Part UHX of the ASME code includes design, fabrication, and inspection rules for shell and tube exchangers. Any parts of UHX that apply to a certain exchanger must be followed for a code-stamped exchanger. UHX includes rules and formulas to design tubesheets (U-tube, fixed, and floating types), expansion joints (bellows or flexible shell types), and adjacent shells and channels. The TEMA Standard also covers design of heat exchangers, but the two standards don’t overlap. TEMA has rules and guidelines for design of non-pressure boundary (but still critical) exchanger components, such as tie rods, baffles, and impingement plates. TEMA also includes recommendations for exchanger thermal design, operation and maintenance, tolerances for exchanger-specific components, and recommended good practice for exchanger design. In summary, ASME Part UHX and TEMA standards complement each other in the design of heat exchangers. ASME UHX establishes design rules for main pressure-retaining components, while TEMA offers specific guidance to ensure proper performance, heat transfer, and longevity. Integrating both references results in a well-designed, safe, and high-performing heat exchanger.