Estimate wax appearance temperature (WAT) — the cloud point at which solid paraffin first crystallises out of a crude oil — from °API gravity and wax (n-paraffin) content. Includes pour-point estimate, ΔT-margin vs operating line temperature, and a prioritised mitigation list. Lab measurement per ASTM D2500/D3117 is the reference; this calc is for FEED screening before lab data is available.