technical of 3 BOLTED TYPE SINGLE TENSION HARDWARE CLAMP
1. Ultimate Tensile Strength (UTS)
1. Clamp Body (Aluminum alloy):
I. UTS: ~150–250 MPa, depending on alloy and casting integrity
2. Bolts (HDG steel / SS 304):
I. UTS: 400–800 MPa, depending on grade (e.g., Class 8.8 or SS304)
2. Working Load / Safe Working Load (SWL)
1. Generally 40–50% of UTS
2. Designed to bear static and dynamic loads under:
I. Conductor tension
II. Wind-induced movement
III. Occasional surge currents
3. Typical SWL range: 4–8 kN depending on the conductor type and size
3. Conductor Diameter Compatibility
1. Designed for specific conductor sizes:
I. Compatible with conductor diameters from 7 mm to 25 mm
2. Grooved interior surface ensures snug fit, no conductor damage
4. Slip Strength:
1. The clamp must not allow the conductor to slip under load
2. Minimum slip strength: ≥95% of RTS of the conductor
3. Achieved by:
I. Proper groove depth
II. Serrated gripping surface
III. Correct bolt torque (typically 45–60 Nm)
5. Temperature Withstanding Capacity:
1. Operating range: –40°C to +85°C
2. Short-term withstand: up to 250°C during fault conditions
3. Aluminum alloy body resists:
I. Thermal expansion
II. Localized heating due to current surges
4. Maintains mechanical grip in fluctuating temperatures
6. Corrosion Resistance:
1. Hot-dip galvanized bolts & inserts: ≥80 µm coating thickness
2. Aluminum body offers natural corrosion resistance
3. Optional: Anodized or epoxy coating for high-pollution or coastal zones
4. Must pass Salt Spray Test (ASTM B117) for ≥ 500–1000 hours
7. Impact & Fatigue Strength:
1. Withstands:
I. Conductor vibration (aeolian, galloping)
II. Installation hammering or mechanical tightening
2. No cracking or material loss during 10,000+ vibration cycles
3. Maintains torque and mechanical pressure over time
8. Mechanical Endurance:
1. Service life: ≥30 years
2. Maintains holding capacity and material properties under:
I. Cyclic mechanical loads
II. UV and moisture exposure
III. Varying conductor tensions due to seasonal expansion
9. Design Safety Factors:
1. Mechanical safety factor: ≥2.5 to 3.0
2. Designed to handle 2.5× normal service loads without failure
3. Electrical safety also maintained through:
I. Low contact resistance (<100>
II. Stable current flow through clamp-conductor interface
Top 5 Quality Assurance
1. Type & Routine Testing (as per IS 5561 / IEC 61284)
a. Tensile load test (proof load and ultimate load)
b. Slip test under rated conductor tension
c. Current cycle and short-circuit withstand test
d. Galvanizing thickness test (as per IS 2629)
2. Material Verification
a. Aluminum alloy (LM6 / LM25 / A356): Checked for composition & casting quality
b. Bolts/Nuts: Grade 8.8 or SS 304 tested for:
I. Hardness
II. Thread tolerance
III. Tensile load
3. Dimensional & Visual Inspection
a. Groove depth, width, and alignment checked with gauges
b. Hole alignment for bolts, symmetry in casting
c. Visual checks for:
I. Cracks, porosity, sharp edges
II. Burrs or incomplete casting
4. Corrosion Resistance Testing
a. Salt Spray Test (ASTM B117): ≥500 hrs
b. Optionally tested for:
I. UV stability (if coated)
II. Humidity & acid fog tests (for coastal or industrial installations)
5. Traceability & Documentation
a. Each clamp batch labeled with:
I. Manufacturer code/logo
II. Conductor size
III. Production batch number
b. Supplied with:
I. Routine Test Certificate
II. GTP (Guaranteed Technical Particulars)
III. ISO 9001:2015 compliance
IV. Optional: Third-party lab test reports (CPRI/ERDA)