work took place in the production building. This building was of post and beam construction with a metal roof. As the building was open on the sides, it was wrapped in shade cloth to provide some protection from the elements. Both ends of the building were used as the main entrance and exit points for raw material and equipment; a large overhead electrically powered crane was built into the structure. There was an additional entrance on each side of the building. The roof line of the building had been recently extended to cover the shipping container, allowing for additional storage on the top of the container. A wooden stairway had been built to facilitate access from within the production area. Several pieces of mobile equipment were located in and around the production building, including a fork lift, a zoom-boom telehandler, and a mobile crane in the yard area. The primary use of the modular trailer was as a lunch and break room for the company s staff members. It was also used as a heated storage area. The trailer was unlocked by staff at the start of each workday and locked at the end of each workday. The metal shipping container was 8 feet wide, 8 feet high, and 40 feet long, with double doors that were sealed from the elements by rubber gaskets. It had four small vents, one located in each top corner of both long sides of the container. The container was used for the storage of tools and equipment such as gasoline-powered chainsaws, electric power tools and hand tools, wheeled tool carts that were brought in and out each day, and a gasoline-powered pressure washer. Just prior to the start of the project that the construction business was working on at the time of the incident, the contents of the shipping container had been removed and reorganized by one of the senior employees. The only combustible liquids stored in the container were the gasoline and oil inside the individual reservoirs of the gasoline-powered tools; methyl hydrate, used to keep water-cooled saws from freezing in the winter; and a small amount of compressor oil. The manner in which the shipping container was being used at the time of the incident conformed to the British Columbia Fire Code. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 3 of 17

4 A separate metal fuel storage bin was used to store propane cylinders and flammable liquids such as gasoline and oil for the chainsaws and pressure washer. This storage bin was located a few feet from the shipping container and was kept locked. 1.3 Sequence of events Workday before the incident The construction business s production employees arrived for work and unlocked the front gate, the modular trailer, and the shipping container. Tools and equipment were removed from the shipping container as required, and chainsaws were fueled as needed. Approximately 10 minutes before the scheduled end of the shift, the work area in the production building was cleaned up and the tools and saws were returned to the shipping container, which was then locked. Chainsaws were not refilled with fuel before they were put away at the end of the day Responding to the fire Early the next morning, a witness called and reported seeing a fire start somewhere around the modular trailer and then spread quickly to the production building. He also called the company director and one of the company s employees, and they came to the incident site. The fire dispatch centre paged the members of the fire department. The members responded to the page and went to the fire hall, where they obtained their personal protective equipment, consisting of a fire helmet and turnout gear (jacket, pants, boots, and gloves) before boarding the trucks. The fire department responded with two pumper trucks, a rescue truck, and 15 firefighters, including the deputy fire chief and four fire captains. When the first fire truck arrived at the scene, the modular trailer was fully engulfed in flames. The roof of the production building was on fire, which was rapidly spreading throughout the entire structure (See Figure 1.) Figure 1: The production building and the modular trailer (on the right) after the incident. BC Ambulance Service was also called out to the fire. An ambulance stood by, parked on the street at the entrance to the facility, in the event it was needed. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 4 of 17

5 1.3.3 Assessing the hazards The deputy fire chief was the senior officer at the scene and the incident commander. He began to deploy the firefighters and equipment and walked around the entire structure to assess the situation while looking for potential hazards such as visible propane tanks. Two propane tanks near the stairs leading to the top of the shipping container were venting burning fuel; they were cooled with water from a fire hose. Another propane tank on the end of the modular trailer was moved from the trailer to a safe location. This tank was later found to have been empty. Visibility was good. With the fabric shade cloth burned away, both the interior and exterior of the production building could be clearly seen, including the overhead crane, which one of the fire captains had noted shortly after arriving at the scene. The deputy fire chief determined that the fire would be attacked only from the exterior. Three fire captains were overseeing the firefighters work on all sides of the production building. The deputy fire chief instructed Fire Captain 1 to fight the fire on the side where the shipping container was located. The deputy fire chief, along with a firefighter and two fire captains, then had a conversation with the company director about the contents of the shipping container. The company director said that the container was used for the storage of tools including chainsaws and hand tools that were used every day. The deputy fire chief asked if there was anything explosive in the shipping container such as propane tanks or jerry cans of fuel, and the company director told him there was not. The deputy fire chief was confident the information was accurate. The deputy fire chief, the company director, and the other officers and senior firefighters did not consider the shipping container and its contents to be a hazard. This was conveyed to the other firefighters at the incident. Not long after arriving at the incident, the employee who the witness had called saw that the rubber gaskets on the doors of the shipping container were burning and that smoke was coming out of its small vent holes. (See Figure 2.) Shipping container vent holes Figure 2: Vent holes on the shipping container. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 5 of 17

6 1.3.4 Fighting the fire Although the shipping container and its contents were not considered to be a hazard, it was still a focal point in the attack of the fire. Throughout the next hour of firefighting, water was directed at or near the container on an almost continual basis. Approximately an hour into the firefighting, Fire Captain 2 climbed a ladder and took a hose to the top of the shipping container to spray the surroundings and get a better view of the higher portions of the production building. While spraying the container from the ladder, he noted that no steam was coming off the container and that the wooden structure around the container (see Figure 3) had limited scorching. He then got on top of the container and felt the metal top with a wet gloved hand; it was not hot to the touch. Figure 3: A view of the shipping container, showing the wooden structure that had limited scorching. While on the shipping container, Fire Captain 2 saw that some of the roof trusses in the production building had begun to collapse. After getting down from the container, he radioed the deputy fire chief and recommended pulling back for safety. The deputy fire chief conferred with the other senior firefighters at the scene and ordered all of the firefighters to pull back so that the supports on one side of the building could burn through and the building would collapse in a safe direction away from everyone. All firefighters pulled back as instructed. One of the firefighters spoke with Fire Captain 1 near the end of the modular trailer. As nothing was falling at that point, together they decided to start slowly moving forward while remaining outside the building. Fire Captain 1 held the nozzle and the firefighter stood a few feet behind him to help hold the hose in place. Without notifying the deputy fire chief, they moved forward, spraying flare-ups near the shipping container, until they were approximately 10 to 15 feet from the doors of the shipping container and next to a forklift. (See Figure 4.) The firefighter saw the deputy fire chief walking in their direction and intended to update him when he arrived. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 6 of 17

7 Figure 4: The circled area is where Fire Captain 1 and the firefighter were working at the time of the explosion The explosion Before the deputy fire chief reached the location where Fire Captain 1 and the firefighter were working, the shipping container exploded without warning. Both of the steel doors were blown off the shipping container with the padlock still in place. The right door struck Fire Captain 1 s helmet, causing him to be thrown into the air. The door then struck and damaged a mobile crane more than 100 feet from the container. The left door flew in the other direction and went through the production building before striking a log pile almost 200 feet from the container. Fire Captain 1 received first aid immediately by firefighters and BC Ambulance Service; he died at the scene. The firefighter he was working with was not injured. 1.4 Evidence of the explosion Agencies participating in the investigation into this incident included WorkSafeBC, the Office of the Fire Commissioner, the RCMP, the BC Coroners Service, and the BC Safety Authority. While fire investigators were unable to determine the specific cause of the fire, there was no indication that the fire was the result of a criminal act. During the investigation, the shipping container was thoroughly examined. It sustained significant damage from the explosion (see Figures 5 and 6): One side was torn open near the roof line. Two sides were bent outward. The roof was bent upward at one end. Both of the 250-pound metal doors were blown off. The right door was bent from impact. o The padlock was still in place. o There were red and yellow transfer marks on the exterior of the door, consistent with having made contact with Fire Captain 1 s helmet. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 7 of 17

8 Figure 5: The shipping container after the explosion. Note the outward bending of the sides and roof. Figure 6: Interior view of the shipping container after the explosion and with most of the contents removed. The contents of the shipping container were examined after the explosion. Investigators confirmed the company director s description of the contents to the firefighters at the time of the fire and the information provided by the company s employees to investigators afterwards. The contents of the shipping container included numerous chainsaws. Two of the chainsaws had melted plastic housings. It was subsequently learned that these two chainsaws had been fitted with a specialized attachment and had been hanging inside the shipping container on the wall closest to the production building. (See Figure 7.) Figure 7: One of the chainsaws with a melted plastic housing. A 3.78-litre container of methyl hydrate, with approximately one quarter remaining, had been kept on an upper shelf, just inside the door on the wall furthest from the production building. After the incident, investigators noted a small amount of melted plastic in the location where the methyl hydrate had been kept, which indicated that the container had melted and the contents vaporized. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 8 of 17

9 1.5 Firefighter training The training standards for fire service personnel in British Columbia are those published by the National Fire Protection Association (NFPA). Training for firefighters and officers is also addressed in the fire department s health and safety program, where the NFPA standards are referenced as guidelines in the development of training. The health and safety program states: The Fire Department will maintain written procedures that describe the actions to be taken in situations involving special hazards and dangerous goods and must include these in the training and education program. The employer (the municipality), as the local governmental authority, sets the standard of service that the fire department provides and determines what training is required. The employer s fire department training policy states that new firefighters must complete a specific recruit firefighter training program or its equivalent. It goes on to state that the fire chief may develop training programs based on the NFPA and International Fire Service Training Association firefighting standards and publications. In accordance with this policy, at the time of the incident, all firefighters working for the fire department had taken the recruit firefighter training program. The course covers a variety of topics based on NFPA 1001: Standard for Fire Fighter Professional Qualifications; NFPA 1403: Live Fire Training Evolutions; and the recruit firefighter training program mentioned in the training policy. The course is designed to expose new volunteer firefighters to the basics of firefighting. It provides a standardized minimum training level so that new firefighters can work effectively in their departments and function safely at fire scenes. In addition to the training noted above, the employer s fire department training policy states that individual firefighters may take further training as required by the fire department s operational guidelines, occupational health and safety program, and respiratory protection program. The fire chief, the deputy fire chief, and the fire captains also took supplementary training courses as required. Volunteer firefighters are required to participate in weekly training sessions held at the fire hall, in a classroom setting as well as practical exercises. These weekly practice sessions are delivered by a senior member of the department, most often the training officer. Practice sessions are based on topics selected from the International Fire Service Training Association textbook and study guide, Essentials of Fire Fighting and Fire Department Operations. At the time of the incident, none of the training available to or provided by the fire department specifically addressed fighting fires that involve shipping containers. 1.6 Fire department operations Operational guidelines The fire department has a set of written operational guidelines that cover safety, operations, training, working with other agencies, and administration. Details about the health and safety program and the respiratory protection program, as well as background and reference documents, are also included in the binder of information. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 9 of 17

10 1.6.2 Incident command At a fire scene, the incident commander is always the senior officer present; in this incident, the deputy fire chief was the incident commander. The incident commander deploys resources, conducts a hazard assessment, and makes operational decisions based upon the circumstances of the event and the resources available. As this is a volunteer fire department, those firefighters and officers who may be able to respond to a page varies from call to call. This may alter how firefighters are deployed. For example, when all four fire captains are present, each will be assigned one side of the structure to supervise the tasks to be done; however, if extra firefighters are needed, a fire captain may participate in the actual firefighting process Communication Communication at a fire scene is done in person and by radio. All officers, including Fire Captain 1 during this incident, carry a portable radio and are in regular communication with the incident commander. They are responsible for relaying information to the firefighters they are supervising. In addition to the officers, individual firefighters may be issued a radio, depending on their assignment Supervision At all fire scenes, supervision is the shared responsibility of the incident commander and all officers. In this incident, there were five officers on the scene including the deputy fire chief and four fire captains to supervise 10 firefighters. There is no indication that a lack of supervision was a contributing factor in this incident. 1.7 Safety systems Several safety systems must be in place during firefighting operations Hazard assessment Both the fire department s operational guidelines and the employer s health and safety program require that a workplace inspection be conducted to assess the fire scene and identify hazards. In this incident, the deputy fire chief conducted a 360-degree walk around the site area. He identified hazards, such as the propane tanks, and discussed the contents of the shipping container with the company director. Other officers noted the presence of additional hazards and reported them to the deputy fire chief, thus providing additional ongoing information to work with. For example, one of the fire captains noted the overhead crane in the production building, and another fire captain observed the falling roof trusses. The deputy fire chief, in consultation with the other officers, took that information and developed an action plan to pull everyone back and allow one side of the building to burn while protecting the other. The building would then collapse away from everyone and the danger would be gone. This demonstrates the effectiveness of the hazard assessment process in that area. Although the hazard assessment of the building and the surrounding area was effective, it still did not identify the unknown hazards inside the shipping container. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 10 of 17

11 1.7.2 Accountability system The fire department has written procedures, as required by the employer s health and safety program, and a system designed to keep track of firefighters responding to and conducting firefighting operations at a scene. This personnel accountability system is the responsibility of the incident commander unless it is assigned to another firefighter, as it was during this fire. The accountability system was used effectively during this incident and was not a factor in the circumstances Personal protective equipment All firefighters involved in active firefighting must wear approved personal protective equipment including a helmet, jacket, pants, boots, and gloves as well as a personal alert safety system when wearing a self-contained breathing apparatus. In this incident, Fire Captain 1 was using all the approved personal protective equipment including a personal alert safety system device as required. 1.8 Explosion elements For an explosion to occur, four elements must be present: fuel, oxygen, an ignition source, and containment. In this incident all of these elements were present. The primary source of fuel was the vaporized gasoline and methyl hydrate. The ignition source will be discussed in the Analysis section of this report. If any of these elements is missing or is removed, an explosion cannot occur. However, just because the four elements are present does not mean that an explosion will occur in all cases. The upper and lower explosive limits must also be considered. The Canadian Centre for Occupational Health and Safety explains upper and lower explosive limits as follows: A material's flammable or explosive limits also relate to its fire and explosion hazards. These limits give the range between the lowest and highest concentrations of vapour in air that will burn or explode. The lower flammable limit or lower explosive limit (LFL or LEL) of gasoline is 1.4 percent; the upper flammable limit or upper explosive limit (UFL or UEL) is 7.6 percent. This means that gasoline can be ignited when it is in the air at levels between 1.4 and 7.6 percent. A concentration of gasoline vapour in air below 1.4 percent is too lean to burn. Gasoline vapour levels above 7.6 percent are too rich to burn. 1 In this incident, all four elements were present. While the vaporized gasoline from the melted chainsaws and the methyl hydrate from its melted container were the most significant source of fuel vapour in the shipping container, it is likely that they were not the only source. Given the high heat inside the shipping container, it is probable that other gasoline-powered tools, such as the other chainsaws and the pressure washer, were also venting fuel vapour to the atmosphere, as well as any other petroleum-based products such as oil or other lubricants. 1 WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 11 of 17

12 2 Analysis WorkSafeBC accepts the ruling of the Office of the Fire Commissioner and the RCMP that the cause of the fire was undetermined; therefore, this report does not analyze the cause of the fire. This analysis focuses on the following: The cause of the explosion Failure to recognize the shipping container as a hazard Usage of shipping containers 2.1 Cause of the explosion With respect to the cause of the explosion, the primary fire investigator from the Office of the Fire Commissioner stated in his report: It is theorized that the missing fuel from the chainsaws and melted container of Methyl Hydrate liquid in combination and within the closed sea container may have had the potential to create a loworder explosion due to the heating of the sea container with minimal ventilation in this confined space. The estimated missing fuel was approx ½ litre to 1.5 litres of gasoline and oil mix and approximately 500 millilitres of Methyl Hydrate It is this investigator s opinion that this explosion was caused by extreme heating from flame impingent on the exterior sides and doors of this sea container, creating an explosive atmosphere inside this vessel from the flammable vapours released from the melting of the chainsaws fuel tanks and the Methyl Hydrate container. NFPA 921: Guide for Fire and Explosion Investigations deals specifically with explosions. Explosion damage (see the outward bending of the walls of the shipping container in Figures 5 and 6) is explained in Chapter 21 of the 2011 edition: The terms high-order damage and low-order damage have been used by the fire investigation community to characterize explosion damage The differences in damage are a function of the blast load applied to surfaces (rate of pressure rise, peak pressure, and impulse, achieved in the incident) and the strength of the confining or restricting structure, or vessel, rather than the maximum pressures being reached Low-order damage is produced when the blast load is sufficient to fail structural connections of large surfaces, such as walls or roof, but insufficient to break up larger surfaces and accelerate debris to significant velocities. Investigators confirmed that the container was used primarily for the storage of various tools and equipment: gasoline-powered chainsaws, a gasoline-powered pressure washer, and methyl hydrate. On the day of the incident, approximately one quarter of the original 3.78-litre container of methyl hydrate remained. While this amount of methyl hydrate differs from the 500 millilitres that the primary fire investigator mentions in his report, an employee of the construction business confirmed that it was about 1 litre. The two chainsaws with the specialized cutting attachments were normally stored inside the shipping container by hanging them on the wall adjacent to the production building. The other chainsaws were kept on the floor or in a specially built storage block. Of all the chainsaws in the shipping container, only the two that were hanging on the wall had their plastic housings melt off, exposing their fuel reservoirs to the atmosphere. It is believed that the extreme heat of the wall closest to the burning production building caused the plastic to melt and the gasoline from these two chainsaws to vaporize. Without that extreme heat, the gasoline would have poured out in WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 12 of 17

13 liquid form. According to the manufacturer of the chainsaw, gas tanks are made from a type of plastic that has a melting point of approximately 200 degrees Celsius. Therefore, at some point during the fire, the shipping container must have become extremely hot and reached at least 200 degrees Celsius in the area where the chainsaws were hanging. Given that hot air rises and that the other chainsaws did not have the same kind of damage, it is likely that the temperature inside the container varied from floor to ceiling. An explosive atmosphere of gasoline is achieved once the gasoline occupies a minimum of 1.4 percent of the volume of a fixed volume container that contains air. For the size of this shipping container, the explosive atmosphere can be calculated to have been formed by the evaporation of 6.7 litres of gasoline at 20 degrees Celsius or 4.2 litres of gasoline at 200 degrees Celsius; at higher temperatures, a given volume of liquid gasoline will occupy a larger volume once evaporated. It should be noted that this calculation is based on the assumption that the container was empty at the time of the incident. However, the shipping container was not empty; approximately 25 percent of the space inside the container was occupied by shelving, tools, and equipment. This use of the available space would mean there was less air volume, so an even smaller amount of vaporized fuel would be needed to reach the lower explosive limits. Typical grades of gasoline are mixtures of flammable hydrocarbons that boil at 100 to 400 degrees Celsius; the more flammable components boil off first. The shipping container contained gasolinepowered chainsaws with vented fuel tanks of approximately 0.75 litres each as well as a gasolinepowered pressure washer. Other combustible or flammable materials, such as methyl hydrate, oil, and greases, were also present. While the exact quantity of liquid gasoline present prior to the explosion is not known, it is probable that there was enough gasoline available to produce the explosive atmosphere. It is not known exactly how the fuel vapours inside the shipping container ignited. Both gasoline vapour and methyl hydrate vapour are heavier than air and would have settled to the bottom of the container, well away from the small vents that the sealed containers are normally equipped with. Investigators believe there were two possible ignition sources: Although the shipping container was designed with only the small vent holes on the corners, given that the door gaskets were burning (as the company employee noted before the explosion), there might have been enough openings in the container to allow flammable and/or combustible vapours to escape. Any source of ignition nearby, such as the burning wooden structure or the disturbance of hot ash by water spray from fire hoses, could have resulted in flame flashing back into the container and igniting the explosive atmosphere. Another possibility is that the gasoline auto-ignited. Gasoline has an auto-ignition temperature of between 232 and 280 degrees Celsius. From the melting of the plastic on the chainsaws, it is known that the temperature inside the shipping container reached at least 200 degrees Celsius and could have been higher. Given that this is near the range where gasoline can auto-ignite, it is therefore possible that the temperature became high enough for the gasoline vapour to auto-ignite. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 13 of 17

14 2.2 Failure to recognize the shipping container as a hazard In examining why the shipping container was not seen as a hazard, there are several things to consider. The first is that the contents were known. The deputy fire chief was confident that the information the company director gave him was truthful and accurate. He knew the shipping container was vented, so he did not consider pressure buildup to be an issue. Once he was told that there were no bulk quantities of fuel or other flammable liquids and that the shipping container was vented, the deputy fire chief gave no further thought to the small amount of fuel in the shipping container as a potential threat. In addition, throughout the firefighting operation, there were no indications of a potential problem with the metal shipping container. Threat cues would have included physical or audible signs from the container, such as noise, peeling paint, smoke, or flame, other than those normally associated with the fire or the burning door gaskets seen earlier by the company employee. These observations and opinions were shared by senior officers and firefighters at the scene. For example, two veteran firefighters told investigators that they did not see the shipping container as a risk or hazard. 2.3 Existing firefighter training In looking at why the shipping container was not considered to be a hazard, the issue of training must also be considered. At the time of this incident, this type of scenario had never been dealt with previously by the employer s fire department. There is currently no specific training available to fire departments in British Columbia for fighting fires involving shipping containers. There is also no available training with respect to the presence of explosive fuel vapour that could be present from very small amounts of combustible and/or flammable liquids. Neither the deputy fire chief nor the other more experienced members and officers of the fire department recognized the hazard that was present. Other professional firefighters, both volunteer and career including the primary fire investigator with the Office of the Fire Commissioner, who has many years of firefighting and investigation experience stated that if they were placed in the same situation, they would not have recognized this hazard either. All firefighters interviewed stated that this hazard is not something that was previously known in the firefighting industry. 2.4 Usage of shipping containers Shipping containers like the one involved in this incident are designed for the safe and secure shipment of goods on ships, by rail, and by truck. They are designed to be weather-resistant, with little venting and seals around the doors and no windows. This makes them ideal for transporting goods across the ocean or on land (by rail and truck). It also makes them a common choice for storing just about anything at home or at a job site such as a farm, construction site, or commercial business. In fact, there is a large secondary market for shipping containers, both new and used. As a result, they can often be found to store a wide variety of tools, equipment, and machinery, including flammable and/or combustible liquids, in a manner that they were not designed or intended for. As they are sealed and have only small vented areas, shipping containers have the potential to trap escaping gases or vapours from fuels stored in these containers. This very limited ventilation contributes significantly to the retention of heat inside the container and the risk of an explosive atmosphere developing within the container if flammable and/or combustible liquids are stored where they can vaporize. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 14 of 17

15 The placement of a shipping container on a property or job site or at commercial facility can create a risk of an explosive atmosphere if it is located next to a combustible structure. In the event of a fire, the heat radiating from the burning structure and the surrounding area would certainly have an effect on the shipping container and its contents. This condition was clearly evident in this incident: the temperature inside the shipping container became hot enough to melt the plastic housing off of two chainsaws, allowing the fuel inside them to escape and vaporize, which contributed to the explosive atmosphere. 3 Conclusions 3.1 Cause Ignition of fuel vapours in enclosed metal shipping container Fuel vapours accumulated inside the enclosed shipping container and then ignited, resulting in an explosion that blew the steel doors off. Fire Captain 1 sustained fatal injuries when he was struck by the right door from the shipping container. 3.2 Underlying factors Hazard of fuel vapours inside the shipping container not recognized The company director told the deputy fire chief and other senior officers that there were gasolinepowered tools, such as chainsaws, but no bulk combustible fuel stored in the shipping container. The firefighters did not recognize the small amount of fuel in these tools as a potential hazard Lack of available training on hazard of fuel vapours in shipping containers At the time of the incident, no training was available for firefighters with respect to fighting fires in and around shipping containers or for the recognition of the potential for fuel vapour buildup and ignition within these sealed and enclosed spaces, even with small amounts of fuel Use of shipping container next to combustible structure Metal shipping containers were originally intended only for shipping goods; however, these containers are now widely used in various settings for storage of items including flammable liquids. Placing a shipping container next to a combustible structure can leave it susceptible to exposure to extreme temperature in the event that the combustible structure ignites Limited ventilation in shipping containers Metal shipping containers are designed to be sealed, with the exception of small vent holes near the upper corners of the side walls. When these containers are used in the secondary market and are not modified to increase their ventilation, the potential to enable a hazardous mixture of fuel vapour to remain within the atmosphere of the container is significantly increased. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 15 of 17

16 4 Health and Safety Action Taken 4.1 Office of the Fire Commissioner In July 2012, the Office of the Fire Commissioner, Emergency Management BC, published a safety advisory bulletin to inform fire personnel about safe conduct when working around metal shipping containers and similar buildings where flammable liquids or explosives are stored: This bulletin was distributed to all fire departments throughout British Columbia. 4.2 WorkSafeBC In April 2012, WorkSafeBC published a hazard alert that identified the hazards associated with firefighting in the vicinity of a metal shipping container that contains even a small amount of flammable liquid: This hazard alert was sent to local governments and fire departments throughout British Columbia and was also posted on the WorkSafeBC website. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 16 of 17

17 Copyright 2014 Workers Compensation Board of British Columbia. All rights reserved. WorkSafeBC (Workers Compensation Board of B.C.) encourages the copying, reproduction, and distribution of publications to promote health and safety in the workplace, provided that WorkSafeBC is acknowledged. However, no part of this publication may be copied, reproduced, or distributed for profit or other commercial enterprises or may be incorporated into any other publications or product without written permission of the Workers Compensation Board of B.C. WorkSafeBC Investigations WorkSafeBC (Workers Compensation Board of B.C.) Page 17 of 17