Published by pultrx, the export trading company of Henan Zhongsheng. This is a buyer planning guide; the manufacturer confirms project specifications in writing.
If you are buying rather than researching, start with our pultruded FRP and GRP profiles
What FRP stands for, and the other names
The same family of materials goes by several names. The letters describe the fiber and the matrix; the regional habit decides which one a buyer uses. When the fiber is glass, FRP, GRP, GFRP and fiberglass all describe the same kind of product.
| Term | Stands for | Where you meet it |
|---|---|---|
| FRP | Fiber (or fibre) reinforced plastic or polymer | General and North American industry use: FRP profiles, FRP grating, FRP panels |
| GRP | Glass reinforced plastic | Common in British usage: GRP grating, GRP roofing, GRP box section |
| GFRP | Glass fiber reinforced polymer | Engineering standards and design codes, for example for reinforcing bar |
| Fiberglass / fibreglass | Everyday name for glass fiber composites | Retail and trade: fiberglass tube, fibreglass rod |
| CFRP, AFRP, BFRP | Carbon, aramid and basalt fiber reinforced polymer | Same principle with a different fiber |
| GFK | Glasfaserverstärkter Kunststoff | German for GRP |
What FRP is made of
FRP is a composite: two materials that work together. The fibers carry the load; the resin holds them in place, transfers load between them and protects them from the environment.
Reinforcement
- Glass fiber: the most common and lowest-cost reinforcement; gives fiberglass, GRP and GFRP
- Carbon fiber: much stiffer and more expensive; used where stiffness per weight is critical
- Aramid and basalt fiber: niche uses
- Forms: continuous rovings for strength along the length, mats and fabrics for strength across it, a surfacing veil for a resin-rich skin
Resin (matrix)
- Polyester, including isophthalic grades
- Vinyl ester
- Epoxy
- Polyurethane
- Phenolic
- Plus fillers, pigments and additives; the resin is chosen for the service environment
Most industrial FRP uses a thermoset resin, which cures by chemical reaction and does not melt again when heated. That is why an FRP part keeps its shape in sun and moderate heat, and why it is cut and drilled rather than welded.
How FRP products are made
| Process | How it works | Typical products |
|---|---|---|
| Pultrusion | Fibers are pulled through a resin bath and a heated die, which cures a continuous profile of constant cross-section | Tubes, rods, angles, channels, I-beams, grating bars, GFRP rebar, window profiles |
| Filament winding | Resin-wetted fiber is wound around a rotating mandrel | Pipes, tanks, pressure vessels |
| Hand lay-up and spray-up | Fiber and resin are laid or sprayed into an open mold and cured | Boat hulls, covers, large one-off shapes |
| Molding of grating | Glass and resin are placed in a grid mold and cured as one panel | Molded fiberglass grating |
Profiles, rebar and most structural shapes are pultruded; see the pultrusion process, step by step
FRP properties against steel and aluminum
For structural pultruded profiles the European standard EN 13706 sets two grades of minimum properties, E23 and E17. The table sets those minimums beside the Eurocode design values for steel and aluminum. They are grade minimums. The properties of the profile you buy are in its test report, so ask for it.
| Property | FRP, EN 13706 E23 | FRP, EN 13706 E17 | Structural steel | Aluminum alloy |
|---|---|---|---|---|
| Modulus of elasticity, length direction | 23 GPa minimum | 17 GPa minimum | 210 GPa | 70 GPa |
| Tensile strength, length direction | 240 MPa minimum | 170 MPa minimum | Set by steel grade | Set by alloy and temper |
| Tensile modulus, across the fibers | 7 GPa minimum | 5 GPa minimum | Same in all directions | Same in all directions |
| Density | About one quarter of steel | About one quarter of steel | 7,850 kg/m³ | 2,700 kg/m³ |
Where FRP is strong
- Does not rust; resists many chemicals, salt water and wastewater with the right resin
- Glass-fiber FRP is electrically insulating and non-magnetic
- Light: easy to carry and install without heavy lifting
- Low thermal conductivity
- Color through the material; no painting needed for protection
Where FRP needs care
- Stiffness: an E23 profile has about one ninth of the modulus of steel, so beams are sized for deflection
- Direction: properties across the fibers are much lower than along them
- Heat and fire: limits depend on the resin; specify a fire-retardant system where codes require it
- Sunlight: a surfacing veil or coating keeps glass fibers from blooming outdoors
- Connections: bolted and bonded joints are designed differently from welded steel
For a member-by-member comparison and how to size a fiberglass section for stiffness, read FRP vs steel
Where FRP is used
- Walkways, platforms, handrails and ladders in chemical plants, water treatment and offshore sites
- Cable trays, crossarms and supports where electrical insulation matters
- Cooling tower structures exposed to warm, wet air
- Concrete reinforcement (GFRP rebar) where steel would corrode or interfere with magnetic fields
- Window and door frames, where low thermal conductivity reduces heat loss
- Tool handles, poles, stakes and masts that must be light and non-conductive
Each end use, with the products and documents buyers cite, is described under applications of pultruded FRP
Buying FRP products
Specify FRP by the product form, the section and the service conditions rather than by the material name alone. State the resin system or the environment it must resist, the required grade or test values, the dimensions and tolerances, the color and surface, and the quantities by length. Our factory pultrudes tubes, rods, flat strips, angles, channels, I-beams, grating, sheet piles and GFRP rebar, with inch and metric sizes made to order.
Standard inch sizes with weights per foot are in the FRP size chart in inches
Sources and further reading
- Wikipedia: Fibre-reinforced plastic
General definition: a polymer matrix reinforced with fibers, usually glass, carbon, aramid or basalt.
- Wikipedia: Glass-reinforced plastic
Names (fiberglass, fibreglass, GRP, GFRP, GFK, FRP); typical polyester, vinyl ester and epoxy matrices; hand lay-up, spray-up, filament winding and pultrusion; density 1.5 to 2.5 g/cm³.
- Strongwell: How is industrial fiberglass manufactured?
Resins used in pultruded fiberglass: polyester, vinyl ester, epoxy, urethane and phenolic.
- Fiberline: European standard EN 13706, minimum requirements for E23 and E17 profiles
Reproduction of EN 13706-3 Table 1; grade minimums for structural pultruded profiles, not properties of a specific product.
- Fiberline: low weight of fibreglass profiles
Glass-fiber profiles have about one quarter of the density of steel.
- EN 1993-1-1, EN 1991-1-1 and EN 1999-1-1 (Eurocodes 3, 1 and 9), via the European Commission JRC Eurocode portal
Values are from the standards themselves, not the portal page: E = 210 GPa for structural steel (EN 1993-1-1, 3.2.6), 7,850 kg/m³ steel density (EN 1991-1-1, Annex A), E = 70 GPa and 2,700 kg/m³ for aluminium alloys (EN 1999-1-1, 3.2.5).
- American Composites Manufacturers Association: Discover composites
Industry association definition of composites as resins and fibers combined to enhance material properties.
Questions buyers ask
- What does FRP stand for?
- Fiber reinforced plastic, also written fiber reinforced polymer or fibre reinforced plastic. It is a composite of strong fibers, usually glass, held in a cured resin.
- Is FRP the same as fiberglass?
- When the fiber is glass, yes. Fiberglass is the everyday name; FRP is the technical one. FRP can also use carbon, aramid or basalt fiber, which is why codes add a letter: GFRP for glass, CFRP for carbon.
- What is the difference between FRP and GRP?
- None in practice for glass fiber products. GRP, glass reinforced plastic, is the name used in the UK, Ireland and Australia; FRP is more common in North America and in general industry use.
- What is GFRP?
- Glass fiber reinforced polymer. The term is used in engineering standards, especially for reinforcing bar in concrete, to make clear that the fiber is glass.
- Is FRP stronger than steel?
- Along the fibers, EN 13706 sets 240 MPa as the minimum tensile strength of an E23 structural profile, comparable to the yield strength of S235 structural steel. It is far less stiff, about one ninth of steel's modulus, so FRP members are usually sized by how far they deflect.
- Does FRP rust or conduct electricity?
- Glass-fiber FRP does neither: it does not corrode like steel and it is an electrical insulator (carbon-fiber FRP does conduct), which is why it is used in chemical, marine and electrical utility work. Chemical resistance depends on the resin, so specify the environment.
Ready to move from reading to a scoped quotation?
Ask about an FRP product