The Dangers of Simultaneous Operations

The Dangers of Simultaneous Operations


Simultaneous operations, or SIMOPs, can introduce unexpected danger and risk to a facility. The danger happens when activities conflict with one another, increasing the risk of either operation or introducing new risks to one or more operations. In a facility, a SIMOP is when two or more operations take place at the same time and location.

Currently, industry guidance and regulation on SIMOPs is lacking. OSHA regulations only address SIMOPs in the context of confined space entry. Yet, employers MUST provide their employees with a workplace that does not have serious hazards (U.S. Department of Labor). We believe that by taking proper steps to reduce the hazards of simultaneous operations, facilities can avoid the dangers of serious human injury or fatality, business interruption, and/or equipment damage.

Safety Issues of SIMOPs

In general when considering SIMOPs, the more hazardous a task is when performed by itself, the greater attention needs to be paid. Below are some specific examples of hazards to be mindful of when simultaneous operations occur.

Hot work – This activity is defined by OSHA as burning, welding, cutting, brazing, soldering, grinding, using fire- or spark-producing tools, or other work that produces a source of ignition. Hot work can provide an ignition source for any release that occurs as a result of other activities in the area. The outcome of an explosion or fire caused due to hot work can be made worse by the presence of additional workers performing unrelated tasks nearby.

Confined Space Entry – The hazards associated with confined spaces can intensify the consequences of incidents that occur due to SIMOPs.

Hazardous Energy – OSHA defines electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or machinery and equipment as sources of hazardous energy. Any maintenance task performed on equipment containing hazardous energy at the same time that another group of workers is performing potentially hazardous tasks may result in workers being present who are unaware of the potential hazards or who are not equipped to deal with them.

Facility Startup / Shutdown – A facility startup and shutdown are often the most vulnerable times for a facility as these processes are a deviation from routine operations. During this time, SIMOPs can expose personnel needlessly to danger. Plant turnarounds require careful planning and scheduling of all activities, including SIMOPs, to avoid incidents.

Lessons from History

Learn important safety lessons from two incidents where poor SIMOPs was among the root causes found by investigators.

Chemical Release at Polysilicon Manufacturer

On November 13, 2020, seven workers were exposed to hydrochloric acid (HCI) after an incident at a polysilicon manufacturing facility in Charleston, Tennessee. The release occurred while a crew of contractors were tightening the bolts on a heat exchanger. At the same time, a separate crew of contractors was installing insulation on the same elevated platform, a task unrelated to the maintenance of the heat exchanger.

Figure 1 - Location of Contractors and Release (Credit:
Figure 1 - Location of Contractors and Release

The workers performing the maintenance on the heat exchanger had over-torqued a bolt, causing a loss of containment and release of HCI. That crew was properly equipped with acid-resistant PPE and respirators and were able to escape down the nearby staircase. However, the contractors installing insulation lacked adequate protection as they were only equipped with standard flame-resistant PPE and no respirators. When they tried to escape, the contractors were unable to reach the staircase through the toxic vapor cloud. As a result, three workers were seriously injured and one died.

The contractors installing insulation had not yet arrived on the fifth-floor platform when the permit authorizer performed his morning inspection walkthrough for heat exchanger hot work operations. Consequently, at the time he did not realize there was the possibility of a hazardous interaction. The facility was also experiencing some chaos in its permission posting system. The incident occurred during the COVID-19 epidemic when foot traffic had to be reduced in the control room. Instead of work permits being posted in just one place per usual, they were posted in a couple of different locations.

The U.S. Chemical Safety and Hazard Investigation Board (CSB) investigation determined that the company’s work permitting process “did not have a policy or procedure for evaluating SIMOPs, a situation in which two or more operations occur together at a time and place” (CSB, June 2023). By developing and implementing a formalized Simultaneous Operations (SIMOPs) program, the risk of death or injury could have been avoided.

Fatal Fire at Paper Packaging Mill

On September 21, 2020, two workers were fatally injured in a fire at a paper packaging mill in Canton, North Carolina. Two groups of contractors were performing maintenance work at the same time in a vessel connected by a crossover line, a confined space. One team was performing abrasive blasting on the walls in the downflow tower. Another team was attempting to apply epoxy vinyl ester resin and sheets of fiberglass to repair the upflow tower.

To combat the challenge of frigid temperatures affecting the fiberglass-reinforced plastic (FRP) coating process, the contractors in the upflow tower decided to use a heat gun to warm up the coating material. When the heat gun accidentally landed in a pail of combustible FRP, it started a fire that quickly spread to the tower's exterior walls. The contractors who were employed in the upflow tower managed to escape the blaze. Unfortunately, the fire spread through the crossover line into the downflow tower, killing two of the contractors performing work there.

Figure 2 - Diagram of the vessel (Credit:
Figure 2 - Diagram of the vessel

The U.S. Chemical Safety and Hazard Investigation Board (CSB) investigation noted multiple factors contributed to this incident. Not recognizing the flammable material hazards of the heat gun was one major deficiency in hot work safety, endangering the workers’ lives. “The Blastco crew did not have a fire extinguisher immediately available, and Evergreen did not require Blastco to have one available” (CSB, September 2021). Another major deficiency was that the towers were identified as two separate vessels, which compromised confined space safety, even though the upflow tower and downflow tower were connected. A lack of pre-job planning led to the companies not taking into account the cold temperatures, creating an unsafe situation for the contractors installing the fiberglass-reinforced plastic (FRP) coating. The construction material of the upflow tower and crossover line also contributed to the severity of the incident, as it was a combustible material that enabled the fire to spread quickly.

Following the incident, the CSB urged the Center of Chemical Process Safety (CCPS) to develop more detailed regulatory guidance on SIMOPs.

Advantages of SIMOPs Programs

Facilities can minimize loss of life, environmental impact, equipment damage, citations, and litigation by putting into place a quality SIMOPs program. Some of the advantages include (amongst others) making sure there is:

  • Coordination between parties performing work close together in one time and place.
  • Analysis of the risk of performing simultaneous facility maintenance prior to execution.
  • Completion of a hazards review process wherever planned work occurs close together.

Optimize Your SIMOPs Program

Safe work permits are designed to ensure safety for the task required. However, a program solely relying on individuals to execute the permit requirements and maintain the documentation can be prone to human error.

Our Safe Work Permit Workflow improves process safety oversight as well as employee and contractor safety. It gathers all relevant information from stakeholders consistently, and approval is not issued until all requirements are met step by step. You can easily assign tasks and notify users via email. The workflow securely enables access to all information related to the task and keeps it properly documented and recorded. Realize cost and safety benefits across all your facilities with the Process Safety Enterprise® platform.

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Safe Work Permit Workflow Demo

We Can Help

You can count on ioMosaic for guidance that not only satisfies regulatory requirements but delivers peace of mind to you. To find out how we can optimize your process safety, please contact us at 1.844.ioMosaic or send us a note via our online form. We would love to hear from you.