A typical plant shutdown will occupy less than 5% of the working time, particularly in industries that demand continuous operation of their equipment. While this period of time may appear brief, plant shutdowns account for over seven out of every ten major accident that occurs during the performance of non-routine tasks, such as plant shutdown, startup or online maintenance.
This increased vulnerability for accidents to occur is a result of the disruption in the routine of a wide variety of factors, some of which include disrupted plant routine, performance of unfamiliar processes, the opening, and cleaning or emptying of equipment, the multiplication of both worker and vehicle, such as forklifts and trucks, movement within the plant at levels that significantly vary as compared to normal operating conditions.
For several decades, a Louisiana manufacturer of chemicals that had previously experienced the harmful effects of numerous plant shutdowns was recognized as a facility that has become particularly adept to addressing related safety concerns in the workplace.
The knowledge that this particular industry has gained led to their adoption of a high-class solution that is used for the detection and surveillance of explosive limits in one of the most accident-prone plant areas, such as entryways and exits as a result of the high movement of individuals and construction vehicles in these areas.
When this Louisiana plant was in the process of a shutdown, hundreds of vans, trucks, welding trucks, forklifts and contractor vehicles, were entering and exiting various areas of the site each day. In particular, the increased movement of these vehicles in hazardous areas that potentially contained inflammable gases or vapors increased the risk of exposing these areas with air, which behaves as an oxidizing reagent.
The mixture of the vapors or gases with air as they enter the engine cylinders create a readymade fuel source that increases the ratio of fuel to air within the engine. This fuel source has the potential to trigger an explosion by increasing the temperature of the engine or causing a spark to ignite.
To prevent this explosion from occurring, the hazardous area surrounding the plant in Louisiana was first demarcated and sealed off by a yellow gate that was used to log the traffic entry during the previous shutdown. Once any vehicle entered the gate, it was confined to a zone that was subject to continuous lower explosive limit (LEL) monitoring. The firm in charge of monitoring safety for the company oversaw this process and determined which option would work best to accomplish accurate LEL detection in this situation.
During this type of situation, one option that could be used is a fire watch safety employee that would use a portable LEL monitor. The use of this tool could be used by the employee to meet each vehicle entering through the gate within the plant and then back out through the yellow gate. However, note that in this particular situation this option would not be feasible since hundreds of vehicles were involved.
After careful consideration the safety provider for the Louisiana company suggested the use of continuous area monitors, and in particular the Radius® BZ1 Area Monitor offered by Industrial Scientific, which was fitted with LENTM Wireless technology. Since the safety team was already familiar with how these devices operated as a result of their previous use from another client, the safety officers felt that the battery life on these devices would be particularly useful for this specific industry.
Each Radius® BZ1 Area monitor is capable of running for seven to eight days on a single charge, thereby allowing the Louisiana company to continuously run each device during this time period. This length in battery life was particularly useful in eliminating the need to deploy ten additional workers to recharge monitors during each shift of each day.
By utilizing a total of 171 Radius monitors, 146 of which were set up in a network over the 60 days or so that it took to shut down the plant, the Louisiana company successfully avoided the need for daily bump testing since each monitor needed to be bump tested only when its battery ran out and it was rotated out for recharging.
“What immediately drove us to choose the Radius was the battery life. We knew that we would be able to let every monitor run for 7 or 8 days instead of having to send out 10 people per shift per day to change out batteries, as was the case with another manufacturer’s instruments that we used in the past.”
In addition to the usefulness of these monitors on their own, the implementation of the Lens wireless technology ensured that each monitor within the network was able to automatically send and receive information from all other devices. This autonomous behavior allowed for any potentially dangerous LEL reading or gas detection alarm detected by one monitor to be instantly received by all the others.
By alerting other users of the type of alarm and its specific location, vehicle drivers are provided with prompt identification of the hazard zone to allow for them to immediately respond to the alarm, shut off their vehicles and leave the area.
The arrangement of the monitors within the Louisiana plant was as follows: groups of 18 to 20 devices were placed at strategic points along the corridors that vehicles passed through. More specifically, the monitors were placed on top of aluminum pedestals that were located approximately two feet above the ground, thereby ensuring that the monitors could withstand the rugged environment, including drenching rains and constant dust clouds.
Additionally, 25 of the total of 171 monitors were always kept fully charged and in reserve in the event that they would be utilized to immediately switch into the network as needed. In the event that one group of 20 monitors was running low on their battery life, their central processing units known as SafeCore® Modules were withdrawn from the base of each unit and replaced with the charged reserve modules.
Finally, 20 DSXi Docking Stations that only needed to be unboxed to be fit for work were used to recharge and bump test the exhausted SafeCore Modules. These docking stations were then kept in a ready to rotate location back into the network when the next group of units needed to be recharged. This cycle provided the plant vehicle corridors with continuous surveillance throughout the 60 days of the project.
Twenty-five instruments were kept on reserve, fully charged, and rotated in as needed. This continuous rotation allowed for uninterrupted monitoring for the 60-day duration of the project.
The safety provider estimated that, as compared to employing a fire safety watch staff, the total cost of using Radius monitors significantly reduced the financial costs of the Louisiana company by over 50%, as well as significantly reduced the number of work permits that were required for this evaluation process. Out of the 171 monitors that were used in this specific situation, only two presented any working issues, thereby resulting in an impeccable performance rate of 99%.
It is also important to note that the Louisiana company managers were extremely impressed with the efficacy of these monitors, as they provided Industrial Scientific with a positive quality notice to the safety provider that also expressed their appreciation of the efficacious Radius monitors.
Following the implementation of these monitors, the Louisiana chemical manufacturing plant has continued to utilize the Radius BZI Area Monitors for eight to ten newly added projects, on a smaller scale, making it their go-to area monitor in such situations.
References and Further Reading
- William Bridges, Process Improvement Institute, Global Congress on Process Safety, 2016; Necessity of Performing Hazard Evaluations (PHAs) of Non-Normal Modes of Operation (Startup, Shutdown, & Online Maintenance).
This information has been sourced, reviewed and adapted from materials provided by Industrial Scientific.
For more information on this source, please visit Industrial Scientific.