CP system design for flowlines with direct electrical heating

You are here: Homepage > Search

CP system design for flowlines with direct electrical heating

Lauvstad, G.Ö. / Paulsen, G.

Since year 2000 a number of offshore projects have utilized Direct Electrical Heating (DEH) for control of hydrate/wax formation in subsea flowlines. In an 'open' DEH system, anodes are required for grounding of the DEH system to seawater, as well as for cathodic protection (CP) of the flowline. CP system design for flowlines with DEH therefore have to consider the impact of DEH on CP design parameters such as CP protection potential, current density required to control AC corrosion on steel and anode consumption rates applicable for design. The paper presents a CP system design approach for flowlines with DEH, addressing the following issues: DEH system design, with emphasis on parameters determining the AC densities experienced by anodes and exposed pipeline steel; AC corrosion and impact of DEH operation on CP design criteria vs. design limits in terms of AC densities on anodes and steel; Impact of DEH on CP (anode) requirements for pipeline and adjacent structures. As DEH has been qualified for use on carbon steel (CS) and supermartensitic stainless steel (13%Cr) flowlines, the paper will focus on these materials.