The presentation is covering points from the Second year civil engineering syllabus which are related to water conveyance. Presentatin also covers poins like pipe material, stress in pipe during conveyance of water.

1. 04-04-2020presentation by Prof. Ms Pooja Taralgatti1
SECTION II
Unit No 4
Conveyance of
water
SY B
Department of Civil Engineering

2. Contents
– Transmission of water,
– pumping and gravity mains,
– choice of pipe materials, stresses in pipes
– economic size of conveying main.
– Distribution reservoir, service storage, necessity, location,
and Design (head and capacity) requirements.
04-04-2020presentation by Prof. Ms Pooja Taralgatti
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3. Transmission of water
The name conveyance is noting but the transportation of water from one
place to another place so there are two stages of conveyance.
There are two stages in the transportation of water:
 Conveyance of water from the source to the treatment plant.
For this type of conveyance we have seen the arrangement called intake
works.
 Conveyance of treated water from treatment plant to the distribution
system.
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4. Pumping
A pump is a device which converts mechanical energy into hydraulic
energy. It lifts water from a lower to a higher level and delivers it
at high pressure.
Pumps are employed in water supply projects at various stages for following purposes:
– To lift raw water from wells.
– To deliver treated water to the consumer at desired pressure.
– To supply pressured water for fire hydrants.
– To boost up pressure in water mains.
– To fill elevated overhead water tanks.
– To back-wash filters.
– To pump chemical solutions, needed for water treatment.
04-04-2020presentation by Prof. Ms Pooja Taralgatti
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5. Types of pumps
Based on mechanical
principle used
Displacement pump
a) Reciprocator pump
b)rotary pump
Centrifugal pump
Air left pump
Based on type of service
called for
Low lift pump
High lift pump
Deep well pump and
booster pump
Based on type of power
required
Steam engine pump
Diesel engine pump
Electrically driven
pump
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6. Main Pump Details
Reciprocating pump Rotary pump
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7. Main Pump Details
Centrifugal pump Air-lift pump
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8. Types of valve
Butterfly valve Globe valve
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9. Types Of Valves
Ball Valve Ball Valve
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10. Types Of Valves
– Gate Valve Air Release Valve
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11. Pipe Material
 Cast Iron
 Steel
 Reinforced Cement Concrete
 Prestressed Concrete
 Asbestos Cement
 Polyethylene – low density and high density
 Rigid PVC
 Ductile Iron
 Fibre Glass Pipe
 Glass Reinforced Plastic
 Fibre Reinforced Plastic
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presentation by Prof. Ms Pooja Taralgatti
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12. Criteria For Selection Of Pipe
Material
• Initial Carrying capacity and its reduction with use
• Strength of pipe for internal pressures & external loads
• Life & durability of pipe
– CI & steel pipes – corrosion
– Concrete & AC pipes– erosion & disintegration
– Plastic pipes – cracking & disintegration
• Ease or difficulty of transportation, handling & laying under
different conditions of topography, geology & communication
• The safety, economy & availability of manufactured sizes
• Availability of skilled labour in construction of pipe lines
• Requirements of maintenance & repair, losses of water by
leakages
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13. Pipe Material Highlights
Cast Iron Pipe
• Good lasting quality
• Heavy weight‐ high transportation
costs
• Short length ‐ high laying & jointing cost
• Low tensile strength
• Liable for defective inner surface
Steel Pipe:
• Higher tensile strength
• Specials of all kinds can be fabricated
• Due to elasticity adopt themselves to
changes in relative ground level without
failure
• Suitable for high dynamic loading
• Internally and externally corrosive –
epoxy lining/ hot applied coal
tar/asphalt lining or rich cement mortar
internally
• Outer coating for underground pipe line
may be in cement sand guniting or hot
applied coal tar asphaltic enamel
reinforced with fibre glass fabric yarn
04-04-2020presentation by Prof. Ms Pooja Taralgatti
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14. Pipe Material Highlights
Ductile Iron Pipe
• Higher mechanical strength
• Resistance to corrosion
• Good casting quality
• Can resist impact without damage
• High wear & tear resistance
• Smooth inner & outer surface
• Free from cracks
• @ 30 % lighter than CI pipes
Asbestos Cement Pipes
• Carrying capacity does not change
over period of time due to water
quality
• Can be drilled & tapped for
connection
• Not suitable for threading
• Unsuitable for use in sulphate soils
• Safety against bursting and
against failure in longitudinal
section is less
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15. Pipe Material Highlights
Prestressed Concrete pipe
– Suitable for pressure in the range of 6 kg/cm2 & 20
kg/cm2.
– Strength achieved by helically binding high tensile steel
wire under tension around a concrete core thereby
putting core into compression
– Economical compared to steel pipes above 600 mm dia
– Physical behaviour of PSC pipes under
internal & external load is superior to RCC pipes.
– Corrosion resistant
– Pipe can not cut to size to close gaps in pipeline.
Plastic Pipes
– Resistance to corrosion
– Light weight
– Toughness
– Rigidity
– Economic in laying, jointing and maintenance
– Ease of frabication
– Unaffected by fungi, bacteria and many chemicals
– Pipes are elastic and resistant to deformation
– Thermal conductivity is low
– Corrosion resistant
– Affected by UV light hence not suitable for laying above
ground
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16. Pipe Material Highlights
High Density Polyethylene
(HDPE) Pipes
– Resilient & confirm to the topography of land
when laid over ground or in trenches
– Coilable, easily bent in installation, eliminating
the use of specials like bents, elbows‐ reduce
cost
– Light weight – can be easily carried on hills
– Withstand movement of heavy traffic
– Good free flowing properties
– Smooth inner surface
– Corrosion resistant
Glass Reinforced Plastic (GRP)
Pipes
– Resistance to internal & external
corrosion
– Better strength
– Durable
– High tensile strength
– Low density
– Inert
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17. Hydraulics of Pipe
– Hazen – Williams Formula
V = 0.849 . C . r0.63 . s0.54
– Manning’s Formula
𝑉 =
1
𝑛
∗ 𝑟2/3 . 𝑠1/2
– Darcy – Weisbach s Formula
Hf
= f . L . V2
2.g.d
– Modified Hazen – Williams Formula
V = 3.83 . CR . d0.6575 .(gs)0.5525
ν0.105
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18. Economic Size Of Conveying Main
– If the diameter of pumping main is decreased , thereby increasing
the velocity of flow for a given fixed discharge , both friction head
loss and velocity head will increase and hence Total dynamic head
will increase.
– This will result in increase in cost of pumping main.
– The pumping main diameter must choose in such a way, which will
minimize the pumping cost along with the annual maintenance.
This diameter is known as Economical diameter of pumping mains
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19. Economic Size Of Conveying Main
• Design Period
• Different pipe sizes against different hydraulic slopes
• Different pipe material with relative costs as laid in
position
• Duty capacity and installed cost of pumps for
different pipe sizes
• Recurring cost on
– Energy charges for running pumps
– Staff for O & M
– Maintenance & Renewal of pumps
– Cost of miscellaneous consumables
• Replacement of pump costs at intermediate stage (15
years)
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Empirical formulae by Lea:
D= a √Q
D= Diameter of pipe
A= 0.97 to 1.22
Q= discharge to be pumped

20. Stress In Pipe
– Internal water pressure
– External pressure due to overburden
– Temperature stresses
– Water hammer
– Longitudinal stresses due to flow arround bends
– Stresses due to foundation
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21. Stress In Pipe
– The internal water pressure causes hoop tension in the pipe
f = pd/2t
p = internal pressure of water
d = diameter of the pipe
t = thickness of pipe shell
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22. Stresses in pipes
Internal Water Pressure
The internal water pressure causes
hoop tension in the pipe
F = p.d/2t
Where,
p = internal pressure of water
d = diameter of the pipe
t = thickness of pipe shell
External Pressure due to overburden
– According to Martson the load on buried
pipes W is given by:
W = C.𝛾. B˄2
Where,
𝛾 = Unit weight of backfill material (kg/m3)
W = Load per meter length of pipe
B = Width of trench
C = Coeficient, which depends upon the type
of soil and the ratio of the depth to the
trench width
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23. Temperature stresses
– Temperature stresses are causes in metal pipes when they are laid above ground.
– Due to temperature variations, length of pipe get changed.
– If this change is restricted due to fixidity or any other reason, the pipe will be subjected
to following stresses:
ft = Ep.𝛼. 𝛥T
– ft = Temperature stress
– Ep = Modulus of elasticity of pipe material .
– 𝛼 = Coefficient of thermal expansion
– 𝛥T = Temperature variation
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24. Water hammer
– Water hammer effect is produced when the velocity of pipe checked suddenly by
sudden closure of valve.
– When valve will be closed their will be sudden rise in pressure.
– The maximum water hammer pressure Ph is given by the following expression:
Ph = w/g Up . V0
Where,
Up = Velocity of pressure wave generated
W = Unit weight of water
V0 = Normal velocity of flow in the pipe line (m/s) before sudden pressure
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25. Stress due to bend
When water flows through pipe bend, two types of forces acting on pipe longitudnaly i.e.
1. Centrifugal force exerted by the moving water
2. Unbalanced internal pressures
The total tension T in the pipe is :
T = P A + W*A*V˄2/g
where.,
P= Internal water pressure
A= Area of section of pipe
W= unit weight of water
V= Velocity of flow of water
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