Coiled tubing is exactly what it sounds like: a continuous string of tubing, rolled onto a spool. It is made from rolling strip material into a tubular form and resistance welding along its length. Upon its manufacturing, the tubing is rolled onto large spools with core diameters ranging from 8 – 12 feet. The strip material is joined together using carefully controlled bias welding processes, such that the final string has no visible butt welds. Strings as long as 26,000 feet have been fabricated.

Tubing outer diameters range from 0.75-in to as great as 4.5-in. It is fabricated in a variety of material grades, characterized by minimum monotonic yield strengths of 60, 70, 80, 90, 100, 110 and 120 ksi. The material is essentially carbon steel, modified for grain size refinement. The grain size of typical coiled tubing material is extremely fine; so fine it lies outside the range recognized by ASTM’s standard series of photomicrographs. The finest grainsize recognized has an ASTM number of "10" while coiled tubing extrapolates to a grain size number of about 12.

Coiled tubing is used for a wide range of oil field services, including but not limited to drilling, logging, cleanouts, fracturing, cementing, underreaming, fishing, completion and production.