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  System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubingUSPTO Application #: 20080042327Title: System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing Abstract: The present invention is directed to a method of extending the life of thin walled tubing by austempering the tubing in a controlled continuous run process involving heating, quenching, and cooling the tubing pursuant to predetermined process parameters. The invention is also directed to a process for austempering tubing having a welded seam and for relieving residual stress in the weld. The invention is further directed to the product of the above processes as well as an austempered weld stress relieved thin walled tubing and such tubing in combination with other apparatus with which it is suitable for use in the production of hydrocarbons. (end of abstract)
Agent: Duane Morris LLP - Houston, TX, US Inventor: Dan Thomas Benson USPTO Applicaton #: 20080042327 - Class: 266112000 (USPTO) Related Patent Categories: Metallurgical Apparatus, Means Treating A Continuum Of Work, With Heating Means, With Fluid Contact Means, In Liquid Bath The Patent Description & Claims data below is from USPTO Patent Application 20080042327. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATION TO OTHER APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 10/943,575, filed Sep. 17, 2004 and still pending. BACKGROUND OF THE INVENTION [0002] 1. Field Of The Invention [0003] The present invention is directed to a method of extending the life of thin walled tubing by austempering the tubing in a controlled process involving heating, quenching, and cooling the tubing pursuant to predetermined process parameters. The invention is also directed to a process for austempering tubing having a welded seam and for relieving residual stress in the weld. The invention is further directed to the product of the above processes as well as an austempered weld stress relieved thin walled tubing and such tubing in combination with other apparatus with which it is suitable for use in the production of hydrocarbons. [0004] 2. Description of the Prior Art [0005] As each instance tubing is rolled on or off a coil tubing reel, it is permanently elongated. The elongation accumulates until exhausted and the tubing breaks. Hence, elongation is a significant property of the tubing material. [0006] The second significant property of tubing material is strength or hardness. This quality resists dilation stresses of pressure and tension stresses of deployments in deep wells. [0007] A characteristic of steel is decreasing elongation with increasing hardness. Metallurgically, an ideal coil tubing is a paradox: hard for strength in deep or high pressure wells, ductile for repetitive reeling. [0008] Present technology coil tubing steels have a martensitic structure. Martensite has unfavorable hardness versus elongation trade-off. On the other hand, austempered steels have a bainitic structure. Bainitic structured steels are not only hard, but also retain commendable elongation. [0009] Austempering of steel is known in the prior art; however, it is typically accomplished in a non-continuous batch process which is unsuitable for coil tubing milling. [0010] Represented by FIG. 1 is the current technology to continuously mill steel tubing: metal strip is introduced to a tube formation device, the seam welded and scarfed, and the formed tubular annealed, e.g., by heating. The tubing is chilled by a cooling apparatus and then travels through additional formation devices, e.g., sizing rolls. The tubular may then be heated and cooled again and taken up, e.g., on a reel. By welding the butts of the strip stock at the front end of the process, very long lengths of tubing can be milled. [0011] In the continuous tube milling process, the sizing operation in FIG. 1 work-hardens the tubing increasing the strength. The thermal processes depicted in FIG. 1 are either palliatives for problems caused by welding, or to soften tubing to the desired grade after work-hardening. The thermal processes used in present tubing milling technology do not harden the tube. SUMMARY OF THE INVENTION [0012] The present inventions are directed toward an apparatus and methods useful for increasing the strength of the tubing while maintaining the elongation of thin walled tubing by austempering the thin walled tubing. The present invention is further directed toward a method for austempering thin walled tubing comprising a welded seam and for stress relieving the welded seam. The present invention is also directed toward a product produced by the methods and/or processes described above. The present invention is also directed toward a thin walled austempered tubing comprising a stress relieved welded seam. DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a schematic overview of a prior art system. [0014] FIGS. 2 and 2a are schematic overviews of an exemplary apparatus for practicing the present inventions' methods. [0015] FIG. 3 is a view in partial perspective of a section of austempered tubing. [0016] FIG. 4 is a schematic view of an exemplary deployment of austempered tubing in a well. [0017] FIG. 5 is a block diagram of a first method of the present invention. [0018] FIG. 6 is a block diagram of a second method of the present invention. [0019] FIG. 7 is a block diagram of a third method of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Continue reading... Full patent description for System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing or other areas of interest. ### Previous Patent Application: High total transmittance alumina discharge vessels having submicron grain size Next Patent Application: Substrate processing apparatus and substrate rotating device Industry Class: Metallurgical apparatus ### FreshPatents.com Support Thank you for viewing the System for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing patent info. IP-related news and info Results in 3.89108 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , |
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