Report: Soil instability, not foul play, led to pipe failure

The Star

17 hours ago

SHAH ALAM: The underground PETRONAS gas pipeline explosion which rocked the nation on April 1 this year was not due to foul play.
Instead, it was caused by ground instability at the blast location.
This was disclosed by Occupational Safety and Health Department (DOSH) Petroleum Safety Division director Husdin Che Amat at a press conference at the Selangor state secretariat yesterday.
Husdin, who presented investigations revolving around the tragedy carried out by DOSH, said the instability had occurred gradually at the location.
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'The bottom part of the pipeline was not fully supported by the ground, which was soft and moist,' he said.
This caused the pipe segment at the location to fail. The physical failure had in turn resulted in gas leakage which ignited and blew up.
Husdin said that the lack of support caused the pipe to move repeatedly in what is known as cyclic loading; this generated repeated stress lines and fatigue striations on the pipe surface.
A metallographic analysis indicated that tensile overload (stress beyond normal operating or design limits) was the primary cause of the failure, and the damage had developed slowly until it resulted in ductile failure (deformation followed by fracture) which released gas and triggered a fire.
'In conclusion, the pipe failure was caused by the ground beneath it not being strong enough to support its weight and pressure, causing instability, leakage, and eventual explosion,' said Husdin.
He added that investigations found that the affected gas pipe met specified technical standards.
Hence the mishap was not due to surface activities but because the ground beneath did not provide adequate support, he reiterated.
Selangor police chief Comm Datuk Hussein Omar Khan, who also spoke at the press briefing, confirmed that no acts of sabotage or carelessness had caused the pipeline blast.
Comm Hussein said police had investigated the incident from two angles: under Section 435 of the Penal Code for committing mischief by fire, and Sections 285 and 286 for negligence with fire or combustible matter.
Selangor Mentri Besar Datuk Seri Amirudin Shari said the state government is of the opinion that the investigation report will serve as the basis for risk analysis in similar areas.
'A special committee under the state Disaster Management Unit will be established and it will involve experts, including from PETRONAS, to recommend legal reforms, procedures for approval of planning permissions, development policies considering climate change risks, and all areas within the gas pipeline right-of-way corridor,' said Amirudin.
He added that these measures are necessary to prevent a repeat of similar tragedies.
The Gas Pipeline Explosion Investigation Committee, led by DOSH, also involved the Mineral and Geosciences Department (JMG), the Public Works Department (JKR), the Fire and Rescue Department, and the police.
Amirudin said technical investigations into the mishap had focused on the integrity of the pipeline structure, external factors, and the geology of the site, which were conducted collaboratively by DOSH, JMG and JKR.
'The criminal investigation involving aspects of sabotage or negligence was led by the police,' he said, adding that technical findings indicated that soil settlement of 24.3cm had occurred over a period of 25 years, since the pipeline was commissioned in 2000.
'The soil subsidence had caused the gas pipeline to shift by 15.9cm.'
Amirudin added that a sampling of the pipe had shown signs of pressure and fatigue in the pipeline structure.
He said the JMG also found the soil in the area water-saturated and containing natural underground water reservoirs, which caused the soil to become soft.
Hence, Amirudin said, the pipe failure was attributed to factors such as unstable soil conditions and long-term underground water accumulation which led to softer ground effecting the monsoon drainage structures and culverts.
The explosion, which happened just after 8am, had caused a large fire that destroyed homes, public infrastructure, and vehicles as well as injured some 150 people.
Flames shot up over 30m high and the heat reached up to 1,000°C. It took almost eight hours to extinguish the fire.
The explosion has left a 9.8m-deep crater at the site.
More than 500 residents were evacuated to relief centres following the explosion.
Some of those whose houses suffered total damage have yet to return home as repairs are estimated to take at least two years.
Eighty-one houses were completely destroyed with structural damage exceeding 40%, another 81 houses were partially damaged and 57 were affected but not burned on the surface.