Building site

Using A Permit To Work System To Manage SIMOPS Hazards

SIMOPS stands for Simultaneous Operations, describing the situation when two or more potentially conflicting activities are taking place simultaneously in the same vicinity. The increasing complexity of modern industrial sites makes it increasingly likely that SIMOPS will occur, and the impact of an unmanaged SIMOP could be catastrophic as the interaction between activities is likely to increase the complexity of operations and also lead to a higher risk level.

SIMOPS Hazards And Controls

There are some unique hazards associated with SIMOPS:

  • Increased risk of accidents: When multiple activities are happening in the same area simultaneously, there’s a risk of errors, miscommunication, and unforeseen interactions between the activities. This can lead to injuries to personnel and/or damage to equipment.
  • Safety violations: The complexity of managing multiple activities can lead to a breakdown in safety protocols. Workers may feel pressured to skip safety steps or take shortcuts. For example, workers operating near each other may have to configure equipment in a non-standard way to accommodate space restrictions, resulting in increased risk.
  • Reduced situational awareness: With multiple activities happening at once, it can be difficult for workers to be focused on their own tasks while being aware of the risks posed by other teams working nearby.

Controls For Mitigating SIMOPS Hazards:

  • Planning and risk assessment: Although not unique to SIMOPS a thorough risk assessment should be conducted before any SIMOPS activity. This assessment should identify potential hazards, evaluate their severity, and recommend control measures. Of course, planning should also allow activities to be rescheduled to remove the risks associated with SIMOPS.
  • Work permits: A permit system can be used to ensure that all relevant parties are aware of the planned SIMOPS activities and the associated risks. A permit board or layout diagram should be configured to display all planned jobs for each area so that conflicts between tasks in the same vicinity can be identified and resolved prior to work starting. Remember that tasks may be ‘vertically adjacent’ e.g. an activity involving working at height on the ground floor may affect tasks being performed on the floors above!
  • Communication: Although again not unique to SIMOPS effective communication between all involved teams is essential. This includes pre-job briefings, clear communication channels during the activity, and debriefings afterwards.
  • Isolation and separation: When possible, physically separate the different SIMOPS activities. This can involve using barriers, establishing buffer zones, or scheduling activities at different times. All equipment to be worked on should be safely isolated from energy sources – a good permit management system should have a module to allow details of isolations to be centrally stored and made available to all relevant parties.

SIMOPS Example

In 2022 one fatality and three serious injuries resulted from a hydrogen chloride discharge at Wacker Polysilicon facility in Charleston, Tennessee.

A heat exchanger outlet pipe containing hydrogen chloride was accidentally cracked due to over tightening of fasteners, resulting in an uncontrolled release which impacted workers engaged in another task nearby. No coordination had taken place between the two tasks and therefore no controls had been put in place to mitigate potential issues. While the workers involved in the fastener tightening wore full protective suits the workers on the other task wore only flame retardant suits which did not protect them from the release.

Recommendations made after the incident by the U.S Chemical Safety and Hazard Investigation Board (CSB) included measures to identify SIMOPS, spot potentially dangerous interactions and to coordinate activities to mitigate risks.

The Role Of A Permit To Work System In SIMOPS

Normally, all activities likely to result in SIMOPS will also be covered by a permit to work. The permit should as a matter of course contain detailed information about the location and type of activity to be performed as well as the time window within which it is likely to occur.

SIMOPS can be detected by looking at the location and time window relating to each permit. A traditional permit board uses cards containing information on each permit – although the information required to identify SIMOPS is technically available to a paper-based system it is unlikely to be effective as it requires a proactive effort by those involved in permit issue to manually search for other permits which may cause SIMOPS issues

SIMOPS Procedure On Multi-Level Sites

One particular scenario with added complexity is where activities may happen on different levels, for example in a multi-floor building or an offshore vessel with multiple decks. This introduces an additional dimension since many activities (e.g. welding) can affect spaces all around them. The increased use of isolations and LOTO (lock-out tag-out) also means that the likelihood of adjacent areas being affected is increased.

A competent Electronic Permit to work system will include a detailed layout of the work area with all permit activity indicated. New permits will be checked against existing permits and any potential SIMOPS will be flagged, allowing appropriate measures to be taken (e.g. delaying a job until a conflict has cleared). The layout should be detailed enough to provide a good reference for staff, and permit information should be presented in a highly visible way.

Plot Plans and their role in SIMOP management

Traditional PTW systems use permit boards to display information on all permits in force. However, since the permit boards are often manually updated they can often be out of date. It is also often difficult for the information on the board to be visible to both those managing permits and performing tasks, particularly where SIMOPS could cause an issue. 

Having a clear picture of all activities in a worksite helps everyone – as long as this information is presented in a way that is easy to interpret and which does not cause confusion. Layout diagrams (or ‘Plot Plans’) can be produced using existing CAD drawings and easily updated. 

There are several factors which affect the complexity of SIMOP management in a permit to work system.  Complex worksites with a large number of areas can make identifying SIMOPS more difficult, especially if it is difficult to visualise the areas (e.g. rooms in a large office building may all be of similar sizes and have no particular unique characteristics other than location). 

Ideally, activities likely to be in close proximity should be automatically highlighted so that they can be easily identified. Multi-level sites can also introduce complexity however a capable PTW system should provide the facility to access multiple plot plans covering all levels easily, with automatic identification of activities which may affect jobs on other levels (for example hot work on a ceiling area may affect the level directly above).

Scroll to top