4　Materials

4.1　General Requirements

4.1.1　Materials used in the construction of the tanks shall satisfy the requirements of this Chapter.When using the material other than those listed in this Chapter，their Standards shall not be lower than all the requirements of the materials listed in this Standard.

4.1.2　When selecting the materials for tanks，service conditions（such as design temperature，fluid characteristics and position on which material is used），chemical composition，mechanical properties，weldability and processability of the material，and economic rationality shall be considered.

4.1.3　When determining the materials，the minimum design metal temperature of tanks（see 5.1.1 c）shall be considered.

4.1.4　I When special requirements（such as special smelting process，raising of impact energy value，more requirements for non-destructive examination and more percentage of mechanical property tests etc.）are necessary to be set forth for steels，the Designer shall prescribe them on the drawings or in corresponding technical documents.