Analysis and Recommendations on the Cause of Leakage Failure in CT90 Colied Tubing

The CT90 coiled tubing experienced leakage during operation. This study aims to investigate the causes of tubing failure, improve its service life, and provide a reference for similar issues. The analysis includes the use of metallographic microscopy, optical microscopy, hardness testing, and other experimental methods to examine the metallographic structure, macro morphology, and hardness of the material. The findings reveal that during the pipeline's use, environmental factors led to brittleness, stress corrosion, crack formation, crack propagation, and subsequent leakage.