This paper is addressed to the engineer responsible for preparing the heat transfer equipment data sheet, on which will be specified all the parameters required by the vendor for tendering for the equipment. Initially, the engineer must decide the type of equipment best suited for his application; guidelines for this selection are given in Part A of this paper. Finally he must supply all the data required by the specialist for preparing his design. In the case of proprietary equipment, this data will be limited to process details. For more general equipment, especially shell and tube heat exchangers, he also needs to supply some equipment specifications. Part B of the paper gives guidelines for preparing shell and tube heat exchanger data sheets.