Patent EA-003755-B1 (EA)
Title: Method and device for joining oilfield tubulars
Inventor: BLIAULT ALAN EDGAR JOHN
IPC: B23K13/02
Filed: 1998-02-03
Abstract: 1. A method for joining oilfield tubulars, the method comprising the steps of: - positioning a body of welding material (16) between adjacent end surfaces of a pair of oilfield tubulars (3,4) that are to be joined; - arranging a welding device near said end surfaces, which device is equipped with an internal mandrel (1) and external clamp (11,12), seal and inert gas injection mechanisms (5,6,17); - inducing the external clamp mechanism (11,12) to press the end surfaces against the body of welding material (16) such that the end surfaces of the tubulars (3,4) are maintained in an accurately defined axially aligned position relative to each other; - activating the external seal mechanism (5,6) to create a sealed external chamber (17) that surrounds the end surfaces of the tubulars (3,4) and the body of amorphous material (16); - activating the inert gas injection mechanism (7) to fill the sealed external chamber (17) 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; and - removing 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 (14,15) 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. 2. A device for joining oilfield tubulars comprising: - an external clamp mechanism (11,12) and a mandrel (1) that is insertable into the interior of the tubulars (3,4), to press the end surfaces against a body of welding material (16) between the tubulars such that the end surfaces are maintained in an accurately defined axially aligned position relative to each other; - an external seal mechanism (5,6) for creating a sealed external chamber (17) that surrounds the end surfaces and the body of welding material (16); - an inert gas injection mechanism (7) for filling the sealed external chamber (16) with inert gas; - means for heating the body of welding material (16) such that it melts and on cooling a metallurgical bond is created between the end surfaces of the tubulars (3,4); and - means for moving the tubulars (3,4) into and from the device; characterized in that the device is an amorphous bonding device which is equipped with an induction heating coil (9) and that the mandrel (1) is equipped with axially spaced seals (14,15) that are in use expanded against the inner surfaces of the oilfield tubulars (3,4) to form a sealed internal annular chamber inside the tubulars during the amorphous bonding process. 3. The method according to claim 1, wherein the oilfield tubulars are well tubulars and the method comprises the steps of: - lowering the first tubular element (3) into a well until the upper end of the element is located in a substantially vertical orientation near the entrance (20) of the well, - hoisting the second tubular element (4) to a substantially vertical position above the first tubular element, - positioning the body of amorphous material (16) between the adjacent end surfaces of the first and second tubular element (3,4), - fixing the tubular elements (3,4) in axial alignment with each other using the external clamp mechanism (11,12) and the internal mandrel (1) which is inserted into the interior of the first and second tubular element (3,4), - placing the induction coil (9) and seal mechanism (5,6,14,15) adjacent the end surfaces to be joined, - flushing the area to be joined with an inert gas, - inducing the external clamp mechanism (11,12) to press the end surfaces of said tubular elements (3,4) against the body of amorphous material (16) to ensure intimate contact between said end surfaces and the body of amorphous material (16), - activating the induction coil (9) to melt the amorphous material (16) and create a metallurgical bond between the tubulars elements (3,4), - releasing the clamp (11,12) and seal mechanisms (5,6,14,15), and - lowering the interconnected tubular elements (3,4) into the well. 4. The method of claim 3 wherein a non-destructive method is used for testing of the bond, which test method includes pumping inert gas at elevated pressure into a sealed annular sealing chamber (17) formed adjacent to the location of the bond and monitoring whether any leakage of inert gas from the chamber (17) occurs. 5. The method of claim 3 wherein before and during the step of induction heating of the amorphous material (16) the mandrel (1) is placed inside the tubular elements and clamped against their internal surfaces by means of a pair of internal clamps (14,15) that are expanded against these surfaces at locations opposite to the locations where a pair of external clamps (11,12) of the device are positioned. 6. A device for joining oilfield tubulars for use outside a hydrocarbon production well, comprising an external clamp mechanism (11,12) and a mandrel (1), that is insertable into the interior of the tubulars (3,4) to press the end surfaces against a body of welding material (16) between the tubulars such that the end surfaces are maintained in an accurately defined axially aligned position relative to each other, an external seal mechanism (5,6) for creating a sealed external chamber (17) that surrounds the end surfaces and the body of welding material (16), means for heating the body of welding material (16) such that it melts and on cooling a metallurgical bond is created between the end surfaces of the tubulars (3,4) and - means for moving the tubulars (3,4) into and from the device, wherein the device is equipped with an induction heating coil (9) with axially spaced seals (14,15) that are in use expanded against the inner surfaces of the oilfield tubulars (3,4) to form a sealed internal annular chamber inside the tubulars during the amorphous bonding process, and an inert gas injection mechanism (7) for filling the sealed external chamber (16) with inert gas. 7. The device of claim 2 wherein the mandrel (1) is at its upper end connectable to a hydraulic hoisting line (13).