PR445-233902-R01 Operating Range of Vibrating Wire Strain Gauge for Pipeline Monitoring

This report details the laboratory testing program conducted to assess the operating range of the spot-weldable vibrating wire (VW) strain gauges with a specific focus on most commonly used strain gauges for pipeline monitoring. These strain gauges are commonly used by the pipeline operators for long-term monitoring of a change in the pipe strain due to geohazard activities. The primary goal of the laboratory testing program was to assess the response of these strain gauges within the operating range and their behavior as they approach or exceed the manufacturer-specified operating range. This study aims to provide pipeline operators with a framework for evaluating the strain gauge data and to differentiate between the measured strain changes due to geohazards or the measured strain changes due to other environmental factors, instrument malfunctioning, or erroneous readings which may not be related to geohazards.

This report evaluated various strain gauges with total operating ranges from 2,500 to 10,000 microstrain. In this report, principles of operation for vibrating wire strain gauges, examples of responses from vibrating wire strain gauges installed on the pipeline, materials and methods used for the laboratory testing program of bending plate tests, results of the laboratory test and strain gauges responses during these tests, and summary of findings are discussed.