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Engineering ToolBox > Supporting Ductwork
Support spacing for the ductwork is typical based upon deflection, stress and cylinder buckling analysis.
For sheet metal ductwork the spacing between hangers should not exceed the maximum distances listed in the table below.
| Ducts Size | Maximum Spacing (Feet) | |
| Area (Sq.Ft) | Diameter (Inches) | |
| less than 4 | less than 5 | 8 |
| 4 to 10 | 5 to 38 | 6 |
| more than 10 | more than 38 | 4 |
| Ducts Type | Maximum Spacing (Feet) |
| round | 12 |
| rectangular | 10 |
Note! The support systems for ducting may provide restraint in three directions against displacement and rotation and consideration must be given when restraining ducts to avoid the development of excessive internal duct stresses such as possible expansion or contraction due to temperature variations.