Method of Increasing the Fatigue Life and/or Reducing Stress Concentration Cracking of Coiled Metal Tubing

Author:  Lawrence W Smith, Humble, TX
Source:  US Patent 5,515,707
Doc ID:  1996153
Year of Publication:  1996
Abstract:  
A method of increasing the fatigue life and/or reducing stress corrosion cracking of metal coiled tubing made from a continuous length of strip material by shot peening one or both sides of the strip material along substantially the entire length of the strip material prior to milling the strip material into tubing. The continuous length of strip material is made up of individual strips welded together in end to end abutting relation and the welds are finished before the strip material is shot peened. Alternatively, or in addition to shot peening at least the side of the strip material that forms the interior surface of the tubing, the exterior surface of the tubing is continuously shot peened as the tubing is wound onto a real or spool.