Updated July 25, 2024
In today’s episode of the Dust Safety Science podcast, we are doing an incident update on the 2021 potato starch explosion in Tuas, Singapore. Earlier this year, the Ministry of Manpower released its investigation report on this incident, which occurred on February 24, 2021. This investigation took about a year to complete, from February of 2021 to January of 2022.
As we discuss both the potato starch explosion and the results of the investigation, we answer the following questions:
- What makes this incident so interesting?
- What was initially reported about the explosion?
- What happened afterward in Singapore?
- What were the results of the investigation report?
We’ll conclude with a summary of what all this information tells us about this explosion in Tuas, Singapore.
What Makes This Incident So Interesting?
Firstly, this is a case where there was a large-scale explosion that resulted in multiple fatalities and serious injuries. Authorities assumed it was caused by combustible dust involving potato starch, and conducted a number of activities involving combustible dust within Singapore to respond to this large-scale explosion – the exact opposite of what traditionally occurs with combustible dust.
An explosion usually occurs without dust being considered. Once it is determined that dust caused the problem, almost everyone is in disbelief. It was the exact opposite in this case. Initially, they assumed it was combustible dust, ran with it, and took a lot of proactive measures in Singapore to protect industries handling combustible dust and powders. As it turned out, it wasn’t a combustible dust incident, and we’ll talk about that a little bit in this episode.
What Was Initially Reported About The Explosion?
According to local news reports, a dust explosion occurred at a fire protection system manufacturer in Tuas, Singapore on February 24th, 2021. Potato starch was said to be involved. The Ministry of Manpower (the MOM) Occupational Safety and Health Division within Singapore did a preliminary investigation right at the time the explosion occurred and said that they believed it was a combustible dust explosion.
A logistics manager on-site in the next building said that he heard a large explosion, followed by two smaller ones. Employees were working on an industrial mixer inside the fire protection systems manufacturing facility at the time of the explosion. Tagically, three workers lost their lives in this incident. Seven more were injured and five of those were quite severe injuries from burns due to these explosions and flash fires.
This facility made fire-resistant wraps for ducting and piping. These wraps were made by making what they called “fire clay” – which was a mixture of potato starch and other raw materials. Then they poured the clay between plastic, aluminum and ceramic fibre sheets in different layers. They pressed these layers, rolled them, and got a final wrap material.
A heated mixer was used to create the fire clay, which was made by pouring potato starch and other raw ingredients into it by hand. The mixing chamber was heated by an oil-filled jacket. When heated, the oil acted as a thermal material, which heated the contents of the mixer as well.
When the explosion occurred, the mixer was elevated on a platform at the back of an assembly and manufacturing facility for fire wraps. It was a single room with up to ten operators or so. It also had an area for rolling and pressing wrap material. In the back of that room, on an elevated platform, they had this mixer that they used to mix potato starch with other ingredients to make fire clay.
In the aftermath of the explosion, the building sustained significant damage, with the back wall rupturing and the side walls damaged as well. It was reported that windows shattered up to 60 metres, or 180 feet, away in adjacent buildings. Unfortunately, this incident also caused fatalities and injuries due to the large-scale explosion.
What Happened Afterward in Singapore?
Seven days after the explosion incident, the Ministry of Manpower announced that almost 500 companies were being inspected for combustible dust hazards. By the 19th of March, three weeks after the explosion in Tuas, three companies were issued stop-work orders after they were found to have inadequate control measures despite significant risks of combustible dust explosions.
In April, a full month after the explosion, the Ministry of Manpower announced that 400 more work safety inspections would be conducted in May and June because during the initial 500 inspections, over 3200 workplace safety and health citations were found. Within three months after the incident, over 900 Singaporean sites were inspected for combustible dust.
Twelve weeks after the explosion, Enterprise Singapore launched SS6672020, the Code of Practice for Handling, Storage, and Processing of Combustible Dust. The following week, the National University of Singapore and the Health and Environmental Society held virtual workshops to discuss technical aspects of combustible dust, including the nature of combustible dust, awareness activities, process safety concerns, risk management approaches, and applicable local and international standards.
This outcome is truly remarkable. Within three months, a combined effort to tackle combustible dust challenges on a national scale took place, which is really inspiring.
What Were the Results of the Investigation Report?
This report was released on January 21st, about eleven months after the original incident. This is a pretty big feat in its own right. It has taken multiple years for some of these reports to be released. Having this one come out so quickly is really helpful for the community to understand and learn from this incident.
The report is quite lengthy. Among other things, they reviewed the history of the mixer, the challenges that came up during its purchase and installation, the use of incorrect heating fluids, and attempts to fix the many problems.
This mixer was purchased and installed in late 2019. As a closed system, it presented a number of problems. In order to keep pressure from building up inside the mixer, it was supposed to have a venting pipe on the back. There were a number of other issues that caused a bunch of problems – leaks, darkened heating oil, combustion thermal events – all in the years leading up to this incident.
There were several warning signs that the heating oil was unstable during operation. It was operating at a temperature that was too high. It was breaking down. After draining it out, it was black and discolored, the machine was smoking, and eventually, pressure built up inside the mixing jacket.
A report concluded that overpressure caused mechanical failure and fracture of welds in the jacket containing the oil, and that the jacket was designed to operate as an open system. When the welds failed, oil was forced out and aerosolized into an oil mist cloud which ignited due to the heat, causing a large explosion.
They reached this conclusion after analyzing the oil spray patterns on the building’s sides, the amount of oil, potato starch and damage that were on-site after the explosion, as well as the level of damage. They did note that there were secondary flash fires from dispersed potato starch but did not believe that they caused the majority of the damage, as the building envelope had already ruptured at this point and the injuries had already occurred due to this large-scale oil mist explosion that happened in the vicinity of the mixer.
Conclusion
The Tuas potato starch explosion demonstrates how global awareness and understanding of combustible dust explosions is improving. Multiple people lost their lives in this explosion incident, which was tragic. But at the end of the day, having this awareness really can drive change, and we hope that it will spread.
Resources mentioned
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Dust Safety Academy
Dust Safety Professionals
Dust Safety Share
Incidents
Explosion at Singapore Fire System Manufacturer Kills Three Workers
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