Abstract: The invention relates to the measurement of the ovalization of a ferromagnetic pipe.An electromagnetic pickup is moved in a circular path around the pipe, the pickup transmitting signals influenced by the radial distance between the pickup and the pipe. These signals are compared with signals from previous measurements made on a similar pipe to obtain indications of the radial distance between the pickup and the pipe so as to be able to deduce the transverse configuration of the pipe. The pickup is supplied with ac at a frequency of about 700 Hz and the signals from the pickup are compared with previously obtained signals both as to amplitude and phase.The pickup is mounted on a circular slide movable along a circular track supported on a U-shaped collar which is fixed to the pipe.

Abstract: The invention relates to an internal obturator for a pipe for use in separating two spaces inside a pipe. The obturator comprises a rigid hollow body comprising two end plates connected by a cylinder having a lesser diameter than the end plates between which an annular inflatable bladder of a jack is provided extending around the cylinder. The jack is inflated to apply a cylindrical wall against the inner surface of the wall of the pipe. The wall which is independent of the bladder of the jack may be connected by its ends to the end plates or may simply be inserted therebetween.

Abstract: The characteristics of a weld made by electron beam welding are improved by introducing into the region of the pieces to be welded, which is subjected to remelting during welding, a material which is obtained by applying an arc welding process, or a process for remelting under slag, to a mild or slightly alloyed steel. The introduction of the material into the region of the weld increases the production of acicular ferrite which increases the tensile strength of the weld. The material may be introduced by providing a deposit of it over part or the whole of the surface of one or both of the pieces to be welded, by introducing a mass of it between the surfaces to be welded or as a filler wire.

Abstract: A soft retaining gripper for gripping a surface while stresses are exerted in a longitudinal direction parallel to the surface between the gripper and the surface, comprises a jaw and an inflatable flexible bladder carried by the jaw, the bladder being in use inflated to grip the surface. To prevent creep of the gripper in use, a wall is associated with the bladder and extends between the bladder and the surface, the wall being made of a composite anisotropic material comprising elongate elements which are oriented to extend in the longitudinal direction and are practically inextensible and a flexible synthetic resin in which the elongate elements are embedded, the elongate elements being anchored to the jaw at at least that end in the direction of which creep might otherwise occur.

Abstract: The characteristics of a weld made by electron beam welding are improved by introducing into the region of the pieces to be welded, which is subjected to remelting during welding, a material which is obtained by applying an arc welding process, or a process for remelting under slag, to a mild or slightly alloyed steel. The introduction of the material into the region of the weld increases the production of acicular ferrite which increases the tensile strength of the weld. The material may be introduced by providing a deposit of it over part or the whole of the surface of one or both of the pieces to be welded, by introducing a mass of it between the surfaces to be welded or as a filler wire.

Abstract: In a process for electron beam welding, the electron beam welding gun is controlled to maintain the power absorbed by the pieces being welded substantially constant. In a preferred embodiment the intensity of the electron beam transmitted by the pieces being welded, which corresponds to the power absorbed, is measured, compared with a preset intensity and the difference used to control the focussing current supplied to the gun to maintain the intensity of the transmitted beam constant.

Abstract: In the positioning of an additional tubular element, e.g. a pipe section, on a tubular structure, e.g. a pipe-line in the course of immersion, where the end surfaces to be brought into contact are not in radial planes, the additional element is brought in alignment with the structure and at a short distance from the latter. The end surfaces of the element and structure are then brought into contact, the contacting ends are centered, and a compressive force is applied to them in such a way that the element can pivot about the point of contact between the element and the structure until its end surface is brought into complete contact with the end surface of the structure.

Abstract: In the positioning of an assembly of work tools which are required to operate in the plane of the end face of a tubular structure, which is not necessarily orthogonal to the axis of the structure, a theoretical end face is determined by three sensing arms spaced apart by 120.degree., which, by an axial translatory movement followed by two pivotal movements about axes parallel to lines joining pairs of the arms, is brought into coincidence with the actual end face of the structure, then the plane of operation of the tools is brought into coincidence with the plane of coincidence of the theoretical and actual end faces.The work tools may for example be electron beam welding guns for welding an additional tubular element to an existing tubular structure.

Abstract: An inflatable seal comprises a flexible active part and a rigid part which together define a chamber to be pressurized to place the active part in its operative position and to be evacuated to place the active part in its inoperative position, the active part being made from a composite material comprising an elastic material in which a wide deformable mesh of fibers of low extensibility is incorporated such that the active part has anisotropic elasticity and mechanical strength sufficient to withstand the differential pressures extend thereon in its operative and inoperative positions without the need for external reinforcements.