What are TEMA designations for shell-and-tube heat exchangers?

TEMA (Tubular Exchanger Manufacturers Association) uses a three-letter code describing front head, shell type, and rear head. Common designations: AES (removable channel, one-pass shell, floating head), BEM (bonnet-type head, one-pass shell, fixed tubesheet), AEU (removable channel, one-pass shell, U-tube bundle). The shell types include E (one-pass), F (two-pass with longitudinal baffle), J (divided flow), and K (kettle reboiler). TEMA also specifies mechanical design standards: R (refinery), C (chemical), B (general).