Primary Machine Safeguarding
Hazard Analysis to Prevent Workplace Amputations

Those who operate and care for machinery perform various activities that may pose amputation hazards, which are among the most severe and disabling workplace injuries, often resulting in permanent disability.

According to the U.S. Bureau of Labor Statistics, annually there are more than 8,000 non-fatal amputation cases – involving days away from work – with approximately 44 percent of them occurring in the manufacturing sector. The rest occurred across the construction, agriculture, wholesale and retail trade, and service industries.

These injuries result from the use and care of machines such as saws, presses, conveyors, and bending, rolling or shaping machines, as well as from powered and non-powered hand tools, forklifts, doors, trash compactors, and during materials handling activities.

In a publication titled, “Safeguarding Equipment and Protecting Employees from Amputations,” OSHA says, workplace amputations can be prevented by looking at workplace operations and identifying hazards associated with the use and care of any machines.

A hazard analysis is a technique that focuses on the relationship between the employee, the task, the tools, and the environment. When evaluating work activities for potential amputation hazards, consider the entire machine operation production process, the machine modes of operation, individual activities associated with the operation, servicing and maintenance of the machine, and the potential for injury to employees.

The results from the analysis may then be used as a basis to design machine safeguarding and an overall energy control (lockout/tagout) program.

Controlling Amputation Hazards

Safeguarding is essential for protecting employees from needless and preventable injury. A good rule to remember is: “Any machine part, function, or process that may cause injury must be safeguarded.”

In “Safeguarding Equipment and Protecting Employees from Amputations,” the term “primary safeguarding methods” refers to machine guarding techniques that are intended to prevent or greatly reduce the chance that an employee will have an amputation injury.

Machine safeguarding must be supplemented by an effective energy control (lockout/ tagout) program that ensures that employees are protected from hazardous energy sources during machine servicing and maintenance work activities.

Lockout/tagout plays an essential role in the prevention and control of workplace amputations. In terms of controlling amputation hazards, employees are protected from hazardous machine work activities either by: 1) effective machine safeguarding, or 2) lockout/tagout.

Additionally, there are some servicing activities, such as lubricating, cleaning, releasing jams and making machine adjustments that are minor in nature and performed during normal production operations. It is not necessary to lockout/ tagout a machine if the activity is routine, repetitive and integral to the production operation provided that you use an alternative control method that affords effective protection from the machine’s hazardous energy sources.

Safeguarding Machinery

OSHA holds the employer responsible for safeguarding machines, and they should consider this need when purchasing machinery. Almost all new machinery is available with safeguards installed by the manufacturer, but used equipment may not be.

If machinery has no safeguards, you may be able to purchase safeguards from the original machine manufacturer or from an after-market manufacturer. You can also build and install the safeguards inhouse. But it should be designed and installed only by technically qualified machinprofessionals. If possible, the original equipment manufacturer should review the safeguard design to ensure that it will protect employees without interfering with the operation of the machine or creating additional hazards.

Regardless of the source of safeguards, the guards and devices used need to be compatible with a machine’s operation and designed to ensure safe operator use. The type of operation, size, and shape of stock, method of feeding, physical layout of the work area, and production requirements all affect the selection of safeguards.

Also, safeguards should be designed with the machine operator in mind as a guarding method that interferes with the operation of the machine may cause employees to override them. To ensure effective and safe operator use, guards and devices should suit the operation.

Performance Criteria

ANSI’s B11.19-2003 national consensus standard provides valuable guidance as it addresses the design, construction, installation, operation and maintenance of the safeguarding used to protect employees from machine hazards. The following safeguarding method descriptions are, in part, structured like and, in many ways are similar to this national consensus standard.

Primary Safeguarding Methods

Two primary methods are used to safeguard machines: guards and some types of in safeguarding devices. Guards provide physical barriers that prevent access to danger areas. Safeguarding devices either prevent or detect operator contact with the point of operation or stop potentially hazardous machine motion if any part of an individual’s body is within the hazardous portion of the machine. Both types of safeguards need to be properly designed, constructed, installed, used and maintained in good operating condition to ensure employee protection.

Guards

Guards usually are preferable to other control methods because they are physical barriers that enclose dangerous machine parts and prevent employee contact with them. To be effective, guards must be strong and fastened by any secure method that prevents the guard from being inadvertently dislodged or removed. Guards typically are designed with screws, bolts and lock fasteners and usually a tool is necessary to unfasten and remove them. Generally, guards are designed not to obstruct the operator’s view or to prevent employees from doing a job.

In some cases, guarding may be used as an alternative to lockout/tagout because employees can safely service or maintain machines with a guard in place. For example, polycarbonate and wire-mesh guards provide greater visibility and can be used to allow maintenance employees to safely observe system components. In other instances, employees may safely access machine areas, without locking or tagging out, to perform maintenance work (such as machine cleaning or oiling tasks) because the hazardous machine components remain effectively guarded.

Guards must not create additional hazards such as pinch points or shear points between guards and other machine parts. Guard openings should be small enough to prevent employees from accessing danger areas.

Safeguarding Devices

Safeguarding devices are controls or attachments that, when properly designed, applied and used, usually prevent inadvertent access by employees to hazardous machine areas by:

• Preventing hazardous machine component operation if your hand or body part is inadvertently placed in the danger area;

• Restraining or withdrawing your hands from the danger area during machine operation;

• Requiring the use of both hands on machine controls (or the use of one hand if the control is mounted at a safe distance from the danger area) that are mounted at a predetermined safety distance; or

• Providing a barrier which is synchronized with the operating cycle in order to prevent entry to the danger area during the hazardous part of the cycle.

These types of engineering controls, which either prevent the start of or stop hazardous motion, may be used in place of guards or as supplemental control measures when guards alone do not adequately enclose the hazard. In order for these safeguarding devices to accomplish this requirement, they must be properly designed and installed at a predetermined safe distance from the machine’s danger area. Other safeguarding devices (probe detection and safety edge devices) that merely detect, instead of prevent, inadvertent access to a hazard are not considered primary safeguards.

Applicable OSHA Standards

Machinery and Machine Guarding: 29 CFR Part 1910, Subpart O

• 1910.211 – Definitions

• 1910.212 – General requirements for all machines

• 1910.213 – Woodworking machinery requirements

• 1910.215 – Abrasive wheel machinery

• 1910.216 – Mills and calenders in the rubber and plastics industries

• 1910.217 – Mechanical power presses

• 1910.218 – Forging machines

• 1910.219 – Mechanical powertransmission apparatus

Control of Hazardous Energy

(Lockout/Tagout): 29 CFR 1910.147 Hand and Power Tools: 29 CFR Part 1926, Subpart I

• 1926.300 – General requirements

• 1926.303 – Abrasive wheels and tools

• 1926.307 – Mechanical power transmission apparatus Conveyors: 29 CFR 1926.555 FSM