Abstract: The method and the apparatus relate to the detection of faults in the wall of a passing metal tube. A solenoid or solenoids generate two alternating magnetic fields of different frequenceis, the frequencies being chosen from the range of medium and high frequencies, in order to produce in the wall of a tube eddy currents which interact with the faults. The signals resulting from these interactions are detected by at least one detection solenoid and each difference in amplitude D between the signals obtained at the two frequencies for one and the same fault is compared with a specific difference which constitutes a threshold for rejection of the corresponding tube. Application of the method and of the apparatus to the inspection of ferrous or non-ferrous magnetic and non-magnetic metal tubes.

Abstract: The anti-seizing coating according to the invention relates to the protection of the surfaces of male (7) or female (2) components of an assembly means (1) for metal tubes by threadings coming into contact with one another at the time of screwing.This coating is constituted by a thin lead oxide layer (14) produced by the oxidation of a lead layer, which is itself formed on an underlying layer (13) of a metal such as copper and which has been directly or indirectly deposited beforehand on the surface (4, 5, 9, 10, 11, 6) to be protected against seizing. The invention also relates to the process for producing this coating and the coated assembly means obtained.

Abstract: The assembly arrangement according to the invention concerns the tubes which are used primarily in oil industry installations. It permits the sealing assembly of a male end to a female end, each provided with frustoconical screwthreads.The end region of the male component comprises a convex frustoconical sealing surface for providing a metal-metal sealing connection with a surface of the female component, the internal edge of which is connected to the concave frustoconical abutment region and the external edge of which is connected to the external surface of the end region, having a portion parallel to the generatrix which is tangential to the bottom of the threads of the male screwthread. The diameter of the external edge is such that the prolongation of the generatrix which is tangential to the thread bottoms of the male screwthread passes beyond said external edge.Use for the assembly of tubes with male ends by means of female sleeves.

Abstract: A process for the in-ladle treatment of liquid steels by injecting gas through the ladle bottom. The process comprises injecting at least one inert gas from locations which are distributed over the ladle bottom in such a way as to form at the surface of the liquid steel an annular swelling, the outside edge of which is close to the inside edge of the lining of the wall of the ladle. An oxidizing gas may be mixed with the inert gas for decarburization. The process is applied in particular to the treatment of carbon steels.

Abstract: The device of the invention introduces cooling fluid to a rotary mould (41) surrounded by an annular cooling chamber (42). A non-rotatable annular box surrounds the outer wall of the annular chamber, and two annular nozzles (50, 51) rigid with the box (47) discharge in each case into an annular passage (57, 58) disposed between the outer wall and at least one non-rotatable wall rigid with the box. The fluid from the nozzles, after passing through the annular passage (57, 58), passes through an annular inlet zone (46), and through orifices (44, 45) into the annular cooling chamber (42).