Abstract
Continuous coiled tubing strings have evolved as an attractive alternative to conventional thread and couple tubing and welded flowlines for many oil and gas operations. This paper presents the results of a survey of coiled tubing field failures. A range of applications were covered including exposure to:

1. Production environments with hydrogen sulfide and/or carbon dioxide.
2. Workover and completion fluids.
3. Stimulation acids.

The results of case studies were evaluated in terms of type of corrosion and failure mode relative to the type of service, well conditions and number of strain cycles to failure. The data were also used to identify use scenarios likely to produce corrosion damage that could lead to premature mechanical failure. The findings of he study indicated the concern for localized pitting corrosion due to downhole use or atmospheric exposure during storage. Pitting was found to produced:

1. Locally high penetration rates in nominally thin wall coiled tubing products leading to wall perforation.
2. Stress concentration that magnified the effects of strain cycling which in turn increased fatigue damage and reduced service life.