Pipe support spans — MSS-SP-69 / B31.3
Recommended span between supports
Pick NPS + service + material + duty modifier; get the maximum recommended span between supports per MSS-SP-69 with B31.3 Table 321.1 cross-check. Plus a sanity-check on a user-specified span.
Inputs
Reduces base span for vibrating, slug-flow, insulated, or cryogenic service
m
Optional — leave blank to just see the recommendation
baseline (MSS-SP-69) · normal water/process service
Results
Base span (MSS-SP-69)5.2m
× material factor1.00
× service factor1.00
Recommended max span5.2m
Allowable max sag (~L/360)14.4mm
MSS-SP-69 reference table (current modifiers applied)
| NPS | OD mm | water (m) | vapor (m) | your conf. (m) |
|---|---|---|---|---|
| 1 | 33.4 | 2.1 | 2.5 | 2.1 |
| 2 | 60.3 | 3.0 | 3.6 | 3.0 |
| 3 | 88.9 | 3.7 | 4.4 | 3.7 |
| 4 | 114.3 | 4.3 | 5.2 | 4.3 |
| 6 | 168.3 | 5.2 | 6.2 | 5.2 |
| 8 | 219.1 | 5.8 | 7.0 | 5.8 |
| 10 | 273.1 | 6.4 | 7.7 | 6.4 |
| 12 | 323.9 | 7.0 | 8.4 | 7.0 |
| 16 | 406.4 | 8.2 | 9.8 | 8.2 |
| 20 | 508.0 | 9.4 | 11.3 | 9.4 |
| 24 | 609.6 | 10.4 | 12.5 | 10.4 |
| 1-1/2 | 48.3 | 2.7 | 3.2 | 2.7 |
MSS-SP-58 covers hanger / support component design; SP-69 gives recommended spacing. These spans assume single-supported flexible pipe; rigid pipe (heavy-wall thick-flange) can use longer spans. For full B31.3 §319 flexibility analysis with modal frequencies see /console/transport/vibration.
Download all inputs + calculations + outputs as a single PDF.