Bulk buying of Galvanized Iron GI sheets is a significant investment, particularly in constructions, roofing, and industries. The unit cost is reduced through bulk purchasing, but even little quality problems can result in great losses, rework, and delays. Before buying GI sheets in bulk, check the following top 10 critical factors for safe and profitable purchases.
1. Zinc Coating Thickness (GSM Rating)
The zinc coating determines how well GI sheets resist rust and corrosion.
✔ Common zinc coating grades:
- 120 GSM – Basic use
- 180 GSM – Standard roofing
- 275 GSM – Heavy-duty & coastal areas
👉 For long-term durability, always prefer 180–275 GSM for roofing and outdoor use.
2. Sheet Thickness (Gauge / mm Accuracy)
Never rely on “nominal” thickness claims.
✔ Verify actual thickness using:
- Micrometer testing
- Third-party lab reports
Approximate thickness reference:
- 26G ≈ 0.45–0.50 mm
- 24G ≈ 0.55–0.60 mm
- 22G ≈ 0.70–0.75 mm
⚠ Even a 0.05 mm shortage across bulk orders results in significant material loss.
3. Manufacturing Standards & Certifications
Ensure GI sheets comply with recognized standards such as:
- IS (Indian Standards)
- ASTM
- JIS
Ask for:
- Mill test certificates (MTC)
- Zinc coating test reports
- Quality compliance documents
4. Surface Finish & Uniformity
Check the surface for:
- Even zinc coating
- No peeling, cracks, or black spots
- Consistent spangle pattern (if applicable)
Poor surface quality often leads to early rusting.
5. Sheet Profile & Design Accuracy
Confirm the profile type required:
- Corrugated
- Trapezoidal
- Ribbed
- Plain
Ensure:
- Correct rib height & pitch
- Uniform shape across batches
Incorrect profiling can affect structural strength and water drainage.
6. Mechanical Strength & Bending Performance
Quality GI sheets should:
- Bend without cracking
- Withstand load without deforming
Ask suppliers for:
- Yield strength data
- Bending test results
This is especially important for roofing and industrial structures.
7. Supplier Reputation & Track Record
Bulk purchases demand reliable suppliers.
✔ Evaluate:
- Years in business
- Past project references
- Customer reviews
- Repeat clientele
Avoid unknown suppliers offering prices far below market rates.
8. Pricing Transparency & Hidden Costs
Confirm the price includes:
- GST
- Loading & packing
- Transportation
- Insurance (if applicable)
⚠ Cheap base price with hidden costs can inflate final expenses.
9. Packaging, Handling & Transportation Safety
Poor packaging leads to:
- Edge damage
- Zinc coating scratches
- Rust formation before use
Ensure:
- Proper bundling
- Moisture protection
- Safe unloading practices
10. Warranty, After-Sales Support & Replacement Policy
Reputed manufacturers offer:
- Product warranty
- Clear replacement terms
- Technical support
Always get:
✔ Written warranty terms
✔ Batch-wise traceability
Bonus Tips for Bulk Buyers
- Always inspect sample sheets before full order
- Conduct random checks during delivery
- Maintain proper storage at site to prevent moisture exposure
- Document batch numbers for quality tracking
Quick Checklist Before Finalizing Bulk Purchase
✔ Zinc coating ≥ 180 GSM
✔ Verified thickness
✔ Standard certifications
✔ Surface finish inspection
✔ Correct profile & dimensions
✔ Transparent pricing
✔ Secure packaging
✔ Warranty assurance
