High Density Polyethylene (HDPE) piping is a versatile product suited for multiple applications in communications, oil and gas, power utility, municipal and water industries. The most common benefits cited for selection of HDPE over other piping solutions include its light weight, low cost, resistance to corrosion, strength, flexibility, reliability and recyclability. However, another unique benefit is HDPE piping’s specifications and temperature limits in extreme low temperatures.
HDPE pipe is a safe and long-lasting choice for projects in the water infrastructure market. It is durable, corrosion-resistant and will not leach harmful chemicals into drinking water. Once HDPE pipe is installed, there is no maintenance required, removing the costly burden for municipalities, corporation bodies and water authorities. Like ductile iron, HDPE can be recycled at the end of its long service life.
HDPE popularity and usage continues to increase. Plastic, particularly HDPE, is part of our everyday lives, from household products to industrial applications. Since its creation almost 70 years ago, HDPE piping and conduit has become a preferred material in the power, communications, and energy industries. HDPE conduit is a flexible and versatile product well-suited for numerous industrial settings. Specific applications include conduit for telecommunications and fibreoptic lines; flowlines for oil and gas; gas transmission and cross-country pipelines; and municipal water and sewer lines.
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HDPE Pipes (High Density Polyethylene)
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DI (Ductile Iron)
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Maintenance
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HDPE pipes are corrosion-resistant and don't require maintenance. Very low maintenance if any.
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DI Pipes can corrode and leak. It require extra lining and special coatings to prevent the iron pipes from corroding or rusting, like Zinc Coating or Cement mortar or polyurethane are used for internal linings, and loose polyethylene sleeving (LPS) is used as an external lining to protect the pipe from corrosive soil
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Production
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HDPE pipes are made at lower temperature and require less energy to produce.
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The manufacture of Ductile Pipes require a large amount of energy and emits greenhouse gases such as carbon dioxide and methane.
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Flow Velocity
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Can handle higher flow velocities up to twice its pressure class. Acts as a shock absorber with low elastic modulus, allows less surge pressure.
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Low Flow For eg.,a two foot per second velocity change in a DI Pipe can cause 100 psi of surge pressure, while the same change in a HDPE Pipes cause only 22 psi. |
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Surge Pressure
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HDPE pressure pipe will produce very low surge pressure. Surge pressure is about 20% of Metal Pipe. No Surge Pressure Protection device is required. HDPE pipe can withstand pressure up to 2.3 times Rated Pressure.
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Surge pressure is 5 times that of HDPE pipe surge pressure. Need surge protection devices. Surge Pressure protection device Concrete-Thrust blocks. Is required DI pipe can withstand only up to 1 .5 times Rated Pressure.
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Chemical Resistance
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HDPE pipes has superb chemical resistance and is the material of choice in harsh chemical environment. Pipe is safe over pH Value 1 to 14.
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There is no safe PH range i.e., no resistance. These pipes are Corroded by even small quantity of any chemical. Resistance to Internal Corosion and “C” value depends on quality of CM and Epoxy Lining Cement Mortar Lining may fail due to following reason (Negative Surge Pressure, Disbonding, Deflection of Pipes, Cracks and Difference in temperature) Sockets do not have protection by Cement Mortar Lining. Socket is not protected (by CMC). Hence Corrosion may start at the socket and result in improper seat for rubber ring i.e. Leakage, Contamination of Water, Pitting in Pipe etc.
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Bending of Pipes
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HDPE pipes have excellent joints because of which the pipe can bend with radius of 25 times the diameter. The Flexibility & Strong joints make HDPE Pipe well suited for dynamic soils including areas prone to Earthquake.
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Only 1 to 2 degree deflection is possible which is almost negligible and hence bends are required at each change direction. May have major Leakage problems after Soil Movement or Earthquakes.
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Special Alkyds coatings for corrosion protection on DI Pipes.
In extremely cold weather, the water in DI pipelines can freeze, cutting off supply to homes and businesses. This inconvenient problem can be remedied in through the process of electrical thawing.
HDPE piping’s flexibility and elasticity allow water inside the pipe to freeze and thaw repeatedly without causing permanent damage.
PE pipes with less than 200 mm dia can be supplied in 100 meter coils. Compared to 16 joints of 6 meter DI Pipes, only 1 joint is required for HDPE.
This is big savings in terms of cost and installation time and in reducing chance of leakage.
Despite claims by the Ductile Iron pipe manufacturers that DI does not suffer from corrosion as Cast Iron does, recent research by independent bodies such as the Institute for Research in Construction, Canada shows that DI pipes suffer the same incidence of corrosion failure as CI pipes.
Because of its thinner wall compared to CI, Dl may not survive as long as CI Pipes would in the same soil. There is need for protective coating, cathodic protection and addition of corrosion inhibitors in water. Experience with DI pipes in India shows a widely variable performance with pipes failing within two years, on the other hand some Cast Iron pipes have lasted 50 years or more.
Being a thermoplastic material and a non-conductor of electricity, HDPE pipes do not suffer from electrolytic attack.
World wide experience is that HDPE pipes have performed well over the last fifty years in Water and Gas and are fast becoming the pipes of choice for water distribution.
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Size of pipe
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Weight of DI/CI per 6 m pipe
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Weight pf PE-100 per 6 m pipe
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% saving
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500 mm 10 kg/cm2
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669 kgs
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254 kgs
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62
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PE pipes with less than 200 mm dia can be supplied in 100 meter coils. Compared to 16 joints of 6 meter DI Pipes, only 1 joint is required for HDPE.
This is big savings in cost and installation time and in reducing chance of leakage.
Iron pipes are prone to inner diameter scale formation, even when protected by an inner lining of sulphate resistant cement (Type V Portland cement), simply because of the polar nature of the inner wall makes it hydrophilic and attracts polar CaCO3 (scale) to deposit on the walls. Being a thermoplastic material and a non-conductor of electricity, HDPE pipes do not suffer from electrolytic attack.
HDPE is a hydrophobic substance (water forms beads on it). It is completely non-polar hence does not need Cathodic Protection. Maintains optimum flow rates. Does not tuberculate, has a high resistance to scale or biological build-up.
Within the 100mm to 500mm OD range, DI pipes are uniformly more expensive than HDPE pipes.
Being heavier, DI pipes are more expensive to transport and install. Being rigid pipes, requirements of specials is higher for curved trenches. Almost two times excavation and back filling is needed as jointing is necessarily done inside the trench. Jointing is needed every 6 m or in some cases 3 m.
HDPE pipes are half the price of DI pipes in the lower diameter range. The prices are closer in the larger (> 500mm) diameter ranges. Fewer requirements of specials due to flexibility. Pipes can be supplied in Coils of 50 – 100 m for small dia, and 12 m for large dia, reducing jointing and installation cost. Lighter pipes are easy to handle, hence jointing is performed outside the trench and the pipe then lowered, makes for less expensive installation.
Manufacture of DI pipes is very energy intensive and consumes about 8 times the amount of energy needed to make HDPE pipes on a meter to meter basis.
Manufacture of HDPE pipes is far less energy intensive and results in “Carbon Credit” for the country in terms of lower green house gas releases.
Study by SADE, France showed PE to be 77% lower in environmental impact than iron in production and was 74% lower equivalent carbon emissions in transportation.
DI pipes use push on jointing. The ‘V’ grooves of the joint while self sealing under internal pressure, tend to collapse and allow external water to enter the pipe once the water pressure outside the pipe is higher than the internal pressure. This happens in areas where the water table is high as in coastal areas.
HDPE pipes are joined by Butt fusion or Electrofusion welding which results in a joint stronger than the pipe. The joint is monolithic, and considered safe for gas distribution. There is no chance for water to infilterate or leak from such a system.
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Material
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Mains
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Branches
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Services
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Total
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Steel
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00
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4607
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6151
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10758
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Cast Iorn
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583
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00
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33
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616
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PE
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00
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00
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00
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00
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HDPE Pipes clearly outperform Ductile Iron (DI) Pipes across key parameters, including durability, corrosion resistance, flexibility, and ease of installation. Their ability to withstand extreme temperatures, chemical exposure, soil movement, and surge pressure makes them ideal for modern water infrastructure systems. Unlike DI Pipes, HDPE requires no thrust blocks, leak-proof fusion joints, and is resistant to internal scaling and biological growth-ensuring minimal maintenance and long-term reliability.
Moreover, HDPE pipes offer significant cost and environmental advantages. They are lightweight, energy-efficient to manufacture, and help reduce transportation and installation costs. In seismic zones or expansive soils, HDPE pipes maintain their integrity where DI pipes often fail. With growing global adoption in urban utilities and infrastructure, Sudarshan HDPE pipes have proven to be a smarter, more sustainable alternative, making them the superior choice for water distribution networks.
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