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Table 2: Typical allowances (in mm) per run of cable
NPS
DN
Light
inch
mm
valve
(flanged)
0.5
15
300
0.75
20
460
1
25
610
1.5
40
760
2
50
760
3
80
910
4
100
1220
6
150
1520
8
200
2140
10
250
2440
12
300
2750
14
350
3050
16
400
3350
18
450
3660
20
500
3970
24
600
4580
1.
Allowances above are based on typically available fittings and
supports, with an insulation thickness equivalent to the pipe
insulation. Please refer to the engineering documentation for project
specific allowances.
2.
For pipes requiring more than one run of heating cable, apply the
full allowance for each run of cable on each fitting or support as
long as space allows. However, MI heating cables must not touch or
overlap and the minimum spacing between the heating cables must
be respected.
3.
For some applications, it may be physically impossible to install all
of the recommended heating cable directly on the fitting or support.
In this case, install the excess heating cable on the pipe, on either
side of the fitting or support, or distribute the additional heater
length along the entire circuit length if a lower local temperature
is acceptable. This constraint may be difficult for small pipes
and/or multiple cable runs. If required, contact Pentair Thermal
Management for assistance.
4.
The field variance is important to accomodate expansion and
contraction of the heated equipment. Also refer to figures 12-14 for
more detailed information.
12 12
Light
Heavy
valve
valve
(threaded
(flanged)
or welded)
300
300
300
460
300
610
460
910
610
1060
760
1220
910
1520
1060
1830
1220
2440
1520
3050
1830
3660
2140
4270
2440
4880
2750
5500
3050
6100
3660
7320
Heavy
Typical
valve
pipe
shoe
(threaded
or welded)
300
910
300
910
300
910
460
910
610
910
760
910
910
910
1060
910
1220
910
1520
910
1830
910
2140
1370
2440
1370
2750
1370
3050
1370
3660
1370
Flange
Field
pair
variance
300
2%
300
2%
460
2%
460
2%
460
2%
610
3%
610
3%
610
3%
610
3%
910
3%
1060
3%
1220
3%
1370
3%
1680
3%
1830
3%
2140
3%
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