Reducing risks for workers without making major changes

Worker safety is critical in any environment and sometimes it seems the changes required are significant, but that’s not always the case.

Machine safety insights

  • Risk assessment precedes machinery safety evaluations, requiring inventive solutions within standards and budget constraints to mitigate identified hazards effectively.
  • Innovative approaches, like implementing mechanical interlocks and training, can enhance worker safety and meet standards without costly control system replacements.

A risk assessment is the first step when evaluating machinery safety. Risk reduction measures are implemented to reduce risk when it’s determined that it is not acceptable. However, this is not always an easy task and can require some inventive thinking on everyone’s part. Not only does the solution have to be safer, but it also has to fall within the standards guidelines and the company’s willingness.

The default answer might be replacing a control system, but that’s not always needed, said Jenny Tuertscher, VP of technical safety for Fortress Safety in the presentation “Risk Reduction Is Not Always About Changing Your Control System” at Automate 2024 in Chicago.

She used an example of a concrete mixer that was more than 50 years old and had a simple control system. They needed to add a second set of blades that were easier to reach than the current set. Time was, the engineer could open the doors and spray the blades. These blades are reachable and, of course, very dangerous if in operation.

Tuertscher said in this case they had to conduct a risk assessment on new hazards created by the modification as per ANSI B11.0 – 2023 Safety of Machinery. In this assessment, they had to confirm the risks are at an acceptable level and conform the requirements in current applicable standards for new hazards for the modification.

Performing a risk assessment is one of the first steps needed when making changes to a machine.
Performing a risk assessment is one of the first steps needed when making changes to a machine. Courtesy: Chris Vavra, WTWH Media

The risk assessment is determined by the probability of something happening and the severity of harm. It was no surprise that, in this case, it was very likely something serious would happen.

The problem, Tuertscher said, is many of the immediate options aren’t practical because of the age of the machine and because eliminating the hazard or substituting it out aren’t going to work because it takes away the function and how the product is used.

Adding engineering controls weren’t going to work either because they rely on adding a complicated control system. As Tuertscher put it: “Do we want to add $300,000 worth of controls for a 50-year-old machine just to add some blades? Management won’t go for it.”

Not all was lost, though. Training and awareness and personal protective equipment (PPE) some level of safety for the worker. Guiding them through a repeatable and enforceable process can help reduce some of the worker hazards. She added PPE can never be used by itself and, like anything else, it is taught to people through training.

Creating a lockdown solution

The key to adding the blades was by creating a safe shutdown with mechanical interlocks and a trapped key system that keeps the machine off and cannot operate. That safety is enhanced with a key that opens the doors for the machine, which can’t operate until the bay doors are closed and the actuator is in place. Strict enforcement and training help keep things on the up and up and ensure the standards are being adhered to.

Tuertscher said they also used a proactive inhibit function (PIF) by helping ensure the worker is safe so they aren’t exposed to an unexpected start-up.

Adding a second set of blades to this 50-year-old concrete mixer required a lot of thought because many solutions either weren't practical or too expensive.
Adding a second set of blades to this 50-year-old concrete mixer required a lot of thought because many solutions either weren’t practical or too expensive. Courtesy: Chris Vavra, WTWH Media

“It’s critical they give the person with access exclusive control,” she said. “It’s about making that person responsible for themselves so they aren’t exposed to that hazard.”

The final cost for installing the blades was less than $1000, which is impressive considering it was a 50-year-old concrete mixer that needed a new set of blades.

“In some cases, risk reduction on machines can be accomplished without changing your machine control system,” she said. “Standards can help us find solutions without changing control systems and costing a lot of money.”

Chris Vavra, senior editor, Control Engineering, WTWH Media LLC, [email protected].

Written by

Chris Vavra

Chris Vavra is senior editor for WTWH Media LLC.