Alternative Protective Measures, The Bridge Between Lockout Tagout and Machine Guarding

The requirements for using Lockout Tagout (LOTO) to control hazardous energy during machine servicing and maintenance are clearly prescribed in 29 CFR 1910.147, but OSHA enforcement citing of the LOTO Standard consistently remains in the top 10 most frequently cited standards.  Why? LOTO requirements are not always consistently or correctly followed, and they’re often viewed as too time consuming, even though failure to correctly perform LOTO can have life altering results.

Are there exemptions and exceptions to the LOTO Standard?

The standard does not cover activities associated with:

  • Construction, which has focused LOTO requirements in SubParts D, K and Q
  • Agriculture employment
  • Maritime standards covered by 29 CFR 1915, 1917 and 1918, which have focused LOTO requirements for conveyors
  • Electric utility installations for the purpose of power generation, transmission and distribution, including related equipment for communication or metering
  • Exposure to electrical hazards from work on, near, or with conductors or equipment in electric-utilization installations, which is covered by 29 CFR 1910 Subpart S
  • Oil and gas well drilling and servicing

Additionally, the General Industry standard has specific exemption criteria around hot tap operations and single energy source cord and plug equipment, which we won’t delve into here.

When is the LOTO Standard applicable?

For all activities not exempted, the LOTO standard requires the use of energy control procedures during servicing and/or maintenance tasks for machines and equipment.  Additionally, normal production operations are included for which:

  • An employee is required to remove or bypass a guard or other safety device; or
  • An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being proceeded (point of operation) or where an associated danger zone exists during a machine cycle.

What is the “alternative measures” exemption of the LOTO Standard?

We find the most widely misunderstood or misapplied exception is in a “Note” at the end of 1910.147(a)(2)(i) that is associated with some “normal production operations.” It states:

Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).

Hence the term “Alternative Protective Measure,” which are an alternative to LOTO, for very specific tasks, which provide effective protection.  SubPart O is the Machine Guarding Standard. Unfortunately, there is nothing in SubPart O that further explains the connection of machine guarding to this “alternative measures” exemption.  For this, we must go to ANSI Z244.1 Control of Hazardous Energy, Lockout/Tagout and Alternative Methods (R:2020).

First, what are “routine, repetitive, and integral” tasks?

The ANSI Z 244 standard recognizes the need for greater flexibility in machine energy control for tasks that are routine, repetitive, and integral to the production process, or where traditional LOTO prohibits the completion of those tasks.

Tasks that are “routine, repetitive and integral to production” generally exhibit most of the following characteristics:

  • Inherent to the production process
  • Short in duration
  • Relatively minor in nature
  • Occur frequently during the shift, day, or week
  • Usually performed by operators, set-up, service, or maintenance personnel
  • Do not involve extensive disassembly
  • Represent predetermined cyclical activities
  • Expected to occur regularly to maintain process continuity within the nominal performance range and output quality
  • Minimally interrupt the production process
  • Exist even when optimal operating levels are achieved
  • Require task-specific personnel training
  • Predictable based on operating experience and product demands

Example activities that might be performed using alternative methods include die changing, jam clearing, make-ready, lubrication, tool changes, roll polishing, minor cleaning, adjustments and set-up.  Based on these criteria, the user should identify those tasks that are "routine, repetitive and integral to production" and proceed with a risk assessment. If the tasks do not substantially meet these criteria, then LOTO must be used.

What does a risk assessment for “routine, repetitive and integral” tasks involve?

Once the candidate tasks for alternative protective measures are identified, we must perform a documented risk assessment, which is when the link to machine guarding becomes clear.  The qualitative assessment, must include the following elements:

  • Identification of the applicable tasks (including foreseeable misuse) and related hazards
  • Consideration of existing machine safeguards (and safety control system) provided with the equipment that may need to be opened, removed or modified to perform a given task
  • Qualitative estimation of exposure and severity to determine the level of risk, based on the guarding and associated safety control system
  • Identification of potential supplemental control actions considered to reduce the risk of each hazard
  • Verification of the effectiveness of the selected alternative
  • Documentation of the risk assessment process

Information on specific risk assessment methodologies may be found in:  ISO 14121/EN 1050, ANSI B11-TR3, ANSI/RIA R15.06, and MIL STD-882D.

As with any risk assessment, we use the hierarchy of controls in the following order of preference:

  • Eliminate the hazard through design
  • Use engineered safeguards
  • Use warning and alerting techniques
  • Use administrative controls (such as safe work procedures, practices, and training)
  • Use personal protective equipment

While the elimination of hazards through design is the ultimate target, this is rarely achieved, and the risk assessment must evaluate the suitability of engineered safeguards (machine safeguards or safety devices and the safety control system) and their level of reliability for the level risk reduction that is required (Ref. ANSI B11.26 and ISO 13849.1).

Examples of engineered safeguards include guards (both fixed and interlocked), trapped key devices, and presence sensing devices (light curtains, laser scanners, pressure mats, safety rated switches, etc.). Examples of safety devices include emergency stop buttons and enabling or hold to run devices.

Machine guarding considerations include verification that components are “safety rated” and that the safety control systems (the combination of devices, relays, actuators, and software) are constructed to meet the targeted control reliability and are installed such that start up after interruption requires at least two distinct actions.  Where safeguarding control system incorporates or is supplemented by special engineered devices such as blocks, racks, supports, or pins, these devices shall be designed and built using appropriate safety factors.

What is considered an adequate level of protection for engineered safeguards?

Generally, an adequate level of protection is achieved when there are at least two independent engineering controls, supplemented by additional measures.   Examples include:

  • Opening two separate safety rated, interlocked access panels that requires closure of both access panels, control panel reset and restart, (two safety devices and four distinct restart actions) to resume operation.
  • Activation of a Category 2 E-Stop and breaking a light curtain. Restart requires manual reset of the E Stop button, clearing the light curtain and control panel reset and restart (two safety devices and three distinct restart actions) to resume operation.
  • Opening a safety rated interlocked access gate and tripping a laser scanner presence sensing device in the hazard zone. Reset requires clearing the laser scanner, gate closure, control panel reset and machine restart (two safety devices and three distinct restart actions) to resume operation.

Engineered controls (machine guarding) and engineered devices may be supplemented by partial lockout as an added layer of protection.  Examples include:

  • Lockout of one energy control point
  • Lockout of an interlock (e.g. to prevent closure of a door during the task)
  • Lockout of an E Stop (to prevent reset during the task)

It is important to note that the second two examples are not acceptable for performing normal LOTO and are only considered additional levels of control for alternative protective measures.

These safety control/engineering controls may be supplemented but not replaced with warning and alerting techniques such as automated visual and audible alarms, barricades or warning signage, as well as other safe work practices, procedures, training and personal protective equipment to add additional layers of protection.

What’s the requirement for documentation of alternative control measures?

As with normal LOTO energy control procedures, the employer must document the alternative control measures procedures in a procedure format, and train employees to recognize the difference between the requirement for LOTO and use of alterative protective measures.  We recommend a best practice of integrating these in a single machine-specific energy control procedure where all identified servicing and maintenance tasks are identified and procedures for both LOTO and alternative measures are defined.

What about tasks that require partial energization?

Where partial energization is necessary for some tasks (e.g. in order to hold parts, save information, retain heat, or provide local lighting), alternative control methodologies may be used for personnel safety. The employer must conduct a risk assessment to determine the safest method of machine, equipment or process access.

The ANSI Z244.1 Standard provides specific industry-specific example options of alternative methods of hazardous energy control in annexes:  Annex H - Printing Industry; Annex I - Plastics Industry. Annex J - Robotic applications. In any of these examples, all provisions of this standard apply in the development of alternative methods.

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