original & the most extensively
used method for manufacturing
GRP/FRP Pipes is the HELICAL WINDING
The name HELICAL WINDING METHOD
has come from the pattern of the
glass fibers on the Pipe, a criss
cross helical pattern. The angle
of the Helix can be change to
impart various strengths in the
hoop or axial direction as required.
The Helical 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/FRP or
wooden Mandrels as formers for
the 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.
Pipes such as Pressure Pipes,
Drainage & Sewer Pipes, Water
Tube Well Pipes, and Industrial
Pipes etc. can be manufactured
by using this method.
The following Steps will give
a general idea of the various
stages of Pipes Manufacturing
Mandrel Preparation ::::
First of all, the Mandrel is cleaned
& polished. After which a
thin film is wrapped around the
mandrel for better inner surface
finish so that the pipe could
be released easily & smoothly
Liner Preparation & Curing
First we apply a layer
of resin on the mandrel. Then
multiple layer of appropriate
resin is being applied with glass
surface mat & chopped strand
Filament winding the Structural
part of the pipe :::::
Helical winding – continuous
strands of closely spaced Glass
fibers, automatically impregnated
with Isophthalic 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.
After curing the liner layer,
filament winding process with
Isophthalic resin will be start
(helical winding between 50 to
75 Deg. & Hoop winding Process
at 90 Deg) Up to achieved require
reinforcement wall thickness.
Curing the pipe :::::
After completing the filament
winding process, mandrel is being
put for curing up to 1 to 2 hr.
depending upon the weather condition.
Extraction of the pipe from mandrel
After curing of the pipe,
it is released from mandrel by
hydraulic extraction machine.
Final Outside layer :::::
After removing the pipe
from mandrel, a final layer of
resin being applied with U.V.
Both Side end Preparation :::::
After finishing the final
layer with U.V. stabilizer, the
rough end of pipes are being cut
and calibrated in both ends for
coupler jointing and prepared
for hydraulic testing & after
that send to finish goods yard.