The service questions
Share these with the enquiry
- The exact medium: product name, grade, and any water, acid or contaminants it carries.
- Concentration, for chemicals, and operating and upset temperatures.
- Continuous immersion, intermittent contact, splash or vapour only.
- The substrate for a lining (steel, concrete, existing FRP) and its condition.
- Any design standard or client specification for the tank or equipment.
- How the lining will be inspected and repaired.
How the grades divide the work
SPR 301 OT is the isophthalic grade listed for oil-storage-tank linings and chemical equipment. SPR 301 OS, also isophthalic, is listed for organic-solvent storage, sewage and effluent. Vinyl Ester Resin is the route for more corrosive service or where the specification names vinyl ester. The general isophthalic ISO Polyester Resin publishes cured-resin data and covers water and chemical-service laminates.
Isophthalic chemistry improves resistance compared with orthophthalic grades, but it is not a compatibility guarantee for any particular medium. The OT, OS and vinyl ester comparison gives a decision table.
Published typical values
| Property | Oil Storage Tank Grade Resin (SPR 301 OT) | Organic Solvent-Resistant Grade Resin (SPR 301 OS) | Vinyl Ester Resin (SPR 501 VE) | ISO Polyester Resin (SPR 301) |
|---|---|---|---|---|
| Chemistry | Isophthalic unsaturated polyester | Isophthalic unsaturated polyester | Bisphenol-A Epoxy Vinyl Ester | Isophthalic Unsaturated Polyester Resin |
| Viscosity (typical) | 300–600 cPs at 25 °C | 200–400 cPs at 25 °C | 350 cPs (at 25°C) | 500 cPs (mPa·s) at 25 °C |
| Gel time / pot life (typical) | 15–35 minutes at 25 °C | 15–35 minutes at 25 °C | 15–20 minutes at 25°C (see TDS test condition) | 15 minutes at 25 °C |
| Specific gravity / density (typical) | 1.04–1.14 | 1.03–1.15 | 1.05 g/cm³ | 1.12 g/cm³ at 25 °C |
| Styrene content (typical) | 33–45% by weight | 35–50% by weight | 40% | 40% by weight |
| Source of values | 2026 catalogue; grade TDS | 2026 catalogue; grade TDS | Vinyl Ester Resin TDS | ISO Polyester 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.
How corrosion-resistant laminates are built
Chemical-service FRP is usually built in layers. The inner, resin-rich surface — often reinforced with a thin veil — faces the medium. Behind it, chopped-strand layers complete the corrosion barrier, and the structural laminate carries the load. Most chemical attack is resisted, or not, in that inner barrier.
For linings, surface preparation of the substrate and the bond to it are as important as the resin. Where a design standard governs the equipment, its construction and inspection requirements apply to the finished laminate.
Limits and trials
No chemical-resistance chart, maximum service temperature or cured-laminate data are published for SPR 301 OT. That makes the service review essential rather than optional. Where there is doubt, coupons of the proposed laminate can be exposed to the actual medium at service temperature and examined; the technical team can advise on how to set that up.