Weighing Bridges (Weighbridges) – Inspection & Certification
Weighbridges are critical assets for trade, logistics, and legal metrology, ensuring accurate weight measurements for vehicles and goods. Regular inspection and certification by a third‑party or authorized agency are mandatory to comply with national and international standards.
Inspection & Certification Objectives
- Ensure accuracy and reliability of weighbridge measurements
- Verify compliance with legal metrology regulations
- Detect mechanical or electrical faults affecting performance
Pre‑Inspection Requirements
Documentation Review
- Manufacturer’s specifications and installation details
- Previous calibration / test certificates
- Legal metrology approvals (if applicable)
Site Preparation
- Ensure the weighbridge is clean, level, and free of debris
- Check for structural integrity (cracks, corrosion, foundation issues)
- Verify load cell condition (no physical damage, proper sealing)
Inspection & Testing Process
Visual & Mechanical Inspection
- Foundation & Structure: Check for cracks, settlement, or corrosion; verify alignment and load distribution
- Load Cells & Connections: Inspect for damage, moisture ingress, or loose wiring
- Junction Box & Cabling: Ensure waterproofing and secure connections
Functional Testing
- Zero Load Test: Ensure the weighbridge returns to zero after unloading; check for drift (unstable readings when empty)
- Span Calibration (Using Test Weights): Apply known certified weights (e.g., 10T, 20T, max capacity); verify readings match within permissible error (e.g., ±0.1% to ±0.5%)
- Eccentric Load Test (Corner Test): Place test weights on different sections of the weighbridge; ensure readings are consistent across all areas (no imbalance)
- Repeatability Test: Weigh the same load multiple times to confirm consistent results
- Material Test (Optional – For Legal Metrology): Compare weighbridge readings against a pre‑weighed truck (if required by authorities)
Certification & Compliance
If the weighbridge passes all tests, a certificate of conformity is issued. The certificate includes:
- Calibration report with test results
- Permissible errors as per standards
- Next due date for re‑inspection
- Sticker/seal applied (for legal metrology compliance)
Standards & Regulations
Frequency of Inspection & Re‑Certification
- Annual/Mandatory: Required for trade‑approved weighbridges
- Every 6 months: For high‑usage or harsh environments
- After repairs/modifications: Re‑calibration required if load cells or structure are altered