IS 3757 : 1985
Bolts, Nuts & Fasteners - High Strength Structural Bolts
1. Summary about High Strength Structural Bolts
High strength structural bolts are engineered fasteners used in steel structures, bridges, industrial plants, and heavy construction. They are designed to withstand high tensile and shear loads while maintaining joint integrity under stress.
2. Why BIS Certificate is Mandatory for High Strength Structural Bolts
BIS certification is mandatory because these bolts are critical load-bearing components. Failure can lead to catastrophic structural collapse and safety hazards.
3. What is BIS Certified for High Strength Structural Bolts
BIS certification confirms conformity with the applicable Indian Standard issued by the :contentReference[oaicite:0]{index=0} through testing of tensile strength, hardness, dimensional accuracy, and surface condition.
Tests required for High Strength Structural Bolts
| Title | Mandatory/Optional |
|---|---|
| Dimensions | Required |
| Thread Requirements | Required |
| Raw Material | Optional |
| Tensile test under wedge loading | Required |
| Tensile test | Required |
| Tensile test for full-size fasteners | Required |
| Proof load test | Required |
| Head soundness test | Required |
| Torsional test | Required |
| Hardness test | Required |
| Decarburization test | Required |
| Carburization test | Required |
| Retempering test | Required |
| Anti-seizing test | Required |
| Surface discontinuities | Required |
| Galvanizing | Required |
| Nuts (if supplied with bolt) | Optional |
| Washers (if provided) | Optional |
4. Benefits of BIS Certification for High Strength Structural Bolts
- Ensures structural safety and reliability
- Mandatory for infrastructure and construction projects
- Improves resistance to fatigue and load stress
- Reduces risk of joint failure
- Enhances confidence of engineers and regulators