eSubsea provides subsea corrosion protection design, calculation and analysis using aluminium based sacrificial anodes for any offshore construction project. The calculations of required anode mass, the analysis and design are performed in accordance with DNVGL-RP-B401 Cathodic Protection Design, NORSOK M-501 Surface Preparation and Protective Coating and NORSOK M-503 Cathodic Protection. In addition, we do third party design and verification of corrosion protection calculations and design done by others.
Subsea Corrosion Protection
The corrosion protection system is basically the same for all types of subsea structures and foundation structures and consist of both protection by coating and by using cathodic protection with sacrificial anodes. There are other methods, like impressed current but they are used more on platforms where electricity is more available.
Subsea structures as template and manifold, protection structure, suction anchors and PLEMs will all have both cathodic protection and protective coating as per NORSOK M-501 most System 7. Structures that are only to be used on drilling rigs, vessels, platforms will only have protective painting to NORSOK M-501 System 1.
Anode Mass Calculations
The required anode mass for the subsea structures design life is calculated and suitable sacrificial anode sizes selected. The types of anodes are stand-off anodes and slender type anodes. These zinc aluminium based anodes evenly distributed and are welded to the structure. If the structures are allowed to rust, eSubsea can calculate the corrosion rate.
Cathodic protection design calculations can be performed in accordance with and using the methods described in DNVGL-RP-B401 using project specific parameter values. Surface area can either be manually calculated or taken direct from CAD models.