ISO 20313:2018规定了保护标准，并对船舶外加电流和原阳极阴极保护系统的设计和规范提出了建议。包括外部船体和压载舱的阴极保护。 ISO 20313:2018适用于船舶、船只和其他自航浮式船舶的船体和装有海水的水箱的浸入部分。它包括船体上常见的固定装置，例如: -舵； -螺旋桨； -竖井； -稳定剂； -推进器； -海箱； -进水口（至第一个阀门）。 ISO 20313:2018不包括非自浮式结构物的保护- 推动。 ISO 20313:2018适用于主要由碳锰钢或低合金钢制成的船体的阴极保护，包括其他黑色或有色金属合金（如不锈钢和铜合金等）的固定装置。 ISO 20313:2018适用于涂层和裸船体及储罐；大多数壳体和罐内构件都有涂层。 ISO 20313:2018不适用于主要由铝合金、不锈钢或混凝土等其他材料制成的船体的阴极保护。 ISO 20313:2018适用于海水中的船体和固定装置，以及船舶航行期间可能遇到的所有水域- 广泛部署。

ISO 20313:2018 specifies protection criteria, and makes recommendations for design and specifications for both impressed current and galvanic anode cathodic protection systems for ships. Cathodic protection of external hull and ballast tanks are included. ISO 20313:2018is applicable to the immersed sections of hulls and tanks containing seawater for ships, boats, and other self-propelled floating vessels. It includes fixtures generally encountered on ship hulls such as: - rudders; - propellers; - shafts; - stabilizers; - thrusters; - sea chests; - water intakes (up to the first valve). ISO 20313:2018 does not cover protection of floating structures that are not self-propelled. ISO 20313:2018 is applicable to the cathodic protection of ship hulls fabricated principally from carbon manganese or low-alloy steels including fixtures of other ferrous or non-ferrous alloys such as stainless steels and copper alloys, etc. ISO 20313:2018 is applicable to both coated and bare hulls and tanks; most hulls and tank internals are coated. ISO 20313:2018 is not applicable to the cathodic protection of hulls principally made of other materials such as aluminium alloys, stainless steels or concrete. ISO 20313:2018 is applicable to the hull and fixtures in seawater and all waters which could be encountered during a ship's world-wide deployment.