Pipe Thrust Block Calculator
Size thrust blocks for water mains per AWWA M23
Use test pressure (typically 1.5x working pressure)
Thrust Block Requirements
Required Bearing Area
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Block Dimensions
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Thrust Force
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Pipe Area
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Thrust Coefficient
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Concrete Volume
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Note: Block must bear against undisturbed soil. Backfill behind block is not adequate.
Thrust Force Diagram
Thrust acts perpendicular to bisector of bend angle
Thrust Force Coefficients
| Fitting Type | Angle | Thrust Coefficient | Formula |
|---|---|---|---|
| Bend | 90 | 1.414 | 2 x sin(45) |
| Bend | 45 | 0.765 | 2 x sin(22.5) |
| Bend | 22.5 | 0.390 | 2 x sin(11.25) |
| Bend | 11.25 | 0.196 | 2 x sin(5.625) |
| Tee | 90 | 1.000 | Full area |
| Dead End | -- | 1.000 | Full area |
| Reducer | -- | Varies | A1 - A2 |
Soil Bearing Capacity Reference
Soft Soils
500-1,000 PSF
Wet clay, silt
Medium Soils
1,000-2,000 PSF
Firm clay, sandy clay
Dense Soils
2,000-3,000 PSF
Dense sand, gravel
Rock
4,000+ PSF
Bedrock, hardpan