SINGAPORE, Sept 23 — Days before it ruptured, a leaking mixer machine was being fixed by a worker, but it had voids, discontinuities and cracks after the repairs.
The worker, Molla Mohammad Nasim, merely looked when checking if his welding had been done right, but a sectional metallographic examination conducted after an explosion that killed three men showed up deficiencies in the repairs.
These details emerged yesterday (September 22), the third day of public hearings by an inquiry committee looking into the causes and circumstances leading to the blast at 32E Tuas Avenue 11, the premises of Stars Engrg, which supplies fire protection systems.
Anisuzzaman Md, 29, S Marimuthu, 38, and Shohel Md, 23, died from severe burns to 90 per cent of their bodies following the explosion in the building on February 24.
The impact of the blast was so great that the walls and windows of the building were blown off, seven other men were injured and the identities of the three who were deceased took a while to ascertain due to the extensive injuries they sustained.
The committee earlier heard that there were problems related to a mixer machine that was bought from Chinese e-commerce retailer Alibaba in 2019 and installed on a platform at the workshop in June last year.
Workers alerted their superiors to oil leaks, heater damage, smoke and small fires from as early as August last year.
After the explosion, the bulk of the damage to the mixer machine was at the lower portion of the back of its oil jacket, which had ruptured open along its welding seams. The oil jacket contained thermic oil used to heat the contents in its mixing compartment.
Nasim, who was Stars Engrg’s only certified welder from early 2020 onwards, performed welding work on the mixer machine on October 12 last year, and between February 13 and 16. The blast happened on February 24.
Throughout the hearing yesterday, the 36-year-old Bangladeshi insisted that he had done the welding properly to the best of his knowledge.
It was only after Deputy Senior State Counsel Ang Feng Qian showed him a sectional shot of the machine’s original weld, which did not come with discontinuities, and compared it to his repair work that he conceded that the welding he did was not of good quality.
“I don’t have a machine to check after I finish welding I only see from the naked eye that it is okay,” Nasim said.
The worker was also grilled on why he did not follow the instructions of Chua Xing Da, the sole director of Stars Engrg, which were conveyed through another worker, India national Pandi Muruganantham.
The instructions were given via a series of text messages before Nasim started welding works in February.
Chua’s instructions, which were backed by annotated photographs showing where the weldings should go on the machine, read: “All the corner(s) here leaking, so we overlap slightly to cover the leak. Weld dead.”
When carrying out the work, Nasim did apply layers of welding to all four corners of the oil jacket, but he welded L-shaped plates onto its front bottom right and left corners. He also welded a base plate to cover the underside of the mixer machine as instructed.
Nasim told the committee that he did not put L-shape plates onto the back corners because Marimuthu, one of the deceased workers who was supervising operations at the Tuas site workshop, had told him that the two front sides were leaking more than the back two sides.
When Ang pressed him for an answer on why he did not put L-shaped plates on all four sides since all sides were leaking, Nasim said: “I followed (Marimuthu’s) instructions. Whatever he told me to do, I just follow.
“He was the one who operated the machine and he knew what was leaking, so he showed me and I just followed his instructions. I do not know which part of the machine was leaking... I just followed his instructions.”
He added that Marimuthu had told him to do welding at the back corners as well, but did not tell him that the corners would require an L-plate as well.
The committee also heard that Nasim was hesitant to perform any welding works on the machine at some point because it was “new and big”.
Imam, the foreman who goes by one name and who preceded Marimuthu, had approached Nasim to do welding on the mixer machine before Chua did on October 11.
Nasim said he told Mr Imam that he could not do it unless Chua personally gave him instructions to do so.
Small fire during Chinese New Year
Muruganantham, a project manager at Stars Engrg who relayed Chua’s welding instructions to Marimuthu and Nasim, also testified yesterday.
He said that after a small fire broke out on February 12, which happened to be the first day of Chinese New Year, Chua asked him to go to the Tuas workshop to help the workers deal with its aftermath and told him to “prepare a few extinguishers for fighting oil”.
When he was on his way to the Tuas site, Chua sent more messages saying that the workshop’s ventilation vent needs to be fixed to dissipate any smoke at the workshop.
When he arrived more than 45 minutes after the fire broke out, Muruganantham said that the entire workshop was filled with white smoke, and he worked with workers to fan smoke out of the workshop.
Chua later asked Muruganantham to help check the mixer machine and gave him several instructions via text messages, including running the motor to see if the mixer blade was moving and checking where the burnt area was.
A few of Chua’s assessments of the burnt areas could be seen in a series of messages to Muruganantham, which the project manager said he did not understand.
The messages were: “No dripping flame”, “The flame stick to the side wall”, and “The fire stay on the body, no drip flame, so cannot be oil flame”.
Later, when Muruganantham sent him a photo of some burn marks at the corner of the insulation that had been installed on the mixer machine, along with a video of it, Chua replied saying: “Correct la, the (aluminum) tape catch fire”.
The committee earlier heard that new insulation, comprising only fibre, was installed on the oil jacket’s exterior surfaces on February 17, a few days after the small fire on February 12. It came with no aluminum foil or aluminum tape.
The hearing continues today, with Chua expected to take the stand. ― TODAY