(61b) A Model to Evaluate Pipeline Failure Frequencies Based on Design and Operating Conditions

Underground pipelines are widely used in the petrochemical industry to transport raw materials and products. Historical evidence reveals the loss of mechanical integrity of such pipelines on many occasions, due to a variety of causes such as corrosion, external impact, defects and natural hazards. Such failures present a risk to people and the environment from the hazardous effects of the released material, which is often transported at high pressure.

In order to predict the level of risk to people and the environment, data is required that will predict the likelihood of failures and material release.

Generic failure frequencies derived from local databases are largely used in pipeline risk assessments. However, the generic nature of the databases means that it cannot be used to take pipeline-specific factors (including wall thickness, depth of cover, country of operation, or specific local issues) into account. As a result, risk assessments for pipelines may not reflect accurately operational experience for a specific pipeline or country of operation, and it is not possible to use the guidance to quantify the beneficial effect of any pipeline-specific risk reduction measures (such as physical protection, increased surveillance, etc.) that may be taken to reduce the likelihood of failure.

A new model has been developed to estimate the annual failure frequency of onshore cross-country pipelines. The model uses historical databases, such as CONCAWE (liquid hydrocarbons), EGIG (natural gas) and DOT, and develops failure frequencies as a function of several influences, including both design and operational parameters.