SINGAPORE - For one minute on Monday (Sept 20), everyone in the courtroom stood in silence, reflecting on the deaths of three men.

Mr Anisuzzaman MD, 29, Mr Subbaiyan Marimuthu, 38, and Mr Shohel MD, 23, died from severe burns to 90 per cent of their bodies following an explosion in a Tuas industrial building on Feb 24.

The force of the blast, which was linked to a mixer machine, blew out the window panels in the building, caused the rear wall of the workshop to collapse, and ripped a large hole in the adjoining wall of the unit.

The court heard that minutes before the explosion, Mr Subbaiyan had taken a photo of the damaged heater on the machine and sent it to an engineer overseeing production at the site.

But after the accident, the engineer, Mr Lwin Moe Tun, deleted this photo from his and Mr Subbaiyan's phone.

An Inquiry Committee, chaired by Senior District Judge Ong Hian Sun, was appointed on March 2. The first tranche of hearings for the incident began on Monday.

At the opening of the hearings, Judge Ong called for the minute of silence, saying the three men, from India and Bangladesh, had left their home towns to work here and had tragically lost their lives.

"We thank them for their contributions to Singapore and extend our condolences to their loved ones," he said.

The employees of Stars Engrg were in a workshop on the first floor of the building at 32E Tuas Avenue 11 when the explosion happened at about 11.20am that day.

A total of 10 men were injured in the blast, including five others working for Stars Engrg.

A State Counsel team led by Ms Kristy Tan gave an opening statement.

Ms Tan noted that Stars Engrg, a fire protection contractor in the business of providing design-built fire protection systems, was participating in the inquiry hearing as an interested party.

In the opening statement, Ms Tan directed the committee to a mixer machine used by Stars Engrg.

It was purchased via online platform Alibaba in August 2019 and installed at the workshop in June last year.

The machine was used to mix several ingredients including potato starch to make fire clay, which is used to make the fire wrap produced by Stars Engrg.

The machine used nine heaters which were meant to heat oil placed in a compartment that wrapped the mixer.

Investigations found that the amount of oil used by Stars Engrg may not have covered the heaters as it was supposed to.

The machine was tested in June last year and full production began only in October last year.

When it was used on Aug 8 last year, a heater emitted a spark and smoke.

A former employee of Stars Engrg, Mr Imam, 34, found that some of the oil had depleted and that one of the heating rods was deformed from the burning.

He replaced the rod and closed the front and back pipes of the oil compartment on the instruction of Mr Chua Xing Da, the sole director of Stars Engrg.

Mr Chua later bought more oil, which was added to the machine.

On Aug 28, Mr Imam noticed smoke from the machine again and found that the gaskets on the heater openings had deteriorated. The gaskets were then replaced.

Smoke was again seen from the machine on Sept 21.

One week later, on Sept 28, the workers noticed a leak at the front bottom corner of the machine and informed Mr Chua. But the leak was not immediately dealt with.

On Oct 12, workers again told Mr Chua about the leak, saying it was larger than it had been on Sept 28. It was subsequently welded close.

On Jan 8, Mr Chua was told about smoke coming from the bottom of the machine when the heaters were turned on. He bought more oil on Feb 5.

Of the four buckets he purchased, two were not used.

On Feb 12, a fire broke out at the corner of the machine. But this was put out by workers.

Mr Chua later instructed workers to weld the four bottom corners of the machine and also an additional base plate. This was completed on Feb 16.

On the morning of Feb 24, at about 8.40am, a small fire broke out at the machine.

This was put out by one of the workers and reported to Mr Chua.

Mr Chua spoke to Mr Subbaiyan four times within 15 minutes from about 10am to 10.15am.

At about 11.15am, Mr Subbaiyan sent a photo of the damaged heater to Mr Lwin Moe Tun, who deleted it after the accident.

A large explosion happened at 11.22am and was followed in the next few minutes by flash fires.

The blast damaged the mixer and its oil compartment was ruptured along the welding seams.

Investigators agreed that the explosion was a chemical one, involving the ignition of oil aerosols.

Mr Imam, a Bangladeshi who worked for Stars Engrg between 2015 and April this year, was called as the first witness on Monday.

In his statement, which was read out during the inquiry, he described the many incidents involving the machine prior to the explosion.

He also said he was the one who installed the electrical connections for the mixer, but did not refer to any instruction manual, relying instead on the instructions given by Mr Chua.

It was also revealed that it was only after he left Stars Engrg that he was given formal training on electrical work for the first time about two months ago, despite having done electrical work as an employee for Stars Engrg since 2015.

Mr Imam was not at the workshop on the day of the explosion as he had been deployed to another work site.

But he said he grieves the deaths of his co-workers, especially that of Mr Anisuzzaman, as the two of them were from the same district in Bangladesh and were very close.

"I am very saddened that three of my co-workers have passed away and that some were seriously injured as a result of the incident," he said.

"My relationship with all of my co-workers was very good... all of us were very close."

He added that he still keeps in touch with one of the workers who was injured in the blast to keep updated on how the others who were injured are doing.

Ms Tan called the incident an "absolute travesty" that should never be repeated.

She said that the evidence to be heard during the inquiry will help to prevent the recurrence of such an accident.

"There will no doubt be many important lessons to learn from this tragic accident to ensure it is never again repeated," she added.

The first tranche of hearings will last till Oct 8, while the second tranche is expected to be from Nov 15 to 19.

Among the witnesses expected to present their statements in the coming days are the other workers who were injured, investigators from the Singapore Civil Defence Force and Ministry of Manpower, and Mr Chua.