Method of increasing the fatigue life and/or reducing stress concentration cracking of coiled metal tubing
AssigneePrecision Tube Technology, Inc.
InventorLawrence W. Smith
Life of this patent
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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 reel or spool.
Claims14
A method of making a continuous length of un-coated coiled metal tubing having increased fatigue life and/or reduced stress concentration cracking for use in the oil and gas well service industry comprising the steps of joining the ends of a plurality of individual metal strips to form a continuous length of strip material having a length substantially corresponding to a desired continuous length of tubing to be milled therefrom, shot peening one side of the continuous length of strip material along substantially its entire length to induce compressive stresses in such one side, continuously milling the continuous length of strip material into a continuous length of tubing with the one side of the strip material that was previously shot peened forming the interior surface of the tubing, continuously shot peening substantially the entire exterior surface of the tubing after the tube milling step to induce compressive stresses in such exterior surface, and thereafter coiling the continuous length of tubing onto a spool.
A method of making a continuous length of un-coated coiled metal tubing having increased fatigue life and/or reduced stress corrosion cracking for use in the oil and gas well service industry comprising the steps of making up a continuous length of strip material having a length substantially corresponding to a desired continuous length of coiled metal tubing to be milled from the strip material, the continuous length of strip material being formed by joining the ends of a plurality of individual metal strips each having one side and an other side opposite the one side, shot peening the one side of the continuous length of strip material along substantially its entire length to induce compressive stresses in such one side, coiling the continuous length of strip material onto a storage reel, and subsequently uncoiling the continuous length of strip material from the storage reel and continuously milling the continuous length of strip material into a continuous length of tubing with the one side of the strip material that was previously shot peened forming the interior surface of the tubing, and coiling the continuous length of tubing onto a spool.
Dependencies are inferred from the claim text.