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DUCTILE IRON SPUN PIPE. – Brief Presentation –. Technical Presentation. Electrosteel Castings Limited. 4, B. B. D. Bag (East), Calcutta – 700 001. PIPE MATERIAL – BASIS OF SELECTION. Desired properties: Structurally strong Fast and easy laying No / Minimum Maintenance

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DUCTILE IRON SPUN PIPE

– Brief Presentation –

Technical Presentation

Electrosteel Castings Limited

4, B. B. D. Bag (East), Calcutta – 700 001


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PIPE MATERIAL – BASIS OF SELECTION

Desired properties:

  • Structurally strong

  • Fast and easy laying

  • No / Minimum Maintenance

  • Bottle-tight and Flexible Jointing System

  • Ability to resist “Corrosion”

  • Tamper-proof

THE ANSWER IS CENTIFUGALLY CAST INSIDE CEMENT MORTAR LINED DUCTILE IRON PIPE

ELECTROSTEEL CASTINGS LIMITED


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WHAT IS DUCTILE IRON (DI)?

Cast Iron

Corrosion Resistant but Brittle

Mild Steel

Strong but Corrosion Prone

Ductile Iron

Corrosion Resistant + Strong

ELECTROSTEEL CASTINGS LIMITED


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WHAT IS DUCTILE IRON?

In 1949, a process was invented by which flaky graphite in cast iron could be changed to nodular graphite by adding little magnesium in molten iron. The nodular graphite helps to maintain the continuity of iron matrix providing excellent properties of flexibility, ductility and impact resistance.

Grey Iron

Ductile Iron

ELECTROSTEEL CASTINGS LIMITED


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DUCTILE IRON PIPE – ADVANTAGES

Better physical and mechanical properties compared to other pipe materials:

  • High tensile and beam strength

  • Withstands severe crushing load

  • Extremely high impact resistance

    More water carrying capacity, as internal diameter is greater than nominal diameter.

    Highly corrosion resistant due to smooth inside cement mortar lining, thus offering a higher C value (HWC = 140), corresponding Darcy’s Friction Factor (f = 0.012).

    The ISO, BS, DIN and IS specifications are identical.

ELECTROSTEEL CASTINGS LIMITED


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DUCTILE IRON PIPE – ADVANTAGES

Offers high working pressure and safety against water hammer - Every DI pipe is hydrostatically tested to a minimum of 40 kg./cm2 before application of lining and coating.

  • Speedy Laying / Installation procedure.

    Ease in handling – Light weight and superior mechanical property makes DI pipe easier to handle.

    Welding is possible.

    Offers impressive energy savings, due to less frictional losses.

    Offers a virtually maintenance free pipeline.

ELECTROSTEEL CASTINGS LIMITED


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MACHINABILITY – DI PIPE

Cutting

Tapping

Welding

ELECTROSTEEL CASTINGS LIMITED


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COMPARISON OF DI, CI & MS PIPES

Mechanical Properties

ELECTROSTEEL CASTINGS LIMITED


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Type Test

What Is Type Test?

Type Test is testing the pipe and pipe joint at extreme working conditions (the product and use) to ensure satisfactory performance. The recommended Type Tests as per BS EN 545/598, ISO: 2531 are:

  • Leak Tightness of Joints to Positive and Negative Internal Pressure

  • Leak Tightness of Joints to Positive External Pressure

  • Test for Abrasion Resistance

  • Test for Chemical Resistance to Effluents

ELECTROSTEEL CASTINGS LIMITED


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Type Test

Leak Tightness Of Joints To Positive

And Negative Internal Pressure

Spigot end is machined to minimum.

Socket opening is machined to maximum.

Joint assembled with gasket and a shear load is applied on the spigot end.

Joint is tested at a higher pressure than the works test pressure with and without joint deflection.

ELECTROSTEEL CASTINGS LIMITED


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Type Test Initiatives At ECL

Leak Tightness Of Joints To Positive

And Negative Internal Pressure

Without Joint Deflection

With Joint Deflection

ELECTROSTEEL CASTINGS LIMITED


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Type Test Initiatives At ECL

Type Test Results

I=Leak tightness of joints to positive internal pressure (without deflection)

I (4.50)=Leak tightness of joints to positive internal pressure (with deflection)

II=Leak tightness of joints to positive and negative external pressure

ELECTROSTEEL CASTINGS LIMITED


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Type Test

Leak Tightness Of Joints To

Positive External Pressure

The test assembly shall comprise of 2 joints made with 2 pipe sockets welded together.

 It creates an annular chamber which allows testing of one joint under internal pressure and one joint under external pressure.

 The assembly is tested at a pressure of 2 bar for 2 hours to ensure that contaminated water cannot enter through joint even when there is no inside pressure.

ELECTROSTEEL CASTINGS LIMITED


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Type Test

Test For Abrasion Resistance

This test is meant for DI Pipe with High Alumina Cement Lining specially meant for sewerage applications.

1 m. long pipe sample, closed at both ends is filled with gravel.

The gravels are allowed to slide over the cement surface for 1 lakh cycles and resulting abrasion is observed. It has been observed that High Alumina Cement Mortar Lining has better abrasion quality than bare metal.

ELECTROSTEEL CASTINGS LIMITED


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Type Test Initiatives At ECL

Test For Abrasion Resistance

ELECTROSTEEL CASTINGS LIMITED


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Type Test

Test For Chemical Resistance To Effluents

This test is meant for DI Pipe with High Alumina Cement Lining specially meant for sewerage applications.

Pipe sample is filled up to mid height with Sulphuric Acid solution at pH 3.

Another Pipe sample is filled up to mid height with Sodium Hydroxide at pH 13.

The samples are observed for 6 months.

ELECTROSTEEL CASTINGS LIMITED


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HOW CORROSION AFFECTS PIPES

Unlined Cast Iron Pipe

Installed in Calcutta 25 – 30 years back

Condition monitored In November, 2000

ELECTROSTEEL CASTINGS LIMITED


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COMPARATIVE CORROSION OF METALLIC PIPES

Critical Elements In Iron & Steel Pipe

(All Figures Shown Above Indicates %age Weight)

The volume impurities :

CI/DI : 17.0 – 18.5%

MS : 1.1%.

15.5 times more surface area in CI / DI is occupied by non-ferrous species compared to MS.

Hence less surface area open to CI / DI for corrosion.

ELECTROSTEEL CASTINGS LIMITED


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ACCELERATED CORROSION TEST

Results Of Dipping Test With Sea Water

Increasing rate of corrosion with time

Decreasing rate of corrosion with time

Volume Of Corrosion

(mg./dm2/day)

ELECTROSTEEL CASTINGS LIMITED


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MS Pipe – Mandatory Wrapping & Coating

Excerpts From IS : 10221 – 1982

Code Of Practice For Coating And Wrapping Of Underground Mild Steel Pipes

ELECTROSTEEL CASTINGS LIMITED


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DI PIPE – CORROSION PROTECTION

Internal Corrosion Resistance

In order to enhance internal corrosion protection, all Ductile Iron Pipes come with Internal Cement Mortar Lining.

External Corrosion Resistance

 All pipes come with a layer of metallic zinc and a finishing layer of bituminous paint. The following additional external corrosion systems are also available

External polyethylene sleeving

Epoxy paint coating

The type of protection depends on soil condition

ELECTROSTEEL CASTINGS LIMITED


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BITUMEN LAYER

ZINC COATING

IRON OXIDE LAYER

DUCTILE IRON

CEMENT MORTAR LINING

DI PIPE – CORROSION PROTECTION

Corrosion Protection Systems

ELECTROSTEEL CASTINGS LIMITED


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ZINC COATING - EXTRA CARE

How Zinc Coating Helps to Prevent Surface Corrosion

# When pipe is buried,the zinc coating transforms into a dense,impermeable layer of Zinc Oxide and salts.

##The metal exposed becomes cathodic to the rest of the zinc coated surface area which acts as an anode

ELECTROSTEEL CASTINGS LIMITED


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DUCTILE IRON PIPES – BURSTING STRENGTH

P1 = Bursting Strength based on Net Wall Thickness (Bar)

P2 = Bursting Strength based on Minimum Wall Thickness (Bar)

BP – Bursting Pressure

MOP – Maximum Operating Pressure

AOP – Allowable Maximum Operating Pressure

ELECTROSTEEL CASTINGS LIMITED


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ADVANTAGES OF CML

  • CML provides higher Hazen William’s C value. DI CML has a C value of 140 in comparison to 100 for bare metallic pipes.

  • Due to higher C value pumping costs get reduced.

  • CML permanently increases carrying capacity.

  • CML passivates the pipe wall by the alkaline reaction of cement.

  • CML prevents pitting and tuberculation of metallic pipes and there by stops the production of red water.

  • The prevention of internal corrosion by CML helps to maintain same flow area and flow friction co- efficient over a long period of time.

  • Prevents abrasion of pipe wall and thus increases life of pipe.

ELECTROSTEEL CASTINGS LIMITED


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BONDING STRENGTH OF CML

  • No CML failure has ever been recorded in negative surge.

  • Longitudinal bending tests demonstrates the ability of the cement mortar lining to follow wall deflection as long as the metal remains in the elastic range.

  • The maximum allowed service deflection is 3% of initial diameter. In ‘Ring Bending Test’, it has been observed that disbonding do not occur until deflection reaches 7- 12% of the initial diameter.

ELECTROSTEEL CASTINGS LIMITED


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AUTO – HEALING OF CRACKS

  • Cracks / fissures in CML are common. Cracks up to 0.8 mm. width is allowed in all the standards (IS, EN or ISO).

  • Tests had shown that lining cracks/fissures, will heal when line is charged. Details of these test is documented by ISO in their Document No. ISO/TC 5/SC 2 N 382E.

  • When a cement lined pipe is filled with water, some water is absorbed by the pores and voids in the mortar, as also by the capillary channels of the Calcium Silicate gel.

  • As a result the lining swells practically to its initial volume. and the cracks in the lining are closed.

ELECTROSTEEL CASTINGS LIMITED


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DUCTILE IRON (DI) PIPE

Cement Mortar Lining

Recommended Types Of Cement

ELECTROSTEEL CASTINGS LIMITED


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JOINT SAFETY OF DI PIPES IN UNSTABLE SOIL

How DI Pipes offer more safety to design ?

Sudden Soil Movement in unstable ground.

General ground contour followed by pipe line

  • Ductile Iron Pipes with flexible joints are capable of angular deflection, allowing the pipeline to follow ground contour

  • A Japanese study in 1979 following the Miyagi – ken – Oki earthquake showed a 0.04 damage rate / km for DI pipes compared to four times that of grey iron and more than 30 times that of other materials.

ELECTROSTEEL CASTINGS LIMITED


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Electrosteel Castings Ltd.


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