Regional strain caused by earthquakes, landslides and other third-party influences can have a severe impact on pipeline integrity. Since strain is the result of an interplay between a number of very different factors, local and especially regional strain can only be reliably detected by means of combined inspection technologies.
In order to ascertain how effective ROSEN’s combined inspection technologies are in detecting pipeline strain levels, a series of tests was conducted at the ROSEN technology and research Center in Lingen, Germany. Around 50 test runs were performed in a 16In pipeline with ROSEN’s RoGeo Xt inspection tool, both before and after low-level strain was induced by means of hydraulic jacks. A high level of repeatability (89% on average) was achieved for the strain measurements taken.
Combining a range of technologies including the latest generation of geometry sensors, an inertial measurement unit (IMU), and a HiRes ID mapping module, ROSEN’s RoGeo Xt tool provides information on numerous factors affecting pipeline integrity. Determining regional strain can be conceived as out-of-straightness analysis: when the RoGeo Xt inspection tool traverses induced bends, the maximum strain appears where the tool is exposed to the highest changes in orientation.
This information is complemented with other relevant data, e.g. the relative proportions of strain and curvature as well as known data on wall thickness and pipeline diameter. All these measurements are then used as a basis for an indirect calculation of regional and local strain values.
The Lingen test series showed that the multi-purpose RoGeo Xt tool is a reliable instrument for detecting both regional and local strain caused by positional movement: not only did the tool detect even slight pipeline movements resulting in minor strain changes, but the high level of repeatability achieved means that the results are a dependable source of pipeline integrity information.