1/3/2024 0 Comments Deepvacuum twitter![]() ITP has developed a proprietary fabrication process that introduces a plastic deformation of the outer pipe, and also allows welding directly onto the inner pipe. The overall U-value normally will depend on the field jointing.Ī further advantage of the close fit between outer and inner pipes is that it has allowed the elimination of add-on pieces. pipe, 15 mm of insulation yields a U-value of better than 0.5 W/(m2K) in the mainline section. For the Tchibe* installation, in a 10/12-in. The pipe's outer diameter can be reduced because of the more efficient insulation material. Further advantages are its resistance to high temperature/high pressure (HT/HP) environments, to compression (allowing it to withstand high laying loads and hydrostatic pressure), and to vibrations. Izoflex has been proven to out-perform conventional insulation materials on industrially fabricated pipes by a factor of 3-10. This was subsequently qualified on Shell UK's ETAP development. ITP, together with a UK-based insulation specialist, therefore developed Izoflex, a patented material designed specifically for pipeline insulation. This latter method was deem ed more feasible as industrial materials with small-cell structures already existed. Implementing a material with a cell size smaller than the mean free path of the gas molecules, thereby hindering them from exchanging energy.Īssembling pipe-in-pipe for Tchibeli.Drawing a deep vacuum in the annulus to eliminate the gas molecules entirely.The only way to improve thermal efficiency further is to reduce the gaseous conduction, in two ways: This way, thermal conductivity somewhat higher than that of the still gas can be attained. Insulation designĬlassical insulating materials draw their efficiency from their opacity to (infra-red) radiation and their cellular structure, which enables them to capture air or any other thermally efficient gas, in order to prevent it from forming convection cells. Laying of the pipe was completed in February of this year. ![]() A contract for 25 km of this pipe was awarded by Elf early in 1999 for the tieback of the Tchibeli Field offshore Congo to the Nkossa production barge. A first production prototype was built in summer 1998. To address these issues, ITP in Louveciennes, France developed the "Ultimate" system. Reducing the amount of onshore fabrication welding.Diminishing the number of separate elements.Reducing the overall diameter of the assemblies.Three avenues for doing this were identified: Furthermore, each insertion demanded the use of three spacers to ensure proper centering of the two pipes and to protect the glass fiber insulation from compression.Īlthough the principle of the Dunbar pipe was sound, the design had to be simplified to drive down costs. Onshore fabrication of each double joint required 10 welds. However, this system, although performing up to specifications, was complex, consisting of two threaded connectors and two tulips for each double joint. It represented a breakthrough over previous thermally insulated designs as a U-value of 1.2 W/(m2K) was achieved - a factor of 3-4 over what was considered practical at that time. Total Oil Marine's Dunbar multiphase pipeline, installed in 1993, was the first double-walled, thermally insulated pipeline to be laid in the North Sea. The work is mostly welding, of course, but also includes periods for lifting and moving the joints around, plus time spent waiting for a pipe that hasn't been moved into place, either because the lifting equipment is not available or because the previous workstation has not yet finished. Highly insulated pipelines have historically been complex pieces of fabrication and engineering, requiring many man-hours of work per joint.
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