Lockout/tagout and machine guarding
What would the requirement be if a lengthy lockout procedure was needed to shut down complex equipment with numerous energy sources, but we are only working in one area of the machine with a limited number of energy sources?
Responding is Todd Grover, global senior manager – applied safety solutions, Master Lock Co. LLC, Oak Creek, WI.
Complex equipment is challenging to safely service or repair because of the multiple sources of energy to be controlled, as well as productivity pressures during shutdowns to get back up and running. Working safely is the top priority, and most employers take this responsibility seriously.
They do this by carefully evaluating their equipment to prepare documented lockout procedures that itemize all primary and residual energy sources according to a step-by-step method. Each source is then disconnected in an orderly manner, relieving all stored energy, and a zero-energy state in the equipment is verified before hands-on work begins.
Dozens of energy sources may need to be controlled in a complex process to properly complete a full lockout/tagout procedure. However, service or repair work might have to be performed in one specific section of a machine having limited energy sources that safely and realistically can be isolated from other sections of the machine upstream and downstream from the worksite.
Being able to define the lockout activity to control all hazards in that area of focus can help preserve critical settings, maintain optimal operating conditions and prevent the loss of real-time data. A limited sectional lockout procedure can responsibly save the time of a full shutdown to efficiently complete the necessary service or repair work.
Sub-procedural preparations should begin with a careful hazard assessment of the machine section in question. This analysis will identify what the likelihood and consequences of unexpected releases of energy would be if not fully isolated. An overview of a best-practice approach to lockout/tagout risk assessment I recommend is ANSI Z244.1.5.4.1. The full method can be found in Z244.1 Annex A.
Start with the existing written lockout/tagout procedure covering the entire machine, making sure the full procedure has recently passed the required annual auditing scrutiny to ensure you are working from verified information. Identify and document the upstream energy sources feeding materials into – or otherwise creating hazards – for your section of focus. Note the energy sources and residual sources powering the movement or actions in the area where the service or repair work will be performed.
Evaluate any downstream functions or hazardous exposures that could jeopardize the person performing the work. Be sure to note the source, magnitude and location of the energy control points when writing your sub-procedure. All upstream, downstream and energy sources impacting the area of sectional focus need to be accounted for, and then be sure to test your new procedure by verifying a zero-energy state has been achieved in the sectional focus area where your work will be completed. Once proven effective, include the subprocedure in the annual auditing process.
“When in doubt, fully lock out.” If you’re not sure that all primary and residual sources needing to be controlled have been properly secured to protect the exposed authorized personnel, the full lockout/tagout procedure for the complex machine must be implemented.
Editor's note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.