4.2　Design Temperature

4.2.1　The design temperature for columns shall be determined according to those specially required by process systems or those specially defined in project design documents.

4.2.2　The design temperature for a column(excluding skirt)refers to the specified metal temperature of the column components when the column is under normal operation.If it is impossible to determine the metal temperature of column components by heat transfer calculation or actual measurement,the design temperature for a column shall be determined according to the following requirements:

a)Where a column is externally hot(cold)insulated and its inner wall is directly exposed to the operating fluid,its design temperature may be the temperature of the operating fluid contained,as indicated in Table 2;

Table 2　Design temperature for column　(unit:℃)

b)Where column sections have different working temperatures and their working temperatures vary greatly,each section may be designed with specific temperature,and the most severe working temperature shall be taken as the design temperature for the column;

c)The column,if required to operate in different operating cases,shall be designed based on the most severe operating case,and the design pressure and design temperature for each operating case shall be indicated in the design drawings;

d)Where two sides of a column component(cylindrical shell or head)are directly exposed to operating fluids at different working temperatures,the design temperature for the column shall be determined based on the operating fluid at higher working temperature.

4.2.3　The design temperature for skirt shell may be determined in accordance with Table 3.

Table 3　Design temperature for skirt shell

4.2.4　The design temperature for anchor bolts shall consider the effect from the ambient temperature in the region where the column is constructed.