Quick facts
- Grades compared
- SPR 301 OT · SPR 301 OS · SPR 501 VE
- Chemistries
- Two isophthalic polyesters and one bisphenol-A epoxy vinyl ester
- Deciding factor
- The stored product, its concentration and temperature
- Not published
- Chemical-compatibility charts for any of the three
What actually differs between the three
SPR 301 OT and SPR 301 OS are both isophthalic polyesters from the same family, separated by the service the catalogue lists for them: OT for the FRP lining of oil-storage tanks and chemical equipment, OS for organic-solvent storage, sewage pipes and effluent-treatment equipment. Their published processing values overlap closely — the same gel-time range and reference cure — so the name of the stored product, not the numbers, is what separates them.
Vinyl Ester Resin is a different chemistry: a bisphenol-A epoxy vinyl ester, documented for industrial FRP where chemical and corrosion resistance is part of the material choice. It is the grade the range offers when the service moves past what an isophthalic lining is specified for.
How to decide
Start from the tank, not the resin. If it holds oil and the owner’s specification accepts an isophthalic lining, SPR 301 OT is the grade listed for that service. If it holds a named organic solvent, or the job is a sewage pipe or effluent equipment, SPR 301 OS is the listed grade. If the chemical is aggressive, the concentration is high, the temperature is elevated, or the owner’s specification names vinyl ester, the lining moves to Vinyl Ester Resin.
Where two answers seem possible, the more demanding part of the service decides — including anything the tank may hold later, cleaning chemicals and upset conditions.
What the data does not tell you
None of the three records publishes a chemical-compatibility chart, a maximum service temperature for a finished lining, or a lining thickness. “Oil”, “organic solvents” and “chemical service” are descriptions of intended service, not verdicts for a particular product. The Vinyl Ester TDS lists 110 °C as typical thermal data without a stated test or cure condition, so it is not an operating-temperature limit.
The comparison also mixes sources: the two isophthalic grades are described by the 2026 catalogue, the vinyl ester by its TDS. Treat small numerical differences between them with caution and confirm the current documents before ordering.
Sources, roles and the Nepal enquiry path
Values for SPR 301 OT and SPR 301 OS are the typical specification printed in the supplier’s 2026 product catalogue; no Technical Data Sheet for either grade has been published on this site. Vinyl Ester Resin values are from its Technical Data Sheet as shown on its product page.
Samrat Poly Resins, India manufactures the grade and issues its technical information. Samrat FRP Traders is the Nepal supplier and importer and handles enquiries; price, packaging, lead time and stock in Nepal are confirmed on enquiry.
Three lining resins side by side
| Criterion | SPR 301 OT | SPR 301 OS | SPR 501 VE |
|---|---|---|---|
| Chemistry | Isophthalic polyester | Isophthalic polyester, anti-corrosive grade | Bisphenol-A epoxy vinyl ester |
| Listed service | FRP lining of oil-storage tanks; chemical-equipment manufacturing | Organic-solvent storage linings; sewage pipes; effluent-treatment equipment | FRP tanks and chemical storage vessels, pipelines, ducts, scrubbers and other listed industrial uses |
| Listed properties | Good electrical and heat-resistance properties | Resistance to organic solvents; good chemical and heat resistance | Documented for chemical- and corrosion-service selection |
| Viscosity | 300–600 cPs at 25 °C | 200–400 cPs at 25 °C | 350 cPs at 25 °C |
| Gel time | 15–35 minutes at 25 °C | 15–35 minutes at 25 °C | 15–20 minutes at 25 °C |
| Styrene · specific gravity | 33–45% · 1.04–1.14 | 35–50% · 1.03–1.15 | 40% · 1.05 |
| Supply and reference cure | Non-accelerated; MEKP 1.5% + cobalt octoate 0.4%, added separately | Non-accelerated, non-thixotropic; MEKP 1.5% + cobalt octoate 0.4%, added separately | Cure system as stated in the supplier TDS |
| Choose when… | The tank holds oil and the owner’s specification accepts an isophthalic lining | The service is a named organic solvent, sewage or effluent within what the grade is intended for | The chemical, concentration or temperature is beyond what an isophthalic lining is specified for |
Sources: SPR 301 OT and SPR 301 OS — Samrat Poly Resins, India product catalogue, 2026 edition (typical specification); Vinyl Ester Resin — the supplier Technical Data Sheet as published on this site. Typical values describe each grade; they are not batch guarantees or acceptance limits.
Frequently asked questions
Is SPR 301 OS just SPR 301 OT for solvents?
They are separate grades with different listed services and slightly different published ranges. Choose by the service each is listed for, not by the overlap in their numbers.
When does a tank lining need vinyl ester?
When the stored chemical, its concentration or the temperature goes beyond what an isophthalic lining is specified for, or when the owner’s specification names vinyl ester. The service decides, not the resin name.
Can any of these be confirmed for my chemical from this page?
No. None of the three publishes a compatibility chart. Send the chemical, concentration, temperature and contact pattern with your enquiry so the grade can be reviewed against it.
Why does the vinyl ester column show no cobalt dosage?
The site data for Vinyl Ester Resin does not state a reference cure dosage, so none is shown here. Follow the supplier TDS for the cure system.