A continuous length of low-alloy carbon-steel tubing that can be spooled on a reel for transport, then deployed into a wellbore for the placement of fluids or manipulation of tools during workover and well-intervention operations. The process of spooling and straightening a coiled tubing string imparts a high degree of fatigue to the tube material. Therefore, a coiled tubing string should be regarded as a consumable product with a finite service life. Predicting and managing the factors that affect the safe working life of a coiled tubing string are key components of the string-management system necessary for ensuring safe and efficient coiled tubing operations.