Xylem Bell & Gossett Hoffman Speciality Series Engineering Data Manual page 20

Calculation of the running load is figured
using the following formula:
Ibs./hr. running load heat loss =
L x U x ∆T x E
S x H
L = Length of steam line.
U = Heat transfer from curve in Figure 1.
T = Temperature difference between steam
temperature and minimum ambient in
degrees F.
E = 1- Efficiency of insulation (for 80% effi-
cient insulation use 1.80 = .2).
S = Linear feet of pipe to provide 1 sq. ft.
surface area.
H = Latent heat of steam in Btu/lb. (see
Properties of Saturated Steam Table).
S VALUE FT. OF PIPE PER
SQ. FT. OF SURFACE AREA
Pipe Size
1"
1
⁄
1 "
4
1
⁄
1 "
2
2"
3"
4"
5"
6"
8"
10"
12"
14"
16"
18"
20"
24"
Calculation for warm-up load at start-up:
Warm-up load Ib./hr. =
W x(T
W = Weight of pipe (see table below for
T
T
L = Latent heat of steam at final
.114= Specific heat of steel or wrought
WEIGHT OF WELDED SEAMLESS STEEL PIPE
S Value
2.904
2.301
2.010
1.608
1.091
0.848
0.686
0.576
0.442
0.355
0.299
0.272
0.238
0.212
0.191
0.159
- T )x.114 L
1 2
weight per ft.).
= Steam temperature at saturation.
1
= Initial pipe temperature at ambient.
2
operating pressure.
iron pipe.
W VALUES
Schedule 40
Nominal Wt. Lbs.
Pipe Size Per Linear Ft.
1
⁄
" .85
2
3
⁄
" 1.13
4
1" 1.68
1
⁄
1 " 2.27
4
1
⁄
1 " 2.72
2
2" 3.65
1
⁄
2 " 5.79
2
3" 7.58
4" 10.79
6" 18.97
8" 28.55
Schedule 80
Wt. Lbs.
Per Linear Ft.
1.09
1.47
2.17
3.0
3.63
5.02
7.66
10.25
14.98
28.57
43.39
21