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Use of Pipeline Girth Weld Locations for Detection of Axial Strains

IP.com Disclosure Number: IPCOM000240215D
Publication Date: 2015-Jan-13
Document File: 1 page(s) / 41K

Publishing Venue

The IP.com Prior Art Database

Abstract

“A method for estimating axial strain imposed upon a pipeline based on girth weld position is presented. Presently, measurement of strains within a pipeline are limited to bending strains unless a local strain measurement device such as a strain gauge is placed at the location of interest or if a fiber-optic cable for strain measurement is properly attached to the pipeline. The invention described utilizes the girth weld positions and odometer position obtained from smart pipeline inline inspection devices (PIGS) to estimate the axial component of strain.”

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Abstract:

A method for estimating axial strain imposed upon a pipeline based on girth weld position is presented. Presently, measurement of strains within a pipeline are limited to bending strains unless a local strain measurement device such as a strain gauge is placed at the location of interest or if a fiber-optic cable for strain measurement is properly attached to the pipeline. The invention described utilizes the girth weld positions and odometer position obtained from smart pipeline inline inspection devices (PIGS) to estimate the axial component of strain.

Disclosure:

Pipelines may be subjected to longitudinal (axial) and/or bending strains due to geohazards (fault rupture, landslide, frost heave, subsidence, soil erosion, flooding, and iceberg scour) and third party damage such as anchor drag. The figure below illustrates a hypothetical landslide situation. Due to a landslide, several joints of pipe initially 40 ft long have been stretched or compressed (axial strain). In addition, the pipe has been deformed into a bend also producing bending strain. Current procedures using smart PIGS with an inertial measurement unit measure the bending strain by relating the bending radius of curvature to the diameter of the pipeline. Axial strains are left unknown. When inspecting pipelines, girth weld locations are often determined and used to align different data sets over time. The distance between girth welds and changes in that distance between subsequent PIG runs can be us...