Machine Guarding and Risk Assessment

Author

TWG_Jones_Chad

Expertise Includes:

    • Industrial Accident Investigation
    • Machine Design
    • Machine Safeguarding
    • Machinery & Equipment Damage Assessment
    • Products Liability
    • HVAC Systems
    • Risk Assessment

The Occupational Health and Safety Administration (OSHA) “Top 10 for 2018” violations once again have Machine Safeguarding earning a position on the list. Machine safeguarding was the 9th most cited standard as noted in the list below:

  1. Fall protection, construction (29 CFR 1926.501)
  2. Hazard communication standard, general industry (29 CFR 1910.1200)
  3. Scaffolding, general requirements, construction (29 CFR 1926.451)
  4. Respiratory protection, general industry (29 CFR 1910.134)
  5. Control of hazardous energy (lockout/tagout), general industry (29 CFR 1910.147)
  6. Ladders, construction (29 CFR 1926.1053)]
  7. Powered industrial trucks, general industry (29 CFR 1910.178)
  8. Fall Protection–Training Requirements (29 CFR 1926.503
  9. Machinery and Machine Guarding, general requirements (29 CFR 1910.212)
  10. Eye and Face Protection (29 CFR 1926.102)

(Source: www.osha.gov/Top_Ten_Standards.html)

This is down one in the order from 2017 where Machine Safeguarding was the 8th most cited standard. OSHA 1910.212 (a)(1) states: “Types of guarding.  One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards associated with those created by the point of operation, ingoing nip points, rotating parts, flying chips and sparks.  Examples of guarding are-barrier guards, two-handed tripping devices, electronic safety devices, etc.”

So, what goes into an effective “Machine Guard”?  Well before you can guard, you must first understand the risk(s) associated with a machine.  Which leads us to the subject of this blog, risk assessment.
Machine guard for blog

Fixed Perimeter Guard

The hazard control hierarchy, as described in ANSI B11.0 – Safety of Machinery- General Requirements and Risk Assessment, lays out an excellent path for protection from harm.  First a risk assessment must be conducted to understand the potential for harm associated with a machine.  The B11.0 standard states that the outcome of a risk assessment should be: “A clear understanding of risk(s) including the potential severity of harm and the probability of the occurrence of harm.”  Not only is the severity of injury a concern, but how often will we face the risk?  Is it once per year, once per day, once per shift, or multiple times per hour?  The likelihood of injury goes up when we must interact with the hazard more frequently.  However, the severity of harm must also be part of the consideration.   Is the severity grave, such as a fatality or loss of limb, or a mere first aid?  Who will be exposed to the hazard?  Machine operators will be of course, but what about maintenance personnel?  Can maintenance tasks be completed safely?   Additionally, can the machine be properly cleaned and what exposure will cleaning personnel have?    All these factors are handled in detail in the risk assessment.

The next step is to use a formal risk scoring system.  There are various methods to choose from, but the rigor of the process should not be circumvented.   This is a place to sweat the small details.  With the output from the risk scoring system, we can begin applying measures to reduce risk to an acceptable level.  Here is where the hazard control hierarchy comes into play, specifically: design out the hazard if you can, utilize engineering controls such as guarding or presence sensing devices if you cannot design out the hazard, and if you cannot guard use administrative controls such as procedures, personal protective equipment (PPE) or lockout-tagout.

After the correct form of protective measure has been applied, the risk must be reassessed.  Has the potential for harm been reduced to an acceptable level?  Acceptable level is generally defined to mean the level at which further technologically, functionally and financially feasible risk reduction measures or additional expenditure of resources will not significantly reduce the risk any further (ANSI B11.0).  Did our solution create any new risks?  If so, they must be addressed before the job is done.  Finally, the entire process should be formally documented.

With a thorough risk assessment, machine safeguards are much more likely to be effective at preventing injuries.  And preventing injuries is the reason behind risk assessments and machine guarding.  For assistance with evaluating machine guarding, please contact the Warren Group.

Chad Jones, PE has a Bachelor of Science in Mechanical Engineering from Clemson University. Chad has over 23 years of engineering experience including mechanical, process, and manufacturing engineering. He participated in and led industrial incident investigations and participated in in-depth process safety audits. This work has included equipment design, machine safeguarding, cost estimating and safety compliance.

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