Understanding Safety Risk Assessments

Ensuring workplace safety is not just a best practice but a regulatory requirement. A fundamental procedure in ensuring the well-being of personnel working with automated systems, safety risk assessments span sectors such as healthcare, manufacturing, construction, and chemical handling. It is ultimately the responsibility of the facility owner to ensure the safety of the site, which includes conducting thorough safety risk assessments. This article serves as an introduction to the safety risk assessment process and includes an example from a recent assessment conducted by Patti Engineering.

By Patti Engineering Senior Robotics Engineer Dan Sula

What is a Safety Risk Assessment?

Safety risk assessments involve a systematic approach to workplace hazard identification, including the evaluation of each hazard’s level of personal injury risk and the identification of risk mitigation equipment and strategies. The assessment is a living document that requires regular updates to reflect changes in tasks, equipment, or personnel. These assessments are needed in order to meet OSHA’s General Duty Clause (Section 5(a)(1) of the OSH Act), requiring employers to provide a workplace free from recognized hazards that are likely to cause death or serious physical harm to employees. Likewise, the safety risk assessment is outlined in ANSI RIA standards including ANSI B11.0 (managing risks associated with machinery and manufacturing systems) and ANSI/RIA R15.06 (safety risk assessments for management of risks associated with integration of robotics systems).

In addition to regulatory compliance and ensuring the safety of personnel, safety risk assessments limit legal liability for manufacturers by demonstrating due diligence in addressing human safety concerns. Thus, they serve as both a preventive and protective measure.

When are Safety Risk Assessments Required?

A safety risk assessment is required under specific circumstances for all critical systems, specifically those systems whose failure or malfunction has the potential for serious consequences including risks to safety, substantial disruption of operations, and even environmental damage. Critical systems include all robotics, automation, mechanical machinery and associated components, chemical processing systems, as well as the electrical systems that provide the necessary power to all of those mentioned above and their associated safety functionality. According to regulatory and industry standards, a safety risk assessment is required in the following situations for these systems:

• Initial implementation of machinery or systems: New machinery or automated systems are introduced into a workplace.
• Modification of existing equipment: Existing machinery or systems are modified or upgraded.
• Changes in workplace processes: There are significant changes in how machinery or systems are used, including changes in operational processes or the introduction of new materials.
• After an incident: An accident or near-miss involving machinery or automated systems has occurred.

OSHA standards recommend performing periodic reviews to ensure ongoing compliance with safety standards and to address any new risks that may arise over time. This includes updating the living document as part of the assessment review.

Risk Mitigation Begins in the Project’s Design Phase

Safety mitigation must be considered from a project’s early design stages and throughout its implementation, as many risk mitigation strategies involve implementing equipment alongside operating equipment. 

The approaches to risk mitigation include:

• Designing out as many hazards as possible
• Reducing the ways in which a person can interact with the potential hazard
• Providing appropriate training and procedures for safe interaction
• Providing personal protective equipment

Experienced system integrators are familiar with the general risks surrounding automated equipment and the requirements for reducing those risks. Experienced system integrators will implicitly minimize hazards and design the necessary risk mitigation features into a proposed project.

Example

A portion of a recent safety risk assessment report completed by Patti Engineering is depicted in table 1 below. After designing and implementing a robotic cell for a client, Patti Engineering conducted the safety risk assessment for it. The example shown in table 1 is a portion of the safety report generated. 

Table 1: An example portion of a safety risk assessment report for a robotic cell. The project was recently completed by Patti Engineering and involved a cobot working at a conveyor, moving hot containers into a separate inspection station.

The assessment begins with task identification [Tasks], where all tasks involved in operating, maintaining, and interacting with the automated system are defined and documented. This includes activities performed by operators, maintenance personnel, and bystanders. In table 1, identified tasks include loading and unloading operations, and bystander/passersby interactions near the robotic cell. 

Next, hazard identification [Hazards] is done for each identified task. This step involves identifying all the hazardous ways an individual can interact with the system. In table 1, the potential dangers identified included being struck by machinery, stepping on broken glass, or contacting hot materials. 

During the risk assessment [R] phase, the severity, exposure, and avoidance of each identified hazard are evaluated using standardized criteria. In table 1, each hazard is rated with the severity of low (L), medium (M), or high (H). For risk mitigation, appropriate safeguards [Safeguards] and protective measures [Protective Measures] are identified. 

As seen in table 1, Patti Engineering addresses each hazard with a minimum of two safeguards and/or protective measures. Use of multiple approaches to risk mitigation is one way an employer can demonstrate due diligence in providing a safe work environment in compliance with the OSHA requirements mentioned above.

In this example, the safeguards that were applied include:

• Collaborative Robots (Cobots): Selected as part of the original project design due to their ability to work alongside humans, cobots feature built-in safety mechanisms such as force, speed, and power limiting functions, as well as collision detection. These safety features are appropriate to utilize as safeguards addressing the identified hazard of being struck by a robot.
• Light Curtains: These optoelectronic devices create an invisible barrier around hazardous areas. If the light beam is interrupted, the device sends a signal to stop the machines and/or robotics, thereby preventing accidents. In table 1, light curtains are introduced to prevent personnel from accidentally coming into contact with hot objects by stopping machinery if a person enters the hazardous area. This safety feature addresses the identified risk of burns or heat-related injury due to contact with hot materials.
• Safety-Rated Area Scanners: Area scanners use laser technology to create a 3D map of the surrounding area. They detect unexpected changes in the area (such as glass material falling from a conveyor) and then trigger safety stops accordingly. The area scanner mitigates each identified risk in table 1. 
• Safety PLCs: Safety PLCs manage inputs from various safety devices to ensure the system responds appropriately to potential hazards. The safety PLC mitigates each risk identified in table 1. 
• Protective Measures: Protective measures include routine floor cleaning, proper use of personal protective equipment (PPE), and following standard work procedures and training requirements. These protective measures mitigate each risk identified in table 1. 

Post-Assessment Steps

OSHA recommends conducting regular validation tests to ensure the effectiveness of all safety measures, and live documentation should be updated to reflect any changes. 

Patti Engineering has a history of designing in accordance with industry standards and safety requirements, with a goal of minimizing risk from the initial stages of design. Upon project completion, Patti Engineering conducts a comprehensive safety risk assessment for clients, identifying all remaining risks and associated approaches to their mitigation. The team is dedicated to ensuring both the safety of personnel and equipment while also minimizing operational interruptions and legal liabilities. For more information on the safety risk assessment process, contact Patti Engineering at info@pattieng.com.