This standard BS EN 17243:2020 Cathodic protection of internal surfaces of metallic tanks, structures, equipment, and piping containing seawater is classified in these ICS categories:
47.020.30 Piping systems
77.060 Corrosion of metals
This document specifies the requirements and recommendations for cathodic protection systems applied to the internal surfaces of metallic tanks, structures, equipment and piping containing natural or treated seawater or brackish waters to provide an efficient protection from corrosion.
Cathodic protection inside fresh water systems is excluded from this document. This is covered by EN 12499.
NOTE
EN 12499 covers internal cathodic protection for any kind of waters, including general aspects for seawater but excluding industrial cooling water systems. This document specifically details applications in seawater and brackish waters.