Saturated Steam Table — Pressure ↔ Temperature

Why one number fixes the other

On the saturation line, water and steam coexist in equilibrium — and that constrains the system so tightly that pressure and temperature can no longer vary independently. Set one and the other follows. This is the property that makes steam so useful in process plants: control the pressure and you have controlled the temperature, everywhere in the system, without a single temperature sensor.

It also means a steam pressure gauge is a thermometer. If your 10 barg header reads 184 °C, that is not a coincidence to be measured — it is thermodynamics, and a reading that disagrees means either the gauge is wrong or the steam is not saturated.

Reading the numbers

• h_f — sensible heat: energy to raise water from 0 °C to saturation.
• h_fg — latent heat: energy to evaporate it. This is the useful heat in most process heating, released when the steam condenses.
• h_g = h_f + h_fg, the total energy in saturated steam.
• v_g — specific volume, which sets the pipe size for a given mass flow.

Worked example

A process heater fed with 1,000 kg/h of steam at 9 barg (10.01 bara):

1. Saturation temperature ≈ 179.9 °C — the maximum surface temperature available
2. Latent heat ≈ 2,014 kJ/kg
3. Duty = 1,000 × 2,014 ÷ 3,600 = 559 kW from condensing alone
4. v_g ≈ 0.194 m³/kg → 194 m³/h of vapour to carry

Field notes

• Gauge or absolute is the classic error. "10 bar steam" is 179.9 °C absolute but 184.1 °C gauge — a 4 °C difference that matters on temperature-sensitive product. Our gauge ↔ absolute converter settles it.
• Lower pressure delivers more heat per kilogram but needs far bigger pipe: at 1 bara steam occupies 1.69 m³/kg versus 0.194 at 10 bara — roughly nine times the volume for the same mass. Size lines with the pipe schedule lookup and velocity calculator.
• Wet steam carries less than the table says. With 5% moisture you get 95% of the latent heat, so a dryness fraction assumption belongs in every duty calculation.
• Steam temperature control is really pressure control — which is why the control valve on a steam heater is sized on the pressure ratio; see the gas & steam Cv calculator.

Frequently asked questions

What is the temperature of steam at 10 bar?

At 10 bar absolute (about 9 bar gauge) saturated steam is at 179.9 °C. At 10 bar gauge — 11.01 bar absolute — it is about 184.1 °C. Confirming gauge versus absolute is the first step of every steam calculation.

What is latent heat of steam?

The enthalpy of evaporation, hfg — the heat absorbed turning saturated water into saturated steam at constant pressure. It falls as pressure rises: 2,257 kJ/kg at 1 bar, 2,015 kJ/kg at 10 bar, and zero at the critical point of 221.2 bar.

Why does low pressure steam carry more heat per kilogram?

Latent heat is largest at low pressure, so each kilogram delivers more energy when it condenses. Low pressure steam also has a much larger specific volume, so pipework must be bigger for the same mass flow — the classic trade-off in steam distribution design.

What is saturated versus superheated steam?

Saturated steam sits exactly at the boiling point for its pressure, so pressure and temperature are locked together. Superheated steam is heated beyond that point, making temperature an independent variable — this table covers the saturated line only.

Saturation temperature and pressure use the IAPWS-IF97 region 4 equations; enthalpies and specific volume are interpolated from reference data and are accurate to roughly 0.1% for enthalpy and 1% for specific volume — suitable for engineering estimates, not for custody or performance-guarantee calculations. See our disclaimer.