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FRP Manhole Liners

FRP Manhole Liners are prefabricated fiberglass rings or panels that line the interior of concrete or brick manholes, wet wells, and valve vaults to protect against corrosion. The FRP liners are typically formed from continuous filament-wound or pultruded fiberglass with a corrosion-resistant resin (often vinylester) that is specifically formulated to resist hydrogen sulfide and dilute sulfuric acid vapors. By lining manhole interiors, FRP prevents erosion of the structure and prevents root intrusion. They are lightweight and can be custom-fitted to new or existing shafts, locking together or bonded to form a seamless lining. The result is a smooth, non-toxic interior with crack-free waterproofing. FRP manhole liners significantly extend the life of underground sewer structures and reduce maintenance costs by eliminating structural corrosion.

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Key Features

High Chemical Resistance: Engineered resin system designed for hydrogen sulfide and sulphuric-acid environments.
One-Piece Construction: Manufactured as rings or panels bonded on-site to create a continuous, joint-free lining that withstands soil pressure.
Ribbed Exterior: Some liners have external ribs or grooves for mechanical grip in the surrounding concrete when backfilled.
Custom Sizes: Available for diameters typically 600–2400 mm (24″–96″) and various depths. Thickness usually 7–10 mm.
Slip-Resistant Interior: Textured or grated steps/ladders can be integrated; options for embedded ladder rungs or grooves.
UV-Stable Gel Coat: The exposed top section (if any) is UV-protected for durability.

Benefits

Structural Protection: Prevents the manhole or wetwell from degrading, sealing cracks and stops leaks that can undermine structures.
Zero Corrosion: Unlike steel or unprotected concrete, FRP will not rust, rot or erode, so manholes can last 50+ years without rehabilitation.
Smooth Interior: Eliminates rough concrete joints where debris and corrosion products accumulate, improving hydraulic flow and cleaning.
Fast Rehabilitation: Liners can often be installed in an existing manhole with minimal downtime, without excavation.
Lightweight Handling: FRP sections can be transported and inserted by two people, unlike bulky concrete rings.

Applications

Wastewater Collection Systems: New and retrofit sewage manholes, wet wells, storm drain structures, valve chambers.
Industrial Pipelines: Acid neutralization pits, chemical storage sumps, and any underground chamber exposed to corrosives.
Lift Stations: Interior lining of pump stations where metal pumps and piping accelerate corrosion.
Sea Cages & Aquaculture: Saltwater-resistant lining for aquatic enclosures.

Technical Specifications

Resin Type: Vinyl ester or advanced polyester with corrosion inhibitors; gel coat layer on inside.
Reinforcement: Continuous filament glass wound or stitched mat layers with total glass content ~60% by weight.
Panel Assembly: Sealed with epoxy adhesives or mechanical clips; final joint sealed with non-sag laminating putty and top-coated.
Compliance: Meets or exceeds ASTM D-3753 for FRP manholes; NSF 61 optional for potable considerations.
Temperature: Suitable for typical underground temps; maximum ~50°C short-term.

Unique Selling Points (USPs)

Tailored Retrofit Systems: We survey and design liners specifically for the existing structure, ensuring a tight fit and minimal access excavation.
Turnkey Installation: Certified teams can handle removal of old material, cleaning, fitting and sealing so the manhole is immediately operational.
Slip-Resistant Options: Specialty gel coats with grit or integrated ladder rungs for safe personnel access.
Fully Tested: Liner materials and joints are factory-tested to ensure impermeability and strength before shipping.
Minimal Infiltration: Solves groundwater ingress problems – a single liner system will improve infiltration to virtually zero.