Thermal Expansion Coefficient of Copper
| Value | 0.0000168 1/K |
| Status | Measured: ± 3.00e-07 1/K (0.018 relative) |
| Source | ASM Handbook, Vol. 2 / CDA Copper Tube Handbook |
| Categories | Material PropertiesEngineering & Trade |
| part per million per kelvin | 16.8 ppm/K |
| part per million per Celsius degree | 16.8 ppm/°C |
| part per million per Fahrenheit degree | 9.3333333 ppm/°F |
| microinch per inch per Fahrenheit degree | 9.3333333 μin/(in·°F) |
| percent per Celsius degree | 0.00168 %/°C |
| percent per Fahrenheit degree | 0.00093333333 %/°F |
| per kelvin | 0.0000168 1/K |
| per Celsius degree | 0.0000168 1/°C |
| per Fahrenheit degree | 0.0000093333333 1/°F |
| per Rankine degree | 0.0000093333333 1/°R |
Learning zone
Copper tube in a hot-water riser expands about 17 mm per 100 m per 10 °C, and a domestic hot-water line going from 10 °C cold to 60 °C hot moves nearly 1 mm per metre. That is the ticking noise in a wall cavity: tube sliding through a tight hole or hanger. Plumbing codes therefore require oversized penetrations, sleeve or isolate the tube, and put offsets or expansion loops in long runs. Rigidly clamped copper eventually work-hardens and cracks at the restraint.
Copper's coefficient sits neatly between steel's and aluminium's, which matters at every dissimilar-metal joint — copper tube in a steel hanger, copper busbar bolted to aluminium lugs. The aluminium-to-copper connection is the classic failure: different expansion rates cycle the joint, the aluminium creeps, contact pressure falls, resistance rises, and the joint heats and eventually fails. Bimetallic lugs, anti-oxidant compound and Belleville washers exist to fight exactly this mechanism.