This part of ISO 28721 specifies the quality requirements for apparatus, components, appliances and accessories of glass-lined steel (including semi-crystallized enamel coatings) and glass-lined steel castings used for process plants. It specifies the quality requirements and the tests to be carried out by the manufacturer as well as the action to be taken to repair defects. It is also applicable to glass-lined pumps, pump components and fittings. It is not applicable to glass-lined flanged steel pipes or glass-lined flanged steel fittings. NOTE 1 Provisions for glass-lined flanged steel pipes and glass-lined flanged steel fittings are given in DIN 2876 [1]. The test methods specified cover checking the enamel, the dimensional accuracy and the performance of apparatus and components. This part of ISO 28721 applies to new apparatus and components as well as used items that have been re-enamelled. It does not contain requirements regarding the chemical or physical properties of vitreous and porcelain enamels. NOTE 2 Examples of test reports are given in Annex A.