Date of incident: September 2018
Notice of incident number: 2018181890025
Employer: Recycling depot

Incident summary
At a propane container recycling facility, two workers were working in close proximity to one another. One worker was using a propane blowtorch to burn a difficult-to-remove label off a propane cylinder. Suddenly a flame shot from the cylinder toward the other worker. The worker’s clothing, as well as fugitive propane gas in the area, ignited. The worker sustained serious injuries. As the fire spread, propane from other stored cylinders ignited, causing some of the cylinders to explode and become projectiles. The cylinder explosions and subsequent fires resulted in property damage at the workplace and other nearby properties.

Investigation conclusions

Cause

• Direct heating of propane cylinder with low volume of propane. The direct application of the blowtorch to the propane cylinder, coupled with the low volume of propane in the cylinder, likely resulted in a rapid increase of internal pressure. As the high-pressure propane released from the cylinder — either from a pressurized leak or when the pressure-release valve opened — the flame from the blowtorch ignited the propane, sending a high-pressure flame toward the worker nearby.

Contributing factors

• Unsafe work practices. The employer’s practice of using abrasive power tools and/or blowtorches to remove labels and loose or flaking paint from propane cylinders was unsafe and unapproved. The use of abrasive power tools or blowtorches introduces a potential ignition source in direct proximity to the cylinders. Additionally, the use of these items will result in increased temperatures of the cylinders, in turn increasing the internal pressures within the cylinders. The heating of the cylinders and subsequent pressure increases are compounded by lower volumes of propane in the cylinders. Internal pressures of cylinders with volumes less than 10% will increase rapidly when exposed to extreme heat, increasing the risk of explosion. Acceptable procedures for the removal of labels or loose paint include the use of handheld wire brushes or knives.
• Improper purging of propane from cylinders. The employer’s practice of slowly venting the remaining volumes of propane from the cylinders was unsafe and unapproved. Allowing propane to vent into the atmosphere relies on the propane to dissipate; however, propane gas is approximately 1.5 times heavier than air, which allows accumulations to build up in low areas where there is little-to-no air movement. Accumulations of propane gas are hazardous due to its potential to displace oxygen in work areas, which can lead to asphyxiation. Additionally, accumulations of propane greatly increase the risk of a fire or explosion if an ignition source is introduced. Acceptable procedures for the purging of remaining propane from cylinders include transferring the remaining volume to another cylinder or flaring off the propane using an approved heater, torch, or flare stack.
• Improper work instruction. The workers had been instructed to use the abrasive power tools and blowtorch to remove labels and loose paint that were too difficult to remove using knives. These work practices, which the employer permitted, were both unsafe and not in accordance with standard practices, industry requirements, or the Occupational Health and Safety Regulation.
• Inadequate training. The employer had not provided its workers with instruction or training that qualified them to perform cylinder inspections and requalifications.
• Inadequate storage and securement. Propane cylinders were being stored both indoors and outdoors in large quantities. The cylinders were loosely stacked and were not restrained in any manner to prevent them from falling, becoming dislodged, or sustaining damage. Signage indicating the presence of the propane was not displayed at the entrance to the worksite or on the steel building where cylinders were being stored indoors. Furthermore, the building was not equipped with a ventilation system that would safely remove any fugitive propane gas, and the vehicle repair and service work performed in the building by a business the employer rented space to introduced potential ignition sources.

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