GRP Pipes & Fitting - Method of Mfg. GRP/FRP Pipes and Its Process


The Helical Filament Winding Method is also the most flexible method as different sizes of pipes can be manufactured at a time on the same machine.

The method uses Steel, GRP or wooden Mandrels as formers for manufacturing of GRP Pipes. These mandrels are prepared for winding, off-line and are fed one by one to Computer Controller Winding Machine.

The Operator enters the Programme for the particular pipe and the machine winds the pipe automatically.


The following Steps will give a general idea of the various stages of Pipes Manufacturing Process.

1 Mandrel Preparation:

First of all the Mandrel has to be cleaned & polished, on which a thin film is wrapped around the mandrel for better inner surface so that the pipe could be released easily & smoothly from mandrel.

2 Liner Preparation & Curing:

First we apply a layer of resin on film, followed by multiple layers of appropriate resin along with glass surface mat & chopped strand mat and leave for curing.

3 Filament winding the Structural of the pipe:

Helical winding- continuous strands of closely spaced Glass fibers, automatically impregnated with appropriate resin, are wound onto the cured liner by the computer controlled machine. The pre-programmed machine will carry out the winding pattern to the required thickness.

4 Curing the pipe:

After completing the filament winding process, mandrel is being put for curing up to 1 to 2 hr. depending on the weather condition.

5 Extraction of the pipe from Mandrel:

After checking the cured pipe by barcol hardness tester, the pipe is released from mandrel by hydraulic extraction machine.

6 Final outer layer:

After removing the pipe from mandrel, a final layer of resin is applied with U.V.stabilizer (if required).

7 Both side end Preparation:

After finishing the final layer with U.V.stabilizer the rough ends of pipes are cut and calibrated at both ends for coupler jointing or at one end for socket and spigot jointing system and send for hydro testing.