4　Materials

4.1　General Requirements

4.1.1　Steels used for low temperature steel storage tanks for petrochemical service shall be provided with quality certificates supplied by the steel manufacturers.

4.1.2　The materials used to construct low temperature steel storage tanks shall be properly selected based on the tank operating conditions，the material performances and economic consideration.

4.1.3　The materials used to construct concrete components in low temperature environment shall have low temperature resistant performance.

4.1.4　The steel of the primary container and secondary steel container shall be the killed steel produced by oxygen converter or electric furnace.If the design metal temperature is lower than-20℃，secondary refining shall be also used for the low temperature steel plates，the low temperature steel forgings and low temperature steel pipes.

4.1.5　The design metal temperature for each component shall be calculated based on the most pessimistic assumption.

4.1.6　Any special requirements for steels，if any，shall be specified in the design documents.