Tuas deadly explosion: Company director who bought machine online assumed heating controls worked like they do in ‘an air fryer’

25-Sep-2021 Intellasia | Today | 7:05 AM Print This Post

Lawyers sought to show at a public hearing yesterday (September 23) that the boss of a company behind a deadly explosion at Tuas had not set out to use a mixer machine the way it was intended to be used.

Not only did Chua Xing Da, 37, fail to fully read a user guide before putting water into a compartment of the machine meant for oil, he barely used enough oil to surround heaters on the underside of the machine when he eventually replaced the water with thermic oil.

Chua is the sole director of Stars Engrg, which supplies fire protection systems. He took the stand for the first time on the fourth day of public hearings by an inquiry committee looking into the circumstances leading to the blast on February 24, including whether obvious warnings from workers were ignored.

The explosion and fire at the industrial building located at 32E Tuas Avenue 11 killed three workers: S. Marimuthu, 38, from India, as well as Anisuzzaman Md, 29, and Shohel Md, 23, who were both from Bangladesh.

The impact of the blast was so great that two men who were working outside the workshop in the building beyond its front shutters were thrown a distance of 2m. Seven other men were injured and the identities of the three who died took a while to ascertain due to the 90 per cent burns they sustained.

State Counsel Kristy Tan on Thursday pointed out that the machine initially operated with only 40 litres of oil, which experts had determined would only cover the lower part of the machine’s nine heaters.

Chua then explained that he did not suspect more was needed, because with 40 litres of oil, the machine could still generate starch paste when they tested the production process.

His firm’s purchase records showed that, at most, 160 litres of oil were used from June last year onwards.

Did not use designated sensor

The committee, led by Senior District Judge Ong Hian Sun, also heard that Chua did not bother monitoring the temperature of the oil in the oil jacket each time the machine was used, because he needed the machine to supply heat at only 80°C to 90°C.

He simply assumed that the oil would stay within the operating temperature of between 70°C and 160°C because there was a mention in the user guide that thermal jacket was designed to operate within this range.

He pointed out that the user guide also mentioned a centralised electrical control that includes a digital display temperature control, described as making things “convenient for user operation and process control”.

“Basically, I thought (the mixer machine’s) manufacturer (Chinese firm Laizhou Keda) is reputable. I thought (a temperature controller) was built in like an air fryer. There is nothing additional to fix to monitor the temperature,” Chua said.

Therefore, he had never made it a practice for workers to connect the temperature sensor dedicated for use in the oil jacket to a fixture that was meant for it.

Instead, they used it interchangeably with another temperature sensor meant for the materials being mixed.

State Counsel Tan then told him that the machine indeed had a system for heaters to be automatically switched off at a certain temperature, but only if the jacket’s temperature sensor was used at its right fixture: At the oil jacket.

Chua said that he did not know about this.

He was under the impression that the machine was unreliable when he noticed that the heaters did not always automatically stop heating.

He had placed the temperature sensor at the oil jacket only once, when the machine was filled with water which was the wrong fluid on June 12 last year, the day the machine was installed at Stars Engrg’s premises at the building.

The site was used as a workshop to produce fire-rated insulation wrap. The mixer machine was used to mix water, potato starch, boric acid, silicon, aluminium trihydrate and bentonite clay to make fire clay, a key component of the wrap.

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.

Issues with Alibaba vendor

Earlier yesterday when the hearing began, Chua took about four hours to read out a 67-page statement that he had signed off on August 27. State Counsel Tan began her questioning only after that in the late afternoon.

He will continue to take the stand for further questioning today.

In his statement to the committee, Chua covered his educational background, how he started Stars Engrg with his older brother in 2010, and his perspective of the events leading up to the explosion.

Chua had bought the machine from Chinese online retailer Alibaba in August 2019, from a vendor called Laizhou Keda Chemical Machinery. It was delivered in October or November 2019.

He had paid $11,700 (about S$15,700) for it.

Sometime in April last year, he had asked Laizhou Keda for after-sales support in Singapore but was told that there was none.

He received a user guide for the machine on April 6 last year upon his request, and mainly turned to a representative called Sherry when he had questions.

As for why he did not check with Laizhou Keda when workers found a leak at the seam of the oil jacket on October 12 last year, Chua said he thought that the matter was a “small thing”, adding that he was already “very unhappy with the after-sales service” by then.

Notwithstanding this, the committee heard that he took steps to order a new machine from Laizhou Keda on February 12 the day a small fire broke out at the workshop.

He asked to order one that comes with a jacket that is made of “full stainless steel” and is the “water heating type”.

He told Sherry that the mixer machine he had was “very lousy” and asked if it was under warranty. She said that he should have bought a better machine, and that his warranty no longer applied.

Sherry later sent him a quotation on February 20 for the new machine, then chased him twice, on February 21 and 23, for a response to the quote.

Chua replied Sherry only on February 24 the day of the explosion between 10.33am and 11.05am, with him repeating his requirements.

The explosion happened at 11.22am.

Deleted messages

At the hearing, Chua also addressed what Lwin Moe Tun, the engineer overseeing production at the Tuas site, did after the blast.

Lwin Moe Tun deleted a photo showing a damaged heater with a green tape around its wiring, and deleted his own text reply to the photo.

The explosion took place shortly after Marimuthu sent the photo. The engineer replied at 11.32am, about 10 minutes after the explosion: “Ok let me know ASAP.”

Chua said that Lwin Moe Tun had shown him two messages and a photograph while he was driving to the Tuas site the morning after the blast, but he did not see the contents clearly.

“My mind was not stable then, as I did not sleep (on February 24 night), and I had to make funeral arrangements for the deceased workers. I was also driving at that time and was not able to focus on what Moe was showing me.”

He made clear that he did not instruct Lwin Moe Tun to delete the messages or photograph from the latter’s phone, but said that he remembered replying “Ok” when the employee asked if he could delete them.

When Lwin Moe Tun said the next day that he wanted to delete the photographs and messages from Marimuthu’s phone as well, Chua told him “not to do anything stupid”.

Lwin Moe Tun called later that evening to say that he had deleted the contents since Marimuthu’s phone battery was dying. “I was very angry with Moe and scolded him,” Chua said.

https://www.malaymail.com/news/singapore/2021/09/24/tuas-deadly-explosion-company-director-who-bought-machine-online-assumed-he/2008030

 

Category: Singapore

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