Thermal Expansion
Thermal Expansion
Fabrication Information and Thermal Expansion
"Stresses (compressive, tensile, or shear) due to unequal temperature distribution and non-uniform temperature gradients, cause more failures in high-temperature equipment than all other influences combined amounting to approximately 90% of the total number of cases. It is destructive chiefly because the engineer does not include in his design proper allowance for or provision against temperature inequalities or because the operator imposes temperature differentials which cause localized dimensional changes with accompanying stresses greater than the elastic strength of the alloy at the given temperature."
The vast majority of failures reported to Rolled Alloys, involving breaking or deformation in service, are due to restraint of thermal expansion. For successful design and installation of high temperature equipment it is critical to take thermal expansion into account, and to be able to calculate the amount of expansion to be expected. Below is a simple table for calculating total expansion, in inches per foot of length, for a given temperature.
Total Thermal Expansion, inches/foot
| Temp, °F | Carbon Steel | 446 | 304 | 309 | 310 | RA 253 MA | RA330 | RA333 | 601 | 600 | RA 602 CA |
| 70-200 | 0.0139 | 0.00874 | 0.0145 | 0.0137 | 0.0131 | 0.0141 | 0.0129 | 0.0109 | 0.0119 | 0.0115 | 0.0103 |
| 70-400 | 0.0376 | 0.0225 | 0.0372 | 0.0356 | 0.0348 | 0.0370 | 0.0341 | - | 0.0317 | 0.0305 | 0.0297 |
| 70-600 | 0.0623 | - | 0.0604 | 0.0591 | 0.0569 | 0.0610 | 0.0566 | - | 0.0516 | 0.0502 | 0.0496 |
| 70-800 | 0.0885 | 0.0526 | 0.0876 | - | 0.0806 | 0.0859 | 0.0797 | - | 0.0727 | 0.0710 | 0.0710 |
| 70-1000 | 0.0904 | 0.0681 | 0.115 | 0.108 | 0.106 | 0.111 | 0.104 | 0.0960 | 0.0949 | 0.0937 | 0.0915 |
| 70-1200 | 0.113 | 0.0854 | 0.144 | - | 0.133 | 0.137 | - | 0.122 | 0.120 | 0.117 | 0.115 |
| 70-1400 | - | 0.102 | 0.174 | - | 0.160 | 0.164 | - | 0.148 | 0.147 | 0.142 | 0.144 |
| 70-1600 | - | 0.123 | - | 0.185 | 0.186 | 0.193 | 0.180 | 0.173 | 0.175 | 0.167 | 0.174 |
| 70-1800 | - | 0.152 | - | - | 0.214 | 0.224 | 0.208 | 0.201 | 0.204 | 0.193 | 0.201 |
| 70-2000 | - | - | - | - | 0.245 | - | - | - | 0.236 | - | 0.227 |
To convert these numbers to the metric system, multiply by 83.33 to get millimeters of expansion for every meter of length, for the stated temperature, which is in Fahrenheit
For an example of how to use this table, consider a 20 foot long muffle made of RA330, operating at 1800°F. Read 0.208 inch/ft from the chart above, multiply by 20 feet for a total expansion of 4.16 inches
The more general way to calculate thermal expansion is to use the mean coefficients of thermal expansion, such as those given on the next page.
To use the table on page 2, multiply the length of the part in inches, times the difference between room temperature and operating temperature, times the expansion coefficient. Note that these coefficients are all multiplied by 10-6, which is the same as dividing by one million.
For example, consider that 20 foot long muffle made of RA330, operating at 1800°F:
20 feet X 12 inches/foot X (1800-70°F) X 10.0×10-6 = 240 inches X 1730°F X 10×10-6 = 4.152 inches.
Mean Coefficient of Thermal Expansion
| ALLOY | Temperature, °F | ||||||||||||||||||
| 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 1000 | 1100 | 1200 | 1300 | 1400 | 1500 | 1600 | 1700 | 1800 | 1900 | 2000 | |
| 304, 316* | 8.9 | 9.2 | 9.5 | 9.7 | 9.8 | 10.0 | 10.1 | 10.2 | 10.3 | 10.4 | 10.6 | 10.7 | 10.8 | 10.8 | - | - | - | - | - |
| 2205 | 7.2 | 7.3 | 7.5 | 7.7 | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| 321 | 9.3 | - | 9.4 | - | 9.5 | - | 10.0 | - | 10.3 | 10.5 | 10.6 | - | 10.9 | - | 11.1 | - | 11.4 | - | - |
| 309 | 8.8 | 8.9 | 9.0 | 9.2 | 9.3 | 9.4 | - | - | 9.7 | - | - | - | - | 10.0 | 10.1 | - | - | - | - |
| 310 | 8.4 | 8.6 | 8.8 | - | 8.95 | - | 9.2 | - | 9.5 | - | 9.8 | - | 10.05 | - | 10.15 | - | 10.3 | - | 10.6 |
| Carbon Steel* | 6.7 | 6.9 | 7.1 | 7.3 | 7.4 | 7.6 | 7.8 | 7.9 | 8.1 | 8.2 | 8.3 | 8.4 | - | - | - | - | - | - | - |
| RA 253 MA® | 9.06 | - | 9.34 | - | 9.59 | - | 9.81 | - | 9.97 | - | 10.14 | - | 10.3 | - | 10.5 | - | 10.8 | - | - |
| 410 | 5.5 | - | - | - | - | - | - | - | - | - | 6.5 | - | - | - | - | - | - | - | - |
| RA330® | 8.3 | 8.4 | 8.6 | 8.7 | 8.9 | 9.0 | - | 9.2 | 9.3 | 9.4 | 9.6 | - | - | 9.7 | 9.8 | 9.9 | 10.0 | - | - |
| HR-120™ | 7.95 | - | 8.29 | - | 8.56 | - | 8.80 | - | 8.98 | - | 9.24 | - | 9.52 | - | 9.72 | - | 9.84 | - | - |
| 353 MA® | 8.48 | - | 8.68 | - | 8.88 | - | 9.07 | - | 9.27 | - | 9.46 | - | 9.66 | - | 9.86 | - | 10.05 | - | - |
| 800H/AT | 7.9 | - | 8.8 | - | 9.0 | - | 9.2 | - | 9.4 | - | 9.6 | - | 9.9 | - | 10.2 | - | - | - | - |
| 446 | 5.6 | - | 5.7 | 5.8 | - | 5.9 | 6.0 | - | 6.1 | - | 6.3 | - | 6.4 | - | 6.7 | 6.9 | 7.3 | - | - |
| 600 | 7.4 | - | 7.7 | - | 7.9 | - | 8.1 | - | 8.4 | - | 8.6 | - | 8.9 | - | 9.1 | - | 9.3 | - | - |
| 601 | 7.6 | - | 8.01 | - | 8.11 | - | 8.3 | - | 8.5 | - | 8.87 | - | 9.19 | - | 9.51 | - | 9.82 | - | 10.18 |
| RA 602 CA® | 6.6 | - | 7.5 | - | 7.8 | - | 8.1 | - | 8.2 | - | 8.5 | - | 9.0 | - | 9.5 | - | 9.7 | - | 9.8 |
| RA333® | 7.0 | - | - | 8.0 | - | - | - | - | 8.6 | - | 9.0 | - | 9.3 | 9.3 | 9.4 | 9.5 | 9.7 | - | - |
| HH | - | - | - | - | - | - | - | - | 9.5 | - | 9.7 | - | 9.9 | - | 10.2 | - | 10.5 | - | 10.7 |
| HK | - | - | - | - | - | - | - | - | 9.4 | - | 9.6 | - | 9.8 | - | 10.0 | - | 10.2 | - | 10.4 |
| HT | 7.9 | - | 8.14 | - | 8.37 | - | 8.61 | - | 8.85 | - | 9.09 | - | 9.33 | - | 9.56 | - | 9.8 | - | 10.04 |
| HP | - | - | - | - | - | - | - | - | 9.2 | - | 9.5 | - | 9.8 | - | 10.0 | - | 10.3 | - | 10.6 |
| 825 | 7.8 | - | 8.3 | - | 8.5 | - | 8.7 | - | 8.8 | - | 9.1 | - | 9.5 | - | 9.7 | - | - | - | - |
| 20Cb-3® | 8.2 | 8.3 | 8.4 | - | 8.65 | - | - | 8.9 | 8.95 | - | 9.15 | - | 9.3 | 9.4 | 9.5 | - | - | - | - |
| AL-6XN® | 7.9 | 8.3 | 8.37 | 8.42 | 8.6 | 8.7 | 8.8 | 8.85 | 8.96 | - | 9.3 | - | - | - | - | - | - | - | - |
| Ti Gr 2 | 4.8 | - | - | - | 5.1 | - | - | - | 5.4 | - | 5.6 | - | - | - | - | - | - | - | - |
NOTE: All coefficients are reported as inch/inch °F x 10-6, room temp to indicated temp. Multiply by 1.8 for metric units.
*ASME Section II Part D Table TE-1
