Abstract: A seismic streamer comprises a substantially solid core having many of the main components of the streamer, namely hydrophones, electronics modules for digitising the outputs of the hydrophones, the main optical and electrical conductor bundles and Keviar strength members, embedded in it. The core also contains a large number of foam buoyancy elements. An outer skin surrounds the core, defining an annular gap around the core, and this annular gap is filled with open-celled polyurethane foam saturated with kerosene. The capsules containing the hydrophones communicate with the annular gap around the core, so that the kerosene can enter the capsules, each of which contains an open-celled polyurethane foam sheath to cushion the hydrophone. In an alternative construction, made possible by using the buoyancy elements in the core to render the core approximately neutrally buoyant in water, the outer skin and the polyurethane foam are omitted, and the core is used on its own as a solid streamer.

Abstract: In a method for forming an end portion of a plastic pipe wherein the end portion is transferred to softened state and the end portion is provided with an internal groove by axially displacing the pipe end portion in relation to a mould ring which is thereby introduced into the pipe end portion. After the forming of the pipe end portion the mould ring is left in the pipe end portion for forming a sealing ring therein. During the forming operation the pipe end portion is supported on a mandrel. In accordance with the invention the mould ring is displaced into the pipe end portion by displacing the ring along the mandrel while the pipe end portion is in its softened condition supported by the mandrel substantially without being displaced along the mandrel.

Abstract: An apparatus for forming an end portion of a plastic pipe wherein the end portion is transferred to softened state and the end portion is provided with an internal groove by axially displacing the pipe end portion in relation to a mould ring which is thereby introduced into the pipe end portion. After the forming of the pipe end portion the mould ring is left in the pipe end portion for forming a sealing ring therein. During the forming operation the pipe end portion is supported on a mandrel. In accordance with the invention the mould ring is displaced into the pipe end portion by displacing the ring along the mandrel while the pipe end portion is in its softened condition supported by the mandrel substantially without being displaced along the mandrel.

Abstract: A mould and sealing ring constitutes a mould element in forming a socket end on a pipe consisting of thermoplastic material and seals the space in a pipe joint between the socket end and the spigot end of a pipe introduced into the socket end. The mould and sealing ring comprises an annular sealing portion consisting of elastically yieldable sealing material and a second substantially annular portion for reinforcing the mould and sealing ring consisting of a material which is rigid in relation to said elastically yieldable material and is connected with the elastically yieldable material at a connection surface.

Abstract: Reinforced sealing ring for reception in a pipe joint between an annular groove-carrying socket end and an insert end. The sealing ring consists of a main body of rubber in which there is embedded an upsplit steel ring. The sealing ring is adapted to be elastically deformable to such a degree that it can be snapped into place in the annular groove of the socket end by a simple mounting operation while it can be prevented from being torn or pressed unintentionally outwards from the annular groove after mounting. In order to achieve this the main body has a largest external diameter of between 1.08D+16 mm and 1.04D+8 mm, while the cross-sectional diameter or thickness of the steel ring is between 0.01D+2 mm and 0.005D+1 mm, where D constitutes the diameter of the pipe. The steel ring is disposed embedded in a central and/or radially outer cross-sectional portion of the main body.

Abstract: The mandrel uses a single anchoring groove in order to fixedly mount the forming and sealing element thereon for subsequent passage of a heated thermoplastic pipe end thereover. The forward wall of the anchoring groove may be directed radially outwardly or may be inclined rearwardly in order to abut the sealing portion of the element. The sealing portion fills the anchoring groove while the trailing wedge-shaped end fits into a small recess to avoid "fish-mouthing.

Abstract: Combined mould and sealing element suitable for sealing off a joint between a socket end and an insert end of two cooperating pipes formed from a thermoplastic material and for being used as a portion of a body of a mould for both fabricating said socket end of the one pipe and simultaneously inserting said element in an internal groove in the socket end produced thereby. The element consists of a main body of annular form composed of an elastically yielding material housing a reinforcing core of relatively non-elastic material capable of retaining its shape relative to the main body. The main body has a radial outer portion which in its active condition is adapted to abut the bottom of the internal groove and in its inactive condition projects outwardly as a flap. Between the flap and an inner and opposing portion of the main body there is formed an opening dimensioned to facilitate ready introduction and housing of the core.

Abstract: Combined mould element and sealing ring suitable for sealing off a joint between a socket end and an insert end of two cooperating pipes formed from thermoplastic material and for being used as a portion of a body of a mould for both fabricating the socket end of the one pipe and simultaneously inserting the ring in an internal groove in the socket end produced thereby. The main bulk of the sealing ring is composed of elastically yielding material having within its contour at least one zone composed of relatively non-elastic material capable of rendering the zone stable as regards its shape compared with the remainder of the ring. Conveniently, such zones are formed by stiffening rings permanently connected to the main bulk of the sealing ring.

Abstract: Method of bending thermoplastic pipes involving applying a source of heat to those portions of the pipe which are to be fashioned or shaped, applying a bending force to the pipe and cooling the bent pipe. The steps of the method are undertaken at one and the same location while the pipe is internally supported and has one end secured in a fixed position. Apparatus specifically designed to carry out such a method is also included.

Abstract: The combined mold element and sealing ring is formed of an elastically yieldable body and a rigid reinforcing non-elastic member within the body on a side spaced away from the leading edge of the body. The unit may be generally drop-shape, or otherwise, and is formed with minimal bulk.Positioning of the reinforcing member close to the outer radial portion of the elastic body reduces the manufacturing costs of the combined element as the bulk of the element may be reduced and the positioning of the rigid member in the rubber molds is facilitated. The reduced bulk also facilitates the molding of a thermoplastic pipe end over the unit to form a socket by reduced stretching of the pipe.The positioning of the rigid ring member also facilitates the anchoring effect of the combined element when used in a pipeline with internal pressure.

Abstract: Combined mould element and sealing ring suitable for sealing off a joint between a socket end and an insert end of two cooperating pipes formed from thermoplastic material and for being used as a portion of a body of a mould for both fabricating the socket end of the one pipe and simultaneously inserting the ring in an internal groove in the socket end produced thereby. The main bulk of the sealing ring is composed of elastically yielding material having within its contour at least one zone composed of relatively non-elastic material capable of rendering the zone stable as regards its shape compared with the remainder of the ring. Conveniently, such zones are formed by stiffening rings permanently connected to the main bulk of the sealing ring.

Abstract: Method of bending thermoplastic pipes involving applying a source of heat to these portions of the pipe which are to be fashioned or shaped, applying a bending force to the pipe and cooling the bent pipe. The steps of the method are undertaken at one and the same location while the pipe is internally supported and has one end secured in a fixed position. Apparatus specifically designed to carry out such a method is also included.