WARNING! CONSTRUCTION, INDUSTRIAL AND OILFIELD WORKERS ARE FREQUENTLY INJURED OR KILLED WHEN WORKING ON OR AROUND MOBILE CRANES BECAUSE OF TIP-OVER, BOOM COLLAPSE, AND UNCONTROLLED HOISTED LOADS.

WARNING!  Construction, industrial and oilfield workers are frequently injured or killed when working on or around mobile cranes because of tip-over, boom collapse, and uncontrolled hoisted loads.

Here is the latest accident in the oilfield industry.

December 5th, 2014 - Texas-Oilfield Accident Sends One Worker To The Hospital

A 19-year-old oil field worker is recovering from what the Wichita County Sheriff describes as very painful injuries after an accident off FM 367 Thursday afternoon.

It happened around noon between FM 368 and Highway 25 on the Mitchell Ranch. Sheriff David Duke says Iowa Park first responders were able to get Christopher Beck stabilized and AMR was also called out.

He says because of the pain Beck was in and the rough terrain, Air Evac responded.

"It's a very large winch truck, had the booms up, and apparently something occurred when one of the blocks, one of the part of the actual winch stuff shifted, and the booms came down. And, when they came down it struck him in the back and the shoulder area and injured him pretty good," Sheriff Duke said.

Beck was treated and released and is expected to be just fine. Sheriff Duke says the accident happened about a mile and a half onto the Mitchell Ranch, south of FM 367.

Accidents involving winch trucks are not uncommon.  In July 2013 a worker died after being pinned between two trucks while preparing to connect a winch line in Houston, Texas.  In July 2013, another worker was killed when he was pulled into an anchor winch after  becoming entangled in an anchor wire rope in Homer Arkansas.

The National Institute for Occupation­al Safety and Health (NIOSH) requests assistance in preventing injuries and deaths of workers exposed to mobile crane tip-over, boom collapse, and un­controlled hoisted loads. Recent NIOSH investigations suggest that workers may not fully recognize the hazards as­sociated with operating or working near mobile cranes. Crane tip-overs can re­sult from operating a crane outside the manufacturer’s recommended safe lift­ing capacity. Booms can collapse for reasons such as overloading, improper disassembly procedures, and improper rigging. Both crane tip-over and boom collapse can result in workers being struck by parts of the crane or uncon­trolled hoisted loads.

This Alert describes six incidents re­sulting in the deaths of eight workers and injuries to two others that were ei­ther working near or operating mobile cranes. In each incident, these injuries or deaths could have been prevented by using proper safety procedures such as not exceeding the crane’s lift capacity; following proper set-up, maintenance and dismantling procedures; and not working under a suspended load.

NIOSH requests that the information in this Alert be brought to the attention of all employers, managers, supervisors, crane operators, riggers, and ground workers in companies that own or rent mobile cranes. NIOSH requests assis­tance from safety and health officials, construction companies, unions, crane and rigging manufacturers, crane rent­al facilities, building material suppliers and manufacturers, editors of trade journals, and those positioned to com­municate prevention information to employers and workers.

BACKGROUND

Mobile cranes are used to hoist loads to meet various construction and industrial needs. All cranes use cables and pulleys or hydraulics to raise and lower the desired load.  The Construction Safety Association of Ontario’s Mobile Crane Manual [Dickie 1999] lists the basic operational characteristics of all mobile cranes as follows:

·         Ability to lift and lower loads

·         Ability to swing loads around an axis of rotation

·         Adjustable boom lengths

·         Adjustable boom angles

·         Ability to travel about the job site under their own power

Mobile cranes come in a variety of types and configurations such as the following:

·         Boom trucks

·         Industrial cranes

·         Carrier-mounted lattice boom cranes

·         Crawler-mounted lattice boom cranes

·         Carrier-mounted telescopic boom cranes

·         Crawler-mounted telescopic boom cranes

·         Rough terrain cranes

·         Mobile tower cranes

·         Heavy-lift mobile cranes

Cranes are able to lift heavy loads by ap­plying the principle of leverage. The crane’s own weight is balanced against the object or load being hoisted at the tipping point (or tipping axis) [Figure 1]. The crane re­mains stable and can safely lift and move the load so long as the crane’s leverage on the load is greater than the load’s lever­age on the crane [Dickie 1999]. 

The crane’s ability to lift a heavy load, swing it in any direction, and raise it high overhead also contributes to the many re­ported incidents of crane tip-over when the cranes are not set up correctly or prop­er procedures are not followed. During a lift, the distance from the load’s center of gravity to the crane’s tipping axis changes as the boom angle changes, the boom is extended, and as the crane’s upper deck rotates to swing the load. These changes can lead to instability if the crane’s lift ca­pacity is exceeded. Proper inspection, set-up, and operation by the crane operator, along with proper maintenance, are nec­essary to ensure safe crane operation.

A crane’s lifting capacity is reduced as the boom is lowered because the distance from the load’s center of gravity to the tipping axis is increased. Increasing the load’s distance to the tipping axis reduces the ability of the crane’s weight to counter­act or “leverage” the load’s weight.  Extending the boom at any given angle has the same effect. 

A crane is a complex machine requiring considerable knowledge for safe opera­tion. This knowledge can only be gained through proper training and hands-on ex­perience. The ability to understand and correctly use a crane’s load chart is criti­cal to the safe operation of a mobile crane. Each crane’s load chart specifies the rated (maximum) capacity of that machine for every permissible configuration. The load chart also specifies the machine’s opera­tional limitations and conditions necessary for safe operation. An operator must al­ways use these load charts to determine capacity for a lift and know or be able to calculate the weight of each load. Mod­ern cranes may incorporate computerized load-moment indicators (LMI), which mon­itor hoisting data and provide the crane operator with a readout of lift conditions. These LMI devices may be designed to interrupt the hoist operation when the hoisted load reaches a set limit to prevent crane overloading. These devices require periodic maintenance, verification, and re-certification by a knowledgeable person. LMI devices are not intended to take the place of a load chart. The LMI alone does not ensure a safe lift; it is simply an indica­tor to advise a competent operator of load parameters to consider when making op­erational judgments during the lift [Shapiro 2000].

A number of factors are involved with mak­ing a safe lift. For example, if a crane is equipped with outriggers, it is strongly rec­ommended that they be fully extended to the manufacturer’s specifications and used on every lift following load capacity charts supplied by the manufacturer, regardless of the weight of the load. If all outriggers are not fully extended, lift capacity drops sharply [Dickie 1999; Shapiro 2000; ASME 2004]. Unless the manufacturer has supplied specific load charts for partial outrigger extension, load charts designat­ed for on rubber or lifting without outriggers deployed must be followed [AEM 2002]. 

Cranes must be located on solid, stable ground capable of supporting the weight of the crane plus the suspended load. Crane operators often encounter ground at the construction site that has recently been worked or backfilled. A professional engineer should evaluate such conditions to ensure that ground pressures gener­ated by the crane’s weight do not exceed the load-bearing capacity of the soil. Ex­treme caution is needed to ensure crib­bing blocks placed under outrigger pads are firmly supported and of adequate size. When multiple lifts are made from the same location, the condition of the ground and the blocking under the outrigger pads should be checked often to ensure the timbers have not shifted or deteriorated. Some companies use long bolts to join cribbing timbers together to create a more solid base for outriggers to set on, thus preventing timber rollout. 

A mobile crane mounted on a barge acts differently than when being operated on land [Shapiro 2000]. This phenomenon is due to the way in which forces applied to the crane by the weight of the lift are transmitted to the barge. When a barge-mounted crane lifts a load that is not on the barge, the forces applied to the crane are transmitted to the barge and the barge will lean toward the load. Landing a load (resting the load on the ground or another surface) causes the barge to momentarily lean away from the load as the forces ap­plied to the crane are reduced. This leaning or tilting of the barge is known as list. Lifting a load that is already on the barge can also cause the barge to list when the crane swings or changes the boom angle, chang­ing the equilibrium between the weight of the crane and the weight of the load. The listing of the barge will also cause the sus­pended load to swing. The crane opera­tor must expect and compensate for this swinging motion.

Proper maintenance is important to ensure cranes operate safely and efficiently. The Mobile Crane Manual [Dickie 1999] lists a number of factors that contribute to poor crane performance and reduce a crane’s rated capacity. These factors include lack of proper maintenance, machine configu­ration not in compliance with manufactur­er’s specifications, eccentric reeving of cables, and excessive duty cycle opera­tions.* Eccentric reeving occurs when the hoist line is not centered over the boom tip and causes torque (twisting) in the boom. Load charts only apply when the boom is symmetrically rigged (load line centered). Follow the manufacturer’s specifications when reeving cables.

The North Carolina Department of Labor estimates that one crane upsets (tips over) during every 10,000 hours of crane use in the United States [NC DOL 2004]. Nearly 80% of all crane upsets (tip-overs) are attributed to operators exceeding the crane’s operational capacity [Kay 2004]. Approximately 54% of these incidents are the result of swinging the boom or making a lift without the outriggers fully extended [NC DOL 2004; Kay 2004].

Critical Lifts

NIOSH and others have identified certain types of hoisting operations that require special considerations to ensure worker safety. In the crane and rigging com­munity, the term critical lift is commonly used to describe these situations. A criti­cal lift generally identifies hoisting opera­tions for which the margin for error is re­duced. Critical lifts include the following situations:

·         The weight of the hoisted load ap­proaches the crane’s maximum capacity (70% to 90%).

·         Two or more cranes simultaneously lift the same load.

·         Personnel are being hoisted.

·         Nonstandard or specially modified crane configurations are used.

·         Special hazards are associated with the lift, such as

·         the crane is located inside an in­dustrial plant;

·         the crane(s) is mounted on floating barges;

·         loads are lifted close to powerlines; and

·         high winds or other environmental conditions are present.

However, the definition of a critical lift is not as important as the planning neces­sary to safely perform the lift. 

Load ratings developed by crane manu­facturers are based on the principal fac­tors affecting crane stability and include the weight of the hoisted load, the struc­tural strength of the crane, and the crane’s boom length and load-radius. Crane load charts specify maximum lifting capaci­ties for every configuration permitted by the manufacturer and specify the limita­tions and conditions necessary for safe operation [Dickie 1999]. These ratings are based on crane operation under ideal conditions. The actual hoisted load includes the weights of the lifted materi­als, hook block, slings, and other lifting accessories. However, additional loads may be imposed on the crane by factors present in the work environment. These factors may include wind forces acting on the crane structure and the lifted materi­als, dynamic forces due to movement of the crane and lifted materials, and side loads due to out-of-level or unstable ground conditions [Dickie 1999; Shapiro 2000]. When a hoisted load exceeds 85% to 90% of a crane’s rated capacity, little reserve is available to counter unantici­pated loads.

Special hoisting precautions are neces­sary to ensure worker safety during criti­cal lifts [Dickie and Hardy 2000]. 

Critical lifts should follow engineered lift plans that are based on a comprehensive evaluation of the most accurate infor­mation available for all factors affecting crane stability. Critical lift plans should be in writing [Ritchie 2005]. Because a thorough understanding of the relation­ship between the crane design and the dynamic effects of traveling and moving with hoisted loads is crucial to the devel­opment of these plans, the plan should be designed by a registered professional engineer specializing in hoisting opera­tions [NIOSH 1999]. Currently, several Federal agencies require written lift plans for critical lifts conducted under their jurisdiction, including the U.S. Army Corps of Engineers, Department of the Army [DOA 2003], the U.S. Department of Energy (DOE) [DOE 2004], the Nation­al Aeronautics and Space Administration (NASA) [NASA 2002], and the U.S. Navy [Navy 2003].

To prevent crane tip-over, the critical lift plan should be based on the opera­tional limitations specified by the crane load chart, measured (as opposed to cal­culated) weights for the materials to be hoisted, thorough studies of wind speed and its effect on the crane and hoisted load, and consideration of the effects of ground conditions and dynamic forces on the crane’s stability.

CONCLUSIONS

Proper training of crane operators in the mandatory use of load charts is impor­tant for safe hoisting operations. Crane operators need to know and understand how to use load charts provided by the crane manufacturer. LMI devices are an important safety feature on modern cranes. However, these devices can­not replace the judgment of a trained and qualified operator who has knowl­edge of safe practices regarding hoisted loads, swing radius, and load chart infor­mation. LMI devices should be checked per the manufacturer’s recommenda­tions and if not working properly, tagged out-of-service until repairs are made.

Crane operators and workers must follow the manufacturer’s recommendations for crane set-up and rigging.

Workers must use caution so that they do not place themselves in dangerous areas where they can be struck by falling loads or by falling or collapsing crane compo­nents.

Managers and safety professionals need to consider safe work practices for work­ers who are required to work on or near operating cranes. All workers should use and follow established hand signals such as the standard hand signals listed in ANSI B30.5–2004.

RECOMMENDATIONS AND DISCUSSION

NIOSH recommends that employers, workers, and crane rental companies take the following actions to minimize the risk of injury and death to those who work on or near mobile cranes: 

Employers

Make sure your work sites comply with safety requirements found in pertinent regulations and standards including OSHA 29 CFR 1910.180 (general industry cranes); 29 CFR 1917.45 (marine terminals); 29 CFR 1918.66 (maritime, cranes and der­ricks other than vessel’s gear); 29 CFR 1926.550 (construction indus­try cranes and derricks); and ASME B30.5–2004, mobile and locomotive cranes.

·         Inspect and maintain each crane following the manufacturer’s rec­ommendations.

·         Make sure operators are properly trained and qualified.

·         Coordinate communications be­tween the crane operator and rig­gers, spotters, supervisors, and others working near the crane.

·         Use standard hand signals and pro­vide training for signal persons (see Appendix A).

·         Follow manufacturer’s guidelines for crane assembly and disassembly.

·         Make sure wire rope is in good working order.

·         Keep workers clear of hoisted loads.

·         Follow safe work practices when working near energized power lines.

Conduct training to ensure that crane operators understand safe crane op­eration (for example, reading and comprehending load charts) as well as the principles of set-up, rigging, hoisting, extending the boom, swing­ing a load, pinching and crushing points, swing radius warning barri­ers, power line safety, etc.

·         Consider requiring operator testing and certification as a prerequisite for employment, even if not required by law.

·         Consider using fatality case reports in your training programs.**

·         Include principles of crane opera­tion, such as the fact that raising and lowering the boom changes the dis­tance from the load’s center of grav­ity to the tipping axis of the crane.

Review your occupational safety programs and standard operating procedures to ensure that they in­clude safe practices for lifting loads.

Conduct training to ensure that rig­gers and ground workers under­stand the hazards of working around mobile cranes and that they remain vigilant and watch for signs of prob­lems at all times, especially if power lines are nearby.

·         Use a spotter whenever the crane operator’s view of the lift area, swing radius, or the landing area is obstructed.

·         Notify workers before a lift begins.

·         Make sure workers are not located within the swing radius or under a suspended load at any time.

·         Thoroughly evaluate ground condi­tions, wind speed, travel distance, proximity to overhead power lines, and other obstructions.

·         Follow all pertinent OSHA regula­tions.

·         Follow manufacturers’ recommen­dations for safe crane operation and maintenance.

Develop and follow a written engi­neered lift plan for all critical lifts.

·         Make sure that critical lift plans are (1) developed by registered profes­sional engineers with specialized knowledge of hoisting operations and (2) based on a thorough evalu­ation of the following:

·         The rated capacity and opera­tional limitations specified by the crane’s load chart [NIOSH 1999]

·         Measured (as opposed to calcu­lated) weights for the materials to be hoisted [NIOSH 1999]

·         Thorough studies of wind speed and its effect on the crane and hoisted load [NIOSH 1999]

·         Consideration of the effects of ground conditions and dynamic forces on the crane’s stability [Dickie and Hardy 2000; Shapiro 2000; NIOSH 1999]

·         Include specifications for commu­nication during the lift. All parties involved in the lift, including crane operator(s), riggers, signal persons, and supervisors must have a thor­ough understanding of how com­munication will take place [Dickie and Hardy 2000].

·         Identify a single person to direct all operations during the lift [Dickie and Hardy 2000; NASA 2002; DOE 2004].

When multiple lifts are made from one location, such as during duty cycle operations, check the condi­tion of the ground and blocking ma­terials regularly and as often as pos­sible to ensure the crane remains on firm stable ground.

·         Watch for signs of soft or unstable ground compressing or deflect­ing (pushing out) from under­neath blocking due to the down­ward pressure exerted by the crane’s outriggers or the crane’s tracks or wheels.

·         Watch for signs of previously level or unsecured cribbing blocks rolling out from under the outrigger pads.

·         Do not exceed the manufacturer’s recommended load chart.

·         Pay special attention when work­ing around construction and ex­cavation sites, backfilled areas, underground drains and culverts, poorly drained areas, and sandy soils.

·         When in doubt, have the stability of the ground evaluated by a qualified professional engineer to ensure the area will support the weight of the crane plus the suspended load over the entire lift cycle.

Make sure mobile cranes located on floating barges are positively secured to the barge and barge list is accounted for when determining safe load capacity.

·         Reduce load rating charts whenever list exceeds 1 percent [Shapiro 2000]. Consult the crane manual or crane manufacturer for chart re­ductions and maximum list for the crane configuration.

·         Positively secure mobile cranes located on floating barges accord­ing to OSHA standard 29 CFR 1926.550(f)(1)(iv).

Follow the manufacturer’s recom­mended assembly and disassembly and maintenance procedures when working on cranes.

·         Use proper blocking methods to adequately support crane compo­nents during these operations.

·         Block boom sections under each section’s support members to en­sure the weight of the section is safely supported.

·         Do not block between the support members, as this may cause dam­age to the boom section.

·         Always check to ensure boom pen­dants (boom suspension cables or lines) are properly located before removing a connecting pin. The boom pendant should be between the pin and the crane body so that it supports the boom section closest to the crane body.

·         When removing pins, block or sup­port the remaining boom section(s) to prevent their collapse. Refer to the manufacturer’s recommenda­tions for long booms and booms with jibs.

Comply with child labor laws that prohibit construction and manufacturing work by persons under age 16 and that prohibit workers under age 18 from operating or assisting in the operation, repair, servicing, assem­bly, disassembly and similar activi­ties associated with mobile cranes. For more information about Fed­eral child labor laws, visit www.dol.gov/dol/topic/youthlabor/index.htm; or call 1–866–4–USADOL.

·         Do not assign workers under age 16 to any aspect of construction or manufacturing work.

·         Do not assign workers under age 18 to work as crane operators or to perform any crane maintenance, set-up, assembly or disassembly operations.

·         Make sure all workers are aware of any workers under age 18 in the work setting. Inform them about the types of work young workers are allowed to perform and where they should report questionable tasks.

·         Consult a U.S. Department of La­bor Wage and Hour Division of­fice for assistance, if needed. For information about Federal child labor laws, visit www.dol.gov/dol/topic/youthlabor/index.htm or call 1–866–4–USADOL. For links to State labor offices, visit www.ilsa.net or www.youthrules.dol.gov/states.htm or call 1–866–4–USWAGE.

Crane Operators

Take training in safe crane operation offered by your employer.

Always use the crane manufacturer’s load chart provided for each crane.

·         Do not exceed the crane’s lift capacity.

·         Do not operate a crane if the load chart is not available.

Be sure you know or can calculate the weight of each load.

Never use visual signs of tipping as an indicator of lift capacity.

If necessary, use a spotter to en­sure workers are protected from the struck-by hazards of hoisting and swinging loads.

Follow the manufacturer’s proce­dures for proper outrigger deploy­ment to ensure that cranes are properly set up and level with their outrigger pads supported on firm stable surfaces before beginning a lift.

·         Use extreme caution whenever working around trenches, excava­tions, backfilled locations next to new building construction, sew­ers, and underground pipes since the weight of the crane can cause these areas to shift or collapse.

·         Use specially designed mats, steel plates, timber pads, or concrete rafts under cranes to distribute the load if the ground is too soft, wet, or ir­regular to provide solid footing. Make timber mats by joining solid timbers or cribbing blocks with long bolts passed through each timber forming a solid mat to prevent individual blocks from rolling out from under the outrigger.

·         Make sure blocking placed under out­rigger pads is at least 3 times larger than the outrigger pad it is support­ing.

·         Place blocking so that the entire out­rigger pad is supported.

·         Make sure blocking is level and at a right angle (90 degree) with the out­rigger pad to prevent blocking from slipping out from under the outrigger [Dickie 1999].

When multiple lifts are made from one location, such as during duty cycle operations, check the condition of the ground and blocking materials regu­larly and as often as possible to en­sure the crane remains on firm stable ground.

Always check for overhead power lines and other obstructions. Comply with OSHA regulations for safe work­ing distances around power lines.

Avoid hoisting or moving suspended loads over workers and other people within the crane’s swing radius.

Barricade the swing radius to keep un­authorized persons from entering ar­eas of pinch points.

Follow a written engineered lift plan for all critical lifts.

If you are under age 18, do not operate a crane or assist in tasks being per­formed on cranes such as repairing, servicing, assembling, or disassem­bling the machine.

·         For information about Federal child labor laws, visit www.dol.gov/dol/topic/ youthlabor/index.htm or call 1-866- 4-USADOL. For links to State labor offices, visit www.ilsa.net or www.youthrules.dol.gov/states.htm or call 1-866-4-USWAGE.

Riggers and Ground Workers Located near Hoisting Operations

Be aware that the job site is always changing and be observant of hoist­ing operations in your work area.

Never work or position yourself di­rectly under a suspended load.

Be observant and watch for signs of problems during each lift.

Always check for overhead power lines and other obstructions. Com­ply with OSHA regulations for safe working distances around power lines.

Barricade the swing radius to keep unauthorized persons from entering areas of pinch points.

Follow a written engineered lift plan for all critical lifts.

Follow the correct assembly and disassembly procedures when set­ting up or dismantling a crane. Make sure boom sections are blocked or supported before removing pins. Do not stand under the boom.

If you are under age 16, do not per­form any type of construction or manufacturing work. If you are under age 18, do not operate a crane or assist in tasks being performed on cranes such as repairing, servicing, assembling, and disassembling the machine

·         For information about Federal child labor laws, visit www.dol.gov/dol/topic/youthlabor/index.htm or call 1–866–4–USADOL. For links to State labor offices, visit www.ilsa.net or www.youthrules.dol.gov/states.htm or call 1–866–4–USWAGE.

Crane Rental Companies

Make sure cranes are serviced and maintained following manufactur­ers’ specifications.

Make sure each crane is provided with the correct operator’s manual as well as load charts, safety de­cals, maintenance, inspection, and instructional decals, crane signal charts, and other safety information provided by the manufacturer.

·         Periodically inspect each crane to ensure warning labels are present and replace as necessary to en­sure labels are legible and properly identify the appropriate hazards associated with moving parts, ma­chine guards, pinch points, walk-ways, handrails, etc.

·         Replace labels and decals that were damaged or removed dur­ing repair work or maintenance (e.g., cleaning, painting, replace­ment of parts).

Make sure that LMI and other safety devices are functioning properly.

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