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Seminar

on

Pipes in Water Supply System

By

A.N.Saikumar

First Year M.Tech Environmental

Engg.


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Introduction

Water supply is the process of generalrequirement for supply of water frompublic water supply system to individualbuilding.

The water from public water supplysystem to individual buildings is suppliedthrough pipes.

A pipe is a circular closed conduit

through which the water may flow eitherunder gravity or under pressure.A large proportion of capital is invested

on pipes while designing water supply

distribution system.


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Water Supply Components


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Factors

The following factors should beconsidered in selection of pipes :-

Strength of pipe.

Resistance to corrosion. Water carrying capacity.

Life and durability of pipe.

Expenditure on transportation. Jointing process, maintenance and

repairs.

Economy.


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Various Types of Pipes

They may be classified into three groupsaccording to the material used in theirmanufacturing.

Metallic Pipes: The pipes such as CI pipes,Steel pipes, GI pipes, Copper and Leadpipes, Ductile pipes.

Cement Pipes: The pipes such as Asbestoscement (AC) pipes, Cement concrete pipes.

Plastic Pipes: The pipes such as Un-plasticized PVC (UPVC) pipes, Polyethylenepipes.


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Cast Iron (CI) Pipes

These pipes are mostly used in water supply. They are well suited for pressure and can

withstand external load because of theirthickness.

The pipes are easy in manufacturing, layout

and joining. These pipes are manufactured byvertical casting in sand moulds, horizontalcasting in sand moulds and centrifugalcasting.

CI pipes are heavy in weight. Thereforetransportation is costlier and they are notsuitable for inaccessible places.

Due to heavy weight these are generallymade in short length. This increases layout

and jointing cost.


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Features of CI pipes

These are up to 1000mm in dia and

6m long.

They jointing is easy.

Can withstand pressure of 24 kg/cm2.

Strong durable up to 100 years.


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CI pipes


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Steel Pipes

These pipes are also extensively used forwater supply.

They are best suitable for long distance pipelines of high pressure and providesatisfactory performance during service.

These pipes have excellent mechanicalproperties and are ideally suited for welding.

The pipes are made in length more thantwice the length of CI pipes; which saves in

transport, layout of pipe and joining cost. They are particularly suitable on bridges or

under similar conditions where strength andlow weight are desired


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Features of Steel pipes

Contains less carbon than Cast Iron

pipes.

Difficult to make connections henceseldom used for water distribution

systems.

Much stronger and lighter than CastIron pipes.

Cheaper than Cast Iron pipes.


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Steel pipes


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Galvanized Iron (GI) pipes

Galvanized pipes have been used inhouses for years, typically to carry

water in and out of the house.

The galvanized coating preventsrusting, and gives a dull gray

appearance.

Galvanized pipes typically come insizes between inch (1.3

centimeters) and 2 inches (5.1

centimeters) in diameter


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Features of GI pipes

Manufactured by dipping Cast Iron

pipe in molten zinc.

Resistant to corrosion.

Mainly used for plumbing.


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GI pipes


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Copper Pipes

Copper pipes are very costly, and theiruse is restricted for conveyance of hot

water in the interior buildings.

These pipes do not sag or bend due tohot water.

They are also resistant to corrosion by

acidic or alkaline waters. Copper pipes can withstand high

internal pressure.


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Copper pipes


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Lead Pipes

Lead pipes are very soft and caneasily bend.

Due to cumulative poisoning effect of

lead, these are not used in watersupply pipes.

They are used for apparatus required

for alum and chlorine doses.


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Ductile Pipes

Similar to Cast Iron pipes exceptincreased ductility.

Ductile iron is produced by adding a

controlled amount of Mg into molteniron of low sulphur and phosphorous

content.

Stronger, tougher and elastic thanCast Iron pipes.

More expensive than Cast Iron pipes.


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Ductile pipes


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Cement Concrete Pipes

Cement Concrete Pipes may be either plainor reinforced, and are best made by spinningprocess.

They may be either precast, or may beprepared at site. The plain cement concretepipes are used for heads up to 7m whilereinforced cement concrete pipes arenormally used for heads up to 60m.

Reinforced concrete pipes are used only for

large water supply lines, but they are notsuitable for distribution systems.

These pipes are durable, heavier andtransportation costs are less if the pipes arecast in situ.


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Features of Cement pipes

Usual size of Reinforced Cement

Concrete pipe is 400mm dia. andabove.

Not subjected to corrosion.

Average life is 75 years. Low maintenance cost.


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Cement pipes


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Asbestos Cement (AC) Pipes

They are manufactured from asbestos fiberand Portland cement combined underpressure to form a dense homogenousstructure.

These pipes are light in weight and easy intransportation and layout.

They have smooth internal surface and arenot affected by corrosion (rust).

The pipes are extensively used for water

supply systems. Holes can be drilled in thesepipes.

These pipes are not costlier.

Asbestos Cement pipes are economical and

are generally preferred to use in the design ofwater supply systems.


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Features of Asbestos pipes

Sizes are 100mm to 600mm dia.

Average life is 30 years.

Immune to actions of acids, salts, soil

and corrosion.

Less cost for laying and jointing.

Less plumbing cost due to less

friction.

They can be easily cut, fitted or

jointed.


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Asbestos pipes

Un plasticized PVC (UPVC)


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Un-plasticized PVC (UPVC)

Pipes

These pipes are rigid PVC pipes. Theyare light in weight, tough, resistant tochemical attack and large in length.

Due to large in length the cost ofhandling is much whereas transportationand installation cost is less.

Smooth internal surface of pipes provide

less friction which results in saving ofenergy.

These pipes are not suitable for the areawhich is very hot.


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Features of PVC pipes Mainly used for domestic plumbing.

Easy to install and easy to handle.

They have adequate strength, and areresistant to shock.

They are durable and are unaffectedby age, sunlight, weather.

Cheaper in material cost

Accepted life is 50 years.


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PVC Pipes - Light weight still powerful


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Polyethylene pipes

used for water distribution systems mostly ranging from 15-150mm diameter and occasionally up to 350mm

recent developments is the use of high density polyethylenepipes (HDPE)

HDPE pipes are rigid, tough, resilient and conform to the

topography of land when laid over ground or in trenches . easily bent in installation, eliminating the use of specials

like bends, elbows etc

anti corrosive, have smooth inner surface

Medium Density Polyethylene (MDPE) Pipes

being manufactured in India conforming to ISSpecifications (ISO 4427 and BS 6730-1986) for carrying

potable water

are non corrodible, lightweight and robust and are suppliedin coils

H illi C ffi i f Pi


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Hazen williams-Coefficients of Pipes

(ref: CPHEEO manual)


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