The increasing development of marginal offshore hydrocarbon deposits has resulted in production of Increasingly corrosive fluids. This has increased the need for pipelines capable of operating at elevated temperatures in the presence of high concentrations of H2S and C02 gases. Conventional pipelines require the use of stainless steels or corrosion resistant alloys which drives up the cost of materials and fabrication / installation of the system. The use of flexible pipe systems is assuming an important role in these applications where stainless steel and CRA carcass materials may be economically utilized. This paper discuses testing of flexible pipe carcass materials and a new PVDF homopolymer fluid barrier material.
This paper addresses materials concerns for non-bonded flexible pipe (figure 1) in aggressive environmental conditions. The conditions include high concentrations of H2S and C02, as well as temperatures up to 1350 C. These conditions limit the use of rigid pipe to stainless or corrosion resistant alloys thus driving up the price of the pipe materials as well as expenditure for field installation (Hill, OTC 1989). In these types of environments flexible pipe can provide a cost effective and environmentally sound solution to field development problems. A great deal of research has been completed over the past several years by the Force Institute and various material suppliers leading to an increased understanding of corrosion mechanisms in flexible pipe systems. The results of these studies are presented for sour service effects on stainless and carbon steel carcass, testing of a plasticized PVDF homopolymer (Solef 1015) for temperatures up to 1350 C and flexible pipe design requirements.
Each of the layers of non-bonded flexible pipe is free to move relative to the others. This means that there is no composite action in bending or torsion.