Abstract: The invention concerns a steel tube threaded joint particularly useful in the petroleum industry of the type in which the male element (3) and female element (1) are combined by threading (2, 4) wherein a portion of the surface of each thread is forcefully applied to the status of screwing to the thread of the outer element. A first element (1) of the joint has a composite structure and has on at least a certain length of its thread a lining of synthetic material whose volume and shape correspond exactly to the volume and shape of the existing clearance of the screwing status between the metal part and composite element (1) and the second element (3) having dimensions at the limit of the machining tolerances which allow the greatest possible clearance in the assembled state of the joint.

Abstract: A threaded joint for steel pipes useable in particular for the petroleum industry is provided. The joint is formed by threaded male and female elements wherein one part of the thread of a first element is strongly applied against the thread of the other element. One of the elements contains a groove having a length of at least one thread pitch and a depth greater than the height of the threads. A sealing device is provided in the groove consisting of a synthetic lining whose volume and shape essentially correspond to the volume and shape of the play that would exist between the threads of the elements.

Abstract: The invention concerns a process for machining a joint element for steel tubes, intended in particular for the petroleum industry, containing a truncated surface (2) and at least one screw stop.

Abstract: The present invention concerns a new threaded joint for steel tubes, usable in particular in the petroleum industry, which contains a female element equipped with conical threads having an internal screw stop mating and a male element correspondingly threaded with a screw stop having a form corresponding to the female element. The male element stop and the female element stop are each manufactured by cold working using a tool capable of engaging in or on the threads of the corresponding element.

Abstract: The invention provides a process for the determination of the make-up torque to be applied on a joint for pipe, destined to the petroleum industry according to which a reference mark is set on the male element and on the female element, so that when the two reference marks are brought to face each other, the make-up restriction stops (2) on the male element (1) and on the female element come into contact with each other; that after having applied a grease, we proceed to make-up by applying sufficient torque to cause one element to rotate with respect to the other one, at a predetermined angle beyond the point where the reference marks are facing each other, and we proceed to measure the torque; that this operation is repeated on a sufficient number of joints; and that a determination is made of the range of torques to be applied on the joints of this type with the grease that has been used.

Abstract: A method and device for ensuring correct assembly of screwed pipejoints having at least one stop. During assembly the screwing torque is measured continuously, the value of the second differential of the screwing torque is determined uninterruptedly, and the maximum of this second differential is checked to exceed a predetermined value.The device includes in combination: a means of converting into electric voltage the value of the tightening torque applied at every instant during the assembly of the joint, an electronic device for carrying out the calculation of the second differential of the curve of electric voltage so measured, and a device enabling the value of this second differential to be compared with a reference value for giving a signal when the maximum of the second differential exceeds or does not exceed the reference value.

Abstract: Joint for pipes of the type in which an end of a male member (1) provided with a thread is screwed into a female member (2) having a corresponding thread.On its outer surface, the male member has a circumferential groove (9) and on the inner surface the female member has a circumferential groove (10) which, in the screwed position, faces the groove of the male member. A spring ring (12) is provided to simultaneously engage in the said grooves. At least one of the grooves has an adequate radial depth to permit the retraction of the spring ring when the male member is engaged in the female member.