Patent ID: 6078031
Filing Date: 2000-06-20
Classification: B23K

Abstract:
A method for joining oilfield tubulars, the method comprising the steps of:providing a first oilfield tubular having an end surface and an inner surface, and a second oilfield tubular having an end surface and an inner surface;placing the end surface of said first tubular adjacent to the end surface of said second tubular;positioning a body of welding material between said adjacent end surfaces;arranging a welding device near said adjacent end surfaces and said welding material, which device is equipped with an internal mandrel, an external clamp mechanism, an external seal mechanism, and an inert gas injection mechanism;inducing the external clamp mechanism to press the end surfaces against the body of welding material such that the end surfaces of the tubulars are maintained in an accurately defined axially aligned position relative to each other;activating the external seal mechanism to create a sealed external chamber that surrounds the end surfaces of the tubulars and the body of amorphous material;activating the inert gas injection mechanism to fill the sealed external chamber with an inert gas;heating the body of welding material such that it melts and on cooling a metallurgical bond is created between the end surfaces of the tubulars;allowing the joined tubulars to cool down;releasing the clamp and seal mechanisms; andremoving the joined tubulars from the welding device; characterized in that the welding device is an amorphous bonding device which is equipped with an induction heating coil, that the body of welding material is a body of amorphous material which is heated by the induction coil and that the mandrel is equipped with axially spaced seals that are expanded against the inner surfaces of the oilfield tubulars to form a sealed internal annular chamber inside the tubulars which is filled with an inert gas during the step of inducing the heating coil to melt the amorphous material.