World-class welding technologies - Subsea 7

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08 Mechanically lined pipe extends reach Subsea 7’s ground-breaking development work into the installation of mechanically lined pipe has recently been undergoing further qualification following the world’s first contract award to use BuBi ® mechanically lined pipe installed by the reel-lay method for the Guará and Lula NE pre-salt project in Brazil. Working in collaboration with BuBi ® manufacturer BUTTING, Subsea 7 has already qualified BuBi ® mechanically lined pipe for reel-lay installation for flowlines and low-fatigue riser applications globally as a cost-effective alternative to solid corrosion-resistant alloys or metallurgically clad pipe. We are now broadening the product’s applications into areas of higher pressure and fatigue applications. Current testing has demonstrated higher fatigue performance to DNV class C/2 at the time of print to extend the applicability of the technology to even greater water depths and more challenging design criteria. The rigorous fatigue testing programme included: • Manufacture of three test strings (12 girth welds) comprising carbon steel grade X65 for the outer pipe and alloy 625 for the liner, made up of BuBi ® pipe sections welded together using the mechanised PGTAW process (see page 3) with alloy 625 filler metal • A conservative cyclic bending test or reeling simulation, using a radius of curvature of 7.5m • Resonance fatigue testing of the string post-reeling simulation. The endurance of the pipe and its welds was thus confirmed to achieve the minimum target level of fatigue class C/2. DEEP7 May 2012 The full programme was performed in accordance with DNV Qualification (DNV- RP-A203) and was previously awarded the certificate for ‘fitness for service’. An extensive NDE validation programme was conducted between Subsea 7 and BUTTING to qualify the inspection technology (DNV) and demonstrate the capacity to detect any minute defects in the pipe end overlay welds and seal weld at the transition between liner and overlay. The combination of the high-quality manufacturing process and inspection technology is fundamental to ensure the in-service reliability of the technology. Subsea Hydrocarbon Sampling Skid (SHSS) Following the successful development of its Subsea Hydrocarbon Sampling Skid (SHSS), Subsea 7 is now able to offer clients ROVdeployed sampling from live production wells with zero emissions to the environment while maintaining full isothermic and isobaric conditions. Hydrocarbon samples are required in order to determine fluid chemistry to enable calibration of the subsea flowmeter and potential fiscal allocations. The Subsea 7 SHSS takes a true sample with no need to alter production flow or temperature. It also takes samples from individual wells before they are mixed together at manifold or FPSO, and enables production samples or gases from individual wells to be analysed independently. The Welding Institute (TWI) Fatigue Test Rig S-N curves showing the number of fatigue cycles reached to date on three test strings (RF1, RF2, RF3). No failure of the pipe or liner seal welds has been recorded at the DNV class C. For further information contact gregory.toguyeni@subsea7.com The skid comprises the following key elements: • A number of sampling cylinders allowing several samples to be taken from multiple locations/wells • A controlled rate of fill and heating system ensures the sample is taken in an isobaric and isothermal manner. • The host ROV provides the skid with power and telemetry. • Topsides control is via a robust laptop PC. • A heating system maintains the sample cylinders and pipework at a sufficiently elevated temperature in order to mitigate the formation of hydrates during the sampling process and dissolved gases coming out of solution. • A fail-safe connection tool ensures the safe shutdown of the sample interface at the well should the ROV experience a vessel run-off or dead vehicle situation. The SHSS is the latest in a long Subsea 7 tradition of developing pioneering high-quality, cost-effective ROV tooling, including a standard range of manipulator-deployed tools, component change-out tools, bespoke intervention tools and skids. For further information contact mick.fowkes@subsea7.com
Swaged end connection for reel-lay high performance pipe-in-pipe In collaboration with its development partner ITP InTerPipe, Subsea 7 currently offers the market its DNV-qualified Enhanced Thermal Performance Pipe-in-Pipe system for installation by the reel-lay method. This superior technical solution, which benefits from the combination of Izoflex insulation material in conjunction with a reduced pressure in the PIP annulus section, has recently been further enhanced by the development and qualification of the Swaged Field Joint. The Swaged End Connection has already been widely used by Subsea 7 on J-lay and S-lay PIP projects, but this new concept relates to reel-lay applications. The Swaged End Connection is fabricated by swaging the pipe ends of the outer sleeve pipe, followed by welding to the flowline at each end of the fabricated stalk, typically 750m long for reel-lay applications. The sealed annulus within the stalk can then have the pressure drawn down within the annulus offline in advance of reeling onto the reel-lay vessel. As each stalk is subsequently reeled onto the vessel, the PIP swaged end stalks are fabricated together by firstly girthwelding of the flowlines and the use of welded half shells for the outer sleeve pipe. The Swaged End Connection’s primary function is to provide the following: • A leak-tight seal for draw-down of pressure within the annulus • A robust mechanical barrier to act as a water stop in all envisaged water depths in the event that the outer pipe is breached, thus preventing the entire pipeline annulus from flooding • A means of mechanical connection between the flowline and outer sleeve pipe that can be reeled. Testing and qualification has focused primarily on the following areas in order to attain DNV “Fitness for Service” Qualification in compliance with DNV-RP A-203: • FEA modelling • Simulated reeling and straightening trials • Welding and inspection • Post-reeling FEA analysis using strain data collated from the simulated reeling and straightening trials • Material testing • Annulus pressure test Enhanced Thermal Performance PIP incorporating Izoflex insulation material with reduced pressure and no centralisers in the annulus section Sleeve Pipe Flowline Pipe-in-Pipe cross section FE analysis Svalin C reeled PIP Subsea 7’s expertise in high performance Pipe-in- Pipe (PIP) installations covers full-scope design, procurement, construction and installation, and extends to over 40 successful PIP projects including bundle technology, S-lay, J-lay and reel-lay. Our latest project comprises a 5-inch/8-inch gas lift Pipe-in-Pipe, to be designed, constructed and installed for Statoil between the Svalin C Template and the Grane platform in the central North Sea. The contract also covers the installation of the Svalin C template and manifold, a highly wet-insulated production flowline, and an umbilical. In addition to our market-leading versatility in the installation of high performance Pipe-in-Pipe, Subsea 7 can also install electrically trace-heated flowline (ETHF) PIP solutions by reel-lay or in towed bundles. ETHF technology has been successfully commercialised by Subsea 7 in partnership with manufacturer ITP InTerPipe to combine highperformance thermal insulation with low-power resistive heating elements. Now technologically qualified by DNV for reel-lay installation, ETHF offers a highly efficient means of maintaining product temperature in the most challenging subsea environments. 09 For further information contact paul.booth@subsea7.com seabed-to-surface
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World-class welding technologies - Subsea 7

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