1. The risk associated with the pipeline, in terms of the safety of people, damage to the environment, and loss of income, depends on the expected failure frequency and the associated consequence, which is directly related to the type of fluids transported and the sensitivity of locations of the pipeline.
2. In this context, pipeline failures are defined as loss of containment.
3. The potential pipeline failures, causes and their consequences, should be inventorised and taken into account in the design and the operating philosophy.
4. The most common pipeline threats which may lead to the loss of technical integrity are given below.
1. Internal corrosion and hydrogen induced cracking (HIC).
2. Internal erosion.
3. External corrosion and bi-carbonate stress corrosion cracking.
4. Mechanical impact, external interference.
5. Hydrodynamic forces.
6. Geo-technical forces.
7. Growth of material defects.
8. Over pressurisation.
9. Thermal expansion forces.
5. Notwithstanding the requirements of the ANSI/ASME B31.4/8 , the factors which are critical to public safety and the protection of the environment should be analysed over the entire life of the pipeline, including abandonment.
6. The risk should be reduced to as low as reasonably practicable, with the definite objective of preventing leaks.
7. The level of risk may change with time, and it is likely to increase to some extent as the pipeline ages.
