ISO 25312009 Ductile iron pipes, fittings, accessories and their joints for water applications

Ductile iron pipes, fittings, accessories and their joints for water applications 1 Scope This International Standard specifies the requirements and test methods applicable to ductile iron pipes, fittings, accessories and their joints for the construction of pipelines: ⎯ to convey water (e.g. for human consumption and raw water), ⎯ operated with or without pressure, and ⎯ installed below or above ground. NOTE In this International Standard, all pressures are relative pressures expressed in bar 1). This International Standard specifies materials, dimensions and tolerances, mechanical properties and standard coatings of pipes, fittings and accessories. It also gives performance requirements for all components including joints. This International Standard applies to pipes, fittings and accessories cast by any type of foundry process or manufactured by fabrication of cast components, as well as corresponding joints in the size range DN 40 to DN 2600 inclusive. It is applicable to pipes, fittings and accessories which are ⎯ manufactured with socketed, flanged or spigot ends (joint design and gasket shapes are outside the scope of this International Standard), ⎯ normally delivered internally and externally coated. Pipes and fittings are classified according to allowable operating pressure Ductile iron pipes, fittings, accessories and their joints for water applications

General

This section outlines the specified thicknesses, lengths, and coatings for pipes and fittings, as detailed in subclauses 4.2.3, 4.2.4, 4.4, and 4.5 If a manufacturer and purchaser agree on variations in these specifications, the supplied pipes and fittings must still adhere to all other requirements of the International Standard, including compliance with national standards and regulations The standard nominal sizes, referred to as DN, for pipes and fittings are also provided.

The stiffness and allowable diametral deflection of ductile iron pipes are as given in Annex D

Ductile iron pipes, fittings, accessories, and their joints retain their functional characteristics throughout their operational life when installed and operated under specified conditions This reliability is attributed to the consistent material properties, the stability of their cross-section, and the incorporation of high safety factors in their design.

Pipes, fittings and accessories shall be free from defects and surface imperfections which could impair their compliance with the requirements of Clauses 4 and 5

Pipes and fittings can be repaired through methods such as welding to address surface imperfections and localized defects that do not compromise the overall wall thickness It is essential that any repaired components meet the standards outlined in Clauses 4 and 5.

4.1.3 Types of joints and interconnection

Joint design and gasket shapes are beyond the scope of this International Standard

Rubber gasket materials must meet ISO 4633 standards for water applications, while alternative materials for specific uses, such as high-temperature flanged joints, should comply with relevant International Standards.

Flanged joints must be designed for compatibility with flanges that meet the dimensions and tolerances specified in ISO 7005-2 or EN 1092-2, ensuring effective interconnection among all flanged components such as pipes, fittings, and valves of the same DN and PN, while providing optimal joint performance Additionally, bolts and nuts should adhere to the minimum standards of ISO 4016 and ISO 4034, property class 4.6, and any required washers must comply with ISO 7091.

In addition, each type of flange joint shall be designed to meet the performance requirements of 5.3

Although it does not affect interconnection, the manufacturer shall indicate in his handbook whether his products are normally delivered with fixed flanges or loose flanges

Pipes and fittings featuring flexible joints must adhere to the specifications outlined in section 4.2.2.1 regarding their spigot external diameters (DE) and tolerances This ensures compatibility for interconnection between components with various types of flexible joints Furthermore, each flexible joint type must be engineered to fulfill the performance criteria established in section 5.2.

To ensure optimal joint performance under high pressure in DE systems, it is essential to adhere to the manufacturer's guidelines, particularly for joints that operate within tighter tolerance ranges This includes careful measurement and selection of the external diameter to maintain adequate performance standards.

For interconnection with existing pipelines which can have external diameters not in accordance with 4.2.2.1, the manufacturer’s guidance should be followed as to the appropriate means of interconnection (e.g adaptors)

Restrained joints for ductile iron pipelines shall be designed in accordance with ISO 10804 Their spigot external diameters, DE, and their tolerances shall comply with 4.2.2.1

4.1.4 Materials in contact with water intended for human consumption

Ductile iron pipes, fittings, and joints, when utilized as intended in both permanent and temporary water systems for human consumption, do not negatively impact the water's properties for its designated use.

Ductile iron pipeline systems, which encompass pipes, fittings, accessories, and joints, are made from a variety of materials When these systems are utilized for transporting potable water, it is essential that all materials in contact with the water comply with the national standards or regulations applicable in the country of use, ensuring they do not adversely affect water quality.

Pressure classification and dimensional requirements

Components with flexible joints shall be classified by the allowable operating pressure (PFA) in bar, prefixed by the letter C

Components with flanged joints shall be classified by the PN number of the flange

The allowable component pressure relationships are defined as follows: the allowable operating pressure (PFA) is equal to C in bar; the allowable maximum operating pressure (PMA) is calculated as 1.20 times PFA in bar; and the allowable site test pressure (PEA) is determined by adding 5 to 1.20 times PFA, also expressed in bar.

The allowable pressures within a pipeline system shall be limited to the lowest pressure classification of all components within the system

Preferred pressure classes of components with flexible joints are C25, C30, and C40 Other pressure classes are allowable, including C20, C50, C64 and C100

Pressure classes for components with flanged joints are PN10, PN16, PN25 and PN40

Allowable pressures of components are as given in Tables 1 and 2

Table 1 — Allowable pressures of components with flexible joints for preferred classes

Pressure class Allowable operating pressure

C PFA PMA PEA bar bar bar

Table 2 — Allowable pressures of components with flanged joints

Pressure class Allowable operating pressure Maximum allowable operating pressure Allowable site test pressure

PN PFA PMA PEA bar bar bar

The allowable pressure for fittings as specified in Tables 15 to 33 are as follows:

⎯ socketed fittings, except tees, are given in Table 3;

⎯ socketed tees may be less than those given in Table 3 and shall be given in the manufacturer’s handbook;

All flanged fittings, including those with a single flange like double-socketed tees with flanged branches, flanged spigots, and flanged sockets, are constrained by the flange PN specifications outlined in Table 2.

Table 3 — Allowable pressures for socketed fittings

Nominal size Allowable operating pressure

DN PFA PMA PEA bar bar bar

When installing a pipeline, it is crucial to consider appropriate limitations that may restrict the full range of operational pressures For instance, the maximum allowable pressure for a pipeline may be constrained by the lower pressure ratings of components such as flanged pipework, specific types of tees, and certain flexible joint designs Additionally, any limitations arising from joint types or unique design configurations should be referenced in the manufacturer's handbook.

Table 14 presents the external diameter values (DE) for the spigot ends of pipes and fittings, measured circumferentially with a tape as outlined in section 6.1.1 A positive tolerance of +1 mm is applicable across all pressure classes of pipes and flanged spigot fittings.

Negative tolerance is determined by the design of each joint type and must adhere to national standards or, in their absence, to the specifications found in manufacturers' handbooks for the relevant joint type and nominal size.

In addition, the ovality (see 3.21) of the spigot end of pipes and fittings shall

⎯ remain within the tolerances of DE for DN 40 to 200, and

⎯ not exceed 1 % of DE for DN 250 to DN 600 or 2 % for DN > DN 600

It is essential to adhere to the manufacturer's guidelines regarding ovality correction, as some flexible joints can accommodate maximum ovality without requiring spigot re-rounding before jointing.

The nominal values of the internal diameters of centrifugally cast pipes, expressed in millimetres, are approximately equal to the numbers indicating their nominal sizes, DN

The minimum wall thickness for pipes, e min , shall be not less than 3,0 mm and shall be determined using Equation (2): min m

= + × (2) where e min is the minimum pipe wall thickness, in millimetres;

PFA is the allowable operating pressure, in bar;

SF is the safety factor for PFA (= 3);

DE is the nominal pipe external diameter (see Table 14), in millimetres;

R m is the minimum tensile strength of ductile iron, in megapascals (R m = 420 MPa; see Table 8)

NOTE Equation (2) is derived from Barlow’s equation, i.e hoop stress, σ = PD/2t (see 3.14)

Centrifugally cast pipes must have a minimum wall thickness of 3.0 mm The nominal wall thickness is determined by adding 1.3 mm plus 0.001 times the nominal diameter (DN) to the minimum wall thickness.

For non-centrifugally cast pipes, the minimum wall thickness must be at least 4.7 mm The nominal wall thickness is calculated by adding the minimum wall thickness to 2.3 mm plus 0.001 times the nominal diameter (DN).

Centrifugally cast pipes have specific nominal wall thicknesses for preferred ductile iron pressure classes, as outlined in Table 14 For other pressure classes listed in Annex C, users should verify availability with the manufacturer.

Flanged pipes are categorized by their PN number, with the barrel's pressure class needing to meet or exceed the PN value in bars of the flanges For fabricated flanged pipes, the appropriate pressure class for the barrel must align with the specifications outlined in section 8.2, applicable to welded, screwed, and integrally cast flanges.

NOTE Pipe threads are regarded as loss of wall thickness

Nominal wall thicknesses, e nom , are given for fittings in Tables 15 to 29, with allowable pressures given in 4.2.1.3 The minimum wall thickness, e min , for fittings is: e min = e nom − (2,3 + 0,001 DN)

Fittings with varying pressure classifications are permitted, with the manufacturer responsible for their design and wall thickness determination The minimum wall thickness must be at least 3.0 mm.

The design shall be carried out by a calculation method, e.g finite element analysis, or an experimental method, e.g hydrostatic testing, using a safety factor of 3 against failure with respect to PFA

Pipes shall be supplied to the lengths given in Table 4

Table 4 — Standardized lengths of socket and spigot pipe

60 to 600 4 or 5 or 5,5 or 6 or 9

700 and 800 4 or 5,5 or 6 or 7 or 9

900 to 2600 4 or 5 or 5,5 or 6 or 7 or 8,15 or 9 NOTE Not all the standardized lengths are available in all countries a See 3.28

Manufacturers must ensure that the design lengths (L u) of pipes conform to a deviation of ± 250 mm from the specified lengths in Table 4, as outlined in their handbooks The actual length must be measured according to section 6.1.3 and should not vary from the manufacturer's design length beyond the tolerances specified in Table 7 Additionally, for each diameter of socket and spigot pipes supplied, the percentage of shorter pipes must not exceed 10%.

NOTE 1 Pipes cut for test purposes can be excluded from the 10 % limitation and treated as full-length pipes

When ordering pipes based on meterage, the manufacturer can accurately calculate the total quantity needed by summing the lengths of each individual pipe to be laid.

The lengths of flanged pipes shall be as given in Table 5 Other lengths are available by agreement between the manufacturer and the purchaser

Table 5 — Standardized lengths of flanged pipe

Type of pipe DN Standardized lengths, L a

With cast-on flanges 40 to 2600 0,5 or 1 or 2 or 3 or 4

600 to 1000 2 or 3 or 4 or 5 or 6 With screwed-on or welded-on flanges

1100 to 2600 4 or 5 or 6 or 7 a See 3.28

Fittings will be provided in the specified lengths outlined in sections 8.3 and 8.4 However, socket fittings may also be offered in lengths that adhere to the national standards of the manufacturing country.

NOTE Two series of dimensions are shown, series A and series B, which is generally limited to DN 450 maximum

The permissible deviations (see 3.6) on the lengths of series A fittings shall be as given in Table 6

Table 6 — Permissible deviations on length of fittings

Type of fitting DN Deviation

Flanged sockets Flanged spigots Collars, tapers 1400 to 2600 ± 35

− 35 Bends 90° (1/4) 40 to 2600 ± (15 + 0,03) DN Bends 45° (1/8) 40 to 2600 ± (10 + 0,025) DN

The tolerances on lengths shall be as given in Table 7

Socket and spigot pipes (full length or shortened) − + 30 70

Fittings for socketed joints have a tolerance of ± 20, while pipes and fittings for flanged joints have a tolerance of ± 10 Smaller tolerances may be negotiated between the manufacturer and purchaser, with minimum tolerances set at ± 3 mm for DN ≤ 600 and ± 4 mm for DN > 600.

Pipes shall be straight, with a maximum deviation of 0,125 % of their length

The verification of this requirement is normally carried out by visual inspection, but in case of doubt or in dispute, the deviation shall be measured in accordance with 6.2.

Material characteristics

Pipes, fittings and accessories made of ductile iron shall have the tensile properties given in Table 8

During manufacturing, the manufacturer must conduct appropriate tests to verify tensile properties This can be achieved through a batch sampling system, where samples are taken from the pipe spigot or separately cast fittings, with test bars machined and tensile tested according to section 6.3 Alternatively, a process control testing system, such as non-destructive testing, can be employed to establish a positive correlation with the tensile properties specified in Table 8 Verification procedures should utilize comparator samples with known properties, and this testing approach must be supplemented by tensile testing as per section 6.3.

Minimum percent elongation after fracture,

DN 40 to DN 2600 DN 40 to DN 1000 DN 1100 to DN 2600 Pipes centrifugally cast 420 10 7

Pipes not centrifugally cast, fittings and accessories 420 5 5

According to the agreement between the manufacturer and purchaser, the 0.2% proof stress (R p02) must be measured and should not be less than 270 MPa for DN 40 to DN 1000 with an A W of 12%, or for DN greater than 1000 with an A W of 10%; in all other cases, it should be at least 300 MPa.

For centrifugally cast pipes of DN 40 to DN 1000 having a design minimum wall thickness of 10 mm or greater, the minimum elongation after fracture shall be 7 %

The components must possess a hardness level suitable for cutting, tapping, drilling, and machining using standard tools In the event of any disputes regarding hardness, measurements will be conducted in accordance with section 6.4.

The Brinell hardness for centrifugally cast pipes must not exceed 230 HBW, while for non-centrifugally cast pipes, fittings, and accessories, the limit is 250 HBW Additionally, components produced through welding may have a higher Brinell hardness in the heat-affected zone of the weld.

Coating and linings for pipes

Pipes shall normally be delivered internally and externally coated

Ductile iron pipeline systems can be installed in a wide range of external operating environments These environments can be characterized according to their aggressivity For relevant factors, see A.1

Coatings specified by relevant International Standards are available as specified in A.2 Other coatings are available

Ductile iron pipeline systems are versatile and suitable for transporting various types of raw and potable water The internal conditions of these pipelines can exhibit different levels of aggressivity, which is crucial to consider For effective performance, it is important to evaluate specific factors related to cement mortar linings without seal coats, as outlined in section B.1.

Linings specified by relevant International Standards are available as specified in B.2 Other linings are also available

Coatings and linings for fittings and accessories

Fittings and accessories shall normally be delivered internally and externally coated

Ductile iron pipeline systems can be installed in a wide range of external operating environments These environments can be characterized by their aggressivity For relevant factors, see A.1

Coatings specified by relevant International Standards are available as specified in A.3 Other coatings are also available

Ductile iron pipeline systems are effective for transporting various types of raw and potable waters, with their internal environments varying in aggressivity It is essential to consider specific factors for cement mortar linings without seal coats, as outlined in section B.1.

Linings specified by relevant International Standards are available as specified in B.3 Other linings are also available.

Marking

All pipes and fittings must be clearly and durably marked with essential information, including a reference to ISO 2531, the manufacturer's name or mark, the year of manufacture, identification as ductile iron, the nominal diameter (DN), the pressure nominal (PN) rating of flanges if applicable, and the pressure class for socket and spigot pipes.

Items b) to f) shall be cast-on or cold stamped Items a) and g) can be applied by any method, e.g painted on the castings

Pipes and fittings

Pipes and fittings must be engineered to ensure they are leaktight at the specified allowable site test pressure (PEA) They should undergo testing as outlined in section 6.5, demonstrating no visible leaks, sweating, or any indications of failure.

Flexible joints

All flexible joints for ductile iron pipes and components must adhere to the specifications outlined in section 5.2 The design should be verified through testing and documentation by the manufacturer, ensuring its successful application in practical use.

ISO 2531:2009(E) outlines in sections 5.2.3 and 5.2.4 the requirements for external pressure and negative internal pressure, respectively These specifications are essential only when there are significant design changes that may negatively impact the joint's performance.

Joint designs shall be type tested to demonstrate leaktightness to both internal and external pressure under the most unfavourable conditions of castings tolerances and joint movements

A type test must be conducted for at least one DN from each grouping listed in Table 9 A DN is considered representative of a grouping when its performance is evaluated based on consistent design parameters across the entire size range.

Table 9 — DN groupings for type tests

DN groupings 40 to 250 300 to 600 700 to 1000 1100 to 2000 2200 to 2600

Preferred DN in each grouping 200 400 800 1600 2400

If a grouping covers products of different designs and/or manufactured by different processes, the grouping shall be sub-divided

A manufacturer can classify a grouping that consists of only one DN or PN as part of an adjacent grouping, provided that the DN or PN shares an identical design and is produced using the same manufacturing process.

The type tests shall be carried out in the configuration of maximum design radial gap between the components to be jointed (smallest spigot together with largest socket)

In the type test, the maximum gap must match the maximum design radial gap, allowing for a tolerance of -0.5% To achieve this, the internal socket diameter can be machined, even if it slightly exceeds the standard manufacturing tolerance.

All joints must undergo performance testing using a spigot that has an average iron wall thickness, measured over a distance of 2 DN from the spigot face, equal to the specified minimum value for the designed pipe, plus an additional 10% Machining the spigot of the pipe bore to attain the necessary thickness is allowed.

Restrained flexible joints shall be designed and tested in accordance with ISO 10804

Joints must undergo type testing for leaktightness under internal pressure, as outlined in section 7.1, at a pressure of 1.5PFA + 5 bar, ensuring no visible leakage occurs in two positions: first, when the joint is aligned and subjected to a shear force of at least 30 times DN; second, when the joint is deflected at specified angular limits, with a minimum of 3° 30' for DN 40 to DN 300, 2° 30' for DN 350 to DN 600, and 1° 30' for DN 700 to DN 2600 These minimum deflection requirements are not applicable to restrained joint pipes.

Joints must undergo type testing for leaktightness against external pressure as outlined in section 7.2, ensuring that they show no visible leakage when subjected to a shear load of at least 30 times the nominal diameter (DN) in newtons.

The test pressure shall be not less than 2 bar

The leaktightness of joints under negative internal pressure must undergo type testing as outlined in section 7.3, utilizing a test pressure of 0.9 bar below atmospheric pressure (approximately 0.1 bar absolute pressure) During the testing period, the maximum allowable pressure change should not exceed 0.09 bar after two hours The tests are conducted in two positions: first, with the joint aligned and subjected to shear, where the shear force must be at least 30 times the nominal diameter (DN); second, with the joint deflected, adhering to the maximum allowable deflection specified in the manufacturer's handbook, with minimum deflections of 3° 30' for DN 40 to DN 300, 2° 30' for DN 350 to DN 600, and 1° 30' for DN 700 to DN 2600 These minimum deflection requirements do not apply to restrained joint pipes.

Flanged joints as cast, screwed, welded and adjustable

All flanged joints for ductile iron pipes and components must adhere to the specifications outlined in section 5.3 If a design has been tested, documented, and effectively utilized by the manufacturer for at least 10 years, a performance type test as per section 5.3.2 is only necessary for significant design changes that may negatively impact joint performance.

When testing flanges, it is essential to conduct a type test for at least one nominal diameter (DN) from each grouping listed in Table 9 The test should focus on the highest pressure nominal (PN) available for each flange design A single PN can be considered representative of a grouping if the performance characteristics are consistent across the entire size range based on identical design parameters.

If a grouping covers products of different designs and/or manufactured by different processes, the grouping shall be sub-divided

A manufacturer can include a single DN or PN in an adjacent grouping if it shares the same design and is produced using the same manufacturing process.

5.3.2 Internal pressure and bending moment

Flanged joints must undergo a type test to verify their strength and leak-tightness under service conditions According to the specifications outlined in section 7.4, these joints should exhibit no visible leakage when subjected to the combined effects of hydrostatic internal pressure and the bending moment specified in Table 10.

⎯ the pressure is (1,5PN + 5) bar,

The relevant bending moment is determined by summing the bending moments caused by the weight of the components and the water in the test assembly, along with any external load, which is calculated based on the length of the unsupported span of the testing arrangement (refer to section 7.4).

A type test shall be carried out on each type of flange joint available from the manufacturer in accordance with Table 10

The bending moments listed in Table 10 closely correspond to those generated by the weight of selected pipe classes, considering nominal thicknesses, along with the cement mortar lining and water over an unsupported pipe length, L, situated between simple supports This applies to welded, integrally cast, and adjustable flanged joints.

ISO 2531:2009(E) and for screwed flanged joints,

Table 10 — Bending moments for flange joint type tests of preferred classes of pipes

Integrally cast, welded and adjustable Screwed

Dimensions

Pipes featuring sockets and spigot ends should be measured at the spigot using a circumferential tape to ensure compliance with outer diameter tolerances Additionally, verification can be performed using pass-fail gauges.

Pipes must undergo a visual inspection at their spigot to ensure they meet ovality tolerance standards If there is any uncertainty, measurements of the maximum and minimum axes should be taken Additionally, this verification can be conducted using pass-fail gauges.

The frequency of testing is related to the system of production and the quality control used by the manufacturer

Pipe wall thickness compliance shall be demonstrated by the manufacturer; a combination of various means may be used, such as:

Direct wall thickness measurement can be performed using appropriate tools like mechanical or ultrasonic equipment The testing frequency is determined by the manufacturer's production and quality control systems.

The length of centrifugally cast pipes with sockets and spigot ends shall be measured by means of suitable equipment

⎯ on the first pipe cast from a new mold, for full length pipes, and

⎯ on the first cut pipe, for pipes which are systematically cut to a predetermined length.

Straightness of pipes

The pipe must be either rolled on two supports or rotated along its axis using rollers, ensuring that the distance between the supports or rollers is at least two-thirds of the standard pipe length.

The point of maximum deviation from the true axis shall be determined, and the deviation measured at that point shall not exceed the limit fixed in 4.2.5.

Tensile test

The thickness of the sample and the diameter of the test bar shall be as indicated in Table 11

A sample must be taken from the pipe's spigot, which can be cut either perpendicular or parallel to the pipe's axis; however, in the event of a disagreement, the sample cut parallel to the axis will be the standard used.

6.3.1.2 Pipes not cast centrifugally, fittings and accessories

Samples will be collected at the manufacturer's discretion from an integrally cast sample, a sample attached to the casting, or a separately cast sample made from the same metal If the casting undergoes heat treatment, the sample must also undergo the same treatment to ensure consistency.

Each sample must have a test bar machined from its mid-thickness, featuring a cylindrical shape with diameters specified in Table 11 If the required diameter exceeds 60% of the sample's minimum thickness, a smaller diameter can be used, or an alternative sample from a thicker section of the pipe may be taken Additionally, other test bar shapes that meet International or national standards are acceptable.

Test bars must have a gauge length that is at least five times their nominal diameter, ensuring proper dimensions for accurate testing Additionally, the ends of the test bars should be designed to fit securely into the testing machine.

The surface roughness of the machined gauge length of the test bar shall be such that Rz u 6,3 àm

Two methods of measuring the tensile strength may be used at the manufacturer’s discretion:

To ensure accurate testing, produce the test bar with a nominal diameter within ± 10% Measure the actual diameter prior to testing with an accuracy of ± 0.01 mm Use this measured diameter to calculate the cross-sectional area and determine the tensile strength.

Produce the test bar to a nominal area, S o , within a specified tolerance on the diameter (see Table 11) and use the nominal area to calculate the tensile strength

Table 11 — Dimensions of test bar

Tolerance on diameter Type of casting mm mm 2 mm mm Centrifugally cast pipes with wall thickness:

⎯ 6 mm up to but not including 8 mm 3,5 10 3,57 ± 0,02

⎯ 8 mm up to but not including 12 mm 5 20 5,05 ± 0,02

Pipes, fittings and accessories not cast centrifugally:

⎯ thickness 12,5 mm for casting thickness less than 12 mm 6 30 6,18 ± 0,03

⎯ thickness 25 mm for casting thickness

A tensile testing machine must be equipped with appropriate grips to securely attach to the ends of test bars, ensuring the test load is applied axially Additionally, the machine should possess a force range adequate for conducting failure tests on the bars while clearly indicating the applied load.

The rate of stressing shall be as constant as possible within the limits of 6 N/mm 2 per second to 30 N/mm 2 per second

Tensile strength is determined by dividing the maximum force applied to a test bar by its cross-sectional area prior to testing Elongation can be assessed by reconnecting the broken pieces of the test bar and calculating the ratio of the extended gauge length to the original gauge length, or it can be directly measured using an extensometer.

Test results must align with Table 8; if they do not, the manufacturer is required to investigate any deficiencies in mechanical properties and ensure that all castings in the batch are either re-heat-treated or rejected Re-heat-treated castings must undergo retesting as outlined in section 6.3 Additionally, if a defect is found in the test bar, a further test must be conducted; if this test is successful, the batch is accepted, otherwise, the manufacturer may choose to follow the aforementioned re-heat-treatment protocol.

Manufacturers can reduce rejection rates by conducting additional tests during the production process, ensuring that the rejected batch of castings is flanked by successful test results on both ends of the specified interval.

The frequency of testing is related to the system of production and quality control used by the manufacturer (see 4.3.1) The maximum batch sizes shall be as given in Table 12

Table 12 — Maximum batch sizes for tensile testing

Maximum batch size Type of casting DN Batch sampling system

700 to 1000 50 pipes 300 pipes Centrifugally cast pipes

1100 to 2600 25 pipes 150 pipes Pipes not cast centrifugally, fittings and accessories All sizes 4 t a 48 t a a Mass of crude castings, excluding risers.

Brinell hardness

Brinell hardness tests must be conducted on the casting in question or on a sample taken from it Prior to testing, the surface should be properly prepared through slight local grinding The test should adhere to ISO 6506-1 standards and utilize a ball with a diameter of 2.5 mm, 5 mm, or 10 mm.

Works leaktightness test of pipes and fittings

Pipes and fittings must undergo testing as outlined in sections 6.5.2 and 6.5.3 prior to the application of any external or internal coatings However, the metallic zinc coating on pipes may be applied before conducting the tests.

The test apparatus must effectively apply the designated test pressures to pipes and fittings, featuring an industrial pressure gauge with an accuracy limit of ± 3%.

The internal hydrostatic pressure must be increased to the designated hydrostatic test pressure, corresponding to the pressure class and adhering to the limits of Preferred Classes, although higher pressures are allowable The pressure cycle should last a minimum of 15 seconds, with at least 10 seconds at the test pressure A visual inspection is required during or right after the pressure test.

6.5.3 Pipes not cast centrifugally and fittings

At the discretion of the manufacturer, these pipes and fittings shall be submitted to a hydrostatic pressure test or an air test

The hydrostatic pressure test must be conducted similarly to the procedure for centrifugally cast pipes, as outlined in section 6.5.2, with the exception of the test pressures specified in Table 13.

Table 13 — Works test pressure for pipes not cast centrifugally and fittings

DN Pipes not cast centrifugally and fittings bar a

Hydrostatic test pressure for pipes is lower due to challenges in providing adequate restraint against high internal pressure during testing For pipes and fittings with PN 10 flanges, the test pressure is set at 16 bar.

During the air test, an internal pressure of at least 1 bar must be maintained, accompanied by a visual inspection lasting no less than 10 seconds For effective leak detection, castings should either be uniformly coated on the external surface with a suitable foaming agent or submerged in water.

Leaktightness of joints to internal pressure

This type test shall be carried out on an assembled joint comprising two pipe sections each at least 1 m long (see Figure 1)

The test apparatus must ensure appropriate end restraints for joints in aligned, deflected, or shear-loaded positions and should include a pressure gauge with an accuracy of ± 3%.

The shear load, W, should be applied to the spigot using a V-shaped block with a 120° angle, positioned at either 0.5 times the nominal diameter (DN) in millimeters or 200 mm from the socket face, whichever distance is greater.

According to ISO 2531:2009(E), the socket must rest on a flat support, and the load (W) applied should ensure that the resultant shear force (F) across the joint matches the specified value in section 5.2.2 This calculation must consider the mass (M) of the pipe and its contents, as well as the geometry of the test assembly, as outlined in Equation (3).

F is the resultant shear force across the joint, expressed in newtons;

M is the mass of the pipe and its contents, expressed in newtons;

W is the shear load, expressed in newtons; a, b and c are given in Figure 1

Figure 1 — Leaktightness of joints (internal pressure)

The test assembly must be filled with water and properly vented to eliminate air Pressure should be increased gradually, not exceeding 1 bar per second, until the specified test pressure is achieved This pressure must be maintained within ±0.5 bar for a minimum of 2 hours, with thorough inspections of the joint conducted every 15 minutes during this period.

Leaktightness of joints to external pressure

The test assembly for push-in flexible joints consists of two joints made from pipe sockets connected to a double-spigot piece, forming an annular chamber This setup enables the testing of one joint under internal pressure and the other under external pressure.

The test assembly must endure a shear load as specified in section 5.2.3, with half of this load applied to the spigot on each side using a V-shaped block with a 120° angle This block should be positioned approximately 0.5 × DN in millimeters or 200 mm from the end of the sockets, whichever distance is greater, while ensuring the sockets rest on a flat support.

The test assembly must be filled with water and adequately vented to remove air The pressure should be gradually increased to the specified test pressure, maintained within ± 0.1 bar for a minimum of 2 hours During this period, the internal side of the joint exposed to external pressure must be thoroughly inspected every 15 minutes.

Leaktightness of joints to negative internal pressure

The test assembly and test apparatus shall be as given in 7.1 with the pipe sections axially restrained to prevent them moving towards each other

The test assembly must be free of water and evacuated to a negative internal pressure of 0.9 bar, as outlined in section 5.2.4, before being isolated from the vacuum pump It should remain under vacuum for a minimum of 2 hours, during which the pressure should not fluctuate by more than 0.09 bar The testing process should commence at a temperature between 5 °C and 40 °C, ensuring that the temperature of the test assembly does not vary by more than 10 °C throughout the test duration.

Leaktightness and mechanical resistance of flanged joints

The test assembly must consist of pipes and/or fittings with matching flanges, secured using gaskets and bolts specified by the manufacturer Both ends of the assembly should feature blank flanges, and the bolts must be tightened to the torque recommended for the maximum PN of the DN being tested If the bolt material grade is not specified, it should at least meet the minimum requirements of property class 4.6 according to ISO 4016.

The test assembly must be supported on two simple supports, ensuring the flanged joint is centered at mid span The minimum unsupported span length should be either 6 DN in millimeters or 4,000 mm, depending on which is smaller This span can be achieved using a combination of pipes or fittings, but only the tested joint at mid span will be taken into account.

Figure 3 — Strength and leaktightness test for flanged joints

To conduct the test assembly, fill it with water and ensure proper ventilation to remove air Gradually increase the pressure until it reaches the specified test pressure outlined in section 5.3 Apply the external load, F, to the flanged joint using a flat plate positioned perpendicular to the assembly's axis, creating the bending moment indicated in Table 10.

The internal pressure and the external load shall be kept constant for 2 h during which the flanged joint shall be thoroughly inspected

CAUTION — All necessary safety precautions should be taken for the duration of the pressure test

Socket and spigot pipes

The preferred pressure classes for socket and spigot pipes are detailed in Figure 4 and Table 14, while wall thickness specifications for both preferred and alternative pressure classes can be found in Annex C.

The values of L u are given in Table 4 For external and internal coatings, see 4.4

DE nominal external diameter of spigot, in millimetres e nom nominal wall thickness, in millimetres

L 2 depth of socket, in metres

L e = L tot − L i laying length, in metres

L i maximum insertion depth as given by the manufacturer, in metres

L tot total length, in metres

L u = L tot − L 2 standardized length, in metres

Figure 4 — Socket and spigot pipes

Table 14 — Preferred pipe pressure classes

DN DE a Pressure class Nominal iron wall thickness e nom mm mm mm

2600 2702 C25 27,9 a A tolerance of +1 mm applies (see 4.2.2.1) b Thicknesses are greater than calculated for “smoothing” between C40 and C30 and also between C30 and C25

Flanged pipes

Flanged pipework must effectively support external bending moments, which are influenced by the weight of the pipe and its contents over a specified span Therefore, manufacturers are required to validate this capability through performance testing.

Clauses 5 and 7, the minimum thickness of pipe required for the different PN-rated flanges

The values of L are given in Table 5

For coatings and linings, see 4.4

Dimensions of flanges are in conformity with ISO 7005-2 and EN 1092-2 (see 4.1.3.2).

Fittings for socketed joints

In Tables 15 to 23, all the dimensions are nominal values and are given in millimetres The values of L u and l u have been rounded up to the nearest multiple of five

For coating and linings, see 4.5

Table 15 — Dimensions of flanged sockets

Table 16 — Dimensions of flanged spigots and collars

NOTE The length L ′ is the length of the spigot to which the value of DE and its tolerance, as given in Table 14, apply

Table 17 — Dimensions of double-socket 90° and 45° bends

Table 18 — Dimensions of double-socket 22° 30' and 11° 15' bends

Table 19 — Dimensions of all socket tees

NOTE The main nominal size is designated DN and the nominal size of the branch is designated dn

8.3.9 Double-socket tees with flanged branch, DN 40 to DN 250

Figure 13 — Double-socket tee with flanged branch

Table 20 — Dimensions of double-socket tees with flanged branch, DN 40 to DN 250

Table 23 — Dimensions of double-socket tapers

2600 × 2400 37,2 34,8 360 — NOTE The larger nominal size is designated DN and the smaller nominal size is dn

Fittings for flanged joints

In Tables 24 to 33, all the dimensions are nominal values and are given in millimetres

For coatings and linings, see 4.5

Figure 16 — Double-flanged duckfoot 90° bend

Table 24 — Dimensions of double-flanged 90º duckfoot bends

A and B series 90° (1/4) bends 90° (1/4) duckfoot bends

Table 25 — Dimensions of double-flanged 45º (1/8) bends

8.4.4 All flanged tees, DN 40 to DN 250

Table 26 — Dimensions of all flanged tees, DN 40 to DN 250

DN × dn e nom, 1 L Series A e nom, 2 l Series A

Table 29 — Dimensions of double-flanged tapers

2600 × 2400 37,2 34,8 1 210 — NOTE The larger nominal size is designated DN and the smaller nominal size is designated by dn

Table 30 — Dimensions of PN 10 and PN 16 blank flanges

2000 2 325 55 50 5 2 345 75 70 5 For blank flanges of nominal diameter greater than or equal to DN 300, the centre of blank flanges may be dished

Table 31 — Dimensions of PN 25 and PN 40 blank flanges

600 845 42 37 5 — — — — For blank flanges of nominal diameter greater than or equal to DN 300, the centre of blank flanges may be dished

Table 32 — Dimensions of PN 10 and PN 16 reducing flanges

1000 × 800 1 230 68 35 5 5 1 255 77 45 5 5 NOTE The larger nominal size is designated DN and the smaller nominal size is designated dn

Table 33 — Dimensions of PN 25 and PN 40 reducing flanges

400 × 300 620 61 28 4 4 — — — — — NOTE The larger nominal size is designated DN and the smaller size is designated dn

A.1 Factors characterizing aggressivity of external operating environments

A.2 Centrifugally cast pipe coatings for protection against aggressive external operating environments

⎯ Metallic zinc with finishing layer, in accordance with ISO 8179-1;

⎯ zinc rich paint with finishing layer, in accordance with ISO 8179-2;

⎯ polyethylene sleeving, in accordance with ISO 8180

For other types of pipe coatings, including their repair method, refer to national standards or pipe manufacturers

A.3 Fitting and accessory coatings for protection against aggressive external operating environments

⎯ Metallic zinc with finishing layer, in accordance with ISO 8179-1;

⎯ zinc rich paint with finishing layer, in accordance with ISO 8179-2;

⎯ polyethylene sleeving, in accordance with ISO 8180

For other types of fitting and accessory coatings, including their repair method, refer to national standards or pipe manufacturers

B.1 Factors characterizing aggressivity of raw and potable waters

B.2 Centrifugally cast pipe linings for protection against aggressive raw and potable waters

⎯ Portland cement mortar, in accordance with ISO 4179;

⎯ blast furnace slag cement mortar, in accordance with ISO 4179;

⎯ cement mortar with seal coat, in accordance with ISO 16132

For other types of pipe linings, including their repair method, refer to national standards or the pipe manufacturers

B.3 Fitting and accessory linings for protection against aggressive raw and potable waters

⎯ Portland cement mortar, in accordance with ISO 4179;

⎯ blast furnace slag cement mortar, in accordance with ISO 4179;

⎯ cement mortar with seal coat, in accordance with ISO 16132

For other types of fitting and accessory linings, including their repair method, refer to national standards or the pipe manufacturers

Dimensions of preferred pressure classes and other pressure class pipes

Preferred classes and other classes of pipe are given in Table C.1

The minimum nominal diameter available in lower pipe classes, i.e

The C30 DN 300 pressure class and nominal diameter combinations outlined in Table 14 are constrained by the minimum practical casting wall thickness, with values that align with the manufacturing practices established in this International Standard.

Manufacturers can offer smaller diameters in these pressure classes provided they can demonstrate that the components comply with all the technical and performance requirements of this International Standard

Table C.1 — Dimensions of preferred and other classes of pipe

DN DE a Nominal iron wall thickness, e nom mm b mm mm C20 C25 C30 C40 C50 C64 C100

When considering pipe tolerances, a variation of +1 mm is applicable as outlined in section 4.2.2.1 For pipes featuring weld beads, refer to ISO 10804 for specific guidelines It is important to note that preferred classes indicate that thicknesses exceed those calculated for smoothing transitions between C40 and C30, as well as between C30 and C25.

Pipe wall thicknesses, stiffness and diametral deflection

Ductile iron pipes are designed to handle significant diametral deflections during operation while maintaining their essential functional characteristics The permissible diametral deflections for these pipes in service are detailed in Tables D.1 to D.7, which also specify the minimum diametral stiffness required This design enables the pipes to endure substantial cover heights and heavy traffic loads across various installation conditions.

Diametral deflection, expressed as a percentage, is calculated by taking the vertical pipe deflection in millimeters, multiplying it by one hundred, and then dividing by the initial external diameter of the pipe, DE, also measured in millimeters The permissible values for diametral deflection are specified in relevant guidelines.

Tables D.1 to D.7 outline specifications for cement-lined pipes, including grades C20, C25, C30, C40, C50, C64, and C100, ensuring joint integrity and protection against pipe wall overstressing and lining cracking The maximum permissible deflection for cement-mortar-lined pipes is set at 4%, although national standards and manufacturer guidelines may impose stricter limits, such as 3%.

The maximum allowable deflection for other types of linings can be calculated in accordance with ISO 10803

The diametral stiffness, S, of a pipe is calculated using Equation (D.1):

S is the diametral stiffness, in kilonewtons per square metre;

E is the modulus of elasticity of the material, in megapascals (170 000 MPa);

The second moment of area of the pipe wall per unit length is denoted as I, measured in millimeters to the third power The term "e stiff" refers to the minimum wall thickness of the pipe, represented as e min, plus half the tolerance, also measured in millimeters.

D is the mean diameter of the pipe (DE − e stiff ), in millimetres; where

DE is the nominal pipe outer diameter, in millimetres

Table D.1 — Diametral stiffness and allowable deflection of Class 20 pipe

Allowable deflection e min e nom e stiff S mm mm mm mm mm kN/m 2 %

The values of S and deflection have been determined based on a pipe wall thickness that is the minimum thickness plus half of the tolerance This approach accounts for the fact that only a limited number of points exhibit a thickness that is equal to or near the minimum threshold.

The values of S and deflection have been determined using a pipe wall thickness that combines the minimum thickness with half of the tolerance This approach acknowledges that only a limited number of points meet or are near the minimum thickness Additionally, the thicknesses are adjusted to ensure a smooth transition between the preferred classes C30 and C25.

The values of S and deflection were calculated based on a pipe wall thickness that includes the minimum thickness plus half of the tolerance This approach accounts for the fact that only a limited number of points have a thickness that is equal to or near the minimum Additionally, the thicknesses are adjusted to create a "smoothing" effect between classes C40 and C30 in the preferred categories.

The values of S and deflection have been calculated based on a pipe wall thickness that includes the minimum thickness plus half of the tolerance, acknowledging that only a few points meet or are near the minimum thickness Additionally, the allowable deflection is constrained to a lower value than specified in ISO 10803 to ensure design consistency.

The calculations for S and deflection are based on a pipe wall thickness that combines the minimum thickness with half of the tolerance This approach acknowledges that only a limited number of points exhibit a thickness that is equal to or near the minimum standard.

The values of S and deflection have been determined based on a pipe wall thickness that combines the minimum thickness with half of the tolerance This approach accounts for the fact that only a limited number of points exhibit a thickness that is equal to or nearly matches the minimum thickness.

The values of S and deflection have been determined based on a pipe wall thickness that combines the minimum thickness with half of the allowable tolerance, acknowledging that only a limited number of points meet or approach the minimum thickness criteria.

The manufacturer has the responsibility to demonstrate the conformity of his products with this International Standard by:

⎯ carrying out type tests (see E.2);

⎯ controlling the quality of the manufacturing process (see E.3)

Type tests outlined in Clauses 5 and 7 are conducted by either the manufacturer or a qualified testing institute upon the manufacturer's request to ensure adherence to this International Standard The supplier of pipes, fittings, and gaskets retains comprehensive reports of these tests as proof of compliance.

When fittings or gaskets are provided separately from pipes, suppliers must ensure that comprehensive reports detailing the type tests of these components and their compatibility with the pipes are readily available to the client.

The manufacturer controls the quality of his products during their manufacture by a system of process control in order to comply with the technical requirements of this International Standard

It is recommended that the manufacturer’s quality system conform to ISO 9001

If certification to ISO 9001 is involved, it is recommended that the certification body be accredited to the relevant International Standard, as applicable

The following safety factors are used in the design for minimum thicknesses for ductile iron pipes:

Table F.1 — Safety factors for ductile iron pipes Design criteria Safety factor Mechanical property

PFA 3,0 Minimum ultimate tensile strength of 420 MPa PMA 2,5 Minimum ultimate tensile strength of 420 MPa External loads 1,5 Yield bending strength of 500 MPa

[1] ISO 4179:2005, Ductile iron pipes and fittings for pressure and non-pressure pipelines — Cement mortar lining

[2] ISO 6708:— 2) , Pipework components — Definition and selection of DN, NPS and A

[3] ISO 7268, Pipe components — Definition and selection of PN, Class and K

[4] ISO 8179-1, Ductile iron pipes — External zinc-based coating — Part 1: Metallic zinc with finishing layer

[5] ISO 8179-2, Ductile iron pipes — External zinc coating — Part 2: Zinc rich paint with finishing layer

[6] ISO 8180, Ductile iron pipelines — Polyethylene sleeving for site application

[7] ISO 9001, Quality management systems — Requirements

[8] ISO 16132, Ductile iron pipes and fittings — Seal coats for cement mortar linings

Tiêu đề	Ductile Iron Pipes, Fittings, Accessories And Their Joints For Water Applications
Trường học	ISO Central Secretariat
Chuyên ngành	Ductile Iron Pipes
Thể loại	international standard
Năm xuất bản	2009
Thành phố	Geneva

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Số trang	78
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