First of all, what in the world is coiled tubing? Otherwise referred to as CT, coiled tubing is a manufactured product used in field operations such as well service, workover applications (petroleum industry well work), and drilling and completion applications. Just as is sounds, CT is essentially a continuous tube with a diameter of .75 inches up to 4.5 inches that is reeled onto a spool, which has a core diameter of approximately eight to twelve feet. The tubing is made from rolling strip metal, usually a carbon based steel, into cylindrical form and weld along its entire length. The longitudinal weld is made using a high-frequency induction electrical resistance method. The welding process produces a small amount of weld flash on both the inside and outside of the tube. This is removed from the outside diameter of the tube after welding by a carbide cutting tool contoured to the diameter of the tube being produced. The weld vein is instantly re-heated to re-crystallize the welded zone to match the grain composition of the base metal. So in other words, you have this extremely long steel tubing coiled up like a garden hose on reel without any visible end welds. The entire length is non-destructively inspected, then gauged and hydrostatically tested to assure the pipe meets customer specifications prior to shipment. A single spool can carry an average length of approximately 15,000 feet but have been fabricated up to 30,000 feet depending on the diameter of the tubing.
