Basic Pipe ConstuctionDeepFlex pipes are made using polymer liners, membrane extrusions and protective jackets that provide smooth, chemically resistant conduits for fluid transport. These are surrounded by combinations of large section hoop and tensile reinforcements that offer resistance to both internal and external pressure as well as additional structural integrity to cope with imposed loads such as tension and bending. A typical construction is illustrated below.Order of Construction |
- Liner extrusion (primary fluid conduit)
- Application of large section torque balanced helical windings of composite pressure reinforcement splines separated by low friction polymer tapes
- Application of composite hoop reinforcement helix separated by low friction polymer tapes
- Extrusion of the Membrane (anti-collapse fluid barrier)
- Application of winding of additional tensile reinforcements required by installation and other loads
- Extrusion of protective jacket and application of markings.
|
click for an enlarged image |
|
Liner ExtrusionPipe liners are generally thermoplastic polymers which are extruded and sized by a machined die to meet dimensional requirement. Typical polymers for liners are HDPE, PA-11, PA-12, and PVDF. Gas permeating through the liner of the pipe that collects in the annulus between this tubular extrusion and the extruded membrane is vented through check valves located in the flexible pipe topside termination.
|
Pressure ReinforcementPressure reinforcement is typically comprised of two contra-helically wound, large rectangular section wraps of composite material applied as a bonded stack of pre-cured composite tape. These layers are wrapped at opposing angles to support both circumferential and longitudinal forces generated by internal pressure in the liner. The construction of these layers also allows for better gap control and, therefore, support for the liner than hoop wound carcasses. The designer optimizes this design for material usage, low elongation and torque. The layer is protected from seawater and abrasion by polymer tapes.
|
Hoop ReinforcementHoop reinforcement normally comprises one or more thick helically wound rectangular section wraps of composite material. This reinforcement layer is wound at an angle to withstand both radial and longitudinal compressive loads generated by hydraulic or other specified pressure on the membrane extrusion. This layer is protected in the same manner as the pressure reinforcement layers..
|
Membrane ExtrusionThe membrane extrusion is a thermoplastic extrusion designed to seal against the compressive loads generated by external seawater pressure. Not only does it act as a barrier to external water pressure, but it also provides a slip surface for reinforcements.
|
Tensile ReinforcementTensile reinforcement normally comprises two contra-helically wound rectangular section wraps of composite material laid at angles suitable for carrying tensile loads other than those generated by internal pressure.
|
External JacketThe external jacket is a thermoplastic extrusion designed to provide for the pipe, a degree of protection from incidental damage. It also serves as the surface used for monitoring twist and identifying the pipe. A typical marking is a repeating legend in the form of a printed contrasting color "lay-line".
|
TerminationsDeepFlex terminations rely on well-proven “rope-capping” methods used extensively in lifting slings and umbilical terminations. Steel housings are generally used to enable good interfacing with third party equipment and, using a resin fill system, the helical reinforcements in the pipe are bonded into an internal taper forming a mechanical wedge. Pipe reinforcement materials are very compatible with the resins used to secure them in the terminations thereby eliminating most of the problems associated with similar assemblies on steel pipe systems. Seals and mechanical locks on extrusions are pressure and tension actuated accounting for differences between modulii, creep and temperature performance of the materials used. All DeepFlex pipes are verified with terminations attached and certified prior to dispatch. The materials from which they are constructed is traceable.
|
)