scope:

Introduction

Since introduction in the late 1960s, ILI tools have mainly been used to inspect the wall of the pipe for corrosion (metal loss). ILI tools have also become available for performing other tasks, such as the following:

• Crack Detection

• Geometry Measurement

• Leak Detection

• Temperature and Pressure Recording

• Bend Measurement

• Product Sampling

• Wax Deposition Measurement

• Curvature Monitoring

• Pipeline Profile - Mapping

• Photographic Inspection

• Strain Analysis

The increased use of ILI technology reflects the improvement of the technology. Pipeline defect detection has improved in terms of the variety of anomalies detected, increased accuracy of detection, and reliable characterization of anomalies. The increased reliability of ILI, the introduction of pipeline integrity management programs by many pipeline operators, and increased regulatory involvement is expected to push the technology development and use of ILI tools still further.

Besides the development of technologies addressing different types of defects, operational challenges have led to development of dual-diameter ILI tools (collapsible pigs), i.e., tools that can pass through pipelines with two different diameters, inspecting both pipelines. Another addition to ILI tools that has become available is speed control, the ability to bypass flow and establish inspection speeds at much lower speeds than the flow of product. In addition, some of the tools are available as tethered tools, typically for inspecting shorter pipeline sections and sections without flow.

None of the above-mentioned tools and applied NDE technologies is universally applicable. The pipeline operator and the ILI service company jointly choose the proper ILI technology, and match the performance of the tool to the requested defect specifications.