Despite advancements in inline inspection (ILI) technology over the last half-century, inspecting small-diameter pipelines utilizing in-line inspection tools continues to be a challenge as most small-diameter pipelines were designed and built without consideration for ILI tool passage. Even so, those that were built for ILI tool passage may have configurations or operational conditions that do not allow for an ILI tool to successfully navigate a pipeline.

Arguably, modifications could be made to make the pipeline piggable, however, this would likely require an interruption of service to modify or remove any unpiggable features. A task that would likely be expensive, time consuming, and in some cases impossible due to technical feasibility, risk factors and a host of other considerations.

This paper will detail some pipeline features and configurations that make small-diameter pipelines difficult and at times seemingly impossible to navigate with a in-line inspection tool and present new technology that overcomes many of these challenges particularly in low-flow gas lines where tool surging often occurs.