Uninsulated valves (especially gate and globe valves) are the largest per-unit loss points — a DN150 gate valve at 250 °C can lose 1.5–2.5 kW. Flanges, pump housings and vessel heads follow. Steam mains and process pipework account for the largest total area. A heat loss survey typically finds 15–40 % of losses concentrated in valves and fittings.
From our guide: How Insulation Reduces Scope 1 Emissions — full context, charts and sources there.
