Abstract:
Interconnecting two insulation sheathed conductors in subsea environments is done using a subsea connector including a metal conductor splice pin arrangement and a splice insulation sleeve. A metal tube is placed over the splice insulation sleeve. The conductor insulation sheaths are molded to respective opposite sides of the metal tube.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and means for interconnecting two insulated conductors in subsea environments and in particular for use with conductors having non-compatible insulation material such as PE and a rubber. 
     2. Background Information 
     High water pressures and with time it is difficult and nearly impossible to prevent water from entering joint compartments. One entrance to a joint compartment is along the cable conductor underneath the conductor insulation. Remedies have been proposed for filling all spaces within a multifilament conductor and good effects have been obtained at low outer water pressure. 
     In conventional joints the whole joint is covered with a common insulation sleeve. The problem is however to obtain sufficient bonding between the conductor insulations and the common insulation sleeve. When the two conductors to be jointed have identical or compatible insulation sheaths, sufficient bonding will be obtained with a common joint sleeve. This is, however, not possible when one conductor has PE insulation and the other has rubber (e.g. Hypalon, Neoprene) insulation. 
     SUMMARY OF THE INVENTION 
     One object of this invention is to improve subsea cable conductor joints. In particular the object is to improve an interconnection between the conductor insulation of an umbilical cable and the conductor insulation of the interfacing subsea equipment according to the invention. With a conductor joint as defined there is obtained a unique waterproof connection between two insulated conductors, in particular between conductors having sheaths of different insulation material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Above mentioned and other features and objects of the present invention will clearly appear from the following detailed description of embodiments of the invention taken in conjunction with the drawing which shows a splice between conductors schematically. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the figure is schematically illustrated a splice or joint 1 between two conductors 2 and 3 having insulation sheaths 4 and 5. The conductor insulation 4 is polyethylene (PE) which is commonly used in umbilical cables and the conductor insulation 5 may be Hypalon, Neoprene or some other suitable rubber material which is used for wiring within offshore installations. 
     As mentioned the main object of the invention is to provide a waterproof splice between a PE insulated conductor and a conductor with a rubber (e g Hypalon, Neoprene) insulation. A secondary object is to prevent water which may have entered the umbilical cable and the PE conductor insulation from entering the offshore installation. The two conductors 2 and 3 are therefore joined with a splice pin arrangement 6 and 7 so that water within the multifilament conductor 2 cannot penetrate to the multifilament conductor 3. 
     The splice pin arrangement 6,7 which is preferably made of brass is covered by an insulator 8 of, for example, glass fiber reinforced epoxy material. Part of the outer surface of the pin arrangement 6,7 is provided with grooves 18,19 in order to provide good bonding to the joint compounds. Over the insulator 8 there is arranged a tube 9 of metal such as stainless steel. The tube 9 is advantageously provided with corrugated outer surfaces 10,11 in order to obtain good bonding and increase the bonding surface to the insulation material used in the joint. 
     In the case where the two conductors have different conductor insulation, it may be necessary to pretreat the surface of the pin 6 and the surface 10 of the tube 9 up to the flanged section, differently from the treatment of the surface of the pin 7 and the surface 11 of the tube 9. Low density polyethylene is baked into the surface on the PE side of the tube and pin, whereas the rubber side of the tube/pin is treated with a two component primer compatible with the rubber. 
     Application of joining compounds may involve heating to different temperatures and one feature of the invention is therefore to separate the surfaces 10 and 11 by a partition 12. The partition 12 can have a U-shaped cross-section including an airspace 15 between two partition walls 16,17 for separating the two sheath moldings 13,14. 
     The PE sheathed conductor 2,4 is molded to the surface of the pin 6 and to the corresponding side of the tube 9 by using a compound consisting 13 of low density polyethylene which is applied at a temperature of some 180° C. for a period of some 10 minutes after a soaking period. 
     The rubber sheathed conductor 3,5 is molded to the surface of the pin 7 and to the corresponding side of the tube 9 by using a compound 14 consisting of a compatible rubber compound which is applied at a temperature of 150°-170° C. for a period of 30 to 60 minutes. 
     The PE sheathed conductor 2,4 which requires higher molding temperature, is molded to the tube/pin 9,6,7 prior to molding of the rubber sheathed conductor 3,5 in order to prevent melting of the insulation material. This problem is also minimized by the unique design of the partition of the tube 9. 
     With such a design of the joint, the insulation 4 of the conductor 2 may be bonded or molded to the pretreated surface 10 of the tube 9 with an insulation compound 13 which is compatible with the material 4 (and not with the insulation material 5). The arrangement can be similar on the other side of the joint where insulation compound 14 compatible with the insulation material 5 is bonded or molded to a pretreated surface 11 of the tube 9. 
     The molding compounds 13 and 14 must also be capable of bonding to the pretreated surfaces of the splice pin arrangement 6,7.