By the Department of Labour.
Following up from our June/July 2018 ‘Safety at the Cutting Edge’ feature, the Department of Labour shares invaluable insight into the nitty-gritty of health and safety in sawmilling.
With health and safety a number one priority in any workplace, the topic takes centre stage in sawmilling, one of the most hazardous sectors around. Here’s what you should know to keep sawmilling safety in check.
Occupational health and safety issues in sawmills and wood manufacturing plants are common to those of most large industrial facilities, and their prevention and control is similar to those used in such large industrial companies.
Logs are generally unloaded from railroad cars or heavy trucks and stacked by machines before being moved to log conveyors and log decks for processing in the sawmill. Injuries due to vehicle movement in log yards are common, in addition to injuries from logs that roll off or are dropped by handling equipment or are dislodged from log stacks. Logs may also be stored in log ponds prior to being conveyed to the sawmill.
The occupational health and safety issues associated with sawmilling and wood products manufacturing primarily include machine safety and conveyor systems; lifting, repetitive work and work posture; as well as noise, chemicals, dust and explosions.
Delivering machine and worker safety
Wood processing plants employ various kinds of cutting equipment, for example saws, routers, chippers, planers, sanders, slicers, peelers and more. Debarkers may also expose workers to injury –cutting and debarking equipment is often in rapid motion, and accidents often happen when machines are inadvertently switched on during maintenance and cleaning.
There are various recommendations which, where appropriate, should be adopted to prevent, minimise and control injuries from cutting and debarking equipment. All cutting and debarking equipment, such as circular saws and rotary debarkers, should be fitted with safety guards or interlocks capable of preventing access to moving parts. Work stations should be aligned to minimise human danger from fragments which could arise from breakage, while saws and debarking equipment should be regularly inspected and maintained to prevent equipment failure.
Workers should be trained on the safe use of cutting and debarking equipment, such as the use of push-sticks and other means to move timber past a blade while keeping all parts of the body away from the blade. All personnel operating cutting equipment should use protective eyewear and other Personal Protective Equipment (PPE) as necessary. Saws should be equipped with screens or other devices to protect workers from log kick-back.
Sawmills typically transport wood using electric, movable, multi route conveyor systems. Conveyors under high tension may break, resulting in injury. Clothing or limbs can also become entangled in conveyors. In order to prevent injury from conveyor systems, various measures should be adopted.
Plant design should emphasise simple conveyor routes that are clearly demarcated, with the use of skirt boards to prevent access as necessary. Moving gears, chains and rollers should be fully enclosed, and hard hats should be worn in areas where elevated conveyors are in use.
Conveyor belt arrestors should be installed to stop the conveyor in the event of a belt failure. Belts should be inspected on a daily basis by trained personnel to ensure that they are in good working order. Furthermore, loose clothing is a hazard as it can be caught in a conveyor belt and injure the worker.
Sawmill and wood manufacturing activities may involve working in awkward postures, movement of heavy pieces of equipment or timber, resulting in injuries to the back if lifting is not done correctly. In addition, many of the process tasks are repetitive and can lead to strains or injuries to hands and arms.
Highlighting sawmill manufacturing hazards
Sawmill and wood manufacturing operations may result in high noise levels. A number of guidelines can be used to address this problem – machines and equipment with high noise emissions, in excess of 85dB(A), should be enclosed in noise reduction housing. Regular maintenance, including water lubrication of machines and cutting blades as well as resin build-up removal, should be conducted.
Circular saw parameters (such as bite depth, blade angle and blade speed) should be adjusted in relation to the timber being cut and the machinery used. One
should consider the use of low noise sawblades in addition to other less noisy equipment. In addition, conduct audiometric testing for workers and provide them with appropriate PPE including hearing protection.
Workers may also be exposed to elevated levels of hazardous chemicals, including solvents, during painting, varnishing, or the application of preservative treatments. Working with chemicals without suitable PPE may affect the worker’s lungs, kidneys, liver, brain and skin.
Recommended techniques to prevent and control chemical exposure include the substitution of solvent-based coatings and adhesives with less toxic alternatives, as well as the use of automated techniques for coating and adhesive application. Other methods include using local exhaust ventilation in areas with high chemical vapour concentrations such as manual spraying, rolling and brushing, as well as dip coating and other automated coating processes.
Manual spraying and dip coating should be undertaken in separate ventilated areas, using enclosures or capture hoods supplemented by the use of PPE such as masks and respirators. When necessary, workers should have adequate protective clothing to prevent chemical contact with the skin, eyes or via inhalation.
Another hazard is dust – wood dust inhalation may cause irritation, asthma, allergic reactions, dusty lungs, as well as nasopharyngeal cancer among wood processing workers. The potential hazard to human health depends on the type of wood being processed, with the wood from some tree species having a more serious potential impact than others, including hardwoods such as oak, beech, teak, walnut, mahogany and birch.
Dust exposure should be prevented and controlled through the adoption and maintenance of effective extraction and supplemented by the use of PPE such as masks and respirators, as necessary.
Wood products manufacturing, particularly when machining dried wood, may produce fine combustible dust which can be explosive in the air. Where solvents are used for the application of coatings by spraying, there is a high risk of solvent explosions.
Regular housekeeping is needed to ensure that dust is removed from the facility, including a biannual blow down or vacuuming of the entire facility, namely in the roof rafters. One should eliminate all sources of ignition from the working environment, including the elimination of naked flames, such as burner flames, welding or cutting torches, matches, cigarette lighters and heaters.
The control of hot surfaces, such as operating internal combustion engines, frictional sparks, heated wires, glowing metals and overheated bearings, is crucial. The control of portable battery-powered equipment, such as radios and mobile phones, is also important. The safe use of certain chemicals, for example, peroxide hardening products which can be self-heating or result in spontaneous combustion, is paramount.
Installing spark detection and dousing systems in dust control equipment is key, while electrical grounding of conveyors and dust control systems to prevent the discharge of static electricity is equally critical.
Another method used is the utilisation of explosion relief panels on all dust moving equipment and in buildings. Mills and plants should be equipped with adequate and accessible firefighting equipment, including automatic sprinkler systems. Workers should be trained in emergency evacuation procedures as well as first line of attack firefighting techniques.