FRP Guides

FRP Chemical Resistance Guide: How to Read Resin Compatibility Charts

In short: FRP's chemical resistance comes mainly from its resin and its resin-rich surface layer. To check compatibility, look up each chemical in the resin manufacturer's corrosion guide. Find the listed concentration and the maximum recommended temperature, and decide whether exposure is immersion, splash or fumes. If a chemical is listed as "not recommended" or isn't listed, ask for testing or an alternative. Never rely on a generic "FRP is chemical resistant" claim.

FRP Chemical Resistance Guide: How to Read Resin Compatibility Charts – In short summary: key points at a glance

Diagram: How to read a chart: step by step – FRP Chemical Resistance Guide — How to read a chart: step by step: summary diagram from this guide.

Why "chemical resistant" needs qualifying

FRP is chosen across chemical plants because it doesn't rust. But each resin has limits:

Some chemicals attack the resin, such as certain solvents or strong oxidizers at high temperature.
Some attack the glass fibers if they reach them. Hydrofluoric acid and hot strong alkalis are well-known examples, which is why synthetic veils are used in those services.
Temperature accelerates almost every degradation mechanism.

So compatibility is always a combination of chemical + concentration + temperature + exposure type + resin + laminate construction.

Diagram: Product-specific considerations – FRP Chemical Resistance Guide — Product-specific considerations: summary diagram from this guide.

Where resistance data comes from

Major resin producers publish corrosion resistance guides for their polyester and vinyl ester resins. They are based on laboratory immersion testing and field experience. Typical entries list:

The chemical and its concentration (%)
The maximum recommended service temperature for that resin
Sometimes notes on veil type (glass or synthetic), post-cure requirements, or "splash and spill only"
"NR" for not recommended

Grating and profile manufacturers often publish simplified charts for their own products, grouping chemicals by resin grade. These charts are useful for screening. For critical services, the resin manufacturer's data and the fabricator's experience should be checked too.

How to read a chart: step by step

List every chemical, including cleaning agents, neutralizing agents and anything present during upsets.
Find each chemical in the chart for the resin you are considering.
Match the concentration. Resistance at 10% may differ greatly from resistance at 98%. Some chemicals are more aggressive when dilute.
Check the temperature. Your maximum operating temperature must be at or below the listed limit, with a margin for upsets.
Define the exposure. Immersion (tanks, pipes) is the most severe. Splash and spill, typical for grating, and fume exposure, typical for ducts and scrubbers, may allow other options. Many charts state which they apply to.
Check the surface construction. For aggressive services, a resin-rich layer with a suitable veil is needed. Synthetic veils are commonly used where the glass itself would be attacked.
Mixtures need care. A mixture can behave differently from its components. Ask for advice when chemicals are combined.

Diagram: Common mistakes – FRP Chemical Resistance Guide — Common mistakes: summary diagram from this guide.

Typical patterns (for screening only)

These general patterns are widely reported in resin manufacturer guides, but the exact limits vary by product:

Environment	General pattern
Water, salt water, many salt solutions	Isophthalic polyester and vinyl ester are commonly suitable; vinyl ester tolerates higher temperatures
Dilute mineral acids (e.g. hydrochloric, sulfuric)	Vinyl ester is commonly used; limits depend on concentration and temperature
Alkalis (e.g. sodium hydroxide)	Vinyl ester generally performs better than polyester; synthetic veils are often recommended
Sodium hypochlorite (bleach)	Vinyl ester with appropriate construction and cure is commonly used
Hydrofluoric acid	Requires special construction; glass attacked if exposed
Organic solvents	Varies widely; some attack resins; check each solvent

Confirm every chemical against the resin manufacturer's data for your conditions.

Product-specific considerations

Grating: Usually splash and fume exposure. Choose resin from the chart, and seal all cut edges, because exposed fibers at cuts are a weak point. See FRP Grating: Complete Guide.
Tanks and pipes: Immersion service. Corrosion barrier thickness and veil type are specified. See FRP Storage Tanks Guide and FRP Pipe Basics.
Scrubbers and ducts: Gases, condensate and scrubbing liquid together. See FRP Scrubbers Guide.
Cable tray and profiles: Atmospheric exposure, often with splash. See FRP Cable Tray Guide.

Signs of chemical attack

During inspection, look for:

Softening, or a tacky surface
Blistering
Discoloration and loss of gloss
Exposed fibers ("fiber bloom") or a whitened surface
Cracking or crazing

Record conditions and compare against the original service. Changes in chemistry or temperature are a common cause of early degradation.

What to send your supplier

Chemical names and CAS numbers if available
Concentrations (normal, minimum, maximum)
Operating and maximum temperatures
Exposure type: immersion, splash, fumes
Cleaning chemicals and frequency
Required service life and any past failure history

We review this data against resin manufacturer guidance and recommend a resin and construction. If a service is outside published data, we will tell you, and we can discuss sample testing.

Customization

FIBROVX products can be built with isophthalic polyester, vinyl ester or other resin systems, with surface veils matched to the service. See our molded grating, hydrochloric acid tanks, acid fume scrubbers and the tanks, pipes and covers collection.

Need a quote or a drawing check?

FIBROVX manufactures FRP products in our own factory in China and builds every item to order: sizes, resin system, color, molds and OEM branding. Send your application, dimensions or drawing, quantity and destination port.

Request a Quote

Common mistakes

Specifying by material name only. "FRP" or "fiberglass" does not define chemical resistance. The resin grade and laminate construction do.
Ignoring temperature. A resin that is suitable at ambient temperature may not be suitable at higher temperature for the same chemical.
Forgetting cleaning chemicals. Washdown, cleaning and maintenance chemicals are part of the exposure and should be included.
Ignoring mixtures and trace components. Solvents, oxidizers or abrasive solids in a stream can change the recommendation.
Not sealing cut edges. Cut edges expose fibers. Seal them with a compatible resin.

Key terms

Corrosion barrier: The resin-rich inner layers of a laminate that face the chemical.
Surface veil: A thin fiber layer that creates a resin-rich surface.
Post-cure: Heating a part after molding to complete the cure.

Watch: FRP Chemical Resistance Guide in 27 Seconds

A 27-second visual summary: FRP Chemical Resistance Guide (captions on screen).

Lining chart by resin and liner

For catalog maximum temperatures of common acids in polyester, epoxy, furan, phenolic, PP-FRP and PVC-FRP linings, see the FRP lining chemical resistance chart and the lining resistance table.

FAQ

Is FRP resistant to all acids?

No. Many acids are handled well by suitable resins, but compatibility depends on the acid, concentration and temperature. Some acids, such as hydrofluoric acid, require special construction.

Is vinyl ester or polyester better for chemicals?

Vinyl ester generally resists a broader range of chemicals and higher temperatures. Polyester may be adequate and more economical in milder services.

Why do cut edges need sealing?

Cutting exposes glass fibers. Chemicals and moisture can wick along exposed fibers, so sealing cut edges with compatible resin protects them.

What if my chemical isn't listed?

Ask your supplier. Options include consulting the resin manufacturer, testing coupons, or choosing another material.

Does higher temperature matter even if the chemical is mild?

Yes. Temperature accelerates degradation, and every resin has an upper limit.

Related guides

Sources

A US grating supplier, "Molded Grating Chemical Resistance Guide"
A US grating supplier, "FRP Resin Selection Guide"
A resin manufacturer, epoxy vinyl ester resin chemical resistance guide (resin manufacturer data)