Pipe materials and types of joints [autosaved]

Pipe Materials and Types of
Joints
Environmental Engineering – I
Reference Text Book :- S.K GARG

Types of Pipe materials
• Metallic Pipes :
– Unlined metallic pipes –
• Cast Iron(C.I)
• Galvanized Iron(G.I)
• Mild Steel(M.S)
• Ductile steel (D.I)
– Metallic pipes lined with cement mortar or epoxy lining
• Non metallic pipes
– Reinforced Concrete, Pre-stressed Concrete, Bar
Wrapped Steel Cylinder Concrete, Asbestos Cement
– Plastic pipes: PVC, Polyethylene, Glass Reinforced
Plastic, UPVC etc.19 July 2018 Prakash Kumar Sekar

Cast Iron pipes Galvanized Iron pipes
Ductile Iron pipes
Mild steel pipes19 July 2018 Prakash Kumar Sekar

Reinforced concrete pipes Asbestos cement pipes
Prestressed pipes
PVC pipes19 July 2018 Prakash Kumar Sekar

HDPEPolyethylene pipes
Bar wrapped Steel cylinder pipes
19 July 2018 Prakash Kumar Sekar

CAST IRON (C.I) PIPES
• Widely used for city water supplies
• Sufficiently corrosion resistant
• Available in lengths of about 3.7 and 5.5m and
diameters of 50 – 900mm
• Manufacturing methods:
– Sand moulding
• Casting in Horizontal position – “McWane” pipes
• Casting in vertical position – “Pit cast pipes”
– Centrifugal process
• Sand spun pipes – made in sand moulds
• Delavaud pipes – made in metallic moulds

Advantages and Disadvantages of C.I
pipes
• Advantages
– Cost – moderate
– Economical
– Strong and durable
– Corrosive resistant if coated
– Easy to join
– Resists impact without damage
• Disadvantages
– Interior of pipe becomes rough with age – discharge
carrying capacity is reduced
– Large dia pipes are heavy and hence uneconomical
– Likely to break during transportation or jointing

GALVANIZED IRON PIPES
• GI pipes with circumferential corrugations are
much more stronger than ordinary one.
• Hence they are used where large dia pipes of
smaller thickness is required.
• Widely used for internal connections in
buildings.
• GI pipes are not cast but made by riveting or
welding steel plates

• Advantages
– Cheap
– Light – easy to handle and transport
– Easy to join
– Less Frictional losses
• Disadvantages
– Life is short – 7 to 10 yrs
– Easily affected by acidic and alkalic waters –
incrustations form easily inside the pipe

DUCTILE IRON PIPES
• Manufacturing process:
– Addition of magnesium into molten iron of low
sulphur content
– Mg causes graphite in the iron to precipitate in the
form of microscopic spheres. This improves the
properties of ductile iron
– Generally manufactured by centrifugal cast
process.

• DI pipes have excellent properties of
– Impact resistance
– High wear and tear
– High tensile strength
– High ductility
– Corrosion resistance
• DI pipes are strong, both inner and outer
surfaces are smooth.
• Diameter: 80mm to 1000mm
• Length : 5.5 to 6 m

CEMENT CONCRETE PIPES
• Plain cement concrete pipes – small sizes ( dia 0.6m)
• Reinforced cement concrete pipes – large sizes (dia 1.8
m upto 4.5m)
• Manufacturing Methods (based on location)
– Cast in-situ
– Precast
• Manufacturing process of RCC pipes
– Ordinary methods of concrete pouring and tamping
– Centrifugal type
– Cylinder type

• Mix used – 1:2:2 with max. aggregate size as 6mm
• Diameter : 0.1m to 1.2m
• Thickness : 2.5cm to 6.5cm
• For head greater than 30m, Prestressed pipes are
used.
– Laid with a welded steel cylinder to ensure water
tightness.
– High tensile wire is wound around it to cause
prestressing of the core.
– Concrete is laid by centrifugally.
– Available in dia ranging from 80 mm to 1800 mm.

• Advantages
– Inside of pipe is smooth hence friction losses are low.
– Durable.
– Low maintenance cost.
– Life is at least 75 years.
– Resist external compressive loads and do not collapse
under nominal vacuums and traffic loads.
– Easy to construct at site or at factories with local
ingredients
– No need of expansion joints when laid above the
ground.
– If laid under water, empty pipes do not float because
of their heavy weights

• Disadvantages
– Heavy and difficult to handle.
– Likely to crack during transportation.
– Repair work is difficult.
– Likely to corrode by ground water due to the
presence of acids, alkalis or sulphur compounds.
– Cannot withstand very high pressures.
– Difficult to join
– Tend to leak due to shrinkage cracks and porosity

VITRIFIED CLAY PIPES
• Used for carrying sewage and drainage at partial
depths.
• Not used as pressure pipes for carrying waters
since clay is very weak in tension and formation
of watertight joints becomes difficult.
• Free from corrosion
• Provide a smooth hydraulically efficient surface.
• Available in lengths of about 0.6m.

ASBESTOS PIPES
• Asbestos, silica and cement are converted under
pressure to a dense homogeneous material – Asbestos
cement possessing high strength.
• Asbestos fiber serves as reinforcement
• Diameters: 10 to 90 cm
• Length : 4m
• Made in 4 different grades to withstand pressure of 350
kN/m2 to 1400 kN/m2 as per IS 1592 -1989.
• Used as distribution mains in India.
• Can withstand pressure from 50 to 250m head of water
depending on the type and class of manufacture.

• Advantages
– Light and easy to transport
– Easily assembled without skilled labour
– Highly corrosion resistant
– Highly flexible and allows 12° deflection in laying them
around curves.
– Expansion joints are not required
– Used as small size distribution pipes
• Disadvantages
– Costly
– Not much strength, brittle and soft.
– Liable to get damaged by excavation tools or during
transportation or transits.
– Rubber joint seals may deteriorate if exposed to gasoline or
petroleum products.
– Cannot be used for high pressure.

POLYETHYLENE PIPES
• Rigid PVC and High Density PolyEthylene pipes(HDPE) –
water distribution systems
• Dia ranges from 15 to 150 mm and sometimes upto 350 mm.
• Advantages
– HDPE pipes are rigid and tough.
– These pipes can be joined with detachable joints and can be
detached at the time of shifting the pipeline.
– Easily bent in installation
– Eliminates the use of specials like bends, elbows etc.,
– Easy to carry and install.
– Lighter in weight and can be carried to heights
– Has excellent free flowing properties
– Non-adherent surfaces so that it rejects the foreign materials
– Anti-corrosive
– Friction and pressure loss is less

CLASSIFICATION OF PIPES BASED ON
PRESSURE
1. Types of cast iron (spun) pipes as per IS
1536:1976
S.No
Category of pipes in the
order of increasing
thickness for the same
diameter
Test Pressure
in kN/m2
Working
Pressure in
kN/m2
1 Class LA 3500 1200
2 Class A 3500 1800
3 Class B 3500 2000

2. Test Pressures in Vertically Cast Iron Pipes as per
IS 1537 -1976
S.No Diameter
Test pressure kN/m2 using
socket and spigot joint
Class A Class B
1
Upto and including 300
mm 2000 2500
2
Over 300 mm and upto
and including 600 mm
2000 2500
3
Over 600 mm and upto
and including 1000mm
1500 2000
4
Over 1000mm and upto
1500mm
1000 1500

3. Ordinary R.C.C pipes as per 458 - 1988
Category
Dia
available
(mm)
Test
pressure in
kN/m2
Places where used
Class P1 80 – 1200 200
Used on gravity mains,
design pressure not
exceeding 2/3 of test
pressure
Class P2 80 – 600 400
Used on pumping mains,
the design pressure not
exceeding ½ of the test
pressure
Class P3 80 – 400 600 -do-

4. Steel cylinder R.C.C pipes as per IS 1916 -1989
Category
Test pressure in
kN/m2 Working pressure
Class 1 500
In general, working
pressure for pumping
mains is taken as 50%
of the test pressure;
and for gravity main
is taken as 2/3rd of
the test pressure.
Class 2 1000
Class 3 1500
Class 4 2000
Class 5 2500
Special class
Above 2500; to be
specified by
purchasers

JOINTS IN PIPES
• Categories of joints depending upon their capacity of
movement
– Rigid joints - No movement
• Flanged
– Requires perfect alignment
– Close fittings are frequently used
– Gaskets – compressed fiber board or natural or synthetic rubber
• Welded and turned
– Produce continuous line of pipes
• Bored joints
– Semi rigid joints
• Spigot and socket with caulked lead joint
– Flexible joints
• Comprises mechanical and rubber ring joints or tyton joints
• Allows some degree of deflection – able to stand vibration and
movement

Types of joints in cast iron pipes
• Socket and spigot joint
• Flanged joint
• Mechanical joint
• Flexible joint
• Expansion joint

Socket and Spigot Joint
• Also known as bell and
spigot joint.
• Enlarged end – bell or
socket
• Normal end – spigot
• Quantity of lead needed
per joint – 3.5 to 4 kg for
15cm dia pipe, to about 45
to 50 kg for 1.2m dia pipe.
• Somewhat flexible joint
• Allows the pipes to be laid
on flat curves without any
specials.

Flanged joint
• Rigid and strong
• Cannot used where
deflections or vibrations
are expected.
• Expensive and mostly
used for indoor works –
pumping stations, filter
plants.

Mechanical joint or dresser coupling
• Used to join the plain
ends of CI pipes
• Strong and rigid
• Can withstand
vibrations - useful for
pipes to be carried over
bridges or below
bridges in hangers.

Flexible joint
• Used where large scale
flexibilities are required.
– Ex: River with uneven
beds, on curves.
• Socket – spherical
• Spigot – plain end
having bead.

Expansion joint
• Provided at suitable
intervals in the pipeline –
to counteract the thermal
stresses produced
• Socket end is cast flanged
• Spigot end is plain
• On expansion, socket end
moves forward, the gap
(equal to L. α. T) just
closed.
• On contraction, the socket
end moves backward
creating gap.

Joints in Galvanized steel pipes
• Generally, steel pipes of different lengths are
connected by riveted or welded joints.
• Expansion joints are not required in steel
pipes which are buried under the ground,
because they are not subjected to large
temperature stresses
• Pipes which are exposed to atmosphere may
require expansion joints to minimise
temperature stresses.

Typical expansion joint for steel pipes

Joint in Hume steel pipes

Joint in Asbestos Cement pipes –
Simplex joint

Reference
• Environmental Engineering(Vol. I) – Water
supply Engineering – Santhosh Kumar Garg –
Khanna Publications

Pipe materials and types of joints [autosaved]

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