Tuas explosion: Workers reported ‘red flags’ like fires, oil leaks and smoke at machine before fatal incident

SINGAPORE: An explosion in a Tuas industrial building on Feb 24 this year killed three people, but even before that, workers had reported fires, oil leaks and smoke at a machine where the incident happened.

The details of the issues that plagued the machine came to light on the first day of the inquiry committee hearings into the explosion at the workshop of Stars Engrg, a fire protection contractor.

State Counsel Kristy Tan referred to them as "red flags" in her opening statement.

The mixer machine was bought on online platform Alibaba in 2019 and first used at the workshop in June 2020. It was used to manufacture a component used in the making of a fire insulation wrap, “sometimes” needed in connection with the firm’s fire protection systems, according to court documents. The firm provided design-built fire protection systems such as sprinklers, risers and fire alarm systems.

The machine, which worked by heating oil held in an oil jacket, would “cook” ingredients such as water and potato starch flour to make the component called fire clay. It was operated on a raised platform.

THE BEGINNING OF THE ISSUES

As early as about two months after the machine was put into operation, workers started reporting issues. It had been used at least three times before that, the court heard.

On Aug 7, one of the workers reported that the oil in the machine was running low to owner and overall-in-charge of production at the Tuas site, Mr Chua Xing Da. 

The next morning, when the same worker, Mr Imam, was making a batch of fire clay, a spark and smoke came out from one of the heaters in the machine. The heater was replaced and the machine was used again the same day. More oil was bought and added to the machine, but the court heard that the amount was not sufficient to fill up the oil jacket that needed to be filled.

Later in the month, Mr Imam saw smoke coming out from the location of the heaters in the machine. With the help of a colleague, he drained the oil from the oil jacket to check the heaters.

The drained oil was black and contained black sediments, according to court documents. The court heard that the gaskets on the heater openings of the oil jacket had deteriorated. The drained oil excluding the sediments was poured back into the oil jacket.

The issues did not end there. Over the next few months, smoke continued to be seen at the machine near the heaters, oil was leaking from the oil jacket, and the machine caught fire twice - once on the same day of the fatal explosion.

SMOKE, OIL LEAK

On Sep 21, Mr Imam noticed smoke or oil vapour coming out from the bottom of the oil jacket near the heaters and notified his superior, Mr Lwin Moe Tun, an engineer overseeing production at the Tuas site.

A week later, Imam and his colleague noticed a leak in the front bottom left corner of the oil jacket when the machine was operated and again informed Mr Lwin Moe Tun. Mr Chua was also informed of this leak.

Mr Imam had said that the leak should be closed by welding. But that was not done until around mid-October, when the leak appeared larger than before, and was again reported.

In January this year, the smoke issue first reported in August 2020 was brought up again. Mr Lwin Moe Tun informed Mr Chua that that he saw smoke coming out from the bottom corners of the oil jacket when the heaters were turned on. The same thing would happen in the last 10 minutes of the operation of the heaters whenever the machine was used to make fire clay after that.

FIRE AT THE MACHINE

On Feb 12, a fire broke out at the front bottom right corner of the mixer machine. Workers managed to put out the fire. A senior employee went down to manage the situation, the court heard. Mr Chua gave instructions to another worker to weld the four bottom corners of the oil jacket, and to weld an additional base plate to the underside of the oil jacket.

During welding operations the next day, two workers observed a hairline crack on each of the two front bottom corners of the oil jacket and reported this to Mr Chua. The welding work was completed on Feb 16.

On Feb 24, the day of the fatal explosion, eight workers were at the workshop. Mr Imam was not present at the time.

At about 8.40am, a “small fire” broke out at the machine near the heaters, the court heard. A worker put it out with a fire extinguisher.

For more than two hours following the incident, Mr Marimuthu, a supervisor at the Tuas site who started work there about a month before, discussed the incident with Mr Lwin Moe Tun and Mr Chua. In these discussions, Mr Marimuthu said that one of the heaters had caught fire, the court heard.

At about 11.15am, Mr Marimuthu took a photo showing the damaged heater bolted into the oil jacket, with green tape around its wiring. He sent the photo to Mr Lwin Moe Tun, who acknowledged it. The explosion happened about five minutes later, followed by flash fires.

The court heard that Mr Moe deleted the photo both from his and Mr Marimuthu’s phones after the explosion.

THE AFTERMATH

Mr Marimuthu, 38, Mr Shohel Md, 23, and Mr Anisuzzaman Md, 29, suffered burns to about 90 per cent of their bodies, and died after being taken to hospital.

Five other men suffered between 35 and 58 per cent burns on their bodies, the court heard. Among them, one of them felt an intense heat and impact that caused him to fall about 2m away while a “huge push” caused another to “fly” about 2m. Hot oil splashed on another man, the court heard. Two men working in a unit opposite Stars Engrg were also injured- their injuries were relatively minor.

In a walk-through scan of the workshop done by experts in March which was shown in court, a part of the wall near the machine, which is shared with a neighbouring unit, could be seen missing. It was “blasted out”, the court heard. Glass window panels were also “blasted out” of their frames.

The inquiry committee is chaired by Senior District Judge Ong Hian Sun. He was the Senior State Counsel who presented evidence in the inquiry into the collapse of the Circle Line at Nicoll Highway in April 2004.

Mr Ong is assisted by two assessors, Mr Lucas Ng Hong Kiang, the general manager of Plant, Petrochemical Corp of Singapore, and Dr Peter Nagler, the Agency for Science, Technology and Research’s chief innovation officer.

The group will determine the causes and circumstances of the accident, recommend ways to prevent such accidents, consider evidence presented by the Attorney-General’s Chambers’ State Counsel, submit a report of its findings and recommendations, and decide whether criminal prosecution is necessary.

The State Counsel said that the evidence to be heard on the circumstances and causes of the explosion in the first tranche of the inquiry hearing will “facilitate the evidence to be led on recommendations to prevent the recurrence of such an accident at workplaces” in the next tranche of the hearing.

The last day of the first tranche is expected to be on Oct 8 this year. The second tranche is expected to begin on Nov 15.