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LINER (PVC membranes reinforced with polyester / EPDM)

LINER (PVC membranes reinforced with polyester / EPDM)

Sealing systems in bolted metal tanks are a critical component for ensuring the tank's watertightness and hydraulic integrity. Due to the presence of bolted joints between panels, proper sealing determines the tank's long-term reliability against leaks, internal corrosion, and degradation. There are two main technologies: mastic sealing and flexible membrane or liner sealing.

The internal membrane or liner system consists of installing a flexible lining inside the tank, acting as the primary barrier between the stored fluid and the steel. In this case, watertightness does not depend directly on the sealing of metal joints, but rather on the integrity of the liner, which is supported by the walls and bottom using mounting profiles.

There are two main types:

From an operational point of view, they allow tanks to be assembled with:
  • Reduced sensitivity to internal corrosion
  • Additional protection against varying pH levels
  • Greater tolerance to small movements or deformations

Polyester-reinforced PVC
  • Excellent flexibility
  • Heat sealing welding
  • Good impact resistance
  • Suitable for drinking water (according to certification)
  • Good cost/durability ratio

EPDM (synthetic rubber)
  • Greater elasticity
  • High chemical resistance
  • Superior durability in continuous contact
  • UV stability
  • uso en aguas industriales y pluviales

Liners are particularly useful when:
  • The fluid is chemically aggressive
  • The aim is to completely isolate the steel.
  • Rehabilitation of existing tanks is required
  • The watertightness must be independent of the coating.

In terms of installation, they require proper geometry, wrinkle control, and edge fixings. Maintenance involves  liner inspections , partial replacement if perforation occurs, and consideration of maximum compatible temperatures. 

Key Advantages


  • Independent sealing of steel
  • High chemical insulation
  • Ideal for rehabilitation
  • Low risk of internal corrosion

Recommended Applications


  • Aggressive Waters
  • Aggressive Waters
  • Rehabilitation of existing tanks
  • Diluted fertilizers
  • Moderate wastewater

Limitations


  • Limited serving temperature
  • Risk of abrasion perforation
  • Mandatory periodic inspections

Comparison for Engineering

System It works like Fluid-steel contact Chemical compatibility Serving temperature Maintenance
Mastic Sealed joint Yes (depending on the coating) Moderate High Low
PVC liner Complete barrier No Medium/High Average Half
EPDM liner Complete barrier No High Average Half