Technical Tables and Calculators

Superheated Steam Table: Enthalpy by Pressure and Temperature

Enthalpy of superheated steam from 1 to 25 bar a and 200 to 400 °C, with a calculator for intermediate points and a degree-of-superheat example.

ORFA Technical TeamUpdated: Oct 30, 20265 min read

Superheated steam table – enthalpy by pressure and temperature

A superheated steam table gives the enthalpy (heat content) of steam heated above its saturation temperature at different pressures and temperatures. It is used for steam turbines, superheated steam mains, superheaters and steam conditioning (desuperheating) calculations.

The table below lists the specific enthalpy of superheated steam in kJ/kg for absolute pressures of 1–25 bar and temperatures of 200–400 °C. The calculator above the table interpolates between table points and shows the degree of superheat.

What Is Superheated Steam?

Water boils at the saturation temperature corresponding to its pressure, producing saturated steam. If saturated steam is heated further at the same pressure, its temperature rises above saturation; this is superheated steam, and the difference between actual and saturation temperature is the degree of superheat. At 10 bar a, for example, the saturation temperature is about 179.9 °C, so steam at 300 °C has roughly 120 K of superheat.

Superheated steam is preferred in power generation because it can travel long distances without condensing and prevents droplet erosion on turbine blades. In heating processes, where heat is transferred mainly by condensation, saturated or desuperheated steam is normally used.

How to Read the Table

Pressure (bar a): Absolute pressure, roughly the gauge reading plus 1 bar. (Our saturated steam table uses gauge pressure, bar g.)
Temperature columns: Actual steam temperature.
Cell values: Specific enthalpy of 1 kg of steam in kJ/kg. Divide by 4.1868 to convert to kcal/kg.
Dash (“–”): At that pressure the temperature is below saturation, so the steam is not superheated (liquid region).

Worked Example

At 10 bar a and 300 °C the table gives an enthalpy of 3047 kJ/kg. Dry saturated steam at the same pressure has about 2777 kJ/kg, so the superheat adds roughly 270 kJ per kilogram. If this steam fully condenses in a heater and the condensate leaves at saturation temperature (hf ≈ 763 kJ/kg), it releases about 3047 − 763 ≈ 2284 kJ per kilogram.

Tip: Superheated steam mains produce little condensate in operation, but condensate can collect during start-up and in dead legs. At these points use steam traps rated for high temperatures and suitable for superheat, such as bimetallic or thermodynamic types.

Superheated Steam Enthalpy Table (kJ/kg)

Superheated Steam Enthalpy Calculator

Absolute pressure (bar a)Temperature (°C)

Values are bilinearly interpolated between table entries and are approximate. The rows used are highlighted in the table.

Pressure (bar a)	200 °C	220 °C	240 °C	260 °C	280 °C	300 °C	320 °C	340 °C	360 °C	380 °C	400 °C
1	2872	2914	2955	2994	3031	3073	3114	3152	3194	3236	3278
2	2867	2909	2951	2993	3031	3068	3110	3152	3194	3232	3274
3	2863	2905	2951	2989	3027	3068	3106	3148	3190	3232	3274
4	2859	2901	2947	2985	3022	3064	3106	3148	3190	3232	3274
5	2855	2897	2943	2985	3022	3064	3102	3144	3186	3228	3269
6	2851	2893	2939	2981	3018	3060	3102	3144	3186	3228	3269
7	2847	2888	2934	2976	3014	3056	3098	3140	3181	3223	3265
8	2838	2884	2930	2972	3014	3056	3098	3140	3181	3223	3265
9	2834	2880	2926	2972	3010	3052	3094	3135	3177	3219	3265
10	2830	2876	2922	2968	3006	3047	3094	3135	3177	3219	3261
11	2821	2872	2918	2964	3001	3047	3089	3131	3173	3219	3261
12	2817	2867	2914	2960	3001	3047	3085	3127	3173	3215	3257
13	2809	2859	2909	2955	2997	3043	3085	3127	3173	3215	3257
14	2805	2855	2909	2955	2993	3039	3081	3127	3169	3211	3257
15	2796	2851	2905	2951	2993	3035	3081	3123	3169	3211	3253
17	–	2842	2901	2947	2985	3031	3077	3119	3165	3207	3253
19	–	2830	2893	2939	2981	3027	3073	3114	3161	3202	3248
21	–	2817	2884	2934	2972	3018	3064	3110	3156	3198	3244
23	–	2802	2876	2926	2968	3014	3060	3106	3152	3194	3240
25	–	–	2855	2909	2960	3010	3056	3102	3148	3194	3236

Values are specific enthalpies in kJ/kg and agree with standard steam tables (differences from IAPWS-IF97 are below 0.5%).

Frequently Asked Questions

What is the difference between superheated and saturated steam?

Saturated steam is at the saturation temperature for its pressure and starts to condense as soon as it loses heat. Superheated steam is above that temperature; when it loses heat its temperature falls first and it does not condense until it reaches saturation.

Are the pressures in the table gauge or absolute?

The pressures in this table are absolute (bar a). Add about 1 bar to a gauge reading before using the table.

Why are some cells empty?

Saturation temperature rises with pressure. At 25 bar a, for example, it is about 224 °C, so steam cannot be superheated at 200 °C or 220 °C; those cells are left empty.

Is superheated steam suitable for heating?

While steam is superheated it behaves like a gas and its heat transfer coefficient is low. Heat exchangers and heaters therefore normally use saturated steam; if necessary, the steam is brought close to saturation with a desuperheater.

Conclusion

The superheated steam table is the basic tool for energy balances in steam turbines, superheated steam mains and steam conditioning. Remember that the pressures are absolute, read the enthalpy from the table and use the calculator for intermediate points. For steam traps suited to superheated steam lines, see our bimetallic steam traps product group.

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