ISO/TC 156/WG 10 - Cathodic protection of buried and immersed metallic structures

This document specifies requirements for the design, installation, positioning, sizing, use and maintenance of coupons for the assessment of the effectiveness of cathodic protection (CP) of buried and immersed metallic structures, such as pipelines, in the case of normal operation as well as AC and DC interference conditions.

This document specifies protection criteria for determining the AC corrosion risk of cathodically protected pipelines. It is applicable to buried cathodically protected pipelines that are influenced by AC traction systems and/or AC power lines. In the presence of AC interference, the protection criteria given in ISO 15589-1 are not sufficient to demonstrate that the steel is being protected against corrosion. This document provides limits, measurement procedures, mitigation measures, and information to deal with long-term AC interference for AC voltages at frequencies between 16,7 Hz and 60 Hz and the evaluation of AC corrosion likelihood. This document deals with the possibility of AC corrosion of metallic pipelines due to AC interferences caused by conductive, inductive or capacitive coupling with AC power systems and the maximum tolerable limits of these interference effects. It takes into account the fact that this is a long-term effect, which occurs during normal operating conditions of the AC power system. This document does not cover the safety issues associated with AC voltages on pipelines. These are covered in national standards and regulations (see, e.g., EN 50443).

ISO 19097-2:2018 specifies accelerated life test method of mixed metal oxide anodes for impressed current cathodic protection used in soil or natural waters. The accelerated life test results can be used to compare the durability of the anodes and to evaluate whether the anodes can comply with required specifications of design life expectancy at rated current output.

ISO 19097-1:2018 specifies accelerated life test method of mixed metal oxide anodes for impressed current cathodic protection used in concrete. The accelerated life test results can be used to compare the durability of the anodes and to evaluate whether the anodes can comply with required specifications of design life expectancy at rated current output. ISO 19097-1:2018 is also applicable to other anode systems that are used as impressed current anodes embedded in concrete with suitably modified apparatus to hold anodes of different geometry.

ISO 12473 covers the general principles of cathodic protection when applied in seawater, brackish waters and marine mud. It is intended to be an introduction, to provide a link between the theoretical aspects and the practical applications, and to constitute a support to the other standards devoted to cathodic protection of steel structures in seawater. ISO 12473 specifies the criteria required for cathodic protection. It provides recommendations and information on reference electrodes, design considerations and prevention of the secondary effects of cathodic protection. The practical applications of cathodic protection in seawater are covered by the following standards: - EN 12495, Cathodic protection for fixed steel offshore structures; - ISO 13174, Cathodic protection of harbour installations (ISO 13174); - EN 12496, Galvanic anodes for cathodic protection in seawater and saline mud; - EN 13173, Cathodic protection for steel offshore floating structures; - EN 16222, Cathodic protection of ship hulls; - EN 12474, Cathodic protection of submarine pipelines; - ISO 15589‑2, Petroleum, petrochemical and natural gas industries ? Cathodic protection of pipeline transportation systems ? Part 2: Offshore pipelines. For cathodic protection of steel reinforced concrete whether exposed to seawater or to the atmosphere, ISO 12696 applies.

ISO 15257:2017 defines five levels of competence (detailed in Clause 4) for persons working in the field of cathodic protection (CP), including survey, design, installation, testing, maintenance and advancing the science of cathodic protection. It specifies a framework for establishing these competence levels and their minimum requirements. Competence levels apply to each of the following application sectors: - on-land metallic structures; - marine metallic structures; - reinforced concrete structures; inner surfaces of metallic structures containing an electrolyte. These application sectors are detailed in Clause 5. ISO 15257:2017 specifies the requirements to be used for establishing a certification scheme as defined in ISO/IEC 17024. It is not mandatory to apply all of the levels and/or application sectors. This certification scheme is detailed in Annexes A, B and C.

ISO 12696:2016 specifies performance requirements for cathodic protection of steel in cement-based concrete, in both new and existing structures. It covers building and civil engineering structures, including normal reinforcement and prestressed reinforcement embedded in the concrete. It is applicable to uncoated steel reinforcement and to organic-coated steel reinforcement. ISO 12696:2016 applies to steel embedded in atmospherically exposed, buried, immersed and tidal elements of buildings or structures. NOTE 1 Annex A gives guidance on the principles of cathodic protection and its application to steel in concrete. NOTE 2 ISO 12696:2016, while not specifically intended to address cathodic protection of steel in any electrolyte except concrete, can be applied to cathodic protection of steel in other cementitious materials such as are found, for example, in early 20th century steel-framed masonry, brick and terracotta clad buildings. In such applications, additional considerations specific to these structures are required in respect of design, materials and installation of cathodic protection; however, the requirements of this document can be applied to these systems.

ISO 13174:2012 defines the means to be used to ensure that cathodic protection is efficiently applied to the immersed and driven/buried metallic external surfaces of steel port, harbour, coastal and flood defence installations and appurtenances in seawater and saline mud to provide protection from corrosion. ISO 13174:2012 specifies cathodic protection of fixed and floating port and harbour structures. This includes piers, jetties, dolphins (mooring and berthing), sheet or tubular piling, pontoons, buoys, floating docks, lock and sluice gates. It also specifies cathodic protection of the submerged areas of appurtenances, such as chains attached to the structure, when these are not electrically isolated from the structure. ISO 13174:2012 is to be used in respect of cathodic protection systems where the anodes are exposed to water or saline mud. For buried areas, typically in soil or sand filled areas behind piled walls or within filled caissons, which may be significantly affected by corrosion, specific cathodic protection design and operation requirements are defined in EN 12954, the anodes being exposed to soils. ISO 13174:2012 does not cover the cathodic protection of fixed or floating offshore structures (including offshore loading buoys), submarine pipelines or ships. ISO 13174:2012 does not include the internal protection of surfaces of any components such as ballast tanks, internals of floating structures flooded compartments of lock and sluice gates or the internals of tubular steel piles. ISO 13174:2012 covers the cathodic protection of structures fabricated principally from bare or coated carbon and carbon manganese steels. As some parts of the structure may be made of metallic materials other than carbon steels, the cathodic protection system should be designed to ensure that there is a complete control over any galvanic coupling and minimize risks due to hydrogen embrittlement or hydrogen-induced cracking (see ISO 12473 ). ISO 13174:2012 does not address steel reinforced concrete structures (see EN 12696). ISO 13174:2012 is applicable to the whole submerged zone in seawater, brackish waters and saline mud and related buried areas which can normally be found in port, harbour, coastal and flood defence installations wherever these structures are fixed or floating. For surfaces which are alternately immersed and exposed to the atmosphere, the cathodic protection is only effective when the immersion time is long enough for the steel to become polarized. Typically, effective cathodic protection is achieved for all surfaces below mid tide. For structures such as sheet steel and tubular steel piles that are driven into the sea bed or those that are partially buried or covered in mud, ISO 13174:2012 is also applicable to the surfaces buried, driven and exposed to mud which are intended to receive cathodic protection along with surfaces immersed in water. Cathodic protection may also be applied to the rear faces of sheet steel piled walls and the internal surfaces of filled caissons. Cathodic protection of such surfaces is specified by EN 12954.

ISO 18086:2015 is applicable to buried cathodically-protected pipeline that is influenced by AC traction systems and/or AC power lines. In the presence of AC interference, the protection criteria given in ISO 15589 1 are not sufficient to demonstrate that the steel is being protected against corrosion. ISO 18086:2015 provides limits, measurement procedures, mitigation measures, and information to deal with long term AC interference for AC voltages at frequencies between 16,7 and 60 Hz and the evaluation of AC corrosion likelihood. It deals with the possibility of AC corrosion of metallic pipelines due to AC interferences caused by inductive, conductive or capacitive coupling with AC power systems and the maximum tolerable limits of these interference effects. It takes into account the fact that this is a long-term effect, which occurs during normal operating conditions of the AC power system. It does not cover the safety issues associated with AC voltages on pipelines. These are covered in national standards and regulations.

ISO 12696:2011 specifies performance requirements for cathodic protection of steel in cement-based concrete, in both new and existing structures. It covers building and civil engineering structures, including normal reinforcement and prestressed reinforcement embedded in the concrete. It is applicable to uncoated steel reinforcement and to organic-coated steel reinforcement. ISO 12696:2011 applies to steel embedded in atmospherically exposed, buried, immersed and tidal elements of buildings or structures.

ISO 12473:2006 covers the general principles of cathodic protection including the criteria for protection, environmental and design considerations and secondary effects of cathodic protection, and is intended as an introduction to other European Standards in the general series "Cathodic Protection of Steel Structures in Sea Water".