Cathodic Protection of Stainless Steel Piping and Components—A Review of Experiences Related to Seawater Systems with High Temperatures

In the mid 80`ies stainless steel alloys like 6Mo i.e. 254SMO and 25Cr super duplex .i.e. SAF2507 were approved for use in chlorinated seawater systems with temperatures up to 35^oC. These alloys became the preferred materials for seawater cooling and firewater systems. However, during operation one has experienced corrosion attacks even if temperatures peaked slightly above and also at lower temperatures than as approved for. This has resulted in a series of research investigations to find mitigations and alternatives to upgrading the already installed piping systems, and also to make it possible to use these alloys at relatively high temperatures. Through more than 15 years of operation one has collected important information and experiences with CP of stainless steel piping and components such as heat exchanger tubing. One frequently used application is using these alloys cathodically protected with Resistor controlled Cathodic Protection (RCP^TM [1]). A recent study was carried out to determine if also plate heat exchangers could be cathodically protected with similar approach as for piping and tubed heat exchangers. The paper will discuss the past experiences with CP properties of actual alloys and present the recent test results on plate exchangers.

Key words; Stainless steel seawater piping systems, RCP, plate heat exchangers.

[1] Trademark of FORCE Technology Norway AS