Why solvent linings are demanding
Organic solvents do not attack thermoset laminates the way acids or alkalis do. Many act by absorption: the solvent diffuses into the resin, swells it and weakens it, and some extract components as they go. The rate depends heavily on the solvent’s chemistry and the temperature. Aromatics, ketones and chlorinated solvents are generally more aggressive towards polyester laminates than aliphatic hydrocarbons, but the specific solvent always has to be judged on its own.
Service questions
Information that decides the lining
- The solvent by name, or the blend and its proportions.
- Storage temperature, and any heating or sun exposure of the tank.
- Whether the lining is immersed, splashed or only in the vapour space.
- Water or other contaminants in the stored solvent.
- Cleaning or product-changeover practice for the tank.
Where SPR 301 OS fits
SPR 301 OS is the anti-corrosive, non-thixotropic isophthalic grade the catalogue lists for FRP linings for organic-solvent storage. It is the natural starting point for a solvent lining in the SPR 301 family, and the one to discuss first.
Where the named solvent is aggressive towards polyester, or the specification requires it, Vinyl Ester Resin is the next route. For oils rather than solvents, the catalogue lists SPR 301 OT.
Published typical values
| Property | Organic Solvent-Resistant Grade Resin (SPR 301 OS) | Vinyl Ester Resin (SPR 501 VE) |
|---|---|---|
| Chemistry | Isophthalic unsaturated polyester | Bisphenol-A Epoxy Vinyl Ester |
| Viscosity (typical) | 200–400 cPs at 25 °C | 350 cPs (at 25°C) |
| Gel time / pot life (typical) | 15–35 minutes at 25 °C | 15–20 minutes at 25°C (see TDS test condition) |
| Styrene content (typical) | 35–50% by weight | 40% |
| Source of values | 2026 catalogue; grade TDS | Vinyl Ester Resin TDS |
Typical values, reproduced from each product’s own published data. They describe the liquid resin at its reference condition, not a finished part, and are not guaranteed limits.
The vapour space and the tank roof
The liquid is not the only exposure. Above it, solvent vapour condenses on the roof and upper walls, and those areas can see cycles of wetting and drying that are harder on a lining than steady immersion. When a lining is specified, the whole internal surface — including the roof and nozzles — should be considered, not only the wetted wall.
Testing before commitment
Because no solvent-by-solvent chart is published for SPR 301 OS, coupon testing is the sensible way to reduce risk: laminate panels made with the proposed resin and construction are immersed in the actual solvent at service temperature, and weight change, hardness and surface are checked over time. The technical team can help frame such a test. The grade’s high styrene content — 35–50% by weight typical — also calls for good ventilation during lining work inside tanks.