Belzona 5721
Wind Turbine Leading Edge Protection Coating
High Performance & UV-Stable Coating for Leading Edge Protection
A 2-component, 100% solids, UV-stable coating specifically formulated to protect the leading edges of wind turbine blades from erosion and impact damage.
- SeriesBelzona 5000 Series
- Documents3
Overview of Belzona 5721
Belzona 5721 is a 2-component, high-performance coating specifically formulated for protecting the leading edges of wind turbine blades from erosion and impact damage.
The system is well suited to the rigours of in-situ application, being easy to apply by brush in a single coat. Combined with low-temperature cure technology, Belzona 5721 maximises available maintenance opportunities and helps ensure the turbine's fast return to service.
It is safe to use, cold-applied, and requires no specialist tools or equipment. Belzona 5721 is 100% solids, making it suitable for factory application as well.
The Belzona 5711 and 5721 leading edge protection system has been independently validated under DNV-RP-0573 and demonstrates excellent fatigue resistance, durability, and long-term adhesion when applied and tested under harsh environmental conditions.
Key Benefits
Suitable for application on to similar types of equipment, including fan blades.
Outstanding adhesion to GRP (Glass Reinforced Plastic).
Fast return to service at low ambient temperatures. Overcoatable in 30 mins, with full cure in 6 hours at 5°C (41°F).
Excellent long-term protection against the effects of UV degradation.
This solvent-free system is easy to mix and apply by brush, without the need for specialist tools.
Erosion protection against rain and debris, with the system validated under DNV-RP-0573 for leading edge protection.
Application Areas
Technical Data
Mechanical Properties (20°C / 68°F cure & test)
- Shore D Hardness (ASTM D2240)
- 84
- Barcol Hardness Model 935 / 934-1
- 82 / 11
- König Pendulum (ISO 1522)
- 146 seconds
- Compressive Strength (ASTM D695)
- 62.9 MPa (9,119 psi)
- Compressive Modulus
- 1,342 MPa
- Flexural Strength (ASTM D790)
- 76.2 MPa (11,045 psi)
- Flexural Modulus
- 4,290 MPa
- Reversed Notched Izod (ASTM D256)
- 9.2 kJ/m² (109.2 J/m)
- Falling Weight (ASTM D2794, 500µm)
- 0.63 kg.m (55.1 in.lbs)
Adhesion (20°C / 68°F cure & test)
- Pull-Off on GRP Composite (ASTM D4541)
- 12 MPa (1,735 psi) — cohesive failure of GRP
- Pull-Off on Grit-Blasted Steel
- 38.7 MPa (5,615 psi)
- Tensile Shear (ASTM D1002)
- 25.1 MPa (3,640 psi)
- Cleavage Adhesion (ASTM D1062)
- 203 N/mm (1,160 pli)
- Combined 5711+5721 system on GRP — Baseline
- 5.58 MPa (809 psi)
- Combined system — 25-week aged
- 4.52 MPa (656 psi)
Erosion, Weathering & Fatigue
- Taber Abrasion (CS17, dry)
- 23 mm³ loss per 1,000 cycles
- Grit Impact (5 × 2kg G34, 80 psi, 90°)
- 115 mm³ total volume loss
- Solid Particle Impingement (ASTM G76, 500 µm)
- 8.8 mm³ loss
- Salt Spray (ASTM B117)
- No failure after 1,000 hours continuous exposure
- Xenon Arc Weathering (ISO 4892-2)
- No chalking or color change after >1,000 hours
- Cyclic Aging (ISO 12944-9)
- No significant degradation over 25 weeks
- DNV-RP-0573 validated
- Yes (Belzona 5711 + 5721 system)
- Fatigue (ISO 13003, 4,000 µ-strain)
- 2,000,000 cycles at 23°C with no failure
- Heat Distortion (ASTM D648)
- 48°C (118°F)
Working Life
- At 68°F (20°C), 50% RH
- 40 minutes
Curing Time
At 41°F (5°C)
- Cure time
- 30 minutes
Overcoating Window
- Across 41-104°F (5-40°C) range
- Minimum 30 minutes, maximum 24 hours
Service Temperature Limits
- Application temperature range
- 41-104°F (5-40°C)
- Heat distortion (20°C cure)
- 118°F (48°C)
- UV resistance
- >1,000 hours Xenon Arc with no chalking or color change
- Salt spray resistance
- No failure after 1,000 hours continuous exposure
Mixing & Application
Product PDFs
Gallery
Videos
Frequently Asked Questions
How is Belzona 5721 applied?
Belzona 5721 is a 2-component, 100% solids coating applied by brush in a single coat at a target thickness of 500 microns (20 mil), giving a theoretical coverage rate of 1.3 m² (14 sq.ft) per kg. It mixes 2:1 by volume (3.04:1 by weight) and has a 40 minute working life at 68°F and 50% relative humidity.
Has Belzona 5721 been independently validated?
Yes. The combined Belzona 5711 and Belzona 5721 system has been fully validated in accordance with DNV-RP-0573, with rain erosion testing showing no significant degradation after 25 weeks of cyclic UV, salt spray, and low temperature aging. The system also withstands 1,000 hours of continuous salt spray exposure (ASTM B117) without failure.
Can Belzona 5721 cure at low temperatures?
Yes. Belzona 5721 is engineered with a low-temperature cure technology that allows curing in as little as 30 minutes at 5°C (41°F). The minimum overcoat time across the 5°C to 40°C application window is 30 minutes, with a maximum overcoat window of 24 hours, helping to maximize available maintenance windows on wind turbine blades.
Related Products
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