As I mentioned in my earlier post regarding about Steam Trap, while selecting a steam trap the most important data required is the condensate load.
This data is generally provided by the process department but as a piping engineer too should be in a position to estimate the condensate loads initially. The selected steam tarp shall be functionally at the maximum condensate load.
CALCULATING CONDENSATE LOADS:
Very often one may be faced with the situation where precise data regarding the condensate loads may not be available (sometimes may not be worthwhile). In such situations the condensate loads can be approximately estimated as per following.
Condensate Loads/ Hour from the insulated Steam Mains at 21º ambient temperature:
The table provides and estimated condensate load for a 30 Meter of Pipe run.
Steam Pressure 
Main Size (NS..MM) 

50 
80 
100 
150 
200 
250 

0.7 
3 
4 
5 
8 
10 
12 
4 
5 
7 
9 
14 
17 
21 
7 
6 
9 
11 
16 
20 
25 
20 
10 
15 
19 
28 
35 
44 
42 
15 
22 
28 
41 
52 
64 
Figure1, Exhibit 34.19
Steam Tracer Lines:
Approximate load can be considered as 30 Kg/ Hour for each 30 Meters of tracer line.
Heating Water with Steam:
Kg Condensate/ Hour = (LPH * Temperature rise in ºC )/500
Heating Fuel Oil with Steam
Kg Condensate/ Hour = (LPH * Temperature rise in ºC)/1000
Heating Air with Steam:
Kg Condensate/ Hour = (NM 3/ Min * Temperature rise in ºC)/27
Heating Solid Materials (e.g Sterilizers, Autoclaves, Retorts):
Kg Condensate/ Hour = (W * Cp * Temperature rise in ºC)/(L * t)
Where:
W = Weight of Material in Kg.
Cp = Specific Heat of Material in K Cal./ Kg. ºC
L = Latent Heat of Steam K Cal./ Kg
T = Heating Time in Hours
Heating Liquid in Steam Jacketed Kettles:
Same as above except that the Specific Heat of Liquid will apply.
Steam Jacketed Dryers:
Kg Condensate/ Hour = (600 (Wi – Wf) + (Wi * Temperature rise in ºC))/L
Where:
Wi = Initial Weight of Material in Kg./ Hour
Wf = Final Weight of Material in Kg./ Hour
L = Latent Heat of Steam K Cal./ Kg
Heating Air with Steam (e.g. Pipe Coil and Radiation):
Kg Condensate/ Hour = (A * U * Differential Temp. ºC (steam and ambient))/L
Where:
A = Area of Heating Surface in Sq. Meters
U = Heat Transfer Coeff. K. Cal. / Sq Mt. ºC
(Consider a value of 2 for free convection)
L = Latent Heat of Steam K. Cal./ Kg
Note: Condensate Load to heat the Equipment shall be added wherever applicable.