01-10-2012, 04:49 PM
RIGID P.V.C. PIPES
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INTRODUCTION:
Rigid PVC Pipes are fast replacing the conventional metal pipes in many
applications. Use of PVC pipes as electrical conduits is well accepted in
household and industrial activities. PVC conduits have been accepted by all
Electricity Boards. PVC pipes of different diameters have gained wider
acceptance for water supply. Their light weight, low cost, easy installation, noncorrosiveness,
high tensile strength to withstand high fluid pressure make them
ideal for number of purposes. They also offer resistance to most of the
chemicals and have excellent electrical and heat insulation properties.
PROCESSING:
The basic material which on Polymerisation produces P.V.C. Pipes is Poly
vinyl chloride which in resin form is hard and rigid. The rigidity can be
controlled by controlling the percentage of plasticizer at the time of
compounding. Production of Rigid PVC pipe is based on plasticizing and
homogenizing PVC compound and then passing the compound through an
extruder. The hot molten PVC compound is extruded through a circular slit.
Circular slit governs the size of pipe to be extruded. Different dies are used for
manufacturing different size of pipes.
The Pipes thus extruded through the die is then passed through a vacuum
sizing tank wherein the dimensions of the pipe can be accurately set. It also
helps in surface finish of the pipes. Vacuum sizing reduces the percentage of
wastage considerably.
As the pipe being extruded is rigid in form they cannot be wound into
coils. So an inline motorized cutting device should be provided for cutting the
pipes into required sizes. For ascertaining the consistency in product quality the
unit should be equipped with process control laboratory for preliminary testing
of raw materials. The unit may also have arrangement for quality testing of
finished products.