Fabrication Shop Ergonomics
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Fabrication Shop Ergonomics Fabrication Shop Ergonomics Document Transcript

  • University of Houston-Clear Lake Fabrication Shop Ergonomics INDH 4231 - Ergonomics, Human Factors, and Workplace Design William Bell, Teresa Long, and Dustin Triplett 12/5/2012
  • Table of Contents Abstract ........................................................................................................................................................ 2 Introduction.................................................................................................................................................. 3 Ergonomics of Awkward Body Positioning and Injury Statistics for Fabrication Shops..... ............. 4 Mitigation Measures to Prevent Awkward Body Positioning Injuries............................... ..................9 Cost-Benefit Analysis for Implementing Engineering Controls in Fabrication Shops .................... 11 Conclusion ................................................................................................................................................. 16 Work Cited. ........................................................................................................................................17 List of Figures Figure 1 - Description of Neutral Posture for Various Body Joints........................................................5 Figure 2 - Chart of Various Awkward Body Positions.............................................................................6 Figure 3 - OSHA Hierarchy of Controls...................................................................................................10 Figure 4 - Table of Cost-Benefit Analysis of Engineering Controls for Fabrication Shop Operations.......................................................................................................................15 Page 1 of 18
  • ABSTRACT Fabrication Shop Ergonomics Fabrication shop workers have numerous dangerous hazards to deal with every day. The most obvious fabrication shop hazard risks are fire, burns, lacerations, combustible materials, working at heights, inhalation exposures, and burns to the retina of the eye. These are the hazards that get the most attention from management, supervision, and the employees actually doing the work. When making a visit to a fabrication shop, these hazards are very evident, but upon closer observation, there are just as many, if not more, ergonomic hazards as those which seem more obvious. Workers often assume awkward and uncomfortable positions to do things like grinding or cutting, gouging, and welding. Welders commonly complain of back and neck pain from standing slumped over a pipe or another piece of material for as long as twelve to sixteen hours a day. Grinding a piece of material might require kneeling for an entire day. These activities being performed in awkward positions are continuously repeated over time, often leading to serious worker injuries. Worker body positions can also cause potential harm from the other hazards present in fabrication shops because the human body can't react fast enough to prevent an incident or injury when the reflexes are needed to react. The awkward body positioning requires the worker to return to normal posture or stature first, and then react to the new hazard, slowing the reaction time. Ergonomically correct body positioning can significantly decrease cumulative trauma disorder (CTD) aches and pain effects, prevent injuries from other fabrication shop hazards, and prevent debilitating and often disabling musculoskeletal disorders (MSD) workplace injuries. Achieving an ergonomically correct body position can be accomplished with several different measures. Some of the mitigations can be as simple as giving a welder a chair or stool to use, but others require capital investment in expensive engineering controls ranging in cost expenditures of $200,000 to over $1,000,000. This study will examine the ergonomics of awkward body positioning and injury statistics associated with fabrication shops, identification of some mitigation measures to prevent future injuries, provide a cost-benefit analysis of those mitigation measures, and enable management and supervisory readers to conclude that implementing an ergonomics program at their fabrication shop or company can actually provide tremendous benefits and provide a huge cost savings. Page 2 of 18
  • Introduction "Musculoskeletal disorders account for 70 million doctor’s visits and approximately 130 million visits to outpatient facilities, hospitals, and emergency rooms in the United States annually. Direct costs attributed to musculoskeletal disorders (MSDs) total $50 Billion annually"1. A musculoskeletal disorder is defined by the National Institute for Occupational Safety and Health (NIOSH), as: "Musculoskeletal disorders (MSDs) are injuries or disorders of the muscles, nerves, tendons, joints, cartilage, and disorders of the nerves, tendons, muscles and supporting structures of the upper and lower limbs, neck, and lower back that are caused, precipitated or exacerbated by sudden exertion or prolonged exposure to physical factors such as repetition, force, vibration, or awkward posture"2. Employers incur extremely high costs associated with MSDs. "An estimated 600,000 MSDs reduce worker productivity, increase healthcare costs and require employee time away from work. MSDs are responsible for 34% of all lost work-day injuries and illnesses. One of every three worker’s compensation dollars, $15 Billion to $20 billion, are paid to workers experiencing MSDs each year"3. Disorders caused by slips, trips, or falls are not considered MSDs. Effects of these types of injuries develop slowly over time and more attention is paid to other types of workplace injuries. Fabrication shops where welding and grinding operations take place, have many hazard risks that employers and workers must guard against. The most obvious fabrication shop hazard risks and injuries include fire, lacerations, burns, working at heights, combustible materials, inhalation exposures, and burns to the retina of the eye. These types of hazards and injuries require constant vigilance by management, supervisors, and the workers themselves. An ergonomic hazard with significant injury risk that is often overlooked is body positioning, with work tasks being performed in awkward positions for prolonged periods of time. "Ergonomic injuries aren’t as high profile as Page 3 of 18
  • other types of workplaces issues although MSDs are more severe than average nonfatal injuries or illnesses such as hearing loss, and occupational skin diseases"4. Every muscular workplace injury does not start out as an MSD, however, because of the repetitive nature of welding and grinding operations in fabrication shops, they do result in a significant number of MSDs costing these companies millions of dollars annually. This study will examine the ergonomics of awkward body positioning and injury statistics associated with fabrication shops, identification of some mitigation measures to prevent future injuries, provide a cost-benefit analysis of those mitigation measures, and enable management and supervisory readers to conclude that implementing an ergonomics program at their fabrication shop or company can actually provide tremendous benefits and provide a huge cost savings. Ergonomics of Awkward Body Positioning and Injury Statistics "Ergonomics - is the science of designing the job and the workplace to suit the capabilities of the workers. Simply stated, ergonomics means "fitting the task to the worker." The aim of ergonomics is the evaluation and design of facilities, workstations, jobs, training methods, and equipment to match the capabilities of users and workers, and thereby reduce stress and eliminate injuries and disorders associated with the overuse of muscles, bad posture, and repeated tasks"5. Posture refers to the position of the body during an activity. Neutral positions are typically where joints are used close to the middle of their range of motion, such as when the head and trunk are upright, arms are by the sides of the body with forearms hanging so that hands are in the handshake position, as described in Figure 16. Page 4 of 18
  • Figure 1 - Description of Neutral Posture for Various Body Joints. DHHS, NIOSH Publication No. 2009-107, Information Circular 95-09, Ergonomics Processes: Implementation Guide and Tools for the Mining Industry7. Awkward postures are positions of the body that are well beyond the neutral position that occur when job tasks are being performed. Awkward postures require additional muscular effort to maintain. Muscle efficiency is reduced when joint angles are at their extremes. Friction and compression, such as leaning on the elbow or gripping a tool with the hand, exposes soft tissue structures to reduced blood flow and leads to ergonomic injuries. The more awkward the posture, the more strain on muscles, tendons, and ligaments and likelihood of injury. Page 5 of 18
  • Some awkward positions that workers in fabrication shops regularly experience for long periods of time are shown below in Figure 3. Bending at the Back Kneeling or Squatting More than 2 hrs per Day AWKWARD BODY POSTURES Bending the Wrists >30° More than 2 hrs per Day Bending at the Neck >30° More than 2 hrs per Day Standing or Laying More than 2 hrs per Day Reaching and Twisting the body Figure 2 - Chart of Various Awkward Body Positions. Another body position capable of causing an ergonomically based injury is static body postures. Static body positions occur when a part of the body is held in a position for an extended period of time with little or no movement to allow soft tissues to relax, such as standing or kneeling. Loads or forces on the muscles and tendons are increased, which contributes to muscular fatigue. Static postures add to the amount of muscular effort required to perform a job task. Not moving impedes blood flow needed to bring nutrients to muscles and carry away waste Page 6 of 18
  • products, and muscles will fatigue very quickly. The longer or more frequently static loading occurs, the greater the risk of injury from overuse of muscles.8 Conducting a site survey of a fabrication shop yields the astute observer to notice ergonomic workplace hazards contributing to muscular injuries almost instantly. Fabrication shops perform functions where metal fabricators fit parts together, usually by welding, grinding, and cutting. Job tasks associated with metal fabrication often require awkward postures. Employees don’t always use the tools or safety aids provided by their employer to enable the task to be performed in an ergonomically correct fashion. Performing job tasks requiring long reaches exposes workers to awkward positions of their shoulders, elbows, and back that deviate significantly from neutral positions. Performing job tasks at surfaces which are too high can affect the neck, head, shoulders, elbows, arms, hands, and wrists. Performing job tasks at surfaces that are too low can cause workers to hunch over, bending their backs and necks. If the surfaces are extremely low, worker are required to kneel or squat to perform their job tasks. These positions affect the knees, lower back, and neck. This type of work also involves frequent handling of heavy loads. The risks aren’t perceived by supervisors and workers because symptoms take long periods of time and repetition to develop, unlike cuts, inhalation exposures, and burns. Metal fabricators, like many other workers, become "victims" of back trouble and cannot tell how it started. In most cases a worker cannot point to sudden pain related to a certain action, but rather the problem developed slowly until it was strong enough to disable".9 Workers typically will complain of aches and pains from their knees, back, neck, legs, arms, hands or feet in the evening when they go home to their wife or girlfriend. The "macho" psychological makeup of most fabrication workers will prevent them from complaining to management, supervisors, or co-workers in the work environment much like the "blue code of silence" in police Page 7 of 18
  • departments. As the body continues to be strained by heavy loads, repetitive motions, and awkward body positions, the aches and pains become to much to bear and an injury is finally identified. Hopefully, the injury is only a minor problem or a cumulative trauma disorder (CTD) that can be treated and corrected. However, just like workers in other construction trades, it often is too late and ends up with a musculoskeletal disorder (MSD) diagnosis. Risk of developing an MSD increases with repetitive motions that are performed without frequent breaks. Workers performing job tasks that include highly repetitive motions suffer fatigue and tissue damage, which eventually results in pain, discomfort and reduced productivity or total disability. Risk occurs when level of force exerted is low, and postures are not very far away from the neutral position. If higher force is required to perform the task, the number actions or speed they are performed at increases, and if awkward postures are endured the risk of developing an MSD is even greater. As a result, of the ergonomic factors from awkward positions, repetitive motions, and failure to take steps to mitigate or eliminate the hazards, significant numbers of injuries occur in fabrication shops each year. Examination of 2010 workplace non-fatal injury data from the United States Bureau of Labor Statistics yields the following statistics:10 In 2010, non-fatal injuries in fabrication departments consisted of: 2,670 cuts, lacerations, or punctures 1,820 breaks or fractures 310 amputations of limbs or fingers280 heat burns from cutting, welding, or grinding In 2010, ergonomic-related non-fatal injury cases in fabrication departments in the U.S. consisted of: Page 8 of 18
  • 3,550 overexertion cases (i.e. lifting heavy items) 1,270 soreness pain (i.e. lower back, neck) 790 repetitive motion injuries 280 cases of carpal tunnel syndrome Evaluation of these statistics with the ever increasing cost of medical care, workman's compensation and difference in lost wages costs, loss of productivity, and disability compensation costs, it is very easy to visualize the annual costs to fabrication companies totaling in the millions of dollars. Therefore, fabrication companies need to evaluate the ergonomic risks and hazards of ergonomic injuries resulting from awkward positions and develop an ergonomic plan of action to minimize the hazards through engineering and administrative controls. Mitigation Measures to Prevent Awkward Body Positioning Injuries Ergonomics, unlike other workplace hazards can only be corrected primarily through engineering and administrative controls. OSHA illustrates the hierarchy of controls as depicted in Figure 3. The inherent tasks being performed in a metal fabrication shop do not readily allow the elimination or substitution of the task. Welding, cutting, grinding, and gouging tasks still must be performed to continue production and enable the metal items to be fabricated. Personal protective equipment (PPE) does not really apply to ergonomic hazards in this situation. Engineering controls to prevent fabrication shop ergonomic hazards are the best control method and do require significant capital expenditures for purchasing equipment necessary to eliminate or significantly reduce the intended target hazard risk. Engineered controls require little or no employee actions other than training on operating the machinery that has been Page 9 of 18
  • purchased. Some machinery will save time and increase profits by elimination of the worker performing the actual welding or cutting, and also reducing human error on the production. Figure 3 - OSHA Illustration of Hierarchy of Controls. OSHA.11 Engineering controls which can be applied to fabrication shops and help to prevent ergonomic and other injury hazards are numerous: Installation of overhead cranes to aid in the lifting and movement of the inherent heavy metal objects present in the workplace. Only way to move extremely heavy objects, lifting capacities can reach as high as 250 tons. Installation of jib overhead cranes that can slide down the jib and swing up to 180 degrees with a load capacity of up to 4,000 lbs to bring the work to the worker. Page 10 of 18
  • Installation and use of computerized cutting-burn tables to save time, raw materials, reduce production costs, and increase profits during operations requiring the cutting of metal materials and provides less ergonomic and other hazard exposure to workers. Used for metal fabrication of products from large flat sheets of metal with thicknesses of up to 1 inch. Machine performs cutting, saving time, reducing worker exposures and saves costs by eliminating worker error during fabrication process. Purchase and use of forklifts to aid in the lifting and movement of the numerous and oddly-shaped heavy metal items being fabricated. Carrying capacities of 7,000 lbs to 50 tons, depending on needed requirements. Installation of maneuverable sub-arc welding machines mounted on tracks to save time, provide for ease of movement of heavy metal items being fabricated, reduce production costs, and the machine performs the required welding thereby reducing ergonomic and other hazard exposure of workers. Installation of sub-arc welding machines to save time, eliminate ergonomic and other hazard exposures. Worker operates a turntable and the sub-arc welding machine performs the welding providing increased profitability. Installation of large turntables equipped with grips and teeth to hold large, heavy, square, round, or oddly-shaped metal production pieces in place affording vertical and horizontal movement and affording 360-degree positioning of the product where it can be accessed by the worker, limiting ergonomic injuries. Installation of medium and small turntables with grips and teeth affording vertical and horizontal movement with 360-degree positioning of heavy, oddly-shaped production pieces such as valves, allowing the work to be brought to the worker. Capable of Page 11 of 18
  • locking metal objects weighing up to 10,000 lbs, depending on turntable size and limits ergonomic awkward positioning work injuries. Purchase and use of ergonomically designed power hand tools to maintain hand-wrist neutral positioning while performing grinding, welding, cutting, and gouging tasks. Tools also equipped with padded grips and trigger mechanisms to prevent contact stress injuries while performing repetitive, or long-term exposure tasks. Purchase and use of adjustable jack stands and tables to bring the task to the worker. These items can be height-adjusted from 3 to 5½ feet to raise and lower the production material to a height that allows the worker to perform the task and avoid awkward body positioning. Load capacities of up to 2500 lbs and reduces cumulative trauma disorders (CTDs), and pain in neck, back, arms and shoulders while performing repetitive motion welding and grinding tasks. Purchase and use of ergonomically designed chairs and stools to allow for breaks from static standing positions and avoid squatting and kneeling when performing fabrication shop tasks. Fabrication and use of stands and sawhorses made from scrap materials and subsequently evaluated by company or external engineer to rate load capacity and ensure they are safe to use. The stands and sawhorses require zero capital expenditure dollars and make use of materials that normally would be recycled as metal scrap waste. Administrative controls involve training the supervisors and workers to avoid risky ergonomic hazard body positions, rotating worker tasks among workers to reduce hazard exposure time, and reinforcing safe work practices. Static postures, and repetitive motions Page 12 of 18
  • require frequent breaks from the task. By changing one's body position by lifting one leg to a table or sawhorse support leg, or after standing, moving to a seated position to perform the task will alleviate muscle strains. Administrative controls require heavy supervisory and worker involvement to reinforce hazard risk and avoidance measures. Another administrative control is to ensure personal and medical history of workers is assessed during hiring process with medical examination and screening performed by a licensed professional medical practitioner. This will prevent hiring workers with pre-existing cumulative trauma disorders (CTDs) and ensure workers can perform the frequent heavy lifting and body movements required for workers in fabrication shops. Administrative controls require time away from production for workers to receive training and medical evaluation costs, but are relatively inexpensive to implement. Clearly the majority of controls to minimize ergonomic injury hazards will require some type of expensive engineering control to be implemented. Cost expenditures present a challenge and need to be analyzed prior to the expenditures. The next section will perform this analysis. Cost-Benefit Analysis for Implementing Engineering Controls in Fabrication Shops Everyone has a family member or neighbor who has recently had an expensive medically required surgical procedure and hospital stay. Surgery, hospitalization, and follow-up treatment costs can easily start at $30,000 and skyrocket well over $100,000 are easy for an individual to visualize for a minimal orthopedic surgical procedures to correct a physical impairment such as those caused by ergonomic hazards at work. "On average, it takes workers 28 days recover from carpal tunnel syndrome, longer than the time needed to recover from amputation or fractures".12 Cumulative trauma disorders (CTDs) can require longer periods of time away from work, which equal lost productivity and profits for the employer, and reduced income that impacts worker Page 13 of 18
  • families who must get the worker to medical treatment causing lower moral for the worker. Increased state-sponsored Worker's Compensation Insurance premiums will be levied on the employer due to the workplace injury. "Workers with severe injuries can face permanent disability that prevents them from returning to their jobs or handling simple, everyday tasks. MSDs account for $1 of every $3 spent for workers’ compensation costs. MSDs each year account for more than $15 billion to $20 billion in workers’ compensation costs. Total direct costs add up to as much as $50 billion annually".13 Indirect costs of poor worker morale and the company not receiving future work contracts due to a poor safety performance rating are difficult to quantify, but do produce significant impacts on company productivity and profits. When weighed against the costs of poor worker morale and lower productivity, impact on worker families when permanently disabling injuries are involved, increased Worker's Compensation medical expenses and insurance premium costs, and loss of future contracts due to a poor safety performance record, the capital expenditure of funds for ergonomic engineering controls becomes easier to justify. Small fabrication shops cannot easily spend one million dollars due to capital availability, but small expenditures of $5,000 to $10,000 can increase productivity and profits while reducing the risk of worker injury from awkward postures and body positioning. Smaller expenditures and self-fabrication of sawhorses and stands, chairs and stools, and adjustable jackstands and tables are easily achievable. Lifting and moving equipment must be a priority to handle the heavy loads and irregular or oddly-shaped production pieces. Larger companies can more easily forecast large capital expenditures in equipment. A table providing a cost-benefit analysis of specific engineering control equipment, identifying the cost and ergonomic risk hazard that is prevented or significantly reduced is provided at Figure 4. Fabrication shop equipment costs can range from $0 to over one million dollars. Page 14 of 18
  • Figure 4 - Table of Cost-Benefit Analysis of Engineering Controls for Fabrication Shop Operations.14 Equipment Cost Benefits Large Turntable (grips and teeth) $50,000$80,000 Medium and Small Turntable (grips & teeth) $5,000$12,000 Jib Crane $5,000$6,000 Chair / Stool $50-$175 ErgonomicallyDesigned Power Hand Tools $80-350 Overhead Cranes $50,000$1,000,000 Sub Arc Welding Machines $20,000$25,000 Maneuverable Sub Arc Welding Machines $40,000$50,000 Adjustable Jack Stands and Tables $150-$500 Fabricated Stands (sawhorses made from scrap metal) $0 Forklift $10,000$1,000,000 Computerized Cutting Burn Table $200,000 Moves the task to the person. Accommodates very large, heavy objects. Can rotate the object 360°. Grips & teeth hold object in place. Allows worker to maneuver an object both vertically and horizontally. Brings the task to the worker. Good for irregular shaped material. Bring the task to the worker. Swings 180 degrees and slides back & forth. Material can be lifted & turned Capable of carrying 4,000 lbs. Eliminates lower back pain and CTDs caused from bending over. Eliminates awkward postures in shoulders & wrists. Reduces hand, wrist, arm, back, and shoulder stress. Reduces contact stress. Allows worker to move heavy objects to ergonomically correct positions to work on them. Only way to move extremely heavy objects produced in the fabrication shop. Capable of lifting up to 500,000 lbs Prevents awkward postures, Decreases time spent bending over (worker operates turntable). Prevents injuries to retina (arcs contained within the machine). Used for precision welding. Prevents awkward postures, decreases time spent bending over (worker operates turntable). Prevents injuries to retina (arcs contained within the machine). Moves the task to the person, elevates material 3-5.5 feet off the ground (adjusts height, product is lowered onto the stands). Decreases CTDs, strains, pain. Holds 2500 lbs of material. Moves the task to the person, elevates material off the ground (adjusts height, product is lowered onto the stands). Decreases CTDs, strains, pain. Engineer-rated to provide up to 10,000 lb capacity. Prevents injuries from lifting (back, knees etc.). Can lift 7-100,000 lbs, depending on model. Nearly eliminates ergonomic hazards from awkward postures. Worker only enters data into a computer. Page 15 of 18
  • The implementation of ergonomic administrative and engineering controls can provide mitigation of awkward body positioning while performing work tasks in fabrication shops. Conclusion Workplace ergonomic programs should implement engineering and administrative controls to effectively prevent, control, or eliminate injuries and illnesses in fabrication shops by eliminating or reducing worker exposure to ergonomic risk factors. Personal protective equipment (PPR) is not an effective control to prevent ergonomic risks, but may be useful in protecting against the other fabrication shop workplace hazards. Adoption of ergonomically correct postures significantly reduces frequent worker aches and pains that can lead to cumulative trauma disorder (CTD) or musculoskeletal disorder (MSD) effects. Reduction or elimination of ergonomic risk factors can often be accomplished without spending a great deal of money, but some measures can be costly. Can any business afford not to provide the appropriate administrative and engineering controls to prevent ergonomic injuries? Page 16 of 18
  • Work Cited 1 National Research Council and the Institute of Medicine (2001). Musculoskeletal Disorders and the Workplace: Low Back And Upper Extremities. Panel on Musculoskeletal Disorders and the Workplace. Commission on Behavioral and Social Sciences and Education. Washington, DC: National Academy Press. Available from: http://www.nap.edu/openbook.php?isbn=0309072840. Web. 03 Dec. 12. http://www.cdc.gov/workplacehealthpromotion/evaluation/topics/disorders.html 2 United States. Department of Health and Human Services (DHHS). Center for Disease Control (CDC) and Prevention, National Institute for Occupational Safety and Health (NIOSH). NIOSH Program: Musculoskeletal Disorders. NIOSH/Centers for Disease Control and Prevention (CDC), 23 May 2011. Web. 05 Dec. 2012. http://www.cdc.gov/niosh/programs/msd/ 3 United States. Department of Labor (DOL). Occupational Safety and Health Administration (OSHA). http://www.osha.gov/Publications/osha3125.pdf/Ergonomics: The Study of Work. OSHA/U.S. Department of Labor (DOL), 2000 (REVISED). 4. Web. 03 Dec. 12. http://www.osha.gov/Publications/osha3125.pdf 4 "Work-Related Musculoskeletal Disorders (WMSDs) Prevention." CDC - Workplace Health - Evaluation: WorkRelated Musculoskeletal Disorder (WMSD) Prevention. Centers for Disease Control and Prevention. United States Department of Health and Human Services (DHHS), 25 Apr. 2011. Web. 03 Dec. 2012. http://www.cdc.gov/workplacehealthpromotion/evaluation/topics/disorders.html 5 "Workplace Health Promotion - Glossary." Centers for Disease Control and Prevention(CDC). Centers for Disease Control and Prevention(CDC). United States Department of Health and Human Services (DHHS), 25 Apr. 2011. Web. 05 Dec. 2012. http://www.cdc.gov/workplacehealthpromotion/glossary/index.html 6 "Risk Factors - Background Information." Health and Safety Executive (HSE). HSE, n.d. Web. 05 Dec. 2012. http://www.hse.gov.uk/msd/uld/art/riskfactors.htm 7 Torma-Crajewski, Janet, Lisa Steiner, and Robin Burgess-Limerich. "Ergonomics Risk Factors - Awkward Positions." Ergonomics Risk Factors - Awkward Positions. NIOSH/CDC, 04 June 2008. Web. 02 Dec. 2012. http://www.ima-na.org/IMANA/files/ccLibraryFiles/Filename/000000000426/4Risk_FactorsAwkwardPostures.pdf 8 "Static Postures." Static Postures - Environmental Health and Safety. Environmental Health and Safety, Iowa State University of Science and Technology/Iowa State University, 2012. Web. 05 Dec. 2012. http://www.ehs.iastate.edu/occupational/ergonomics/static-postures 9 Kroemer, Etienne H., and Karl H. E. Grandjean. "Chapter 7 - Handling Loads." Fitting the Task to the Human: A Textbook of Occupational Ergonomics. 5th ed. London: Taylor & Francis, 1997. 130. Print. 10 "Occupational Injuries/Illnesses and Non-Fatal Injuries Profiles." Occupational Injuries and Illnesses and Fatal Injuries Profiles. United States Bureau of Labor Statistics, 2010. Web. 02 Nov. 2012. http://data.bls.gov/iil/ 11 United States. U.S. Department of Labor (DOL). Occupational Safety and Health Administration (OSHA). Hierarchy of Controls (PDF). Washington, D. C.: U.S. Department of Labor (DOL), N.d. www.osha.gov/dte/ grant.../fy06/.../12_intro_industrial_hygiene.ppt/Hierarchy of Controls. OSHA Directorate of Training and Education, OSHA, 2006. Web. 05 Dec. 2012. http://www.osha.gov/dte/grant_materials/fy10/sh-20839-10/hierarchy_of_controls.pdf 12 United States. United States Department of Labor (DOL). Occupational Safety and Health Administration (OSHA). www.osha.gov/Publications/osha3125.pdf, Ergonomics: The Study of Work, OSHA Booklet 3125. OSHA Directorate of Training and Education, OSHA, 2000. Web. 02 Dec. 2012. http://www.osha.gov/Publications/osha3125.pdf 13 ibid 14 Triplett, Dustin, Safety Manager, OHST, Oil States Industries, Inc. Engineering Control Cost in a Fabrication Shop. 07 Nov. 2012. Raw data. 6120 E. Orem Dr., Houston. Page 17 of 18