Installation Guide

14 | nVent.com/RAYCHEM
Spiral Pitch Table (mm).
NB NPS Spiral Ratio
(mm) (inches) Metres of cable per metre of pipe
1.1 1.2 1.3 1.4 1.5
25 1 250 170 140 110 100
32 1
1/4
310 210 170 140 130
40 1
1/2
350 240 190 160 140
50 2 430 300 240 200 180
65 2
1/2
520 360 290 240 210
80 3 630 430 350 290 260
90 3
1/2
720 490 390 330 290
100 4 800 560 440 370 330
125 5 990 680 550 460 400
150 6 1180 810 650 550 480
200 8 1520 1050 840 710 620
Example:
For pipe of 80 mm NB (3" NPS) requiring 1.3 metres of heating
cable per metre of pipe, pitch is 350 mm.
Figure 2a
Glass cloth tape
(typical)
Heating
cable
Pipe length
Pipe
Apply glass
cloth tape
before spiralling
cable on pipe
Heating cable length
Wrap loops in
opposite
direction
Tape after
spiralling cable
on pipe
Pitch
Heating cable length = pipe length x spiral ratio
Refer to design specication for spiral ratio
Step 1 Make starting loop as shown
Step 2 Grasp loop and wind around pipe
Step 3 Space evenly and attach to pipe.
Thermally insulate and weatherproof to specification
Figure 2b
Pipe
Heating cable
Glass cloth tape
(typical)
Pitch