Internal lining of carbon steel pipelines has been successfully used onshore in both hydrocarbon and water service, and offshore in water injection pipelines in place of existing corrosion protection methods. When compared to carbon steel pipelines, operational costs can be reduced as no corrosion inhibitor is required and material costs can be decreased as there is no requirement for an internal corrosion allowance. The most significant advantage however, is that plastic lined carbon steel pipeline is less expensive than a pipeline fabricated from corrosion resistant alloy. Polymeric liners have been shown to be unstable when transporting hydrocarbons and other fluids with gaseous components. Permeation of these components through the liner can result in pockets of gas becoming trapped between the liner and the host pipe which, on depressurisation of the bore, may expand and partially or completely collapse the liner. Traditionally, onshore, this has been achieved by installing vents at regular intervals and evacuating the gases periodically. This venting system has to date been considered impractical for subsea applications. However, Technip has completed a three year development and testing programme based on a grooved liner system which incorporates a reliable venting mechanism, and which can be installed offshore by a reel ship. The paper introduces the concept of plastic lining for hydrocarbon transport and presents fabrication, installation and operational methods. The findings of the extensive qualification programme are also presented, including the results of engineering analysis, laboratory experiments and full-scale testing. Technip participated to the COREL (Corrosion Resisting Liners) joint industry project which has recently completed a proof of concept testing of grooved and perforated liner systems for hydrocarbon applications. The work presented in this paper relates only to Technip internal qualification of the grooved liner concept, information on the JIP activities may be found in reference.
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