From Nordin Yahaya
On April 1, a major gas pipeline incident occurred in Putra Heights, resulting in injuries, property damage, and significant disruption to the community.
This letter aims to provide a general understanding of how forensic engineering investigations are conducted following a pipeline failure. It does not seek to speculate on the causes of the Putra Heights incident or assign blame.
Instead, it offers insight into the structured and scientific methods that engineers and forensic teams use to determine the root cause of such failures, based on well-established international practices.
What happens during a pipeline failure investigation?
Pipeline investigations are highly technical and multidisciplinary. Once the site is safe and secured, the investigation typically involves:
1. Site control and safety: The area is cordoned off, and gas supply is shut down to ensure no further risks.
2. Crater and damage mapping: The physical characteristics of the failure zone are documented using drones, light detection and ranging sensors, and high-resolution imagery.
3. Pipe segment extraction: Damaged segments are carefully cut, labelled, and removed for laboratory analysis.
4. Soil and environmental sampling: Investigators assess soil conditions, water infiltration, and chemical indicators around the pipe.
5. Laboratory forensics: The pipe material, welds, coating, and fracture surfaces are studied to identify stress points, corrosion, and crack propagation.
6. Operational data analysis: Pressure, flow, and alarm logs are reviewed to reconstruct what happened just before and during the incident.
7. Root cause analysis: Data is integrated to determine what combination of factors led to the failure.
Given the strong public interest in the Putra Heights incident, it is possible that the investigation team may complete its analysis earlier than typical timelines. However, it is important to note that these investigations involve vast amounts of technical data and complex analysis, including operational logs and structural diagnostics that are accessible only to the pipeline operator and designated investigators.
This depth of data and the need for meticulous validation often contribute to longer timelines. Globally, these investigations often take several months to over a year to conclude.
What engineers typically look for
When investigating buried pipeline failures, forensic engineers consider a wide range of potential causes, including:
1. External corrosion: This is one of the most common contributors to pipeline failure. It can occur when protective coatings are damaged or when cathodic protection systems are ineffective. Corrosive soil conditions and stray electrical currents can accelerate metal loss, leading to wall thinning and eventual rupture.
2. Internal corrosion: Caused by contaminants in the transported gas, internal corrosion can produce pitting and localised damage, especially in areas of low flow velocity where liquids may accumulate.
3. Third-party interference (TPI): Damage from nearby excavation or construction activity, whether direct or indirect. TPI can involve heavy machinery operating too close to the pipeline right of way (ROW), or indirect effects such as soil stress redistribution, vibration from construction equipment, or hydro-mechanical impacts from altered water flow. Even shallow trenching activities, if unmonitored, can disturb the soil stability around a deeper pipeline and compromise its coating or support. Delayed failures are possible if prior unreported mechanical damage gradually develops into a crack under normal operating pressures.
4. Material defects or weld failures: These include lamination defects, manufacturing flaws, or inadequate weld fusion. Poor workmanship during fabrication or field installation can create weak points that fail over time due to cyclic loading, pressure fluctuations, or thermal effects. Fracture mechanics analysis is often used to examine the origin and propagation of cracks in these cases.
5. Environmental stress: Soil movement, erosion, or water infiltration can impose stress on buried pipes, potentially bending or distorting them. In hilly or unstable terrain, landslides and soil creep are additional risks.
6. Operational factors: Pressure surges, valve malfunctions, and delayed leak detection can impose abnormal stresses that degrade pipeline integrity. Operational performance also depends on control room decisions, system response, and equipment reliability.
7. Human and organisational factors: Human decisions or procedural lapses – such as inadequate inspection, miscommunication, or deviation from safety protocols – can contribute to or exacerbate technical failures. Investigators often review this alongside physical evidence to understand the broader context.
Each of these factors leaves different traces – be it a particular fracture pattern, corrosion product, or deformation signature.
Many failures are now analysed through a combination of physical evidence and digital diagnostics – drawing from Scada logs, pressure trends, and real-time monitoring data.
TPI, regulations, and ROW management
Pipeline operators and regulatory authorities typically implement strict procedures to prevent TPI. These include maintaining a clearly defined ROW, often 30m wide, and requiring permits or formal notifications before any nearby excavation or construction work can begin.
Coordination between developers, contractors, local authorities, and pipeline operators is imperative.
Despite such safeguards, TPI remains one of the most common contributors to pipeline incidents globally due to unintentional oversight, breakdowns in communication, or lapses in compliance.
Clues from fire and damage patterns
In addition to laboratory and operational data, investigators examine the physical signs of the blast site. The shape of the crater, extent of surface damage, and burn patterns offer insight into the nature of the rupture and ignition.
A deep, symmetrical crater with a pipe ejected upward may suggest a sudden, high-pressure failure. Widespread scorch marks and melted surfaces can indicate the fireball’s size and the rapidity of ignition.
In the Putra Heights incident, the scale of surface damage and reports of towering flames point to a significant release of gas with immediate ignition. While not conclusive, these indicators help investigators understand the failure dynamics and timeline.
Why pipeline failures are often complex
In many cases, pipeline failures are not caused by a single issue, but rather by a combination of contributing factors over time.
For example, a coating damaged years earlier during construction may go unnoticed. Over time, this allows corrosion to develop. Then, under the right combination of stress – such as heavy rain, shifting soil, or operational pressure – the weakened pipe may rupture.
These are known as “delayed failures”, and they highlight the importance of ongoing inspection, maintenance, and environmental monitoring.
The public may be tempted to draw early conclusions, particularly around possibilities like TPI.
While such scenarios have occurred in other international cases, only the official forensic engineering investigation – armed with real-time data and metallurgical evidence – can determine whether that is a factor in this case.
Modern pipeline safety doesn’t rely solely on strong material.
It depends on proactive systems, including proper enforcement of ROW clearances, awareness of utility lines before digging, communication between developers, contractors, and pipeline operators, real-time leak detection and Scada systems, as well as regular in-line inspections and corrosion monitoring.
Learning from global contexts
Ghislenghien, Belgium (2004): A gas pipeline explosion occurred weeks after nearby construction gouged the pipe, without immediate failure. The damage was not reported or repaired. The explosion killed 24 people.
Edison, New Jersey, US (1994): A large gas transmission pipeline exploded years after construction activity had unknowingly caused mechanical damage. That damage went undetected until the pipe failed under routine pressure.
Bellingham, Washington, US (1999): A pipeline carrying gasoline failed due to previously unreported construction damage and operational issues, resulting in fatalities and a fire.
Conclusion
As investigations into the Putra Heights pipeline incident continue, it’s important that the process be allowed to proceed carefully and professionally. Engineering failures demand thoughtful analysis, not speculation.
By understanding how such investigations are conducted, and what kinds of technical evidence experts look for, we can appreciate the complexity of the challenge – and the importance of getting it right. - FMT
Nordin Yahaya is head of the science, technology, and innovation cluster at Akademi Profesor Malaysia and a retired professor of Universiti Teknologi Malaysia, specialising in pipeline integrity and risk management. He is also a US-Asean Fulbright visiting scholar at the University of Wyoming, US.
The views expressed are those of the writer and do not necessarily reflect those of MMKtT.
