Written by: Roger Stokes, Principal Engineer, Process Safety
In general, operators are familiar with shutting down and restarting their processes; either following unscheduled trips, brief planned shutdowns for essential repairs, or restart following a major turnaround. It is widely recognized and generally accepted that start-up and shutdown of processes are associated with higher risks that must be carefully managed. However, an unplanned shutdown that sends workers home in response to a government lock-down intended to help control a worldwide pandemic is an unusual situation that presents unique risks. For example: the period of the shutdown is unknown from the start; the planning time for the shutdown may be shorter; the execution of the shutdown may be time-constrained. Additionally, the availability of personnel may be less than ideal for both shutdown and restart, or other unique situations may also arise.
A tragic gas leak occurred in India on Thursday 7 May. Although various media reports suggested that operators had been restarting a process following the coronavirus lockdown, it is unfair to speculate this soon as to the actual cause of the incident. Whether or not there is a direct connection between the incident, the shutdown/ restart, and the pandemic, as more companies start to emerge from pandemic related shut-down, unique situations associated with this restart should be carefully evaluated to manage associated risks. Some of the issues and considerations that should be reviewed when planning to restart processes coming out of the coronavirus lockdown are presented in this article.
The city of Visakhapatnam is in the south-eastern region of India with a population of some 4 million people. LG Polymers India Pvt Ltd has a manufacturing site located about 8 km to the north of the city and just north of the main railway line. The main tank farm, where the incident occurred, is located to the south of the site and about 200m to the west is the village of RR Venkatapuram.
It is understood that at about 0300 hrs on Thursday, 7 May, styrene monomer vapour was emitted from one of LG Polymers’ two styrene storage tanks, which subsequently engulfed the RR Venkatapuram village and four other villages in the surrounding area. At its largest, the vapor cloud dispersed approximately 2 km downwind from the storage tank. As of 11 May 2020, 12 persons were reported to have died as a result of the incident, approximately 400 were hospitalised and over 5,000 people were evacuated.1,2
Styrene monomer is a raw material used for the manufacture of plastics. Exothermic polymerisation of styrene in storage is a known hazard, as a runaway reaction can occur once the temperature exceeds about 65 °C, which leads to vaporisation and release of styrene gas from the storage tank vents/ relief devices. Normally, an inhibitor such as 4-tert-Butylcatechol (TBC) is added as a stabilizer and polymerisation inhibitor, but it is important to monitor the TBC concentration as the level can decrease with time. In addition, the inhibitor also becomes less effective if the concentration of oxygen is low. Finally, polymerisation can also be triggered by contamination or where the material is stagnant.3
At this point in time, the actual timeline of events leading to the eventual release of the styrene monomer gas cloud is unknown. Regardless of the cause of the incident, there is speculation that the impact of the coronavirus lockdown on the start-up process may have contributed to this event as well as other potential complications at other international facilities.
Unplanned Outages Due to Pandemics
The circumstances of a process shutdown and restart due to the impacts of a world-wide pandemic virus have not been encountered on such a scale before; while localised outbreaks of a virus have occurred, the world hasn’t seen an impact on populations to this extent since the 1918 Spanish flu pandemic almost a century ago. Companies that operate hazardous processes have usually identified the risks that are specific to shutdowns and associated restarts and generally have procedures and checklists for short-term shutdowns, emergency shutdowns due to operational issues, or long-term shutdowns that address and control the risks for these circumstances.
However, a shutdown due to a worldwide pandemic may be associated with unique factors including a lack of time for planning; unknown duration of outage; process inventory control (e.g., hold-up of work in progress); supply chain factors for items such as additives and spares, etc. As a result, the process may undergo conditions and operations that are outside the normal operating/ shutdown regime (e.g., temperatures, pressures, flows, levels, concentrations, contamination, holding time, etc.). Furthermore, mechanical inspections and trip testing may have been delayed. Further complications exist around human performance issues such as stress and fatigue, new procedures on social distancing, PPE requirements, decreased numbers of staff and operating personnel, and staff remaining may not be competent to conduct certain activities. Furthermore, morale may be low and pressure to restart may be high, potentially leading to dangerous decisions being made.
Process Safety Management Considerations for Shutdowns Due to Pandemics
Various legislators4,5 have issued guidance focussed on work protocols to control and mitigate the risk of transmitting the virus among workers and between workers and the public. However, guidance specific to the issues associated with the pandemic and hazardous processes are only just starting to appear.
Management of the risks typically associated with hazardous processes fall under various legislation, guidance and recommended practices. In the US, OSHA’s standard for Process Safety Management of Highly Hazardous Chemicals, 29 CFR 1910.119, applies to specific processes above threshold inventories and the Center for Chemical Process Safety (CCPS) has published Guidelines for Risk Based Process Safety. 6 The Energy Institute has developed their High Level Framework For Process Safety Management.7 While many operators have adopted elements of the PSM systems documented in these guides applicable to the circumstances of shutdown/ restart of hazardous processes, the unique situations specific to the current pandemic-influenced shutdown and start up may not have been considered.
CCPS has produced a Process Safety guide entitled Risk Based Process Safety During Disruptive Times8 that provides Insights For Managing Process Safety During And Following The Covid-19 Pandemic And Similar Crises. This document is recommended to be used as a reference as it highlights the various elements of their Risk Based Process Safety (RBPS) Management System that may need to be considered.
Following the Visakhapatnam incident, the National Disaster Management Authority (NDMA) of India issued an order to all state chief secretaries 9 that includes the statement:
“While restarting the unit, consider the first week as the trial or test run period; ensure all safety protocols; and not try to achieve high production targets.”
The order requires Disaster Management Plans to be up-to-date and that Standard Operating Procedures are in place to restart during and after COVID 19 lock-down. It includes specific guidance, detailed in the Appendix, that repeatedly emphasises the importance of checking, inspecting and monitoring critical and potentially hazardous equipment, (rotating equipment, boilers, etc.) during start-up. The publication of this document supports the public speculation that COVID-19 impacted the start-up procedure in normally unforeseen ways. Several PSM elements require special consideration after an extended outage, such as one associated with a pandemic. Some companies periodically arrange for an external audit of their PSM systems using a fresh pair of eyes, and this may be a good time to conduct such an exercise, focussing on key PSM systems as summarized below.
Management of Change (MOC), including Management of Operational Change (MOOC)
The management of change system must be used for situations where process conditions, or operating regimes, move outside the norm. This may involve a systematic review of the hazards and risks associated with the operational change that could lead, for example, to increased physical checks on potentially hazardous equipment and storages. The risks associated with changes in manning levels, changes in PPE requirements, and skills and competencies of the workers and management require assessment. Minimum manning levels while ensuring protection from the virus along with stress and fatigue must also be considered.
Operational Readiness/ Pre-start-up Safety Review (PSSR)
Extra inspections and tests may be necessary before restarting the processes. This may include checking storage facilities, chemical analysis to check the condition of raw materials, intermediates, catalysts and additives, leak tests of rotating equipment, piping and machinery, testing of safety critical devices (such as shutdown and relief systems), nitrogen purging and/ or cleaning of piping and other equipment, etc. Restarts should not be rushed and production rates should be built-up slowly, if possible; do not rush to reach immediate full production.
Competency, Conduct of Operations
Where there are changes in personnel as a result of the pandemic, check whether the staff and management have the necessary competencies to safely operate the process. Existing procedures and start-up checklists must be followed including any new protocols that may arise from any MOC / MOOC studies.
Inspection, Asset Integrity
Scheduled inspections may have been delayed due to the shutdown. It is necessary to ensure that inspections are always up to date and the risks associated with any delayed schedules maintenance are properly managed. Additional inspections may be required due to changes in temperature, pressure, composition etc. during the outage.
Leadership and Process Safety Culture
Leadership and communication are critical at such a time as it is key to have an informed, involved, trusting and motivated workforce that maintains or even improves its process safety culture. A “We are all in this together, let’s think about this” approach is more likely to result in a positive outcome than management pressurising the workforce to get back into production as quickly as possible. A focus on safety starts at the top, which becomes especially important in times of unprecedented stress and anxiety.
Although details as to the actual cause(s) of the Visakhapatnam incident are not yet available, it seems likely there was some connection with the coronavirus shutdown/ restart. Hopefully the immediate and root causes, and in particular the lessons learned will be shared widely in due course.
Either way, this incident reminds us that Process Safety Management systems provide us with the framework and the tools that allow us to identify the situation, evaluate the potential risks and develop the solutions to ensure that risk is properly controlled even when we face unplanned situations like the pandemic. It is important to maintain a sense of vulnerability during such times and to stop, check, inspect, test and increase monitoring of activities to manage the associated hazards and risks. Having a second-party or third-party participant in the PSSR and a review of other key elements of the PSM system, with an unbiased view, may be highly beneficial to ask the right questions ensure the proper amount of rigor is undertaken under the current pandemic.
Appendix –Guidelines for specific industrial processes issued on May 9, 2020 by NDMA, India to Chief Secretaries of States following Visakhapatnam incident
- Storage of Raw Material
- Inspect the storage facilities for any signs of spills, wear and tear during the lockdown.
- Check for already opened storage vessels/containers/bags/silos for possible oxidation/ chemical reaction/ rusting/ rotting etc.
- HAZMAT Chemicals in the storage need to be checked for chemical stability before using for any processes.
- Ensure ventilation and proper lighting before entering the storage areas.
- Sense for abnormalities like strange sounds or smell, exposed wires, leaks and smoke.
- Check supply pipelines/valves/conveyor belts for any signs of damage/wear & tear.
- Check the storage building for any signs of distress and damage to the roof.
- Manufacturing Processes
- Carry out a complete Safety Audit of the entire unit before taking up starting activities.
- Cleaning of pipelines, equipment and discharge lines: Mechanical cleaning followed by air /water flushing and chemical cleaning based on the type of the process equipment.
- Run-in of rotatory equipment under supervision.
- Boilers/ furnaces/ heat exchangers to be checked for lining and signs of wear and tear.
- Check supply pipelines/valves/conveyor belts for any residual material and wear and tear. Also check all the pipelines / valves for obstructions/ pressure levels.
- Ensure all pressure, temperature gauges are functional.
- Tightness test: Many process units handle combustibles or toxic substances (or both), the leakage of which could result in disaster, damage, or economic loss. To prevent the occurrence of such incidents, it is necessary to confirm that the plant complies with the required tightness before start-up.
- Service test need to be performed for all water, compressed air, and steam piping and equipment with normal operating fluids. The system is first pressurized with operating fluids and then checked for leakage. For air lines, leaks can be found using soap solution. For water and condensate lines, the leakage can be observed visually. Leakage points found during the test are retightened. The test is deemed successful if no foam is observed from soap solution, or if no water or condensate is observed visually.
- Vacuum hold test: All vacuum systems must be leak tested. Air inside the system is first evacuated to attain the required vacuum. The best way is to start at one end of the section and work through to the other end, checking flanges, valves, fittings, instruments, and other equipment. Each leak is tagged, making it easy for the maintenance team and personnel of the next shift to continue with the work.
- Trial testing be carried out before the full-fledged production is initiated with full human resources.
- Ensure the arrangement for round-the-clock emergency crews/ professional technical teams provided with MAH and cluster of MAH should have an extended coverage of 200 km to reach transport accident spots for help.
- Storage of Products
- Check the storage facilities / silos for any damage or wear and tear.
 The Hindu, Visakhapatnam gas leak claims 11 lives; over 350 hospitalised, Updated May 08, 2020. Online: https://www.thehindu.com/news/cities/Visakhapatnam/visakhapatnam-chemical-plant-gas-leak-claims-several-lives-scores-hospitalised/article31523456.ece
 The Hindu, Visakhapatnam gas leak, Updated May 11, 2020. Online: https://www.thehindu.com/news/national/andhra-pradesh/visakhapatnam-gas-leak-iaf-airlifts-83-tonnes-of-chemicals/article31558703.ece
 CPChem, Safe Handling and Storage of Styrene Monomer. Online: http://www.cpchem.com/bl/aromatics/en-us/Documents/Safe_Handling_and_Storage_of_Styrene_Monomer.pdf
 OSHA, COVID-19. Online: https://www.osha.gov/SLTC/covid-19/
 UK Government, Advice for employers on social distancing during coronavirus (COVID-19).Online: https://www.gov.uk/guidance/social-distancing-in-the-workplace-during-coronavirus-covid-19-sector-guidance
 CCPS, Guidelines for Risk Based Process Safety, Center for Chemical Process Safety, 2007. Online: https://www.aiche.org/ccps/resources/publications/books/guidelines-risk-based-process-safety
 Energy Institute, High Level Framework For Process Safety Management, December 2010. Online: https://publishing.energyinst.org/topics/process-safety/leadership/high-level-framework-for-process-safety-management
 CCPS, RBPS during COVID-19 and Similar Disruptive Times, Center for Chemical Process Safety, 2020. Online: https://www.aiche.org/sites/default/files/html/544906/RBPS-during-COVID-19-and-Similar-Disruptive-times.html
 NDMA, Guidelines for restarting manufacturing industries after lockdown, National Disaster Management Authority, India, May 9, 2020.