During a late 2013 inspection, OSHA’s area office in Concord, New Hampshire, identified a dolly-type roller device that must not be used for spreading flammable liquid adhesives. The device does not meet the agency’s requirements for dispensing a flammable liquid because its use creates a fire hazard for workers.
The dolly-type roller device and the adhesive are manufactured by different companies and sold separately. The device is designed to spread the liquid adhesive directly onto the roof from a 5-gallon metal container. The manufacturer of the device instructs users to lay the adhesive container horizontally on its side, punch a row of holes along the center, clamp the container to the dolly and turn it over so that the adhesive flows through the holes to the roller to be spread onto the roof.
This dolly-type roller must not be used to dispense flammable adhesives as currently designed because:
- Flammable liquids must be dispensed from a closed system or an approved container—punching holes in the adhesive container nullifies its approval.
- Punching holes in the adhesive container can introduce sparks and cause ignition of the flammable adhesive.
- Neither the storage container nor the roller has an approved shut-off or self-closing latch or valve, so if a fire starts there would be no way to stop the flow of the adhesive.
What are the fire hazards?
The adhesive used during the inspection was a toluene-based liquid. The Safety Data Sheet (SDS) for the adhesive states that it is flammable and warns users not to cut, drill, grind or weld near full, partially full or empty adhesive containers. The product information instructs users to apply the adhesive using a 9-inch, medium-nap roller (back rolling of the adhesive is required) or with approved spraying equipment or power roller equipment.
Punching holes in the storage container using an electric drill or hand tools such as drills, screwdrivers or punches can create sparks and heat, introducing sources of ignition. Sparks or heat can ignite the flammable adhesive and start a fire. The dolly-type device does not have an approved self-closing or shut-off system. As a result, the flammable adhesive will continue to flow from the holes in the container and add fuel to the fire, putting workers at risk of being trapped on the rooftop with only a limited number of exits.
Static electricity can also create sparks. Static electricity is common when the humidity is low, such as during the winter. A spark can be created under some conditions, like for example, just by shuffling the feet across the rooftop and then touching a metal screw or plate. Static electricity can also build up as a flammable liquid flows from its container and by the movement (rubbing together and separation) of certain types of clothing. For example, clothing made of 100 percent silk, polyester, wool or nylon is highly static-producing.
Are there other hazards?
While the risk of starting a fire is the biggest hazard, roofers should also be aware that roofing adhesives may contain chemicals with health hazards like toluene, for example. Workers may be exposed if they breathe the vapors into their lungs, or if the adhesive gets into their eyes or on their skin. A worker may be accidentally exposed by touching his or her face or eating or drinking after handling adhesives without first washing his or her hands. In addition, there is always a risk of falling when working at a height. Increasing this risk is the fact that surfaces coated with adhesives can be slippery.
Precautions to Minimize the Fire Risk
- Use non-flammable adhesives to install roofing membranes when possible.
- Use only non-flammable liquid adhesives—not flammable adhesives—with the type of roller device described.
- If a flammable liquid adhesive is used, ensure that it is drawn from containers and spread onto the rooftop with an approved closed system/device (no leaks of flammable liquid or vapor). Such a device would draw flammable liquids from containers or portable tanks by gravity or by using an approved pump. The device must have an approved self-closing latch or valve and a means for safely removing static electricity (29 CFR 1926.152(a)(1); 29 CFR 1926.152(e)(3) & (5); 29 CFR 1910.106(a)(9)) .
- Provide workers with effective information and training on hazardous chemicals in their work area (29 CFR 1926.59; 29 CFR 1910.1200 (h)(1),(2) & (3) (h)(1),(2) & (3)) .
- Carefully review the label on the adhesive container, SDS and the manufacturer’s product information to find out if the adhesive you plan to use contains hazardous chemicals, and follow the precautions recommended in these documents for using the product safely (29 CFR 1926.59; 29 CFR 1910.1200(b),(f)(10) & (g)).
- Take steps to eliminate sources of ignition. For example, safely discharge any static electricity by using properly connected bonding and grounding methods. Avoid clothing that generates static electricity and instead wear clothing made of cotton or similar materials. Use non-sparking tools and intrinsically safe equipment.
- Make sure that there are no open flames or other sources of ignition (for example, generators, workers smoking, hot surfaces, etc.) in the area where a flammable adhesive is being applied (29 CFR 1926.152(f)(3)). As it dries, the adhesive will give off flammable vapors that can be ignited.
- Keep to a minimum the total area of the roof that is coated with a flammable adhesive and not covered with a roofing membrane by covering the adhesive with the roofing membrane as soon as possible. This will help to reduce the chance of starting a fire and workers’ exposure to any hazardous chemicals.
- Make sure that approved portable fire extinguishers of the appropriate type are readily accessible to workers and that workers have been trained on how to use them (29 CFR 1926.150(a)(2),(3) & (4); 29 CFR 1926.150(c)(1)(vi) and (ix); 29 CFR 1910.157(c)(1) and (c)(2) .
- Do not store containers of flammable adhesives near the exit route(s). If a fire starts and spreads to the containers, it may block the roof exit, trapping workers on the rooftop (29 CFR 1926.152(a)(2)).
- Monitor the air to determine if the levels of hazardous chemicals released from an adhesive when coating a rooftop are above OSHA’s permissible exposure limits (PELs) for workers (29 CFR 1926.55; 29 CFR 1910.1000).
- Use adhesives with less hazardous or non-hazardous chemicals when possible.
- Use the natural ventilation on a rooftop to help reduce the levels of any hazardous chemicals released from an adhesive. Make sure workers, including those who are performing other tasks, are working upwind of the area where the adhesive is being applied. Use other measures, such as local exhaust ventilation, to move hazardous vapors away from workers when natural ventilation is not able to adequately do so. Fans and other ventilation equipment must be selected carefully if the vapors are flammable.
- Ensure that workers receive the appropriate training before using any required protective clothing and equipment, such as respirators (if necessary) (29 CFR 1926.28; 29 CFR 1926.103; 29 CFR 1910.132; 29 CFR 1910.134) .
- Protect workers from falls when they are working on roofs that have unprotected sides and edges and are 6 feet or more above lower levels (29 CFR 1926.501(b)(10) & (11)).
- Train workers on how to recognize fall hazards, ways of reducing the hazards, and how to properly use the right type of fall protection equipment provided by the employer (29 CFR 1926.503(a)(1) & (2), 29 CFR 1926.21(b)(2)).
Source: OSHA