PIPELINE GEOMETRY

The Onstream Inspection System offers an optional mechanical caliper measurement system which can be easily run in conjunction with the metal loss survey or as a standalone system. The system uses a pipe wall contact mechanical caliper system to map the internal geometry of the pipeline. The measurement arms are coated to prevent wear and ride directly on the pipe wall. This system is highly accurate and reports the internal diameter for every joint on the pipeline as well as identifies all dents, ovalaties, wall thickness changes, and other physical restrictions in the line.

Accurately identifying wall thickness changes is crucial to the metal loss data. The signals collected by the Precision Hall Effect sensor array vary with the pipe wall thickness. Having unquantified wall thickness changes can lead to metal loss data accuracy errors. Although the metal loss sensors can detect the wall thickness changes, they can more reliably be quantified with the geometry unit. This is especially significant on pipelines where the construction and maintenance history is unknown.

Geometry defects (dents, gouging, etc.) are among the leading causes of pipeline failure. Even more at risk are areas where metal loss and geometry defects interact to affect the integrity of the pipe wall. In these areas it is greatly beneficial to have geometry data to complement the metal loss data allowing informed decisions regarding the pipeline's total integrity. With both data sets collected off the same odometer system interacting features are accurately identified, eliminating any guesswork involved in aligning different data sets.