Page 134 - GRINNELL Mechanical Grooved Piping Products EMEA

Grooved Couplings
Pressure and Design Data
Thermal Movement
Tech Data Sheets: G810, G820, G8
Directions to calculate the number of couplings required to compensate for the thermal expansion and contraction of pipe (by example):
(1) Thermal Contraction
Utilise the Thermal Expansion Table. Allowance for the minimum installation temperature, in this case 26.6°C to 4.4°C (80°F to 40°F), is calculated as:
26.6°C = 15,5mm per 30,5m
4.4°C = 7,6mm per 30,5m
Difference = 7,9mm per 30,5m
For 45,7m of pipe = 7,9mm x 1.5 = 11,9mm per 45,7m
(80°F = 0.61" per 100'
40°F = 0.30" per 100'
Difference = 0.31" per 100'
For 150' of pipe = 0.31" x 1.5 = 0.47" per 150')
(2) Thermal Expansion
Utilise the Thermal Expansion Table. Allowance for the minimum installation temperature, in this case 26.6°C to 93.3°C (80°F to 200°F), is calculated as:
93.3°C = 38,6mm per 30,5m
26.6°C = 15,5mm per 30,5m
Difference = 23,1mm per 30,5m
For 45,7m of pipe = 23,1mm x 1.5 = 34,5mm per 45,7m
(200°F = 1.52" per 100'
80°F = 0.61" per 100'
Difference = 0.91" per 100'
For 150' of pipe = 0.91 x 1.5 = 1.36" per 150')
(3) Couplings Required
Available linear movement for a 150mm (6") Figure 707 Flexible Coupling on roll grooved pipe = 2.4mm (0.094") per coupling.
• Fully butted together for contraction only. Therefore the number of Figure 707 Flexible Couplings required:
• 11.9mm / 2.4mm per coupling = 4.96 (0.47" / 0.094" per coupling = 5.0)
• Use 5 Figure 707 couplings for pipe contraction
• (b) Fully gapped apart for expansion only. Therefore the number of Figure 707 Flexible Couplings required:
• 34.5mm / 2.4mm per coupling = 14.38 (1.36" / 0.094" per coupling = 14.47)
• • Use 15 Figure 707 Flexible Couplings for pipe expansion
Thermal Expansion of Carbon Steel in millimetres per Metres Between 0°C (-32°F) and Indicated Temperature
Temperature C°
F°
Thermal Expansion mm/30.5m
-40
-40
-30
-22
-20
-4
-10
14
0
32
10
50
20
68
30
86
40
104
50
122
60
140
70
158
80
176
90
194
100
212
120
248
-0.500 -0.375 -0.250 -0.125 0.000 0.125 0.250 0.375 0.500 0.625 0.750 0.875 1.000 1.125 1.250 1.500
Based on coifiecient of thermal expansion = 0.0000125 mm/mm/°C carbon steel
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