FRP Guides

FRP Pipe Basics: Types, Standards, Joints and Selection

In short: FRP pipe (also called GRP or fiberglass pipe) is made from glass fibers and thermoset resin, usually by filament winding. It doesn't rust, it has a smooth bore that stays smooth over time, and it is much lighter than steel or ductile iron. Common standards include AWWA C950 for fiberglass pressure pipe in water service, with pressure classes from 50 to 450 psig in 50 psi steps, ASTM D2996 for filament-wound pipe, and ISO 14692 for petroleum and natural gas industries. Joints can be adhesive-bonded, flanged, or gasketed bell-and-spigot. Resin and liner are chosen for the fluid and temperature.

FRP Pipe Basics: Types, Standards, Joints and Selection – In short summary: key points at a glance

Table: Joint types – FRP Pipe Basics — Joint types. Summary diagram of the table in this guide.

Where FRP pipe is used

Chemical process lines and effluent
Water and wastewater, including force mains and outfalls
Desalination intakes, brine and seawater lines
Cooling water circuits in power plants
Fire water and seawater systems in oil and gas and offshore
Scrubber recirculation and ducting
Mining and fertilizer slurries (with abrasion-resistant liners)

Diagram: Advantages – FRP Pipe Basics — Advantages: summary diagram from this guide.

How FRP pipe is made

Filament winding

Continuous glass rovings are wetted with resin and wound onto a rotating mandrel at controlled angles. A resin-rich liner with veil is applied first for corrosion resistance. Winding angle determines the balance of hoop (pressure) and axial strength. This is the most common method for industrial and pressure pipe. See How FRP Is Made.

Centrifugal casting

Resin, glass and sometimes fillers are placed inside a spinning mold. Centrifugal force compacts the wall. This method is used for some large-diameter gravity and pressure pipes.

Contact molding (fittings)

Elbows, tees and reducers are often hand laid-up or made with a combination of methods.

Key standards

Standard	Scope
AWWA C950 (2025 edition)	Fiberglass pressure pipe for potable, raw and reclaimed water; nominal 1–156 in; pressure classes 50–450 psig in 50 psi increments
ASTM D2996	Filament-wound fiberglass (glass-fiber-reinforced thermosetting resin) pipe
ISO 14692	GRP piping in the petroleum and natural gas industries
BS EN 1796 / ISO 10639	GRP pipe systems for water supply
BS EN 14364 / ISO 10467	GRP pipe systems for drainage and sewerage

When your project names a standard and pressure class, include it in your inquiry. We will confirm what we can design and test to. We don't claim third-party certification unless it is documented for your order.

Diagram: Limitations – FRP Pipe Basics — Limitations: summary diagram from this guide.

Joint types

Joint	Description	Typical use
Adhesive-bonded (taper/taper or socket)	Pipe ends bonded with adhesive	Process and industrial lines
Flanged	FRP flanges bolted together with gaskets	Connections to pumps, valves, tanks
Bell-and-spigot with elastomeric gasket	Push-fit, allows some movement	Water, sewer, buried lines
Laminated (butt-and-wrap)	Joint built up with glass and resin on site	Large diameters, repairs
Mechanical couplings	Sleeve couplings with gaskets	Some water and sewer lines

See our FRP flanges.

Advantages

Corrosion resistance inside and out, with no cathodic protection needed for the pipe itself
Smooth bore with low friction losses that resists scaling in many services
Light weight: lower transport and installation cost
Non-conductive
Long lengths, which means fewer joints

Limitations

Lower stiffness: buried pipe design must consider soil support and deflection. Above-ground pipe needs proper support spacing.
Temperature limits set by the resin
Impact sensitivity: handle carefully and protect from point loads
Thermal expansion greater than steel, so supports and anchors must allow for it

Installation basics

Above ground: follow the manufacturer's support spacing; use wide, padded supports; anchor and guide for thermal expansion.
Buried: use proper bedding and backfill, and compact as specified, since buried flexible pipe relies on side support from the soil.
Joints: follow the bonding procedures, cure times and torque values exactly.
Testing: hydrostatic testing according to the project specification.

RFQ checklist

Fluid, concentration, temperature (normal and maximum) and pressure (including surge and vacuum)
Diameter and length, and the routing drawing
Standard and pressure class required
Joint type and flange drilling standard
Above ground or buried; soil and traffic loads for buried pipe
Fittings list
Quantity and destination port

Customization

FIBROVX manufactures FRP pipes and filament-wound products to order. Options include diameter, wall thickness, liner and resin, joint type, fittings and color. Browse 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

Handling and installation tips

FRP pipe is light and easy to handle, but it needs care:

Lift with fabric slings rather than chains or wire ropes, and avoid dropping pipes or striking them against hard objects.
Store pipes on flat supports or timber bearers, away from sharp stones.
Inspect pipe ends and liners for damage before joining.
For buried pipe, follow the manufacturer's bedding and backfill requirements, because the soil supports the pipe.
For above-ground pipe, support spacing, guides and anchors must allow for thermal expansion and the pipe's lower stiffness compared to steel.
Pressure-test the completed line according to the project specification before putting it into service.

Key terms

Liner: The resin-rich inner layer of the pipe wall that resists the conveyed fluid and gives a smooth bore.
Structural wall: The filament-wound layer that carries internal pressure and external loads.
Pressure class: The rated internal pressure for a pipe, as defined by the applicable standard.
Stiffness class: A measure of the pipe's resistance to ring deflection, important for buried pipe.
Bell-and-spigot: A joint where one pipe end (spigot) fits into the enlarged end (bell) of the next, sealed with a gasket.
Mandrel: The rotating form onto which fibers are wound to make the pipe.

Catalog pipe range

Sand-filled pipe (RPMP): DN300–2800
Pressure classes: 0.6 / 1.0 / 1.6 MPa
Stiffness classes: SN2500 / SN5000 / SN10000 (selected independently of pressure)
Matching elbows, tees and reducers and flanges

See FRP piping systems and fitting and flange dimensions.

Watch: FRP Pipe Range in 27 Seconds

A 27-second visual summary: FRP Pipe Range (captions on screen).

FAQ

What is the difference between FRP and GRP pipe?

None. Both describe glass-fiber reinforced thermoset pipe. See FRP vs GRP vs Fiberglass.

What pressure can FRP pipe handle?

It depends on the design. AWWA C950 covers pressure classes from 50 to 450 psi. Industrial and oil and gas pipe may be designed to other ratings under ISO 14692 or project specifications.

How is FRP pipe joined?

By adhesive bonding, flanges, gasketed bell-and-spigot joints, laminated joints or mechanical couplings, depending on the application.

Is FRP pipe suitable for hot fluids?

Within the resin's temperature limit. Tell us the maximum temperature, including upset conditions.

Is FRP pipe suitable for buried service?

Yes. FRP pipe is widely used for buried water and sewer lines. Buried FRP pipe is designed as a flexible pipe: the stiffness class and the bedding and backfill must be designed together.

Can FRP pipe be joined to steel or PVC pipe?

Yes, usually through flanged connections or suitable mechanical couplings. The joint must be designed for the pressure, temperature and any differences in thermal expansion.

Related guides

Sources

AWWA, C950-25 "Fiberglass Pressure Pipe" (pressure classes 50–450 psig in 50 psi steps; 1–156 in): https://store.accuristech.com/standards/awwa-c950-25?product_id=3095611
ASTM International, D2996 "Filament-Wound Fiberglass Pipe": https://store.astm.org/d2996-17.html
ISO, ISO 14692 "Petroleum and natural gas industries – Glass-reinforced plastics (GRP) piping": https://www.iso.org/search.html?q=14692