A method of producing a tube arrangement, in which a first tube is joined with a second tube, said tubes (1, 4) being metal tubes, wherein said method comprises the following steps: a) providing an end region of the first metal tube with a first outer threading; b) providing an end region of the second metal tube with an second outer threading; c) providing a first sleeve part made of metal with a first inner threading; d) providing a second sleeve part made of metal with a second inner threading; e) positioning the first metal sleeve part on the first metal tube by screwing said first metal sleeve part onto the first outer threading of the first metal tube; f) positioning the second metal sleeve part on the second metal tube by screwing the second metal sleeve part onto the second outer threading of the second metal tube; g) moving the ends regions (3, 6) of the first and second metal tubes (1, 4) into contact with each other; h) butt welding together from the outside the end regions (3, 6) of the first and second metal tubes (1, 4); i) bringing together the first and second metal sleeve parts (8, 10) by screwing at least one of said metal sleeve parts (8, 10) on the outer threading (2, 5) of its associated tube (1, 4); j) butt welding together from the outside the opposed ends of the first and second metal sleeve parts (8, 10); wherein in step g) the first and second metal sleeve parts (8, 10) are positioned such that a joint between the first and second metal tubes (1, 4) is accessible from outside, wherein the first and second metal sleeve parts are separated from each other in the axial direction of the first and second metal tubes, thereby exposing between them, the joint between the first and the second metal tubes and making said joint accessible from outside, and wherein before step a) or before step f), at least one of the first and second metal tubes (1, 4) is subjected to a treatment whereby said end region (3, 6) is provided with a larger outer diameter and a larger wall thickness than an adjacent part of the corresponding tube (1, 4). a) providing an end region of the first metal tube with a first outer threading; b) providing an end region of the second metal tube with an second outer threading; c) providing a first sleeve part made of metal with a first inner threading; d) providing a second sleeve part made of metal with a second inner threading; e) positioning the first metal sleeve part on the first metal tube by screwing said first metal sleeve part onto the first outer threading of the first metal tube; f) positioning the second metal sleeve part on the second metal tube by screwing the second metal sleeve part onto the second outer threading of the second metal tube; g) moving the ends regions (3, 6) of the first and second metal tubes (1, 4) into contact with each other; h) butt welding together from the outside the end regions (3, 6) of the first and second metal tubes (1, 4); i) bringing together the first and second metal sleeve parts (8, 10) by screwing at least one of said metal sleeve parts (8, 10) on the outer threading (2, 5) of its associated tube (1, 4); j) butt welding together from the outside the opposed ends of the first and second metal sleeve parts (8, 10);