Design Guide for Hazardous / Industrial
Self-regulating trace heating systems
21-5400-7D0001/-
05/2023-EHT-466854
Notice Technical data subject to change without notice.
No claims for damage arising from alternations, errors or misprints shall be allowed.
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Step 8: Determine the required allowance for pumps. valves. flanges and pipe supports:
Determine the required allowances for pumps. valves. flanges and pipe supports using the following table:
Table F: Allowance values and pipe support intervals
Pipe diameter
in DN / inch
DN8
1/4"
DN15
1/2"
DN20
3/4"
DN25
1"
DN32
11/4"
DN40
11/2"
DN50
2"
DN65
21/2"
DN80
3"
DN100
4"
DN150
6"
DN200
8"
DN250
10"
DN300
12"
Allowance for pumps
in m
1.5
2
2
2.1
2.3
2.3
2.4
2.4
2.4
2.6
3
3.5
4
4
Allowance for valves
in m
0.5
0.5
0.5
0.6
0.6
0.7
0.7
1
1
1.3
1.5
1.6
1.8
2
Allowance for flanges
in m
0.2
0.2
0.3
0.3
0.3
0.3
0.4
0.4
0.5
0.7
0.9
1
1.2
1.2
Allowance for pipe supports
in m
0.2
0.2
0.3
0.3
0.3
0.3
0.4
0.4
0.5
0.7
0.9
1
1.2
1.2
Typical pipe support interval
in m
1
1.5
1.5
2
2
2.5
3.1
4
4
5
6
7
8
8
→ Example
Pipe diameter: DN25
1 pump
2 valves
6 flanges
24 pipe supports
The total required allowance is calculated as follows:
total required allowance = no. of pumps × pump allowance value +
no. of valves
×
valve allowance value +
no. of flanges × flange allowance value +
no. of pipe supports × pipe support allowance value
= 1 × 2.1 m + 2 × 0.6 m + 6 × 0.3 m + 24 × 0.3 m
= 12.3 m
Step 9: Add all lengths / allowances together:
Add the lengths for piping (as determined in step 6) and allowances (as determined in step 7 and step 8) together to obtain total required trace
heater length.
→ Example
required trace heater length for piping (step 6): 50 m
required allowances for connection kits (step 7): 1.0 m
required allowances for pumps. valves. flanges and pipe supports (step 8): 12.3 m
total required trace heater length = required trace heater length for required allowances
= 50 m + 1.0 m + 12.3 m
= 63.3 m
Determination of the required number of heating circuits
Step 10: Confirm the number of electrical circuits required for the application:
Using Table G on page 17. compare the required heater length and start up temperature to the available circuit breaker allowances to determine
the number of electrical circuits that will be required.
→ Example
total required trace heater length: 63.3 m
circuit breaker voltage: 230 Vac
selected trace heater: 10 PSB
circuit breaker amperage: 25 A
required start-up temperature: -20 °C
allowable trace heater length from table below = maximum of 69 m at -20 °C on 25 A circuit breaker at 230 Vac
= 63.3 m calculated < 69 m maximum allowable for 25 A
= 1 circuit
