Method of manufacturing a reinforcement element for a flexible pipeline

Abstract

For use in the manufacture of reinforcement layers for flexible pipes which are capable of absorbing compressive or tensile forces, and which are used for the transport of oil and gas, a thermoplastic material is applied to a strength-imparting layer. The strength-imparting layers are reeled on reels, and following unreeling they are laminated by application of heat and in direct continuation applied to the flexible pipe. The strength-imparting layer expediently consists of a polymer which is reinforced with at least 20% by volume of fibres. The thermoplastic material is of a reversible type, i.e. it may change from being relatively soft, but non-sticky by changes in temperature. The use of the method according to the invention allows manufacture of very strong reinforcements for flexible pipes which cannot be manufactured using a solid material, such as steel, since high preforming bending forces are required in the shaping. In addition, a reinforcement element is provided which is capable of resisting instantaneous shock loads as the thermoplastic material is protective.

1 . A method of manufacturing a precursor for a reinforcement element for a flexible pipeline, wherein said precursor comprises one strength-imparting layer, said method comprising the step of applying a thermoplastic layer to the strength-imparting layer, on at least one face thereof, said strength-imparting non-thermoplastic layer preferably being non-thermoplastic.  
     
     
         2 . A method of manufacturing a reinforcement element for a flexible pipe-line, wherein said reinforcement element comprises two or more strength-imparting layer(s), said method comprising the steps of applying a thermoplastic layer to at least one of the strength-imparting layer, on at least one face thereof, followed by a lamination with another strength-imparting layer, said strength-imparting non-thermoplastic layer preferably being non-thermoplastic.  
     
     
         3 . A method according to  claim 2 , wherein at least two strength-imparting layers are combined by a lamination process to form a reinforcement element, and heat is supplied to the strength-imparting layers during the lamination process.  
     
     
         4 . A method according to any one of the claims  2 - 3 , wherein the reinforcement element has at least two strength-imparting layers, preferably the reinforcement element has a plurality of strength-imparting layers, and a thermoplastic material is applied to the adjoining faces of at least one of the two strength-imparting layers.  
     
     
         5 . A method according to any one of the claims  2 - 4 , wherein the thermoplastic material is cross-linked after the lamination step, whereby it changes its state from being thermoplastic to being thermosetting.  
     
     
         6 . A method according to any one of the claims  2 - 5 , wherein an energy-dissipating layer is applied to at least one of the outer surfaces of the reinforcement element.  
     
     
         7 . A method according to any one of the claims  2 - 6  comprising the step of reeling the reinforcement element onto a reel, under circumstances where the thermoplastic material is sufficiently soft to adapt to the form provided during the reeling so that the reinforcement element obtains a shape which includes a curvature, said shape preferably corresponding to the final curvature of the reinforcement layer.  
     
     
         8 . A method according to any one of the claims  2 - 7 , wherein said strength-imparting layers are in the form of a polymer reinforced with at least 20% by volume of fibres or whiskers.  
     
     
         9 . A method according to  claim 8  wherein said fibers are carbon fibres, said fibres being reinforcement fibres.  
     
     
         10 . A method according to any one of the claims  2 - 9 , wherein said strength-imparting layers are in the form of a fully or partly metallic material used as a strength imparting layer.  
     
     
         11 . A method according to claims  2 - 10  further comprising the application of the reinforcement element to a flexible pipe, which method comprises the steps of: 
 manufacturing a plurality of flat profiles of a fibre-reinforced thermosetting polymer in a pultrusion process  
 applying a thermoplastic polymer material, e.g. having a thickness of 200 μm, to at least one of the faces of the flat profiles  
 reeling the flat profiles onto reels  
 unreeling the flat profiles, and then laminating them during application of heat  
 in immediate continuation of the lamination process, winding the flat profiles on the flexible pipe, which now constitutes a reinforcement element for the flexible pipe.  
 
     
     
         12 . A precursor for a reinforcement element for a flexible pipeline, which precursor comprises a strength-imparting layer comprising two major faces having on at least one of its major faces a layer of a thermoplastic material, said strength-imparting non-thermoplastic layer preferably being non-thermoplastic.  
     
     
         13 . A reinforcement element for a flexible pipeline, which reinforcement element comprises two or more strength-imparting superimposed layers, said two or more strength-imparting superimposed layers being fixed to each other by intermediate layer or layers of thermoplastic material, said strength-imparting non-thermoplastic layer preferably being non-thermoplastic.