GRP pipes with Flowtite continuous filament winding technology

Our promise: a solid sewer upgrade for solids-free wastewater

Flowtite Technology

Amiblu filament wound pipes are built as a structural sandwich, using the Flowtite continuous filament winding technology. The high-strength continuous glassfibers resist the hoop stresses from internal pressure, while the chopped fibers provide excellent resistance to axial stresses, impact, and handling loads. The structural laminate consists of heavily reinforced skins, separated by a compact, reinforced silica-filled core to provide optimal bending stiffness. Together with the protective layers, this construction provides capacity to resist high internal pressures and maintains excellent long-term stiffness.

Amiblu pipes with Flowtite technology are manufactured using a continuous advancing mandrel process. This process allows the use of continuous glassfiber reinforcements in the circumferential direction. For a pressure pipe or buried conduit the principle stress is in the circumferential direction, thus incorporating continuous reinforcements in this direction yields a higher performing product at lower cost.

A very compressed laminate is created that maximizes the contribution from the three basic raw materials: Continuous glass fibre roving and choppable roving are incorporated for high hoop strength and axial reinforcement, and a sand fortifier provides increased stiffness by adding extra thickness. With the Flowtite dual resin delivery system, the equipment can apply a special inner resin liner for severely corrosive applications while using a standard type resin for the structural and outer portion of the laminate. Other materials such as a glass veil or a polyester veil can be used to enhance the abrasion, the chemical resistance, and the finishing of the pipe.

The filament winding manufacturing machine consists of a continuous steel band mandrel supported by beams in a cylindrical shape. As the beams turn, friction pulls the steel band around and a roller bearing allows the band to move longitudinally so that the entire mandrel moves continuously in a spiral path towards the exit assembly. As the mandrel rotates, all composite materials are continuously metered onto it in precise amounts with the help of electronic sensors. Firstly, mould release film, followed by various forms and patterns of glass fibres, embedded in a polyester resin matrix. The structural layers are made of glass and resin only, whereas the core layer includes pure silica. After the pipe has been formed on the mandrel, it is cured and later cut to the required length. The ends of the pipe section are calibrated to fit the coupling.

Technical data Amiblu pipes with Flowtite technology*

Main materialsresin, glassfibers, sand
Operating temperature-50 °C to +70 °C, higher temperatures may be considered for individual projects
Standard lengths12, 6, and 3 m, other lengths on request
Pressure rangePN 1-32
Expected service lifemore than 150 years
Corrosion protectionnone needed, as materials used are inherently resistant to corrosion
Hydraulic roughnessk = 0.029 mm (Colebrook-White)
Water jetting resistancetested according to DIN 19523

* As currently manufactured and distributed by Amiblu for European markets. For the full range of products with Flowtite technology please refer to the Flowtite website

Amiblu projects realized with Flowtite technology

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Scotland, Balmoral Estates Hydro Energy with Flowtite pressure pipes

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Technical data

Diameter, pressure, stiffness, and so much more… All the technical hard facts you need to plan, lay, and operate our pipelines.


Reference database

Over 30,000 projects in over 125 countries in over 60 years: Discover spectacular and technically challenging construction works with Amiblu’s technologies (Flowtite, Hobas, Amiblu, Amiscreen) in our reference database.


Our footprint

We aim to have life cycle assessments for all products by end of 2022 and a carbon-neutral pipe production by 2030. We use the resources we have—our business, our voice, and our network—to fight the climate crisis and inspire people around the globe to value water as we should.