Why joints fail even when BOQs are correct
Design is correct.
Fasteners are correct.
Quantities are correct.
Yet the joint doesn’t fit.
Why?
Because joints don’t fail on paper.
They fail in 3D.
What causes fit-up problems
- 1. Bolt head orientation not considered
Bolt heads interfere with plates or stiffeners.
- 2. Nut access blocked
Spanners cannot reach nuts.
- 3. Washer stacking wrong
Extra washers change grip length.
- 4. Plate orientation reversed
Holes shift slightly out of alignment.
- 5. Wrong insertion sequence
Bolts installed before plates are aligned.
What this causes on site
- Forced installation
- Ovalized holes
- Damaged coatings
- Slowed erection
- Inspection failures
How to prevent repeat mistakes
Review joint orientation in drawings
Simulate assembly sequence
Check bolt head clearances
Train erection crews
Use mock-up assemblies
Final thought
Fasteners connect parts.
Assembly connects reality.