Risk Assessment in the Machine Safeguarding Process

June 9, 2011
Designers and users of powered equipment and machine tools historically have sought the best methods and controls for preventing injuries associated with use of their equipment.

Early efforts to prevent machine-related injuries were focused on the development of engineering specification standards. These specification standards laid the foundation for further requirements relative to training, maintenance and energy control, as these are the basics for machine safety.

As these basics became institutionalized, promulgators of safety standards came to appreciate the power of machine guarding risk assessments that take a performance approach – as opposed to a specification approach – to preventing accidents. The number of consensus standards that require or recommend machine guarding risk assessments continues to grow (see sidebar below).

While risk assessments are designed to anticipate and reduce hazards that can result in worker injuries, their systematic approaches also can produce many other tangible benefits, including:

  • Increased productivity
  • Improved quality
  • Cost reduction
  • Improved compliance
  • Reduced liabilities

Risk Assessment Methodologies

Formats of risk assessments can vary, but they generally have some common components:

Assessment preparation – Teams must ask some basic questions about the scope of the machine guarding risk assessment. Will all stationary equipment be assessed or will the assessment be limited by some objective or subjective criteria? Organizations may not be prepared for “all equipment.” A common objective limitation would be to focus on equipment that meets certain risk criteria based on incidents, operator input or hours of exposure. Other objective approaches can consider equipment value or perceived its life expectancy. Subjective limitations are at the discretion of the assessment team but often are based on perceived risk.

Basic decisions about team composition also are needed. An interdisciplinary approach is critical, as no single person can possess the necessary knowledge. Internal team members (both managerial and hourly employees) should come from operations, maintenance, engineering and safety. Probabilities for success are increased if the team includes a machine-guarding expert. This individual must be familiar with applicable standards and application of current machine-guarding technology. The “expert” often serves as the team facilitator and helps others realize what is possible. Experience in conducting machine-guarding assessments is a primary criterion in selecting this individual.

Consensus Standards Requiring Machine Guarding Risk Assessments

ANSI B11.0–2010 - Safety of Machinery; General Requirements and Risk Assessment

ANSI B11.TR3-2010 - Risk Assessment and Risk Reduction–A Guide to Estimate, Evaluate, and Reduce Risks Associated with Machine Tools

ANSI B11.19-2010 - Performance Criteria for Safeguarding

ANSI/PMMI B155.1-2006 – Safety Requirements for Packaging Machinery and Packaging-Related Converting Machinery

ANSI/RIA R15.06-1999 (R2009) - Safety Requirements for Industrial Robots and Robot Systems

ANSI/ASSE Z244.1-2003 (R2008) - Control of Hazardous Energy—Lockout/Tagout and Alternative Methods

ISO 12100-2010 – Safety of Machinery - General Principles for Design -- Risk Assessment and Risk Reduction

ISO 13849-1-2006 - Safety of Machinery -- Safety-Related Parts of Control Systems -Part 1: General Principles for Design

NFPA 79-2007 – Electrical Standard for Industrial Machines

Of course, logistics and timetables must also be considered. Machine guarding risk assessments need a sense of urgency to assure timely completion and execution.

Systematic identification of hazards – In order to maximize effectiveness, machine guarding risk assessments must be conducted in a disciplined, systematic fashion. Teams need to meet and jointly conduct reviews to gain common understandings of machine functions, operating procedures, maintenance regimes and practices (including energy control provisions), OEM requirements, history of accidents and near misses and applicable standards. Interviews with operating and maintenance personnel gather critical information to confirm operating and maintenance practices, start-up and shutdown procedures and unusual machine functions and associated practices.

Utilization of a tailored checklist or a recognized process hazard assessment tool helps team members identify risks. These logic-based tools help produce the other tangible benefits that were previously discussed. Nearly all methodologies quantify hazard levels by considering the probability of occurrence, severity of foreseeable incidents and extent of exposure to the hazard.

Risk reduction plan – The assessment has little meaning without documentation and execution of a risk reduction plan. The plan should have a summary of findings and a more detailed appendix that includes a machine-by-machine analysis (e.g., photos, final recommendations and resources needed).

Deployment of the risk reduction plan most strongly should be influenced by the hazard level identified. Other considerations can include ease of deployment, resource availability and cost. (Caution: Using cost as a priority determinant is not recommended and is subject to regulatory and legal challenge).

The most important thing to remember is that properly conducted risk assessments can be powerful tools to help avoid accidents while producing many other tangible benefits. Omron STI has a number of credentialed engineers with the requisite credentials to guide clients effectively complete these critical assessments.

About the author: John Peabody is the vice president of Major Accounts for Omron STI. John holds a bachelor of science degree, and has been with Omron STI for over 20 years, holding positions in Control Engineering, Applications, Business Development and Sales Management. John has been the guest speaker at several global and national safety conferences. John and his team have put a safety service model together to help large companies with machine safety training, machine safety assessments, and installation options of safeguards and devices in order to help companies meet their machine safeguarding goals.

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