M56×5.5 Thread Specifications
Complete dimensions for M56×5.5 coarse pitch thread per ISO 724. Pitch: 5.5mm (4.6 TPI equivalent).
Thread Dimensions
| Designation | M56×5.5 |
| Thread Series | ISO Metric Coarse |
| Pitch | 5.5 mm (4.6 TPI) |
| Major Diameter (d) | 56 mm (2.2047") |
| Pitch Diameter (d₂) | 52.4278 mm (2.0641") |
| Minor Diameter — External (d₁) | 49.252 mm (1.9391") |
| Minor Diameter — Internal (D₁) | 50.0463 mm (1.9703") |
| Thread Depth | 2.977 mm |
| Tensile Stress Area | 2030.02 mm² |
| Fundamental Triangle Height (H) | 4.7631 mm |
Tap Drill Size
Recommended tap drill: 51.0 mm
Calculated minor diameter (D₁): 50.05 mm. Standard metric tap drill (d − P): 51.0 mm.
Closest inch drill: 2-1/64" (2.0156" / 51.2 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 456.8 | 812.0 |
| 4.8 | 310 | 420 | 629.3 | 852.6 |
| 5.8 | 380 | 520 | 771.4 | 1055.6 |
| 8.8 | 600 | 830 | 1218.0 | 1684.9 |
| 10.9 | 830 | 1040 | 1684.9 | 2111.2 |
| 12.9 | 970 | 1220 | 1969.1 | 2476.6 |
Proof load = stress area × proof stress. Per ISO 898-1.
Common Applications
- Structural steel
- Bridge construction
- Heavy industrial equipment
- Foundation bolts
How M56×5.5 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (56 mm) and pitch (5.5 mm):
- Fundamental triangle height: H = (√3/2) × P = 4.7631 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 52.4278 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 49.252 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 50.0463 mm
- Thread depth: 5H/8 = 2.977 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 2030.02 mm²