Galvanized steel ducts
High-Strength Flat Rolled Steel for Construction & Industrial Applications
Product Overview
Prestressed metal corrugated ducts are divided into round corrugated ducts (also known as round metal ducts or round prestressing ducts) and flat corrugated ducts (also known as flat metal ducts or flat prestressing ducts) are specialized metal conduits designed for prestressed concrete structures. They are primarily used in post-tensioning systems to protect and position tendons (strands or bars). Their flat profile makes them ideal for applications with limited space, such as slabs, bridges, and underground structures.
Material & Manufacturing Process
Base Material
High-quality low-carbon steel strip (e.g., SPCC, Q195) or galvanized steel strip (hot-dip or electro-galvanized) for strength and corrosion resistance.
Forming Process
Precision roll-forming creates a continuous helical corrugation, ensuring flexibility and crush resistance.
Corrosion Protection
Hot-dip galvanizing (zinc coating ≥40μm) for standard environments (indoor/dry conditions).
Epoxy coating/PE sheathing for aggressive environments (marine, chemical plants).
4.Quality Assurance & Reliability Checks
Visual Inspection
- Uniform corrugations without cracks; intact zinc coating (visual + copper sulfate test).
- Smooth cut edges to prevent tendon damage during installation.
Performance Tests:
- Radial Stiffness: Withstands ≥500N/100mm load without deformation (per JT/T 529-2016).
- Radial Stiffness: Withstands ≥500N/100mm load without deformation (per JT/T 529-2016).
- Corrosion Resistance: ≥72-hour salt spray test without red rust (ASTM B117).
Certifications:
- Material reports (SGS)
- Third-party test data
- Compliance with GB/T 19687 (China) or EN 523 (EU).
Post-Tensioning Systems:
- Embedded in concrete to form a sealed duct for tendons, preventing grout leakage before stressing.
- After concrete curing, tendons are threaded, tensioned, and grouted for full bond.
Typical Use Cases:
- Building Slabs: Flat design minimizes concrete cover thickness, optimizing structural depth.
- Bridge Webs: Fits confined spaces while ensuring precise tendon alignment.
- Precast Elements: Used in segmental bridges or large prefabricated beams.
Available Types
Positioning
Secured with dedicated supports (e.g., U-clamps or rebar chairs) to maintain design profile.
Blockage Prevention
Duct ends must be sealed to avoid concrete ingress.
Compatibility
Must match anchorages and couplers to prevent slippage during stressing.
Advantages Over Round Corrugated Ducts
Feature | Flat Duct | Round Duct |
Profile Height | Slim (typically 15-30mm) | Larger (45-300mm diameter) |
Best For | Slabs, thin-walled structures | Beams, columns, mass concrete |
Concrete Savings | Reduces cover thickness significantly | Requires more space |
Industry Trends
Lightweighting
High-strength thin steel strips reduce weight.
Smart Integration
Embedded sensors (e.g., optical fibers) monitor prestress loss.
Eco-Friendly
Chromium-free galvanizing processes.
Specification
Parameter of round metal corrugated duct
MODEL | STRAND NO. | INNER SIZE |
YM15-2, 3 | 2, 3 | 50 MM |
YM15-4, 5 | 4, 5 | 55 MM |
YM15-6, 7 | 6, 7 | 70 MM |
YM15-8, 9 | 8, 9 | 80 MM |
YM15-10, 11, 12, 13, 14, 15, 16, 17 | 10, 11, 12, 13, 14, 15, 16, 17 | 90 MM |
YM15-18, 19 | 18, 19 | 100 MM |
YM15-21, 22 | 21, 22 | 120 MM |
YM15-25, 26, 27, 30, 31 | 25, 26, 27, 30, 31 | 130 MM |
YM15-34, 37 | 34, 37 | 140 MM |
YM15-43, 44, 54, 55 | 43, 44, 54, 55 | 160 MM |
How the round corrudated ducts to fit prestressed anchorage
Metal / Plastic Round Corrugated Duct Parameter | Use for Multi-hole Anchorage | |
Inner Diameter | Outer Diameter | Models |
Φ55 | Φ60 / Φ66 | YJM15-3~5 |
Φ70 | Φ75 / Φ81 | YJM15-6~7 |
Φ80 | Φ85 / Φ91 | YJM15-8~9 |
Φ90 | Φ95 / Φ101 | YJM15-10~17 |
Φ100 | Φ105 / Φ114 | YJM15-18~19 |
Φ120 | Φ125 / Φ134 | YJM15-21~23 |
Parameter of flat metal ducts
MODEL | BM13/15-2 | BM13/15-3 | BM13/15-4 | BM13/15-5 |
INNER SIZE | 50 X (22-25) MM | 60 X (22-25) MM | 74 X (22-25) MM | 90 X (22-25) MM |
GET IN TOUCH
- ISO 9001, ASTM A109, JIS G 3141 Certified
- Competitive pricing with bulk order discounts
- Just-in-time delivery & global shipping options