Ductile iron pipe

Short Description:

  • Keywords: Ductile iron pipe,DI pipe,Ductile cast iron pipe,Ductile iron pipe,cast iron pipe
  • Standard: ISO2531/ISO9001/EN545/EN598
  • Pipe class: K7, K8,K9,C40, C30, C25, C20,etc.
  • Range: DN80-2600mm
  • Tensile Strength: Minimun 420 MPa
  • Pressure: PN10/PN16/PN25/PN40
  • Joint type: T type/K type/Self-restrained type
  • Surface Finish: Bituminous Paint Coated
  • Material: Ductile Iron
  • Coating: Black bitumen liner / epoxy resin over coat layer.
  • Zinc coating: Outside sprayed with zinc coating (as per ISO8179, not less than 130 g/m2)
  • Packing: bundled and nude packing
  • Description






    Ductile cast iron is kind of alloy of iron, carbon and silicon, in which graphite exists in the type of spherical, generally the size of graphite is 6-7 class, and spheriodization grade of the pipe should be controlled 1-3 class(spheroidization rate is not below 80%). Thus after spheroidization, ductile cast iron possesses the nature of iron as well as the characteristic of steel. After annealing, its microstructure contains ferrite and a little pearlite possessing excellent mechanical properties.

    Much of the production of ductile iron is in the form of ductile cast iron pipe, used for water and sewer lines. Ductile cast iron pipe is stronger and easier to tap, requires less support and provides greater flow area compared with pipes made from other materials like PVC, concrete, polyethylene or steel. Ductile Iron Pipe is the most widely-used pipeline product in water supply and water drain/sewage projects.

    di pipe

    The standard of pipe: SO 2531, EN545 , EN598. Pipe class: K9, C40, C30, C25, etc.
    Pipe joint: push-on joint(Tyton joint), K type joint, self-restrained joint Effective length: in general, the pipe length is 6m for bulk shipment and 5.7m for container shipment.
    Internal lining: cement mortar lining as per ISO4179 Zinc coating: at least 130g/m2 as per ISO 8179
    Bitumen painting: at least 70um as per ISO 8179 Chemical composition (%) a) C: 3.5 – 4.0b) Si: 1.9 – 2.6c) Mn:0.15 – 0.45c) P: <0.06d) S: <0.02
    Mechanical properties: Tensile strength: ≥420MPab)Yield strength: ≥300Mpac) Hardness: ≤230HBd) Elongation%: DN80 – 1000 ≥10  DN1200 – 2200 ≥7 Process and testing: a) Induction furnace and treated metal (Chemical analysis of raw material, spheroidizing & Nodularity)b) Casting (Visual check and weight check)c) Heat treatment (Micro structure)d) Hydrostatic test (Pressure test)e) Dimensional checks (Checking pipe length and joint, OD, wall thickness, appearance)f) Zinc spraying (Thickness testing)

    g) Lining and coating (100% visual check, thickness testing randomly)

    i) Marking and packing (100% visual check)

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  • specification

    For Potable Water

    • ISO2531-2009:Ductile iron pipes,fittings,accessories and their joints for water applications.
    • EN545-2010: Ductile iron pipes,fittings,accessories and their joints for water pipelines requirements and test method.
    • ISO4179-2005:Ductile iron pipes and fittings for pressure and non-pressure pipelines — Cement mortar lining.
    • ISO8179-2004:Ductile iron pipes — External zinc-based coating — Part 1:Metallic zinc with finishing layer.
    • BS 3416:1991:Specification for bitumen-based coatings for cold application,suitable for use in contact with potable water.
    • ISO4633-2002:Rubber seals — Joint rings for water supply,drainage and sewerage pipelines–Specification for materials.
    • ISO8180-2006:Ductile iron pipelines–Polyethylene sleeving for site application.
    • EN681-1 :Elastomeric seals. Material requirements for pipe joint seals used in water and drainage applications Vulcanized rubber.

    For sewage application

    • EN598-2007:Ductile iron pipes, fittings, accessories and their joints for sewerage applications. Requirements and test methods.
    • ISO4633-2002:Rubber seals — Joint rings for water supply, drainage and sewerage pipelines — Specification for materials.
    • EN681-1:Elastomeric seals. Material requirements for pipe joint seals used in water and drainage applications Vulcanized rubber.

    Chemical composition

    Chemical composition

    Ductile Cast Iron Pipe (%)

    Grey iron pipe (%)

    Steel pipe (%)
























    Mechanical Properties

    Nominal Diameter mm

    Tensile Strength N/m2

    Yield Strength N/m2


    Hardness HB

    Water Pressure Test MPa


























    Corrosion Resistance

    90-day Water corrosion(G/cm2)

    Corrosion in sea water(G/cm2)

    72 hours 5% Hydrochloric acid solution(G/cm2)

    Ductile iron pipe




    Ordinary gray iron pipe








    Ductile Cast iron pipe coatings

    The pipe coating can be customized, such as, zinc-aluminum alloy, PU, etc.

    Internal Lining

    External Coating

    Internal Lining Pipes and Fittings External Coating Pipes and Fittings
    Standard Coating Portland cement or Blast furnace cement mortar Standard Coating Metallic zinc + Bituminous paint
    Reinforced Protections High alumina cement mortar Reinforced Protections Polyethylene sleeve applied
    Special Coatings Please consult us Special Coatings Polyurethane or polyethylene coating or Ceramic

    Anti-Corrosion Types:

    (1) Asphalt paint coating

    The asphalt paint coating is used for conveying gas pipes.

    Preheating the pipe before painting can improve the adhesion of asphalt paint and speed up drying.

    (2)Cement mortar lining + special coating

    This internal anti-corrosion measure is applicable to the pipeline conveying sewage and can improve the corrosion resistance of the inner lining.

    (3)Epoxy coal pitch coating

    Epoxy coal tar tar coating is suitable for both gas pipeline and sewage pipeline.

    It is a two-component coating with high adhesion and a very smooth surface.

    (4)Epoxy ceramic lining

    Epoxy ceramic lining is suitable for sewage pipeline and gas pipeline, but because of the manufacturing process is difficult and the cost is high, so there are some limitations in the use.

    Epoxy ceramic lining is an excellent anti-corrosive coating with high adhesion and finish.

    (5)Aluminate cement coating or sulfate cement coating

    These two kinds of special cement coating are applicable to the anti-corrosion of the ductile cast iron pipe of sewage pipe and improve the ability of resisting the acid and alkali components in sewage.

    (6)Polyurethane coating

    It is a new kind of green special coating developed to meet the needs of environmental protection. It has good wear resistance and corrosion resistance.


    packing of ductile cast iron pipe