Why PEB bracing connections loosen
Bracing connections live in a vibration environment.
Wind load.
Thermal expansion.
Structural movement.
Without a locking method, nuts slowly rotate loose.
Torque alone is not enough.
What lock nuts actually do
Lock nuts resist rotation by:
- Adding prevailing torque
- Creating elastic interference
- Increasing friction
- Preventing back-off
They stop vibration from undoing joints.
Common locking methods
- Nyloc nuts
- All-metal prevailing torque nuts
- Double nutting
- Serrated flange nuts
- Chemical thread locking
Each has specific use cases.
Why loosening keep happening
- 1. Plain nuts used instead of lock nuts
Cost or ignorance.
- 2. Wrong lock nut type
Nyloc used in high temperature zones.
- 3. No locking method specified
BOQ says “nut” only.
- 2. Reused lock nuts
Prevailing torque lost.
What happens on site
- Nuts rotate loose
- Bracing slackens
- Structural stiffness reduces
- Noise and vibration increase
- Safety risk rises
How to prevent this
Specify locking method in BOQ
Match lock nut type to environment
Avoid reusing lock nuts
Inspect locking function before use
Train installers on locking principles
Final thought
If a joint sees vibration, it needs a lock.
Torque tightens.
Locking holds.