This standard specifies the requirements for the design, manufacture, inspection and acceptance of indirect fired shell-and-tube heat exchangers. This standard applies to fixed tubesheet, floating head, U-tube and stuffing box heat exchangers. Applicable parameters are nominal diameter DN≤ 2600mm; nominal pressure PN≤ 35MPa; and the product of nominal diameter (mm) and nominal pressure (Mpa) is not greater than 1.75x10000. Heat exchangers beyond the above parameters can also be designed and manufactured with reference to this standard. The applicable design temperature range of this standard is determined according to the allowable service temperature of metal materials.