Ductile Iron Pipes
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Ductile Iron is an improved variety of Cast Iron invented in 1949. It is also known as Spheroidal Graphite Iron or Nodular Cast Iron. Centrifugally cast Ductile Iron pipes are one of the most preferred materials for water supply and sewerage applications across the world due to its host of advantages. Pipes made from Ductile Cast Iron provide substantial benefits in terms of pressure bearing ability, impact resistance and capacity to sustain external static/ dynamic loading.
Ductile Iron is an alloy of Iron, Carbon and Silicon. If we observe the micro structure of grey caste iron, we will notice that graphite present in it is in the form of flakes. In the year 1948, the flakes structure of graphite was modified by adding magnesium to the molten metal. The resultant product of iron is now typically known as Ductile Iron.
Ductile Iron Pipes have higher tensile strength, yield strength, ductility and impact resistance which are the reasons why the use of Ductile Iron Pipes has grown up at a rapid rate over the last 50 years or so.
Ductile Iron Pipes .
Ductile Iron (DI) Pipes has become the most preferred pipe material for water supply and pressure sewerage applications around the world. Although ductile iron has a chemical composition which is very similar to cast iron, it is considered superior due to its spheroidal micro-structure which has vast advantages such as higher pressure bearing ability, impact resistance, corrosion resistance etc. listed below:
High Tensile Strength
Corrosion Resistant
Flexible and Leak Resistant
Durable Cement Mortar Lining
Excellent Workability
Ductile Iron Pipes
Mechanical Properties
| Mechanical Properties | Values |
|---|---|
| Tensile Strength | Min. 4,200 Kg/cm2 or 420 MPA |
| Yield Strength | 3,000 Kg/cm2 or 300 MPA |
| Minimum Elongation | 10% (upto DN 1000 mm) |
| Modulus of Elasticity | 1.62 x 106 – 1.70 x 106 Kg/cm2 or 162,000 – 170,000 MPA |
| Hardness | Max. 230 BHN |
| Density | 7,050 Kg per cubic meter |
| Coefficient of Thermal Expansion | 11.5 x 10-6 per degree celcious ( 0C ) (for temperature range 200C – 1000C) |
| Impact Strength | At Normal Temperature – 7 ft-lb (minimium) & At Low temperature – 3 ft-lb (minimum ) |
Ductile Iron Pipes
Angular Deflection
| Diameter Range (DN) | Angular Deflection |
|---|---|
| Dn 80 – DN 150 | 5° |
| Dn 200 – DN 300 | 5° |
| Dn 300 – DN 600 | 3° |
| Dn 700 – DN 800 | 2° |
| Dn 900 – DN 1000 | 1.5° |
| Dn 1100 – DN 1200 | 1° |
Ductile Iron Pipes
Key Advantages
Tremendous Tensile Strength
Pressure bearing ability
Withstands Severe Crushing Loads
Great beam Strength
Corrosion resistant
High Impact Resistance
High Bursting Strength
Sustains external static/dynamic loading
Easy to Install
Minimal installation cost
Zero Maintenance
No Cathodic Protection
Low pumping cost
Excellent hydraulic features
Extensive range of pipes, fittings and accessories
Ductile Iron Pipes
Applications
- Raw and clear water transmission (pumping and gravity main).
- Distribution network of portable water.
- Irrigation (lift & gravity irrigation).
- Water supply for industrial / process plant application.
- Ash-Slurry Handling & Disposal system
- Fire-fighting systems-on-shore and off-shore
- Desalination Plants
- Sewerage and waste water force main
- Gravity sewerage collection and disposal system.
- Storm water drainage piping
- Effluent disposal system for domestic and industrial application
- Recycling system
- Piping work inside water and sewage treatment plants
- Vertical connection to utilities and reservoirs
- Piling for ground stabilization
- Vertical connection to utilities and reservoirs
Ductile Iron Pipes
Pre Manufacturing Process
Ductile Iron Pipes
Pipe Dimensions
External Protection System
A metallic Zinc layer is applied by thermal metallization process on the DI pipe surface. The metallic Zinc coating is covered by a finishing layer of a bituminous paint or synthetic resin compatible with zinc. The International Standard ISO: 8179-1 establishes the main features of Zinc coating as well as suitable methods for checking them.
Two options of Zinc coating are available, depending on soil aggressiveness
Standard 130 gm/m2 and finishing layer of 70 microns
200 gm/m2 and finishing layer of 70 microns or 100 microns
Internal Protection System
Cement Mortar Lining
Normally, all pipes are supplied with centrifugally applied internal Cement Mortar Lining.
Centrifugally applied CML Provides higher Hazen William C Value of 140 minimum
Reduce frictional head loss and pumping cost
CML Passivates the pipe wall against corrosion by the alkaline reaction of cement
It prevents pitting and tuberculation of pipes and stops the production of red water
Helps to maintain same flow are and co-efficient of friction over a long period of time
Key Advantages
Procedure
Step 1
Clean the socket grooves and outside spigot end.
Step 2
Hold the gasket as shown and place inside the socket.
Step 3
Apply lubricant on the gasket. Do not use petroleum-based lubricant.
Step 4
Apply lubricant on the spigot also. Please check that the spigot end is properly chamfered.
Step 5
Properly align both the pipes
Step 6
Gently push the spigot into the socket with suitable mechanical means.
Rubber Gasket
The absence of sunlight end oxygen, presence of moisture/water, relatively lower and uniform surrounding temperature in buries conditions help in preservation of rubber gaskets/ Thus this type of joint is expected to lose for more than 100 years.
Good quality Synthetic rubber gaskets made either of SBR (Styrene Butadiene Rubber) or EPDM (Ethylene Propylene Dimethyl Monomer) conforming to IS:5382 are used with Ductile Iron push-on joint pipes.
Gasket should be stored in a cool & dry place. Direct exposure to sunlight should be avoided
It is advised that the users should obtain gaskets through Electro steel only.
Jointing Tips
The sockets face uphill while pipelines is laid on a slope
The direction of flow nothing to do with direction of the socket
Never use petroleum-based lubricant during jointing. It damages the gasket. Liquid soap solution or organic grease many be used.
All Fittings should be suitably anchored against displacement as recommended in the laying specification
Spigots should be inserted into the socket up to the white insertion mark to ensure proper jointing.
The joint deflection should not be more than the recommended deflection
