Magnetic Flux Leakage Inspection of Gas Pipelines: Experience with a CollapsibleTool. Final Report, July 1996

摘要

The Magnetic Flux Leakage (MFL) technique is the most commonly used method toinspect transmission pipelines for corrosion. A typical MFL tool operates in pipelines which have no restrictions. Reduced size valves, a 24 inch valve in a 30 inch pipeline, are one such restriction. A collapsible MFL tool was developed to allow pipelines with reduced size valves to be inspected without expensive valve replacement. The first use, in 1995, of a 30 inch tool succeeded in passing through the valves and inspecting the pipeline. The first use of a 36 inch tool railed due to a partially closed valve, damaging the tool. The tool was ultimately run after some repairs to the tool and most of the reduced size valves were replaced with full size valves. The results of the final run were very good. Additional use of the tools in 1996 has provided excellent results.