No single retrofit anode design or attachment technique will fulfill the requirements of all offshore platforms. Retrofit systems discussed represent designs used in the Gulf of Mexico, West Africa, and the North Sea. Diver-placed U-bolt clamps are the most common method of retrofitting sacrificial anodes on shallow-water platforms with tubular members less than 90 cm (36 in.). Direct attachment of sacrificial anode cores by underwater welding is commonly used when the tubular member diameter exceeds 90 cm as in the case of single-well caissons. Hinged-bracelets are the preferred sacrificial anode retrofit design for big platforms with tubular members whose diameters range from 0.8 to 1.8 m. It is best to clean marine growth prior to attachment of anodes. Air/grit blasting is effective and safe. Suspended anodes using extended pipe cores can provide a long-term solution for water depths up to 9 m. When a design life of less than five years is needed, hanging anodes provide a low-cost solution. This design is highly subject to damage in rough weather. Cylindrical impressed current anodes fixed to the end of supported pipe riser, with positive lead cables protected through the splash zone, was a reliable design for one Gulf of Mexico platform. Numerous designs exist that may provide the best solution for a particular platform. These include impressed current tensioned cable anode strings, impressed current or sacrificial anode sleds, and loaded anode members. Remote operated vehicle deployed configurations may save costs in deep water systems.
Offshore platform cathodic protection retrofits
Sanierung des kathodischen Korrosionsschutzes bei offshore Plattformen
Materials Performance ; 35 , 10 ; 11-16
1996
6 Seiten, 5 Bilder, 1 Tabelle, 4 Quellen
Aufsatz (Zeitschrift)
Englisch
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