5　Materials

5.1　General Principles for Material Selection

5.1.1　Steels for columns shall be selected with considerations to the operating conditions of columns,weldability and hot/cold processability of steels,heat treatment requirements and structure of the columns.

5.1.2　In addition to Article 5.1.1,economic factors shall also be considered in material selection.In general,the following rules shall be applied:

a)When the required nominal thickness of steel plates is less than 8mm,carbon steel plates should be selected,such as Q235B,Q235C,Q245R;

b)When rigidity or structure is a main concern to be addressed for design,carbon steel plates should be selected;

c)When strength is a main concern to be addressed for design,Q235C steel plate,Q245R steel plate and Q345R steel plate shall be selected in importance sequence based on the design pressure,design temperature and the properties of operating fluid;

d)When the required thickness of stainless steel is greater than 12mm,the plates with cladding,weld overlay or lining should be selected;

e)Stainless steel may be used for highly corrosive fluid service to eliminate contamination by iron ions,high temperature service at a design temperature above 500℃or low temperature service at a design temperature below-100℃;

f)Stainless steel should not be used for high temperature service at a design temperature below or equal to 500℃;

g)Low Cr-Mo alloy steel may be used for high temperature service at a design temperature from 450℃to 550℃or for HIC(hydrogen induced cracking)resistant service at a design temperature above 200℃.