The condition of individual pipes is highly variable, often both within an individual pipe and from pipe to pipe along a pipeline.
Variability of 45 years old 450m unprotected cast iron pipeline buried in
very corrosive soil
Several studies of grey cast iron pipelines have shown that only a small number of pipes will be in poor or very poor condition. This proportion would be far less for coated steel pipelines, where typically only very small areas undergo significant corrosion. This phenomenon is an important consideration in designing an efficient and effective Condition Assessment Methodology.
Additionally, materials corrode or degrade differently, and the selected technique should reflect the different modes of degradation. For instance, grey cast iron undergoes graphitisation, steel “dissolves” and rusts, and asbestos cement loses its cementitious matrix.
Finally, the brittle pipe materials, such as grey cast iron and asbestos cement, can fail catastrophically as a result of impact loading, or in small diameters, beam loading. This should be taken into account when estimating future performance of pipelines.
PCA designs its Condition Assessment Methodology according to how each material Performs and Fails – no single technique adequately assesses all of the major pipeline materials! Accordingly, it uses a Staged Approach to identify those sections of a pipeline which need more expensive and more detailed technologies. With more than 25 years’ experience in performance of pressure pipelines and investigative techniques, PCA is well-positioned to recommend effective technologies to perform condition assessment.
Example of output for pipeline life prediction
Example of estimated pipe condition in a section