Development and application of inline inspectors in low-pressure gas pipelines with small curvature radii

Abstract

A specialized inline magnetic leakage inspector has been developed for low-pressure natural gas gathering and transmission pipelines with small curvature radii in oilfields. By replacing the polyurethane guide disc of the leakage inspector with a steel brush, the start-up differential pressure at the elbow of the inline inspectors and the operating speed of the inspector are effectively reduced, optimizing its excitation structure and decreasing the size of the permanent magnet. The modified inline inspectors has been successfully applied in an oilfield gas transmission pipeline, resulting in a significant reduction of approximately 40% in start-up differential pressure at the elbow.The maximum operating speed has been reduced from 11 m/s to 6.8 m/s, with 95% of the detection mileage conducted at a controlled speed below 5 m/s. This ensures more accurate defect data for both the inner and outer pipeline walls. The research outcome represents a substantial improvement in inspector technology for low-pressure gas pipelines with small curvature radii, leading to enhanced intrinsic safety levels in oilfield gathering and transmission pipelines.

Keywords

• gathering and transmission pipeline
• natural gas
• inline inspectors
• small curvature radius
• low pressure
• intrinsic safety