Wood Dust in Sawmills Compilation of Industry Best Practices May 4, 2012 This document is dedicated to the memory of workers who have suffered and lost their lives from the hazards of combustible dusts. It is offered in the hope that it will help prevent such tragedies in the future. Table of Contents Dedication Introduction . 5 INDUSTRY INPUT ...................................... 12 Best Practices and Housekeeping . 13 Canfor – Loss Prevention Manual: Fire Protection . 14 Canfor – Industry Best Practices/Processes for Wood Dust Control . 52 FM Global – Prevention and Mitigation of Combustible Dust Explosion and Fire . 55 Interfor – Dust Control Method Chart . 112 Norbord – Combustible Dust Experience . 115 Weyerhaeuser – Combustible Dust Awareness . 133 Wood Machinery Manufacturers of America – NFPA 664 Combustible Dusts – Overview . 156 Equipment . 181 Buffalo Turbine – Monsoon Atomizing Misters . 182 FM Global – Wood Processing and Woodworking Facilities . 201 Norbord – Combustible Dust Experience . 235 Sinclair Forest Products Ltd – Possible solutions – dust removal systems . 236 Van-Ed Equipment – Air Mister . 238 Wood Machinery Manufacturers of America – NFPA 664 Combustible Dusts – Overview . 241 Risk Assessments and Audits . 242 Aon – Safety Information Bulletin – Combustible Wood Dust in Sawmills: Preventing and Mitigating the Effects of Fire and Explosions . 243 BC Forest Safety Council – Base Audit – Draft Guidelines Version 2 1:. Pellet Industry Addendum . .254 Louisiana Pacific – Fire Prevention Assessment . 272 United Steelworkers – Resource Handout: Controlling Hazards . 275 Weyerhaeuser – Combustible Dust Control Program . 279 Sampling Results . .284 Wood Pellet Association of Canada – Testing of Explosibility and Flammability of Airborne Dust from Wood Pellets . 285 WORKSAFEBC INFORMATION .......................... .305 Combustible Dust Strategy (Handout) . 306 WorkSafeBC Bulletin: Clean-up of Hazardous Combustible Dust . .346 REFERENCES AND RESOURCES ......................... .348 References for WorkSafeBC Documents . 349 Suggested Additional Resources . .352 APPENDICES ......................................... .355 American Industrial Hygiene Conference and Expo (AIHce) – NFPA 654, 2011 Edition – Key Changes/Issues/Impacts (by Brice Chastain, CIH, Georgia-Pacific) . 356 Weyerhaeuser – Combustible Dust and Hazard Mitigation in Lumber Operations – Weyerhaeuser Experience . 372 5 Introduction Two recent catastrophic fires and explosions occurring at BC sawmills have prompted a series of followup actions by industry, government and organized labour. One key step was to quickly poll operations and key organizations on industry practices specific to wood dust cleanup, control and associated fire prevention and protection measures. This information has been compiled in the attached document and is available for your consideration. The materials cover a broad spectrum of fire prevention but do have a focus on combustible wood dust and specifically the cleanup and control of dust in sawmills. When cleaning up combustible wood dust there is a potential to increase the risks associated with a variety of tasks and the potential for fire and explosion. The following introductory pages contain important considerations when addressing dust cleanup and control in your mill. Of upmost importance ……… • Minimize the use of compressed air for cleanup. Airborne dust can explode when in contact with potential ignition sources. • Limit your ignition sources when cleanup activity is underway. No hotwork. • Wetdown and misting is effective but be aware of impact and interface with electrical equipment. • Lockout and de-energized equipment will decrease risks of energy contacts and ignition points. • Dust accumulates in awkward locations – be aware of workers entering restricted, confined and workspaces at heights. • Review the considerations following before you direct workers or engage contractors to cleanup. Key Items for Consideration 1 . Responsibilities • Supervisors (need to know..) ◽ Knowledge of combustible dust conditions & controls. ◽ Risk Assessment Process. ◽ Monitoring Requirements (dust exposure, hotwork, permits, risk assessment etc.). ◽ Requirements for first aid coverage during high risk activities. ◽ Emergency evacuation and response procedures. ◽ Control of ignition sources to prevent explosions: Lockout equipment prior to starting work. Elimination of ‘Hot Work’ and propellant-actuated tools (Hilti-guns) during cleanup activities. Use appropriate electrical equipment and wiring methods. Control static electricity, including bonding of equipment to ground. Control smoking, open flames, and sparks. Control mechanical sparks and friction. Separate heated surfaces from dusts. 6 • Workers (need to know..) ◽ Identification & reporting of combustible dust conditions. ◽ Understanding of emergency response procedures. ◽ Understanding of the job planning needed to perform the task safely. ◽ Dust cleaning methods that do not generate dust clouds: Clean in a manner that eliminates the generation of dust clouds. Blowing down with compressed air or even vigorous sweeping should be minimized. Use combination air/water wands or water wash down. A hazard and risk assessment must be conducted when using water systems in and around electrical components. Methods that create dust clouds should only be used if the following requirements are met: Electrical power and other sources of ignition shall be shut down or removed from the area. Only low gauge pressure 103 kPa (15 psi) compressed air should be used. No open flames, sparks from spark-producing equipment, or hot surfaces capable of igniting dust cloud or layer exist. All fire protection equipment should be in service. If portable vacuum cleaners are used they shall be industrial vacuum cleaners designed for Class II Hazardous Locations or alternately a fixed pipe suction systems (non-pvc) with remotely located exhaust and air material separator dust collectors (cyclones or bag houses). 2 . Pre-Work & Ongoing Hazard/Risk Assessment(s) Pre-work considerations to identify hazards and develop controls. All field level hazard and risk assessments should be conducted by a qualified person before cleanup commences. Assessments need to identify: • Critical areas (Class II Hazardous Locations – see description at end). • Identification of areas to clean, order & priority to clean and appropriate cleanup methods eg., ◽ Open areas ◽ Hidden or enclosed areas ◽ Dust “leaking” from dust capture systems • Ventilation requirements (start-up procedures prior to work commencing, shut down procedures after dust clouds are gone). ◽ NOTE: some lockout procedures may shut down area or machine specific ventilation systems. • All ignition sources. • Coordination of work activities (between cleanup , maintenance and/or contractors). • Potential for changing conditions. • Other things that might cause explosions (examples: propane, natural gas) 7 3. Lockout Lockout procedures should be reviewed to address combustible dust issues. The act of pulling electrical cords from sockets and throwing energy isolating switches can produce ignition sources. Class II Hazardous Location Lockout: • All Class II Hazardous Locations should have the equipment locked out before the dust is cleaned up. • Wear appropriate PPE (Arc Flash Rated Clothing and other PPE if required). • At the end of the work activities wait until the dust cloud has dispersed before re-energizing the equipment or removing your electrical cords from sockets. 4 . Hot Work Hot Work is an ignition source. • No Hot Work should take place in any Class II Hazardous Location without first performing a risk assessment. • All Hot Work should be coordinated with the supervisor who signs all Hot Work permits. 5 . Working At Heights Combustible dust will most likely be found in areas that require working at heights. Some of these areas are: • Structural members • Dust collection systems • Conduit and pipe racks • Cable trays • Above suspended ceilings • Above interior offices • Above operators booths • On equipment • Attics When workers are working at heights a fall protection plan & system must be in place and workers need to be instructed in this system. 6 . PPE Almost all wood dust, especially if very fine, can cause allergic reactions in many people and can cause skin irritation, as well. Workers exposed to wood dust need to understand the potential health effects of such exposure and take precautions to reduce their exposure. Appropriate PPE for cleanup activities in Class II Hazardous Locations are: • Steel toed boots • Hearing protection • Gloves • Goggles 8 • Coveralls ◽ NOTE: Tyvek coveralls with a B suffix do not contain an antistatic agent. Styles like these can build a static charge and should not be used in areas where there is a potential for dust explosion. • Respiratory Protection ◽ Elastomeric half-face respirator with P100 cartridges, as a minimum. ◽ Fit Testing needs to take place prior to starting work. ◽ Single use respirator - Where an N95 filtering dust mask is used the requirement for fit testing would still apply. 7 . Confined Spaces Many confined spaces will also require cleanup and be classified Class II Hazardous Locations. All confined spaces need to be identified and assessed prior to work commencing. The company needs to have a confined space program and workers need to be trained in confined space entry procedures. Confined spaces and combustible dust hazards: • The risk of combustible dust fire/explosion