All pipes and vessels expand and contract in direct proportion to a temperature change. This can be due to the temperature of the flowing media or from surrounding ambient temperature. Wind chill and solar gain are also factors that should be considered
Expansion and contraction can be calculated mathematically using the thermal expansion formula:-
X = L × (T1 -T2 ) × Cexp
Where
- X = Expansion or Contraction (m)
- L = Length of pipe or vessel (m)
- T1 = Starting Temperature (ºC)
- T2 = Final Temperature (ºC)
- Cexp = Coefficient of Thermal Expansion
Coefficients of Thermal Expansion for various common pipe materials are shown below:-
| METALS | PLASTICS | ||
|---|---|---|---|
| Materials | Coefficient | Materials | Coefficient |
| Copper | 16.4 x 10-6 | ABS | 100 x 10-6 |
| Carbon Steel | 12.2 x 10-6 | UPVC | 80 x 10-6 |
| Stainless Steel (Austenitic) | 16.3 x 10-6 | CPVC | 70 x 10-6 |
| Stainless Steel (Ferritic) | 10.9 x 10-6 | PE | 200 x 10-6 |
| Cast Iron | 11.0 x 10-6 | PP | 150 x 10-6 |
Expansion rates of common materials at various temperature changes are as follows:-
| Temp change | Rates of Thermal Expansion for Common Pipe Materials (mm/m) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| ºC | Copper | C.Steel | S.Steel | Cast Iron | ABS | UPVC | CPVC | PE | PP |
| 10 | 0.16 | 0.12 | 0.16 | 0.11 | 1.00 | 0.80 | 0.70 | 2.00 | 1.50 |
| 20 | 0.33 | 0.24 | 0.33 | 0.22 | 2.00 | 1.60 | 1.40 | 4.00 | 3.00 |
| 30 | 0.49 | 0.37 | 0.49 | 0.33 | 3.00 | 2.40 | 2.10 | 6.00 | 4.50 |
| 40 | 0.66 | 0.49 | 0.65 | 0.44 | 4.00 | 3.20 | 2.80 | 8.00 | 6.00 |
| 50 | 0.82 | 0.61 | 0.82 | 0.55 | 5.00 | 4.00 | 3.50 | 10.00 | 7.50 |
| 60 | 0.98 | 0.73 | 0.98 | 0.66 | 6.00 | 4.80 | 4.20 | 12.00 | 9.00 |
| 70 | 1.15 | 0.85 | 1.14 | 0.77 | - | - | 4.90 | - | 10.50 |
| 80 | 1.31 | 0.98 | 1.30 | 0.88 | - | - | 5.60 | - | 12.00 |
| 90 | 1.48 | 1.10 | 1.47 | 0.99 | - | - | - | - | - |
| 100 | 1.64 | 1.22 | 1.63 | 1.10 | - | - | - | - | - |
| 110 | 1.80 | 1.34 | 1.79 | 1.21 | - | - | - | - | - |
| 120 | 1.97 | 1.46 | 1.96 | 1.32 | - | - | - | - | - |
| 130 | 2.13 | 1.59 | 2.12 | 1.43 | - | - | - | - | - |
| 140 | 2.30 | 1.71 | 2.28 | 1.54 | - | - | - | - | - |
| 150 | 2.46 | 1.83 | 2.45 | 1.65 | - | - | - | - | - |
| 160 | 2.62 | 1.95 | 2.61 | - | - | - | - | - | - |
| 170 | 2.79 | 2.07 | 2.77 | - | - | - | - | - | - |
| 180 | 2.95 | 2.20 | 2.93 | - | - | - | - | - | - |
| 190 | 3.12 | 2.32 | 3.10 | - | - | - | - | - | - |
| 200 | 3.28 | 2.44 | 3.26 | - | - | - | - | - | - |
| 210 | - | 2.56 | 3.42 | - | - | - | - | - | - |
| 220 | - | 2.68 | 3.59 | - | - | - | - | - | - |
| 230 | - | 2.81 | 3.75 | - | - | - | - | - | - |
| 240 | - | 2.93 | 3.91 | - | - | - | - | - | - |
| 250 | - | 3.05 | 4.08 | - | - | - | - | - | - |
| 260 | - | 3.17 | 4.24 | - | - | - | - | - | - |
| 270 | - | 3.29 | 4.40 | - | - | - | - | - | - |
| 280 | - | 3.42 | 4.56 | - | - | - | - | - | - |
| 290 | - | 3.54 | 4.73 | - | - | - | - | - | - |
| 300 | - | 3.66 | 4.89 | - | - | - | - | - | - |