Views: 351 Author: NANJING TAIDUN Publish Time: 2026-10-09 Origin: Site
Content Menu
● What Is a Fender Steel Panel? The Critical Interface Component
>> The Two Fundamental Configurations
● Structural Performance Comparison: Rigidity, Load Distribution, and Edge Loading
>> Torsional Rigidity Under Eccentric Loads
>> Load Distribution Characteristics
>> Internal Structural Members
● Corrosion Protection: The Lifecycle Cost Driver
>> Closed Box Panels: Sealed for Longevity
>> Open Frame Panels: Exposed and Vulnerable
>> Corrosion Protection Comparison
● Cost Analysis: Initial Investment vs. Lifecycle Value
>> Material and Manufacturing Costs
● Weight and Logistics Considerations
● Additional Design Features Common to Both Configurations
>> Lead-In Bevels and Chamfers
● Real-World Applications: Case Studies in Panel Selection
>> Case Study 1: Port of Vigo, Spain – Closed Box Panels for Ro-Ro Terminal
>> Case Study 2: Angola Fuel Terminal – Closed Box for High-Energy Berthing
● Selection Framework: Choosing the Right Panel for Your Berth
>> When to Choose Closed Box Panels
>> When Open Frame Panels May Be Considered
● Conclusion: Making the Right Engineering Decision
● Frequently Asked Questions (FAQ)
>> 2. Why are closed box panels now used almost exclusively in high-performance applications?
>> 3. How long do closed box panels last compared to open frame panels?
>> 4. What corrosion protection system is used for closed box fender panels?
>> 5. Can open frame panels be used in high-energy berthing applications?
>> 6. What is the recommended chamfer size for fender panels?
Introduction: Why Panel Selection Determines Fender System Success
Every port engineer faces this decision: closed fender steel panel or open fender steel panel? It appears straightforward—one is sealed, one is exposed. But this choice ripples through every aspect of your fender system: structural performance, corrosion protection, maintenance costs, and ultimately, the 25-year lifecycle value of your berthing infrastructure.
As an OEM manufacturer with over 23 years of experience at NANJING TAIDUN MARINE EQUIPMENT ENGINEERING CO., LTD, we have produced both configurations for ports across 80+ countries. The choice between closed and open panels is not about which is "better"—it is about which is right for your specific berth conditions, vessel mix, and operational priorities.
This guide provides a complete engineering comparison, drawing on real-world project data and PIANC guidelines.
A fender steel panel (also called frontal panel or fender frame) serves three essential functions in a marine fender system:
1. Load distribution: Spreads reaction forces from rubber fender units across the vessel hull, reducing hull pressure
2. Friction management: Houses UHMW-PE face pads to allow controlled vessel movement during berthing
3. Accessory integration: Provides connection points for chains, lifting points, and maintenance access
The panel is not a passive component. It transfers every berthing load from the vessel through the rubber units to the wharf structure. Panel failure means system failure.
Industry insight: Closed box designs are now used almost exclusively in high-performance applications. However, open frames remain relevant for specific scenarios where weight, cost, or inspection access is prioritized.
This is the most significant performance difference between the two configurations.
Closed box panels possess superior torsional rigidity due to their sealed, box-section geometry. When a vessel contacts the panel at an angle or near the edge, the closed structure resists twisting and maintains uniform load distribution.
Open frame panels exhibit moderate rigidity with some flexibility under eccentric loads. This flexibility can lead to uneven load distribution and accelerated wear on rubber fender units.
Why edge loading matters: Vessels with flared bows or angled berthing approaches frequently contact panels near their edges. Closed box panels maintain structural integrity in these conditions; open frames do not.
Both configurations include internal stiffening members. However, in closed box panels, these members are fully enclosed and protected from the marine environment. In open frames, every structural member is exposed to corrosion and requires regular coating maintenance.
Closed box panels achieve their corrosion resistance through complete sealing:
- Fully welded perimeter: No openings for moisture ingress
- Internal cavity sealed: Interior surfaces protected from salt air
- Pressure tested: Every panel verified for watertight integrity before delivery
The standard corrosion protection system for closed box panels follows ISO 12944 C5-M (very high corrosion) classification:
| Layer | Material | Function |
|---|---|---|
| Primer | Epoxy zinc-rich | Adhesion + cathodic protection |
| Intermediate | C5M modified epoxy | Barrier protection |
| Topcoat | Polyurethane (RAL5005) | UV resistance |
Expected service life: 25+ years with proper coating.
Open frame panels have all surfaces exposed to the marine environment:
- Increased corrosion exposure: Every surface requires coating protection
- Difficult access: Internal surfaces are hard to reach for application and repair
- Debris accumulation: Open spaces can trap debris, creating corrosion-prone areas
Expected service life: 15-20 years with regular maintenance.
The initial cost premium for closed box panels is offset by:
- Reduced maintenance frequency: Sealed interior eliminates internal corrosion inspections
- Longer replacement cycle: 25+ years vs. 15-20 years
- Lower operational disruption: Fewer maintenance interventions
Expert insight: PIANC WG211 emphasizes lifecycle cost analysis over initial procurement price. For high-traffic terminals, the closed box premium is recovered within 5-7 years through reduced maintenance and extended service life.
When weight matters: For remote terminals with limited lifting capacity, open frame panels offer logistical advantages. For most permanent installations, the weight difference is manageable.
Both panel types should include lead-in bevels and chamfers at the top and bottom edges. These angled surfaces prevent vessel belting from snagging beneath the panel—a critical safety feature for Ro-Ro vessels and ferries with protruding belt lines.
Recommended chamfer size: 300-500mm for mixed-traffic terminals.
Ultra-High Molecular Weight Polyethylene face pads attach to the front of either panel type. These pads:
- Provide a low-friction surface (coefficient of friction <0.2)
- Protect vessel paint from abrasion
- Are replaceable when worn
Both configurations must be sized to keep hull pressure within allowable limits:
P = ΣR ÷ (A₁ × B₁) ≤ Py
Where:
- P = Actual hull pressure (kN/m²)
- ΣR = Sum of maximum reaction forces (kN)
- A₁ = Valid width of front panel (m)
- B₁ = Valid length of front panel (m)
- Py = Vessel allowable hull surface pressure (kN/m²)
Allowable Hull Pressure by Vessel Type:
| Vessel Type | Allowable Hull Pressure (kN/m²) |
|---|---|
| Gas carriers (LNG/LPG) | 100–200 |
| Bulk carriers | 150–250 |
| Panamax container ships | 150–250 |
| Oil tankers (general) | 250–350 |
| Sub-Panamax container ships | 300–400 |
| Large container ships | 400–500 |
The Bouzas Terminal upgrade required fender systems for Ro-Ro vessels with large tidal variation.
Panel specification:
- Closed-box steel panels (2000×4800mm)
- 500mm-high chamfers to prevent Ro-Ro belting snagging
- UHMW-PE sliding plates
- C5-M corrosion protection
Result: The closed box design maintained structural integrity across the full tidal range while preventing snagging incidents.
A high-energy fuel terminal required panels that could withstand repeated impacts from large tankers.
Solution: Closed-box panels with internal stiffeners and pressure-tested watertight seals.
Why closed box: The combination of high berthing energy, corrosive environment, and limited maintenance access made the closed configuration the only viable option.
Closed box panels are the preferred choice for:
- High-energy berthing: Container terminals, bulk terminals, LNG terminals where significant berthing energy demands superior load distribution
- Large vessel traffic: Ports handling vessels with deep draughts and high freeboard, where angled berthing and edge contacts are common
- Exposed locations with tidal variation: Berths with significant tidal ranges requiring uniform structural integrity across all contact heights
- Corrosive environments: Terminals where maintenance access is limited or costly
- Lifecycle cost priority: Projects where total cost of ownership outweighs initial procurement budget
Open frame panels may be suitable for:
- Low-energy applications: Small craft berths where berthing energy is minimal
- Weight-constrained installations: Facilities with limited lifting capacity
- Inspection-priority operations: Terminals where frequent internal inspection is required and access is prioritized
- Budget-constrained projects: Temporary or short-lifetime installations
| Priority | Recommended Panel Type |
|---|---|
| Maximum service life | Closed Box |
| Lowest lifecycle cost | Closed Box |
| Highest structural rigidity | Closed Box |
| Lowest initial cost | Open Frame |
| Minimum weight | Open Frame |
| Easiest internal inspection | Open Frame |
The choice between closed fender steel panel and open fender steel panel is not a matter of opinion—it is a matter of engineering analysis. For most modern port infrastructure, the closed box configuration delivers superior performance across the metrics that matter most: structural rigidity, corrosion protection, and lifecycle cost.
At NANJING TAIDUN MARINE EQUIPMENT ENGINEERING CO., LTD, we manufacture both configurations to international standards including PIANC, ASTM, and ISO. Every panel undergoes rigorous quality control—from steel inspection to coating thickness verification to pressure testing for closed box designs.
Our OEM partners receive:
- Purpose-designed panels using 3D CAD modeling and structural analysis
- C5-M corrosion protection systems to ISO 12944
- Pressure-tested watertight integrity for closed box panels
- Third-party inspection by CCS, BV, LR, TUV, SGS, INTERTEK, and GL
[CTA]
Need fender steel panels manufactured to your specification?
Contact NANJING TAIDUN MARINE EQUIPMENT ENGINEERING CO., LTD:
- Email: service@taidunmarine.com
- Website: www.taidunmarine.com
- Services: OEM/ODM manufacturing, custom panel design, third-party testing coordination
1. Taidun Marine. "The Ultimate Guide To Marine Rubber Fender Steel Panels: Engineering Excellence, Real-World Projects & Maintenance Innovation." [https://www.taidunmarine.com/the-ultimate-guide-to-marine-rubber-fender-steel-panels-engineering-excellence-real-world-projects-maintenance-innovation.html]
2. PIANC Australia. "Navigating Through PIANC Fender Guidelines 2024 (WG211) for Designers and Asset Owners." [https://pianc.org.au/wp-content/uploads/2025/12/Presentation-Slide-Master-PIANC-Fender-Workshop-30-July-2025-Brisbane.pdf]
3. Taidun Marine. "Closed-Box vs. Open Steel Panels for Marine Rubber Fender Systems: A Comprehensive Technical Comparison." [https://www.taidunmarine.com/sv/Closed-Box-vs-Open-Steel-Panels-for-Marine-Rubber-Fender-Systems-A-Comprehensive-Technical-Comparison-id06542065.html]
4. Taidun Marine. "Corrosion Protection Methods for Steel Panels in Marine Fender Systems." [https://www.taidunmarine.com/fender-panels-closed-box-steel-structure-for-high-performance-berthing-systems.html]
A closed box panel has front and back plates with internal stiffeners, fully welded and sealed to prevent moisture ingress. An open frame panel consists of exposed steel members (H-beams, cross members) with no enclosing plates. The closed configuration offers superior rigidity and corrosion protection; the open configuration offers lighter weight and easier internal inspection access.
Closed box panels provide superior torsional rigidity under eccentric loads, uniform load distribution across all mounting points, and sealed internal surfaces that eliminate internal corrosion. For high-energy terminals, large vessel traffic, and corrosive environments, these advantages translate directly into longer service life and lower lifecycle costs.
With proper C5-M coating systems, closed box panels achieve 25+ years of service life, while open frame panels typically last 15-20 years with regular maintenance. The sealed interior of closed box panels eliminates internal corrosion—the primary failure mode for open frames.
The standard system follows ISO 12944 C5-M (very high corrosion) classification: epoxy zinc-rich primer, C5M modified epoxy intermediate coat, and polyurethane topcoat (RAL5005 blue). Every closed box panel is pressure tested for watertight integrity before delivery.
While technically possible, open frame panels are not recommended for high-energy applications. The reduced torsional rigidity and edge load resistance of open frames can lead to uneven load distribution, accelerated rubber wear, and premature panel failure. For container terminals, bulk terminals, and LNG facilities, closed box panels are the industry standard.
For mixed-traffic terminals handling Ro-Ro vessels and ferries with protruding belt lines, 300-500mm lead-in chamfers are recommended to prevent belting snagging beneath the panel. The Port of Vigo used 500mm chamfers for its Ro-Ro terminal panels.
