Saturated steam table
Saturated steam's temperature is fixed by its pressure alone, and its heat splits into the sensible part (held in the condensate) and the much larger latent part (released on condensing). These are the working figures for steam-system arithmetic.
Last reviewed July 2026. Figures are indicative working values for first-pass estimates; confirm anything compliance- or design-critical against the cited source.
Properties by gauge pressure
hf = sensible heat in the condensate; hfg = latent heat released on condensing; hg = total heat of the steam. All kJ/kg. The right-hand column is the fraction of condensate that flashes to steam when discharged to atmosphere.
| Pressure (bar g) | Saturation temp (°C) | hf (kJ/kg) | hfg (kJ/kg) | hg (kJ/kg) | Flash to atm (%) |
|---|---|---|---|---|---|
| 0 | 100.0 | 419 | 2257 | 2676 | 0.0 |
| 1 | 120.2 | 505 | 2201 | 2706 | 3.8 |
| 2 | 133.5 | 561 | 2163 | 2725 | 6.3 |
| 3 | 143.6 | 605 | 2133 | 2738 | 8.2 |
| 4 | 151.8 | 640 | 2108 | 2748 | 9.8 |
| 5 | 158.8 | 670 | 2086 | 2756 | 11.1 |
| 6 | 164.9 | 697 | 2066 | 2763 | 12.3 |
| 7 | 170.4 | 721 | 2048 | 2769 | 13.4 |
| 8 | 175.4 | 743 | 2031 | 2774 | 14.4 |
| 10 | 184.1 | 781 | 2000 | 2781 | 16.0 |
Heat loss from steam pipework
Horizontal steel pipe at ~170 °C (7 bar g) in still 20 °C air; indicative figures. Insulation retains roughly 90% of the loss, which is why bare pipe and fittings repay lagging within months.
| Pipe size (DN) | Bare (W/m) | Insulated (W/m) |
|---|---|---|
| 25 | 180 | 18 |
| 50 | 300 | 30 |
| 80 | 440 | 44 |
| 100 | 560 | 56 |
| 150 | 760 | 76 |
A working cost of steam
At the platform's reference prices (gas £0.06/kWh, boiler 85% efficient, feedwater at 80 °C), steam at 7 bar g costs roughly £48 per tonne in fuel alone, before water and treatment. Every steam loss can be priced from that figure.
| Assumption | Value |
|---|---|
| Gas price | £0.06/kWh |
| Boiler efficiency | 85% |
| Feedwater temperature | 80 °C (hf ≈ 335 kJ/kg) |
| Heat added per tonne (7 bar g) | 2,769 − 335 = 2,434 MJ |
| Gas per tonne | ≈ 795 kWh |
| Fuel cost per tonne | ≈ £48 |