Abstract: Shell and tube heat exchangers are mostly of single tubesheet structure, and both sides of tubesheet contact with the medium respectively. Once the connection between the tubesheet and the tubes fails, the medium will leak. An isolation cavity is set between the inner and outer tubesheets in the double tubesheets heat exchanger, which can effectively solve such problems. This paper deals with the analysis of many key points with engineering design examples, such as occasions of double tubesheets application, calculation of inner and outer tubesheets thickness, factors for determining the length of the isolation cavity, and tubesheets manufacturing, connection between tubesheets and heat exchange tubes, pressure test, etc. The paper also provides optimization and improvement measures to better the design and manufacturing quality.

Key words: double tubesheet, heat exchanger, separation wall, welding, strength expansion