Latest Developments In Plastic-Lined Flowlines For Deepwater Fields Developments

In deepwater, corrosion protection of flowlines is becoming a major issue as fluid temperature and pressure increase. Conventional corrosion allowance on carbon steel pipe thickness leads to excessive procurement costs, installation weight and welding thickness resulting in non-economic solutions. Clad flowlines require expensive implementation with additional non destructive testing difficulties during installation. Plastic liners present an interesting alternative but have been mostly limited up to now to reel-lay installation. For J-lay operations, the frequency of pipe section welding requires a specific field joint design that limits welding and non-destructive-testing difficulties and, thus, maintains the attractiveness of plastic lining. This paper describes an innovative and cost-effective field-joint system for J-lay (named IFJ for Inconel® Field Joint) that has been developed and patented by Saipem to answer that issue. This system maintains the corrosion barrier across girth weld locations along the flowline using a sleeve made in an austenitic nickel-based alloy crimped into the adequate plastic liner. This technology has a minimal impact on the offshore laying rate as the offshore welds remain standard carbon steel welds. Combined with a self gas release system on every quad-joint, this technology will soon be proposed for production applications within plastic liner capabilities. Riser application shall follow. The paper will discuss the results of the extensive qualification program carried out on the IFJ technology over the last 2 years