Design is not 'pick a U and compute area'. The cases that fail in the field usually failed at specification: wrong fouling, ignored vibration, nozzle too small, no allowance for two-phase inlet, or a code mismatch.
Thermal
- Define rating case vs overdesign (often a percentage on area or on duty — say which).
- Compute LMTD and apply F-correction for the flow arrangement.
- Identify temperature cross; it may need shells in series or an F-shell.
- For condensers, account for desuperheat, condensing, and subcooling zones if they exist.
Hydraulic
Respect allowable ΔP. Check ρv² at inlets for impingement protection. Two-phase inlets need more than a default nozzle.
Mechanical
Tubesheet thickness, shell thickness, flange ratings, and expansion follow the named code (ASME VIII-1 or IS 2825) and TEMA mechanical rules when specified. Saddles, lifting lugs, and anchor bolts belong on the GA — not as site improvisation.
Operability
Vents, drains, and chemical-cleaning connections should be shown if the plant intends to use them. Isolation and spare-unit philosophy is a process decision.
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