Code of Environmental Practice
Fracture Control of Steel Pipelines
The Fracture Control Code of Practice (Second Edition, 2021) provides a comprehensive framework for managing fracture risks in steel pipelines used to transport fluids such as gas, water, and oil. It is designed to support pipeline designers, operators, and engineers in ensuring that pipelines remain safe, reliable, and “fit for service” throughout their lifecycle.
At its core, the document recognises that while pipelines are engineered to be free of defects, this is not fully achievable in practice. Given their length, operating pressures, and environmental exposure, pipelines will inevitably contain imperfections. The Code therefore adopts a defect tolerance approach, focusing on understanding how defects behave and ensuring they do not compromise structural integrity or safety.
The Code explains how fracture mechanics is used to assess pipeline behaviour in the presence of defects. It distinguishes between four primary outcomes: surface defects, leaks, ruptures, and running fractures. Of these, rupture and running fracture represent the most severe risks, potentially leading to significant safety, environmental, and financial consequences.
To manage these risks, the Code sets two key objectives:
- Prevent defects from growing to the point of rupture.
- Ensure that, if rupture occurs, the fracture will arrest within an acceptable distance.
Achieving this requires careful control of material properties, particularly strength and toughness. Strength determines the pipeline’s ability to withstand stress, while toughness governs its resistance to crack growth. The Code highlights the need to balance these properties, as increasing one can negatively affect the other.
The document also outlines how fracture behaviour is influenced by factors such as pipeline diameter, pressure, temperature, and the type of fluid transported. For example, large-diameter, high-pressure pipelines or those operating in cold environments require more stringent fracture control due to higher energy release and reduced material toughness.
Importantly, the Code aligns fracture control practices with Australian standards, particularly AS/NZS 2885.1, and provides detailed methodologies for both new pipeline design and the retrospective assessment of existing (legacy) pipelines, which may not meet modern fracture control expectations.
Overall, this Code of Practice serves as both a technical reference and a practical guide, combining theoretical foundations with applied methods. Its purpose is to ensure that fracture risks are systematically identified, assessed, and controlled—supporting the safe expansion and operation of Australia’s pipeline infrastructure in an evolving energy landscape.