Fabrication Shop Ergonomics

INDH 4231 - Ergonomics, Human Factors, and Workplace Design

William Bell, Teresa Long, and Dustin TriplettDecember 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

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ABSTRACTFabrication 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.

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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

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awkward positions for prolonged periods of time. "Ergonomic injuries aren’t as high profile as

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.

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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.

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Some awkward positions that workers in fabrication shops regularly experience for long periods

of time are shown below in Figure 3.

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

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AWKWARD BODY POSTURES

Bending at the Back

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

Bending the Wrists >30°

More than 2 hrs per Day

Kneeling or Squatting More than 2 hrs per

Day

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 make-

up 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

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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:

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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

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.

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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.

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.

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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

locking metal objects weighing up to 10,000 lbs, depending on turntable size and

limits ergonomic awkward positioning work injuries.

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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

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

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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

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

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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.

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

Moves the task to the person. Accommodates very large, heavy objects. Can rotate the object 360°.

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Grips & teeth hold object in place.

Medium and Small Turntable (grips & teeth)

$5,000-$12,000

Allows worker to maneuver an object both vertically and horizontally. Brings the task to the worker. Good for irregular shaped material.

Jib Crane$5,000-$6,000

Bring the task to the worker. Swings 180 degrees and slides back & forth. Material can be lifted & turnedCapable of carrying 4,000 lbs.

Chair / Stool $50-$175 Eliminates lower back pain and CTDs caused from bending over. Eliminates awkward postures in shoulders & wrists.

Ergonomically-Designed Power Hand Tools

$80-350 Reduces hand, wrist, arm, back, and shoulder stress. Reduces contact stress.

Overhead Cranes$50,000-$1,000,000

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

Sub Arc Welding Machines

$20,000-$25,000

Prevents awkward postures, Decreases time spent bending over (worker operates turntable). Prevents injuries to retina (arcs contained within the machine).

Maneuverable Sub Arc Welding Machines

$40,000-$50,000

Used for precision welding. Prevents awkward postures, decreases time spent bending over (worker operates turntable). Prevents injuries to retina (arcs contained within the machine).

Adjustable Jack Stands and Tables $150-$500

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.

Fabricated Stands (sawhorses made from scrap metal)

$0

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.

Forklift$10,000-$1,000,000

Prevents injuries from lifting (back, knees etc.). Can lift 7-100,000 lbs, depending on model.

Computerized Cutting Burn Table $200,000

Nearly eliminates ergonomic hazards from awkward postures. Worker only enters data into a computer.

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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?

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Work Cited

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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: Work-Related 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/IMA-NA/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 ibid14 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.