Standards Development

Scope

This document defines the requirements and giver recommendations for the external cathodic protection of submerged metallic surfaces of steel offshore floating structures which are static during their usual operating conditions.

This document addresses:

— design and implementation of cathodic protection systems for new floating steel structures and their appurtenances;

— cathodic protection by either galvanic anodes or by impressed current, or by a combination of both [hybrid systems];

— cathodic protection of appurtenances to floating structures including their mooring or station keeping provisions and any interfacing connections to other structures, offshore or onshore;

— cathodic protection in sea water or brackish waters and saline sediments;

—cathodic protection of structures fabricated principally from bare or coated carbon manganese steels;

— the control of any galvanic corrosion due to coupling between carbon manganese steel and more noble materials, such as corrosion resistant alloys (CRAs) including various grades of stainless steels and various copper nickel alloys etc;

— the control or mitigate hydrogen embrittlement or hydrogen induced cracking of possibly sensitive materials including high yield steel alloys, stainless steels and various copper nickel alloys etc;

— cathodic protection of any sea chests and water intakes up to the first valve;

— inspection, performance assessment and monitoring of cathodic protection systems installed on existing structures;

— assessment of residual life of existing cathodic protection systems;

— design and implementation of retrofit cathodic protection systems for improvement of the protection level or for life extension of the protection;

Purpose

EN 13173:2001 is a useful but outdated standard.

There are significant new standards which should be Normative References for this standard. Unlike more recent standards for Cathodic Protection (CP) there are no requirements for competence of personnel; this is a serious omission.

Since the preparation of the present document there have been much increased use of Floating Production Storage and Offloading (FPSO) vessels which is expected to continue for at least the next decade. Further, there is development, increased deployment and significant predicted growth in emerging Tidal Stream Generators or Convertors (TEC). These new and important renewable energy developments which are crucial for our long term environment present new challenges in CP design, application and assessment, based partly on the geometry of and materials used, in particular in station keeping / anchoring systems, risers and electrical cable systems.

Further, many FOW applications and most TEC applications are located in geographic regions of high water flow or significant wave activity. The impact of these on CP design and operating parameters were not adequately understood or documented in EN 13173. The present advice is inadequate.

Since EN 13173 was drafted, there have been significant developments in marine protective coatings, the performance of which impact on the design and performance of CP systems. The present advice is inadequate.