Custom Shell and Tube Heat Exchangers

A worked example is on the surplus market: an IPAC 2000 Inc. double-pass shell and tube exchanger, 16 inches in diameter and 15 feet long, with 8 inch inlet and outlet connections, 304 stainless steel tubes and shell, weighing about 3,500 lb. Nothing in the catalogue comes close to it; it was designed for one duty and built once. The stainless W1500FA SU00-S aftercooler on the Legacy page - 279 tubes in 304 stainless, National Board registered - is the halfway case: a catalogue size in a special material.

Today the line is built in an ASME U- and PP-stamp shop that sizes custom exchangers with HTRI thermal software and builds them to ASME Section VIII Division 1 and TEMA, with Canadian CRN and European PED conformity available. The published brochure puts custom water-cooled aftercooler designs at up to 3,000 PSIG. Materials run from carbon steel and copper through admiralty brass, 90/10 copper-nickel and the 300-series stainless steels; bundles can be fixed or removable; ES (enhanced-surface) tube bundles are offered where the duty rewards them.

For a custom enquiry we need both fluids with flow rates, inlet and outlet temperatures, design pressures and temperatures on each side, the allowable pressure drop on each side, the fouling allowance, any code or registration requirement, and the space and connection constraints. Where a unit is being replaced, the nameplate, the shell diameter and length, the tube count and the connection sizes and positions let us reverse-engineer the design.