Special Flange Joints Used in Floating-Head Shell-and-Tube Heat Exchangers
By Pankaj K. Singla, Fluor Daniel Pvt. Ltd. |
Single-pass, floating-head heat exchangers are common in certain process operations, but they often use flange joints that are not covered in existing design codes. Design details, advantages and disadvantages of the different options are discussed here
Shell-and-tube heat exchangers are an essential element of petroleum refineries, as well as petrochemical and chemical plants. Shell-and-tube heat exchangers can be broadly classified into three types, according to TEMA (Tubular Exchanger Manufacturer’s Association; Tarrytown, N.Y.; www.tema.org) construction classifications. The three types are fixed tubesheet, U-tube and floating-head type. The floating-head type (S or T type) is widely used in petroleum refineries to accommodate fouling service and to allow differential thermal expansion between the shell side and the tube side of the exchanger that results from differences in fluid temperatures. Further, due to limitations in tube-side pressure drop, single-tube-pass floating-head heat exchangers are used. This subclass of shell-and-tube heat exchangers has an internal expansion bellow at the connection between the floating-head nozzle and the tailpipe.
No currently established design code or industrial standard covers the special…