Method of forming a conduit

Abstract

A method of continuously forming heated conduit includes performing a tape for winding onto a spiral pipeline former. At least one conductor is positioned adjacent to the centreline of and parallel with a thin polymer ribbon. The ribbon is folded in half to encapsulate the conductors. The folded ribbon is thermally welded to itself. The folded, welded, ribbon is passed through a creaser, which forms a crease midway across the folded ribbon. The creased pre-formed ribbon is formed into a conduit in a continuous process on a spiral pipeline former.

1 . A method of continuously forming conduit comprising:
 providing a thin polymer ribbon,   heating said ribbon to soften said ribbon, and forming a crease approximately midway across said ribbon, said crease being substantially parallel with said ribbon,   supplying said creased ribbon having “leading” and trailing” lateral edges, spirally around a former with the leading edge of each turn of ribbon overlapping the trailing edge of a previous turn of ribbon on the former and the trailing edge of each turn underlapping the leading edge of a succeeding turn,   said former and rotating and advancing said conduit, and   applying a bead of molten plastic material to said lapping edges of adjacent turns of ribbon, such that said bead welds said adjacent edges of said ribbon and forms a helical reinforcement to said conduit when cooled.   
   
   
       2 . A method according to  claim 1 , wherein said crease is formed by passing said film through at least one set of crease rollers,
 said crease rollers in a creasing region shaped according to the profile of said crease.   
   
   
       3 . A method according to  claim 1 , wherein said crease is substantially ‘v-shaped’ in cross section. 
   
   
       4 . A method according to  claim 1 , wherein said crease is substantially arcuate in cross section and said crease has a width substantially spanning the distance between adjacent turns of said helical reinforcing bead. 
   
   
       5 . A method according to  claim 3 , wherein said crease is located approximately midway between adjacent turns of said helical reinforcing bead. 
   
   
       6 . A method according to  claim 4 , wherein said crease is located approximately midway between adjacent turns of said helical reinforcing bead. 
   
   
       7 . A method according to  claim 1 , wherein said thin polymer ribbon includes at least one integral electrical conductor. 
   
   
       8 . A method according to  claim 3 , wherein said crease faces outwards with respect to said conduit. 
   
   
       9 . A method according to  claim 4 , wherein said crease faces outwards with respect to said conduit. 
   
   
       10 . A method according to  claim 1 , wherein said bead of molten plastic material has a concave underside that is applied to said lapping edges. 
   
   
       11 . A method according to  claim 1 , wherein said bead of molten plastic material has indented sides located toward the base of said bead. 
   
   
       12 . A method according to  claim 10 , wherein said bead of molten plastic material has indented sides located toward the base of said bead.