Machine Safety: How safe is safe enough?

In machine guarding, how safe is safe enough? Over my 40 years in industry I’ve heard this comment many times. Is this attitude driven by “safety culture” or is it just a product of qualitative risk management? Is this why risk management for machine guarding and functional safety is advancing globally to quantitatively derived engineering and validation?

01/12/2012


JB Titus, CFSEIn machine guarding, how safe is safe enough? Over my 40 years in industry I’ve heard this comment many times. Is this attitude driven by “safety culture” or is it just a product of qualitative risk management? Is this why risk management for machine guarding and functional safety is advancing globally to quantitatively derived engineering and validation?

   No, this blog is not about the new EN ISO 13849-1 and Performance Levels, etc.

   This blog is about other efforts being evaluated, created, and launched with the objective of “creating a more actionable outcome and enhance the ability to achieve a more predictable, sustainable and safe work environment. It also can help risk assessment teams realize that the result of a risk assessment is not necessarily a conclusion that the condition is safe, but rather an acceptance that the condition is safe enough.” This is the conclusion of an article in this month’s Professional Safety magazine written by John M. Piampiano and Steven M. Rizzo. My assessment of their article is that it enhances the existing qualitative risk management techniques illustrated by existing standards like ANSI B11.TR3 and ANSI/ASSE Z690.3 by combining severity and probability estimations for the severity of injury, more through definitions of each injury level, and a new Risk Matrix that looks eerily similar to a risk matrix in the new EN ISO 13849-1.

ASSE article and table enhances the existing qualitative risk management techniques illustrated by existing standards like ANSI B11.TR3 and ANSI/ASSE Z690.3 by combining severity and probability estimations for the severity of injury, with definitions of

   The writers take these concepts a step further in their model by introducing Administrative Controls versus Engineering Controls based on the different levels potential injury. They also help the SH&E professional understand that levels of residual risk will always result at this point and that individual company risk tolerance is the responsibility of company management. In my opinion, this clearly places the decisions for various levels of risk mitigation in the hands of company management. Ironically this approach seems to follow ANSI B11 – 2008, General Safety Requirements Common to ANSI B11 Machines. This standard clearly identifies that final risk level mitigation rests with company management because they make the decisions for risk tolerance, aka residual risk.

   Is this model “safe enough” and how does the result compare to the quantitative requirements of EN ISO 13849-1? Only you can answer this question.   

   Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: Machine Safety: How safe is safe enough?

www.asse.org

  Related articles:

How To Integrate Safety

Safe or Safe Enough by John M. Piampiano and Steven M. Rizzo, Professional Safety, Jan., 2012

EN ISO 13849-1, the quantitative approach to machine safety begins with a qualitative process!

Machinery Directive In 4 Days Drops EN 954 and EN ISO 13849-1 Is Fully In Force – What’s Your Impact?

31-Dec-2011 marks the start of mandatory implementation of ISO 13849-1. Are YOU Ready?

Contact: www.jbtitus.com for “Solutions for Machine Safety”.



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