This document specifies the criteria and minimum requirements for selecting internal coatings (often referred to as linings) for pressurized service within process vessels. The document provides the following: — key factors influencing coating selection; — generic composition of test liquids which can be used as references when evaluating supporting testing evidence for coatings; — principal test methods to be used as evidence of performance when selecting suitable coatings; — supporting evidence to be used in evaluating coatings that is relevant to the potential end use. This document covers types of coatings that are generally available, with properties that are known and documented. It also covers other materials to be evaluated and qualified for use. This document is applicable to process vessels coated at the new construction phase. It can be applied only where the coating is applied directly to the substrate. This document does not cover requirements related to metallic coatings nor weld overlay materials.