PR-670-183826-R02 Extended Evaluation of LSM – Magnetic Measurements of Corrosion Flaws

Integrity assessment of pipelines is vital to ensure that oil and gas pipes have adequate strength to prevent leaks and ruptures. Regular inspections are conducted to confirm safe operation conditions of pipelines. The industry’s principle method for assessing pipelines is in-line inspection (ILI), involving the passing of a device along the inside of a pipe to assess the condition of the pipeline. ILI devices can be fitted with a number of sensors allowing various measurement parameters to be obtained simultaneously.

Not all pipelines are suited to ILI for reasons such as small diameter, obstructions within the pipe, or insufficient access to deploy or retrieve the ILI tools. These pipelines are sometimes referred to as ‘difficult to inspect’. Alternative methods for examining pipeline condition are required with a range of technologies collectively known as Large Standoff Magnetometry (LSM) offering a promising solution for detection of pipe defects from a distance, reducing the need for excavation.

LSM utilises coupling between defects and changes in the magnetic properties of the pipeline material as a method for evaluation of pipe walls to identify the location of areas that require repair or further monitoring. Trials of existing commercial instruments by the pipeline industry have shown sufficient promise to investigate these technologies further. However, the vendors have supplied limited information on the underpinning physics of both the materials being tested and the instrument technology, meaning that further study is required in order to build confidence in the technique.

The purpose of the project is to establish the ability of LSM to detect corrosion in API 5L pipe grades B to X70. The aim of Work Package 04 is to measure the magnetic fields of a range of pipe samples containing manufactured corrosion flaws taking into account variables such as standoff distance, pressure, nearby ferromagnetic objects, position of the corrosion flaw around the pipe, track alignment, and orientation with respect to Earth’s magnetic field. The results of these measurements will be used to validate computational models, which can be used to predict the magnetic response of a wider range of pipe geometries.