Ipsco Enterprises, Inc.

Trent M Kaiser

Thomas L Blose

David L Britten

Kevin J Humphreys

John F Reed

A swaged male element of a pipe connection of the type having a frusto-conical sealing surface adjacent to but separate from the load threads. The swaging is effected prior to final machining of the end of the pin and is followed by a cutting operation to remove surplus material from the interior surface of the pin. The swaging extends from the distal end of the pin proximally to include at least the distal end of the effective sealing surface, and preferably extends proximally to a point coinciding generally with the terminating proximal portion of the effective sealing area of the pin.

Swaged pin end of pipe connection

A pipe coupling or connection comprises a female coupling component and a mating male coupling component. Each component is matingly threaded for coupling engagement, and each is provided with an adjacent frusto-conical sealing surface. The sealing surface is provided with a controlled surface roughness, viz. very shallow fine surface variations, preferably formed as microgrooves at a pitch small relative to the pitch of the threads. The slope of the frusto-conical surface of the sealing surface of the male component is slightly mismatched with that of the sealing surface of the female component to simulate the bearing force vs. axial distance characteristic of shrunk-fit circular cylindrical sealing surfaces. The mismatch enables the sealing pressure to be above a design minimum throughout the entire sealing area yet higher at each end of the sealing area. As the coupling is assembled, thread interference in the vicinity of the sealing surface lags the occurrence of interference between the sealing surfaces. Load threads are provided with negatively inclined load flank faces. The slope of the load thread pitch line of the male element is slightly steeper than the slope of the load thread pitch line of the female element. Load thread interference values and tolerances are selected to enable the shrunk-fit cylindrical sealing surface simulation to be met over the range of tolerances provided. The envelope of the range of curves of interference vs. distance along the effective pin sealing surface area has a positive slope. The effective sealing area is at least about one-third and preferably at least about half of the available sealing area.

Pipe coupling

A pipe coupling or connection comprises a female coupling component and a mating male coupling component. Each component is matingly threaded for coupling engagement, and each is provided with an adjacent frusto-conical sealing surface. The sealing surface is provided with a controlled surface roughness, viz. very shallow fine surface variations, preferably formed as microgrooves at a pitch small relative to the pitch of the threads. The slope of the frusto-conical surface of the sealing area of the male component is slightly mismatched with that of the sealing area of the female component to simulate the bearing force vs. axial distance characteristic of shrunk-fit circular cylindrical sealing surfaces. The slight mismatch enables the sealing pressure to be above a design minimum throughout the entire sealing area yet higher at each end of the sealing area. As the coupling is assembled, thread interference in the vicinity of the sealing surface lags the occurrence of interference between the sealing surfaces. Load threads are provided with negatively inclined load flank faces. The slope of the load thread pitch line of the male element is slightly steeper than the slope of the load thread pitch line of the female element.

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Edmonton, Canada

Trent M Kaiser