Perfect Packing And Seals

Belzona 3111 (Lagseal)

Belzona 3111 (Lagseal)


A water-based acrylic emulsion membrane incorporating a polymer bonded glass reinforcing sheet (Belzona 9321) designed to provide seamless, flexible protection to all types of thermal insulation and cladding systems.

Belzona 3211 (Lagseal) is water, weather and fire resistant, and conforms to the requirements for a ‘Class O’ surface for ‘The UK Building Regulations 1991’ and ‘Class A’ in accordance with ‘ASTM E84’. The system provides protection from water ingress whilst its micro-porous nature allows trapped moisture from within the insulation to evaporate. This solvent-free, single pack system requires no mixing and is simple to apply to damp as well as dry insulation.

Key benefits:

  • Fire resistant
  • Easily applied by brush with no mixing required
  • Reduced health and safety risks as it is solvent-free
  • Application and cure at cold temperature – no hot work involved
  • Will not support growth of bacteria or algae  providing a hygienic finish
  • Excellent oil resistance
  • Withstands movement due to temperature fluctuations and vibrations within the system
  • Resistant to water, steam impingement, infra-red and ultra-violet radiation
  • Excellent adhesion to a wide range of materials including calcium silicate, glass fibre, mineral wool, foam, steel and stainless steel

Applications for Belzona 3211 (Lagseal) include:

  • Protection of insulation on pipes, air-conditioning ducting, valve boxes, flange covers, boilers, pressure vessels, bulk storage tanks and heat exchangers
  • Long-term lagging protection on new and existing steam, condensate or chilled pipelines
  • Seamless encapsulation of elbows, T pieces flanges and complex contours
  • Tank base sealing
Key technical data:
Working life at temperatures between 5°C (41°F) to 30°C (86°F) Indefinite
Drying Time at 20°C (68°F) 1st coat 4 hours, 2nd coat 2 hours
Tensile strength (BS 2782) at 20°C (68°F) 370 psi (2.5N per unreinforced system after 7 days at 20°C (68°F)
Vapor resistance at 20°C (68°F) 10 MN/sg
Fire resistance The UK Building Regulations 1991 conforms to the requirements for a Class O surface
ASTM E84 meets class A with flame spread index less than 25 and smoke developed index less than 100
BS 476 Part 6 – 2.8
BS 476 Part 7 meets class 1 surface spread flame
Oil resistance The system is unaffected by immersion for 24 hours in light fuel  and lubricating oil at 50°C (122°F)
Bonds to Calcium silicate, glass fibre, mineral wool, foam and other metal surfaces
Typical applications Protective coating for all types of insulation
Unit size 16 kg. Pack sizes may vary locally
Availability* Global