A wide variety and combination of materials are used in the construction of heat exchangers, as discussed in Section 4.5. Generally the material of construction should comply with the requirements of the design code, but other materials may be used subject to agreement between purchaser, inspecting authority, and manufacturer.

In the case of heat exchangers that are exported, the design, testing of materials, inspection, and certification must comply with the requirements of the regulating authority of the recipient country. It is therefore essential that the manufacturer be fully aware of these requirements at the outset, and such items as valves and fittings should not be excluded when considering these requirements. Nonpressure parts, such as supports, lugs, and baffles, should be of weldable quality and suitable in all respects for the intended purposes.

All material should have identification marks and be supported by certificates giving the physical and chemical properties.