Public health and sanitation

1. MATERIALS OF
SEWER

2. Brick
• Used particularly for large diameter
sewers
• Advantage-
– Can be constructed to any
required shape and size
•Disadvantage-
– higher cost
– Slow work progress
– Larger space requirement
•Cement concrete or stone invert
•To prevent ground water infiltration:
– plaster
mortar
cement
– inside
alumina
outside surface with
using sulphate resistant
surface mortar + high
cement (IS 6452) or
polyurea coating.

3. Concrete
• Advantages
– Relative
required
provided
ease with which
strength may be
– Wide range of pipe sizes
– Rapid trench backfill
• Disadvantages
– crown corrosion by
sulphide gas
– mid depth water line corrosion
by sulphate
– outside deterioration by
sulphate from soil water

4. Precast concrete
• Commonly used for branch and main sewers
• Two types
– Non-pressure pipes
• used for gravity flow
(sewers running partially full)
• Plain (I.D. 80mm-450mm;
thickness:
25mm-35mm) (NP1)• Reinforced (I.D. 80mm-2600mm;
thickness: 25mm-215mm) (NP2, NP3 &
NP4)
– Pressure pipes (P1, P2 & P3)
• used for force mains, submerged
outfalls, inverted siphons and for gravity
sewers where absolute water-tight joints
are required.
• Reinforced (I.D. 80mm-1200mm;
thickness: 25mm-120mm)
• Length : 2-3m
• These pipes have plain ends or spigot and socket
ends.

5. Cast-in-situ Reinforced Concrete
• constructed where they
are more economical
• when non-standard
sections are required
• when a special shape is
required
• when the headroom
and working space are
limited.

6. Stoneware or Vitrified Clay
• normally available in lengths of 90 cm
• Skilled labour required for caulking
the joints with yarn soaked in cement
mortar and packing in the spigot and
socket joints
• Classes
– AA: 100% hydraulic testing of pipes
to be carried out in manufacturing
stage
– A: 5% of the pipes to be tested
by following IS 651
• Resistant to most acids and to
erosion due to grit and high velocities
• A minimum crushing strength of 1,600
kg/m is adopted for all sizes• Special
required
strength
bedding or concrete cradling
to improve field supportive

7. Asbestos Cement
• usually used in sizes ranging from 80 mm to 1000
mm in diameter
• Advantages
– Non corrosiveness to most natural soil
conditions,
–freedom from electrolytic corrosion,
–good flow characteristics,
–light weight,
–ease in cutting, drilling, threading and fitting with
specials,
–allowance of greater deflection up to 12 degrees with
mechanical joints,
–ease of handling,
–tight joints and
–quick laying and backfilling are to be considered
•Disadvantages
– subject to corrosion by acids, highly septic
sewage and by highly acidic or high sulphate soils
– Cannot stand high super imposed loads
and may be broken easily

8. Cast Iron
• Available in diameters from 80 mm to 1050 mm
and are covered with protective coatings
• supplied in 3.66 m and 5.5 m lengths
• A variety of joints are available including
socket,
spigot, and flanged joints.
• Classified as LA, A and B according to
their thickness. Class LA pipes have been taken as
the basis for evolving the series of pipes.
• Application: Cast iron pipes with a variety of
jointing methods are used for pressure
sewers, sewers above ground surface, submerged
outfalls, piping in sewage treatment
plants and occasionally on gravity sewers
where absolutely water-tight joints are
essential or where special considerations
require their use.
• Advantage: long laying lengths with tight
joints, ability when properly designed to
withstand relatively high internal pressure and
external loads and corrosion resistance in most
• Disadvantage:
– corrosion by acids or highly
septic sewage and acidic soils
– the amount of deflection
normallyallowed should not
exceed 2.5 degrees for lead
caulked joints.
•Inside coating shall be by
Cement mortar and outer
coating shall be coal tar

9. Steel• Pressure sewer mains, under water river
crossings,
connections
supporting
bridge
for
spans,
crossings, necessary
pumping
railway
stations,
crossing
self-
and
penstocks are some of the situations where
steel pipes are preferred
•Advantages
– withstand internal pressure, impact
load and vibrations much better than CI
pipe.
– more ductile and withstand water hammer
better.
•Disadvantage
– cannot withstand high external load
– main is likely to
collapse when it is subjected
to negative pressure
– susceptible to various types of corrosion
•Inside coating by high alumina cement
mortar or polyurea and outside by epoxy.
•Steel pipes shall conform to IS 3589.

10. Ductile Iron Pipes• made by a metallurgical process, which
involves the addition of magnesium into molten
iron of low sulphur content.
• The ductile iron pipes are usually provided
with cement mortar lining at the factory by
centrifugal process to ensure a uniform thickness
throughout its length
• available in the range of 80 mm to 1000 mm
diameter, in lengths of 5.5 to 6 m
• Advantages
– excellent properties of machinability,
– impact resistance,
– high wear and tear resistance,
– high tensile strength and ductility and
– corrosion resistance.
– strong, both inner and outer
surfaces are smooth,
– These pipes are approximately 30 %
lighter than conventional cast iron pipes

11. Non-Metallic Non-Concrete
Synthetic Material Pipes

12. UPVC Pipe (unplasticized
polyvinylchloride )
• Advantages
– resistance to corrosion,
– light weight for transportation,
– toughness, rigidity,
– economical in laying, jointing, and
maintenance and
– easy to fabricate
• IS 15328 deals with non-
pressure
unplasticized polyvinylchloride (PVC)for use
system.
in underground
sewerage IS 9271
deals with theunplasticized polyvinyl
chloride (UPVC) single wall
corrugated pipes for drainage.

13. High Density Polyethylene (HDPE)
Pipes
• Advantages
– Offer smooth interior
surfaces and
– relatively higher resistance to
corrosion
– they are available in solid wall
– When laid in straight
gradients without humps or
depressions, they can easily
offer longer life cycle
• joints
welded
are usually
or flange
fusion
jointed
depending on straight runs
or fittings

14. Structured Wall Piping
• These pipes can be manufactured
in PVC-U, PP and PE as per
EN 13476-3 / IS 16098
• These pipes are either
double walled or ribbed walled
• The Type B pipes are generally
known as Double Walled
Corrugated (DWC) pipes.
• In India, DWC pipes are produced
in sizes 75 mm ID to 1,000 mm ID
with a standard length of 6 m for
easy transportation and handling
and to reduce the number
of joints required.

15. Glass Fibre Reinforced Plastic Pipes
(GRP)
countrie
s
resistan
t
• widely
where
pipes
used in
corrosion
are required at
reasonable costs
•GRP can be used as a
lining material for
conventional pipes which
are subject to corrosion.
•Fibre glass can resist
externaland internal corrosion
the corrosion
is
whether
mechanism galvanic or
chemical in nature.

16. Fibre Glass Reinforced Plastic Pipes (FRP)
• FRP is a matrix or composite of
glass fibre, polyester resin
and filters.
• These pipes possess better
strength, durability, high
tensile strength, low density
and are highly corrosion
resistant.
• Fibre-glass pressure pipes are
manufactured in diameters up
to 2,400 mm and length up
to 18 m.

17. Pitch Fibre Pipes
• These are pitch impregnated fibre pipes
• Advantages
– light in weight
– Durable
– pipes can be easily jointed in any weather
condition as internally tapered couplings join the
pipes without the use of jointing compound
–flexible,
–resistant to heat, freezing and thawing and
earth currents, which cause electrolytic action.
–unaffected by acids and other chemicals,
water softeners, sewer gases, oils and greases
and laundry detergents.
–can be cut to required length on the site
• Application
– septic tanks and house connection to sewers,
farm drainage, down pipes, storm drains,
industrial waste drainage
• Available sizes: 50 to 225 mm nominal diameter and
length varying from 1.5 to 3.5 m
• Disadvantage
– susceptible to the
delamination of their inner
surface (blistering)
– susceptible to collapse under
applied loading sooner
than other pipes

18. Sewer material and corresponding standard specification
Material Standard specification
Code
Brick (Inside plaster with mortar using high alumina IS 6452 cement )
Concrete
Pre-cast concrete (Non-Pressure pipes) IS 458
Cast in-situ reinforced concrete (Concrete ) IS 456
Stoneware or vitrified clay (hydraulic testing) IS 651
Asbestos cement IS 6908
Cast Iron IS 1536 (spun pipe) and IS 1537 (vertically cast pipe)
Steel IS 3589
DI pipes IS 8329 (centrifugally cast DI pipes);
manufactured with ISO 9002 accreditation ; IS 9523
(DI fittings);UPVC IS 15328 ( Non-pressurized); IS 9271 (single
walled corrugated pipe for drainage)
HDPE IS 14333
Structured wall pipe EN 13476-3 / IS 16098
GRP IS 14402
FRP -

19. Crown corrosion
With gradual deposition of organic and inorganic
matter at the bottom of the sewer, the flow of
sewage in lower layers become stale leading to
anaerobic conditions favourable for Sulphate
Reducing Bacteria which converts sulphate to H2S as
shown. Thiobacillus thioxidans convert H2S to
H2SO4. The suphuric acid deposited at the crown of
sewer reacts with concrete and forms CaSO4. Which
falls down as droplets making the crown of
sewer uneven and thinner. This phenomenon is
known as crown corrosion.