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M20 socket cap screw size
17 mm Allen key
hex key size for M20 socket cap screw
M20 socket cap screw — Heavy structural, bridges, industrial.
Full specification
| System | Metric coarse |
| Nominal diameter | 20 mm |
| Thread pitch | 2.5 mm |
| Allen key / hex socket | 17 mm |
| Tap drill | 17.5 mm |
| Clearance hole | 22 mm |
| Common grade / class | 12.9 |
| Typical torque | 350 Nm (258.1 ft·lb) |
🔧 Torque unit converter
Pre-filled with the typical torque for M20 (12.9, dry).
About M20 socket cap screws
Heavy structural, bridges, industrial.
Socket cap screws (also called Allen head cap screws) have a cylindrical head with a hexagonal socket. They provide a clean appearance and can be used in tight spaces where a wrench cannot fit.
Grade 12.9 indicates high-strength alloy steel, quenched and tempered. These are commonly used in precision machinery, CNC equipment, and aerospace applications.
Frequently asked questions
- What size Allen key fits M20 socket cap screw?
- M20 socket cap screw uses a 17 mm Allen key (hex key).
- What is the torque for M20 socket cap screw?
- A typical tightening torque for M20 socket cap screw in 12.9 is about 350 Nm (258.1 ft·lb).
- What are socket cap screws used for?
- M20 socket cap screws are used in heavy structural, bridges, industrial.