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BRITISH STANDARD BS 8010-2.1:1987Incorporating

Amendment No. 1

Code of practice for

Pipelines

Part 2: Pipelines on land: design,construction and installation

Section 2.1 Ductile iron

UDC 621.644

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This British Standard, havingbeen prepared under thedirection of the CivilEngineering and BuildingStructures StandardsCommittee, was publishedunder the authority of theBoard of BSI and comesinto effect on27 February 1987

BSI 12-1998

The following BSI referencesrelate to the work on thisstandard:Committee reference CSB/10Draft for comment 85/12791 DC

ISBN 0 580 15570 6

Committees responsible for thisBritish Standard

This publication of this British Standard was entrusted by the Civil

Engineering and Building Structures Standards Committee (CSB/-) toTechnical Committee CSB/10, upon which the following bodies wererepresented:

Association of Consulting EngineersBritish Compressed Gases AssociationBritish Gas CorporationBritish Plastics FederationBritish Precast Concrete Federation Ltd.British Railways BoardChemical Industries AssociationConcrete Pipe AssociationCountry Landowners Association

County Surveyors SocietyDepartment of Energy (Petroleum Engineering Division)Ductile Iron Producers AssociationElectricity Supply Industry in England and WalesEngineering Equipment and Materials Users AssociationFederation of Civil Engineering ContractorsHealth and Safety ExecutiveHome OfficeInstitute of PetroleumInstitution of Civil EngineersInstitution of Gas EngineersInstitution of Mechanical Engineers

Institution of Public Health EngineersInstitution of Water Engineers and ScientistsMinistry of Agriculture, Fisheries and FoodNational Farmers UnionPipeline Industries GuildRoyal Institution of Chartered SurveyorsSociety of British Gas IndustriesUK Offshore Operators Association Ltd.Water Authorities AssociationWater Companies AssociationWater Research Centre

The following body was also represented in the drafting of the standard,

through subcommittees and panels:

Association of Municipal Engineers

Amendments issued since publication

Amd. No. Date of issue Comments

6820 November 1991 Indicated by a sideline in the margin


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PageFigure 1 Push-in joint (type 1) 20Figure 2 Bolted mechanical joint (type 2) 20Figure 3 Slip-on coupling (type 3) 21Figure 4 Flange adapter (type 4) 21Figure 5 Self-anchoring flange adapter (type 5) 22Figure 6 Self-anchoring push-in joint (type 6) 22Figure 7 Self-anchoring tie-bar joint (type 7) 23Figure 8 Self-anchoring bolted mechanical joint (type 8) 23Figure 9 Lead-caulked joint (type 9) 24Figure 10 Flanged joint (type 10) 24

Table 1 Maximum hydraulic working pressures, exclusive of surge,for ductile iron pipes and fittings and flanged joints 6Table 2 Maximum site hydrostatic test pressures forductile iron pipes and fittings and flanged joints 7Table 3 Stacking heights 13

List of references Inside back cover


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Foreword

This Section of BS 8010 has been prepared under the direction of the CivilEngineering and Building Structures Standards Committee. The standard isbeing published in four Parts to form a complete revision of all Parts of CP 2010as follows.

Part 1: Pipelines on land: general; Part 2: Pipelines on land: design, construction and installation; Part 3: Pipelines subsea: design, construction and installation; Part 4: Pipelines on land and subsea: operation and maintenance.

The new Part 1 (which will supersede CP 2010-1:1966) is intended to contain

general information which is relevant to a variety of pipeline constructionmaterials and a variety of transported materials. It deals with those aspects ofpipeline development which affect the owner and occupier of land through whichthe pipeline passes.Part 2 is divided into several Sections which will be published as separatedocuments as follows.

Section 2.1: Ductile iron; Section 2.2: Steel; Section 2.3: Asbestos cement; Section 2.4: Prestressed concrete; Section 2.5: Glass reinforced thermosetting plastics;

Section 2.6: Thermoplastics; Section 2.7: Precast concrete.

Each Section will contain information on the design, construction and installationof a pipeline in the particular material. These Sections will supersede the existingParts 2, 3, 4 and 5 of CP 2010.This Section supersedes CP 2010-3:1972. The content and the title of the 1972edition have been changed to refer to ductile iron only, as grey iron is no longerused as a material for pipelines. By the exclusive use of ductile iron it has beenpossible to raise the pressure ratings and introduce self-anchoring joints.Part 3 will include information relevant to the design, installation andcommissioning of subsea pipelines in steel and other materials.Part 4 will contain advice on the operation and maintenance of pipelines and will

probably be in Sections related to the conveyed material. Appendix A describes and illustrates some typical types of joint used with ductileiron pipe.

Appendix B gives requirements for non-metallic materials for use with potablewater.It has been assumed in the drafting of this British Standard that the execution ofits provisions is entrusted to appropriately qualified and experienced people.

Attention is drawn to the following principal statutory legislation in the UK. Thislist is not intended to be complete and the relevant authorities should beconsulted and reference made to Part 1. These Acts are supplemented byStatutory Instruments.

Acquisition of Land Act 1981;Control of Pollution Act 1974;Countryside Act 1968;


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Countryside (Scotland) Acts 1967 and 1981;

Gas Acts 1965 and 1972;Land Powers (Defence) Act 1958;Pipelines Act 1962;Public Health Acts 1936 and 1961;Requisitioned Land and War Works Act 1948;Water Acts 1945, 1948, 1973, 1975, 1981 and 1983;Water (Scotland) Acts 1946, 1949, 1967 and 1980.

A British Standard does not purport to include all the necessary provisions of acontract. Users of British Standards are responsible for their correct application.

Compliance with a British Standard does not of itself confer immunityfrom legal obligations.

Summary of pagesThis document comprises a front cover, an inside front cover, pages i to iv,pages 1 to 26, an inside back cover, and a back cover.This standard has been updated (see copyright date) and may have hadamendments incorporated. This will be indicated in the amendment table onthe inside front cover.


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Subsection 1. General

1 ScopeThis Section of BS 8010 gives design considerationsand construction and installation recommendationsfor ductile iron pipelines and should be read inconjunction with Part 1 1) .This British Standard code of practice is notintended to replace or duplicate hydraulic,mechanical or structural design manuals.NOTE 1 The numbers in square brackets in the text of thisSection refer to the numbered references in Appendix C.NOTE 2 The titles of the publications referred to in thisstandard are listed on the inside back cover.

2 Definitions

For the purposes of this Section of BS 8010, thefollowing definitions apply.

2.1ductile iron 2)

iron in which graphite is present substantially inspheroidal form, instead of in flakes such as occur ingrey iron

2.2pipeline

a line of pipes, of any length, without frequentbranches. It does not include piping systems such asprocess plant piping within refineries, factories or

treatment plant2.3flexible joint 2)

a connection between individual pipes and/orfittings that provides angular deflection or axialmovement, or a combination of both, in service,without impairing the efficiency of the connectionNOTE See Appendix A.

2.4rigid joint

a connection that is designed not to permit angulardeflection or axial movement in serviceNOTE See Appendix A.

2.5self-anchoring joint

a connection that is designed to prevent separationunder the axial thrust induced by internal pressure,temperature fluctuations or ground movementwhilst still permitting angular deflection and/oraxial movement without impairing the efficiency ofthe jointNOTE See Appendix A.

2.6stringing

the placing of pipes in line on the ground ready forlaying

2.7surge pressure

pressure that is produced by a change in velocity ofthe moving fluid. Surge pressure may be positive ornegative

3 ApplicationsThe pipelines covered by this Section of BS 8010 aregenerally suitable for conveying water, sewage,trade waste, slurries, sludges, non-corrosive gases,brine and certain chemicals. Ductile iron pipes areused in distribution systems for natural and towngases and they may also be used in pipelines for theconveyance of these fuel gases under similar serviceconditions. For limits of pressure adopted by theBritish Gas Corporation in the United Kingdom andguidance in connection with the installation ofductile iron pipelines for gas, reference may be madeto IGE/TD/3 [1]. When used for the conveyance ofsewage, reference should be made to BS 8301 andCP 2005. Ductile iron is suitable for pipelines inlocations where ground instability, traffic loadingand frost effects present potential hazards and inareas where damage risks are high.

4 Safety4.1 General

The recommendations of this Section of BS 8010 areconsidered to be adequate for public safety underconditions usually encountered in ductile ironpipelines, including pipelines within towns, cities,water catchments and industrial areas. Attention iscalled to the need to consider measures to preventdamage or leakage arising from:

a) corrosive soil conditions;b) internal corrosion/erosion;c) external damage by mechanical equipmentused on other works;d) erosion or ground subsidence;e) any abnormal circumstances.

4.2 Preventative measures

Consideration should be given to the use ofpreventative measures such as the following:

a) additional external protection (see 19.2 );

1) In preparation.2) Definition repeated from BS 4772 which is currently under revision.


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b) additional internal linings (see 19.3 ) and/orlimitation of flow velocities;

c) provision of increased cover or a concrete coveras a protection against external mechanicaldamage, or erosion;d) for serious subsidence, additional flexible

joints, anchored joints, rafts or piling;e) indication of the presence of the pipeline withadditional markers particularly in congestedareas or areas where future development isknown to be planned, and adequate marking atriver and water course crossings;f) provision of protection from frost for pipelinesabove ground or in ducts.

5 InspectionThe integrity of a properly designed pipelinedepends more on the standards and quality ofinspection applied at all stages than on any othersingle feature.Particular attention should be given to inspection ofthe pipe and coating before installation for possibledamage, of the bedding of the pipeline, jointing andanchoring and to testing. Any sub-standardmaterials or workmanship detected should berectified or, where necessary, rejected, before any

further work is done.


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Subsection 2. Materials and availability

6 GeneralDuctile iron pipes and fittings should complywith BS 4772. Ductile iron possesses high tensilestrength, ductility and resistance to impactfracture, which makes it suitable for theapplications referred to in clause 3 . It is capable ofdeforming to a significant extent before fracture.

All materials should be compatible with theproducts that are to be conveyed in the pipeline.

All materials, including repair materials, likely tocome in contact with potable water should beincapable of permitting bacterial growth.Non-metallic materials should comply with therequirements for the effect of non-metallic materials

on water quality (see Appendix B).

7 Pipes7.1 Spigot and socket pipes

Ductile iron pipes are manufactured in accordancewith BS 4772 in lengths of 5.5 m for DN 80 toDN 800 inclusive and lengths of 8 m for DN 900 toDN 1600 inclusive.

A percentage of the pipes supplied may be of shorterlength, in accordance with BS 4772. Specialarrangements should be made for procuring shorterlengths, where these are considered necessary.

External diameters for metric size ductile iron pipescomplying with BS 4772 and metric size grey ironpipes complying with BS 4622 are such that thepipes are directly interchangeable. Metric sizeductile iron pipes are not directly interchangeablewith ductile or grey iron pipes in imperial sizes andappropriate change fittings should be used inaccordance with BS 4772.

7.2 Flanged pipes

Flanged ductile iron spun pipes are manufacturedby casting the pipe barrel centrifugally and thenwelding or screwing loose ductile iron flanges on tospecially prepared ends. Short lengths are oftensupplied with integrally cast flanges. The lengthsavailable will vary according to the source of supply.Flanged pipework is available in sizes DN 80 toDN 1600 inclusive.

7.3 Fittings

Fittings are generally of the all socket or flangedtype. BS 4772 permits the supply of fittings beyondthe specified range in certain aspects, such as:

a) laying dimensions;b) pressure rating;

c) permutations of branch/main diameters;d) configurations such as angle branches,crosses, etc;

e) joint ends, e.g. socket and spigot bends.Such fittings are deemed to comply with BS 4772

and are required to be marked as specified inBS 4772.

8 Valves8.1 Control valves

Control valves should comply with one of the BritishStandard specifications listed below.

Valves outside the range of sizes, or differing in typeor otherwise not complying with the specificationslisted may be used, provided that they have at leastequal strength and tightness and are capable of

withstanding the test requirements of theappropriate specifications and the testsrecommended in this Section of BS 8010.

A clear indication should be given on all valves ofthe direction of rotation needed to close the valve(see clause 12 ).

8.2 Air valves

Automatic air valves are available in a number offorms. The most common are single orifice, doubleorifice and kinetic. Reference should be made to themanufacturers recommendations.

9 FlangesDimensional details of flanges designated PN 10,PN 16, PN 25 and PN 40 should comply withBS 4772. These are dimensionally compatible withthe corresponding flanges in accordance withBS 4504. Unless otherwise specified by purchaser,PN 16 flanges are supplied for working pressures upto and including 16 bar.BS 4772 permits the use of high tensile steel bolts ofsmaller diameter than the corresponding low carbonsteel bolts, to facilitate manufacture andinstallation of larger diameter flanges. Such flangesare marked accordingly. Where high tensile boltsare used with flanges holed for low carbon steelbolts, special washers should be used in accordancewith the pipe manufacturers recommendations.

BS 5150 Cast iron wedge and double diskgate valves for general purposes.

BS 5152 Cast iron globe and globe stopand check valves for general

purposes.BS 5153 Cast iron check valves for

general purposes.

BS 5155 Specification for butterfly valves.

BS 5163 Double flanged cast iron wedgegate valves for waterworkspurposes.


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NOTE Flanges complying with other standards may besupplied against special orders.

10 Bolts, nuts and washersLow carbon steel bolts and nuts should comply withBS 4190 and high tensile steel bolts and nuts shouldcomply with BS 3692, minimum grade 8.8. Washersshould comply with BS 4320.

11 Gaskets11.1 General

Elastomeric components of gaskets should complywith the requirements of BS 2494 but othermaterials may be used if they have been proven to

be more suitable.The section of gaskets which is likely to come incontact with potable water, and gasket lubricants,should be incapable of permitting bacterial growthand should comply with the requirements for theeffect of materials on water quality(see Appendix B). Where the product conveyedmight have a deleterious effect on the gasket, thegasket should be provided with a protective tip ofsuitable material to isolate it from the contents ofthe pipeline.Maximum temperature limitations apply to the useof both natural and synthetic rubbers. Theselimitations vary with the type of material used andthe design of joints. The manufacturers adviceshould be sought if the likely temperature isbelow 0 C or above 50 C for mechanical joints orabove 60 C for push-in joints (see Appendix A).Gaskets should be protected from unnecessaryexposure to the effects of ultra-violet light andozone.NOTE Gaskets for flexible joints are frequently referred to as

joint rings.

11.2 Flange gaskets

The dimensions of gaskets for flanges designatedPN 10, PN 16, PN 25 and PN 40 should comply withBS 4865. The use of moulded gaskets designed tosuit a range of nominal pressure ratings ispermitted.


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Subsection 3. Design considerations

12 Pipeline designThe necessary hydraulic, structural and economicassessments should be made in accordance withrecognized practice [2] and [3].On new installations, consideration should be givento standardizing the direction of rotation needed toclose valves as clockwise.

A clear indication should be given on all valves ofthe direction of rotation needed to close the valve.The direction of rotation for closure should be thesame for any one pipeline installation.

13 Pipe design13.1 Works hydrostatic test pressure

Each pipe and fitting should be subjected to ahydrostatic test at the manufacturers works. Thepressure is required to be applied steadily andmaintained for a period sufficient to facilitateadequate inspection and not less than 15 s.NOTE Practical considerations limit the works hydrostatic testpressure to values which may be lower than the site testpressure.

13.2 Working pressure

Maximum working pressures for classes of pipesand fittings in accordance with BS 4772 are given inTable 1.

13.3 Surge pressures

The maximum surge pressure should be calculated.It is essential that the total pressure of the pipeline,including surge, does not exceed the pressure givenin Table 2. Should it be found that this pressure islikely to be exceeded then protective devices, such asthose described in clause 17 , should be installed toreduce the actual surge pressure so that the abovecriterion can be met.

13.4 Site hydrostatic test pressure

The site hydrostatic test pressures for ductile ironpipes and fittings and flanged joints in accordancewith BS 4772 should be not less than:

a) the working pressure + 5 bar;b) the maximum pressure under surge conditions;

but should not exceed the pressures given inTable 2.

14 Service and environmentalconsiderations14.1 General

The pipeline internal pressure may be subject tolimitations according to the service andenvironmental conditions in which the pipelineoperates.

14.2 Pipelines for liquids

The internal design pressures for the conveyance ofliquids should not exceed the pressures given inTable 1.

14.3 Pipelines for gases

Where the pipeline conveys a gas and there is,therefore, a considerable amount of energy stored inthe compressed gas in the pipeline, operatingpressures are restricted, see IGE/TD/3 [1]. Gasoperating pressures of the order of 8 bar may bepermitted in ductile iron pipelines depending on thetype of joint used and the environmental conditions.

At these pressures, consideration should be given tothe use of self-anchored mechanical joints.

NOTE Such joints provide restraint within the joint and thusdispense with the need for the traditional form of concrete thrustor anchor block (see Appendix A).

14.4 Pipelines for liquids and gases

14.4.1 Vacuum and external fluid pressure. Thepipeline should be capable of withstanding adifferential pressure brought about by internalvacuum or external fluid pressure(e.g. ground water). Where external pressureexceeds internal pressure by more than 1 bar, themanufacturers advice should be sought on thechoice of joint.14.4.2 External loading. Ductile iron pipes haveadequate strength for all normal installations whenoperating up to the maximum recommendedinternal pressures for each type of pipe.Where it is necessary to consider the effects ofexternal loads, calculations should be made inaccordance with one of several recognizedapproaches for computing trench loads, pipedeflection and pipe stress, some of which are listedin Appendix D. Consultation with manufacturersshould be made where abnormal laying conditionsare encountered, e.g. very deep or very shallow withvehicular loading.

14.4.3 Thermal insulation. Pipelines carrying waterthat have a depth of cover of at least 0.9 m are notnormally subject to freezing in the UK. Where thisdepth of cover cannot be achieved, adequate thermalinsulation should be provided and maintained(see CP 3009) or the system should be designed sothat there is always a flow through the pipeline.


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Table 1 Maximum hydraulic working pressures, exclusive of surge, for ductile iron pipes andfittings and flanged joints b

Nominalsize DN

Maximum hydraulic working pressures

Class K9 centrifugally cast pipes.Class K12 fittings (including flangepipes with integrally cast flanges)

Class K14 fittings(i.e. tees) and thicker

Flanged joints

PN 10 PN 16 PN 25 PN 40

bar c bar bar bar bar bar

80 60 60 10 16 25 40

100 60 60 10 16 25 40

150 60 60 10 16 25 40

200 60 50 10 16 25 40

250 53 40 10 16 25 40

300 47 40 10 16 25 40350 43 25 10 16 25 40

400 40 25 10 16 25 40

450 38 25 10 16 25 40

500 36 25 10 16 25 40

600 33 25 10 16 25 40

700 31 25 10 16 25

800 29 25 10 16 25

900 28 25 10 16 25

1 000 27 25 10 16 25

1 100 26 25 10 16 25

1 200 25 25 10 16 25

1 400 25 25 10 16 25

1 600 25 25 10 16 25NOTE 1 The maximum hydraulic working pressures of pipes and fittings in other classes will vary from those given in Table 1.The manufacturer should be consulted by the purchaser with regard to the production of such pipes and fittings.NOTE 2 Not all flexible joints are suitable for the pressures given in Table 1 and manufacturers should be consulted for themaximum hydraulic working pressures for particular joint designs.NOTE 3 The maximum hydraulic working pressures given for flanged joints apply to joints in which axial thrustsgenerated by internal pressure impose tensile stresses to the bolting. Where the bolting of flanged joints is not subjectedto tensile stresses created by axial thrusts from internal pressure (e.g. flanged valves connected by flanged sockets and flangedspigots in a spigot and socket non-anchored pipeline) the preferred PN 16 flange is capable of operating at the pressures

given for class K9 centrifugally cast pipe.NOTE 4 The maximum hydraulic working pressure ratings of flanged pipes and fittings is the rating of the flange or the rating ofthe pipe or fitting body, whichever is the lower.NOTE 5 The maximum hydraulic working pressures for pipes and fittings with flanges are applicable in the temperaturerange 10 C to 120 C. The manufacturer should be consulted in connection with maximum hydraulic working pressures fortemperatures outside this range and for information in respect of the suitability of specific gasket materials for operating atparticular temperatures.NOTE 6 Internal pressure induces higher stresses in fittings with branches, i.e. tees, than in fittings without branches,consequently the maximum hydraulic working pressures for tees in classes K14 and thicker are often lower than for class K12fittings without branches.b This table extracted from BS 4772.c 1 bar = 10 5 N/m 2 = 100 kPa.


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14.4.4 Temperature range. The temperature rangefor ductile iron pipelines is limited to that of the

gasket and is normally 0 C to 50 C or 60 C asappropriate (see clause 11 ). Special elastomericgaskets are available for the temperaturerange 10 C to 120 C with peaks of up to 130 C.Gaskets of other materials should be used fortemperatures beyond this extended range. Wheresubstantial variations in pipeline temperature mayoccur, provision should be made for thermalmovement. Flexible joints can accommodate normalthermal movement but special installations, such asbridge crossings where the movement may belocalized, may require the inclusion of a specialexpansion joint. Where pipelines are subjected to

substantial temperature variations, the effects offluid expansion of the internal pressure duringshut-down should be taken into account andpressure-relieving devices should be installed, ifrequired.

15 Pipelines on supports15.1 General

For pipelines or sections thereof carried onsupports, whether above ground, or buried inground having an inadequate load bearing capacity,the spacing of the supports depends upon the type of

joint and the load imposed on the pipeline. Accountshould be taken of the variation in length of pipespermitted in BS 4772. In all cases the beamstrength and the effect of load concentration atsupports should be checked. Adequate anchorage ofthe pipe to the support should be provided.

15.2 Pipelines on piers above ground

15.2.1 Flexibly jointed pipes. In normal installationswhere the pipe is required to carry only its own massand contents, one support per pipe, cradling the pipeover at least 90 and positioned immediately behindthe socket, is recommended.

NOTE This arrangement allows free articulation of the joint toaccommodate temperature movement or settling of the supportand ensures that each support carries an equal share of the load.

Where double spigot pipes and coupling are used,twin supports should be provided adjacent to and oneach side of the coupling.Where a pipeline is required to span more than onepipe length, e.g. at stream crossings, specialsupporting arrangements should be provided toallow a single span of two pipe lengths for socketand spigot pipes. The manufacturers advice shouldbe sought.

15.2.2 Flanged pipes. In installations where thepipe is required to carry only its own mass and

contents, the maximum span should be 8 m for sizesup to and including DN 250 and 12 m for sizesDN 300 and above. These spans may be increased insome circumstances, e.g. where the pipeline isworking at less than the rated pressure of the flangeor where the pipeline can be designed as acontinuous beam. The manufacturers advice shouldbe sought if increased spans are required.In all cases, the supports should be accuratelyaligned to ensure that each carries the designedload and cradles the pipe over at least 90.15.2.3 Pipes carrying superload. Themanufacturers advice should be sought where thepipes are required to carry loads greater than theirown mass and contents.

15.3 Pipelines on piers below ground

Pipelines laid on piers below ground may be subjectto extremely high loads and the manufacturersadvice should be sought. Where buried pipelines aresupported on wooden piers, a layer of isolatingmaterial, e.g. polyethylene sheet., should beinserted to prevent contact between the pier and thepipeline.

16 Access to the pipelineThe design should take full account of the pipelineroute and layout and ensure that adequate access isavailable to all parts of the pipeline. In largediameter pipes, internal access should be providedat suitable intervals for inspection, maintenanceand removal of obstructions and considerationshould be given to the need to provide a safe workingenvironment at all times. Where the use of scrapingor swabbing equipment is contemplated, provisionfor insertion and extraction and the removal ofdebris should be made at suitable locations.

17 Protective devices and underpressure connectionsProtective devices such as relief valves, surgechambers, pressure limiting stations, and automaticshutdown equipment should be provided wherenecessary, to ensure that the internal pressure atany point in the pipeline system does not exceed thesite hydrostatic test pressure of the pipes used. Thisis particularly important where any pipeline isconnected to another pipeline that is designed for ahigher operating pressure.


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17.1 In-line valves

Valves should be placed in the pipeline at intervalsso that sections of the pipeline can be isolated andemptied, if necessary, within a reasonable time andwithout too great a loss of material. At specialcrossings of major roads, water courses, andrailways or other such major points, or in extremelyhazardous locations, consideration should be givento the fitting of valves to isolate the sectionconcerned, having due regard to the material beingconveyed. Consideration should be given toproviding locking arrangements for valves,particularly if butterfly valves are used. Valvesshould be placed in positions which allow easyaccess and minimize interference with the use of theland. On larger pipelines in-line valves should befitted with devices to indicate the degree of opening.Bypass and hydrant arrangements are alsorecommended for ease of operating andrecommissioning sections.

17.2 Air valves

Air release valves should be provided betweenisolating valves on pipelines transporting liquid, forthe release and admission of air during filling andemptying of sections of the pipeline and for bleedingoff air released by solution during operation of thepipeline.

The type of air valve (small single orifice, largesingle orifice, double orifice or kinetic) should beselected after consideration of the duty and locationof the valve and the nature of liquid or gas to beconveyed. Air valves should be located at alltopographic high points and at high points on thepipeline with respect to the hydraulic gradient, andshould also be located at intervals along anysections where the gradient of the pipeline isparallel to or less than the hydraulic gradient. Onlong sections of pipeline of even gradient, air valvesshould be positioned at intervals of approximately 0.5 km, depending on the diameter ofpipeline and the air valve chosen. Air valves mayalso be required where the gradient of the pipelinechanges.The chamber housing an air valve should bedesigned to be free draining and free from risk offlooding or possible back siphonage. It is essentialthat the chamber housing an air valve is properlyventilated or provided with an adequate dischargeinto the atmosphere.

17.3 Drainage valves and washouts

Drainage valves should be provided betweenisolating valves for emptying sections of pipelinestransporting liquids and for flushing out thepipeline while in service. Drainage valves on waterpipelines should discharge to a watercourse or ditchthrough a washout pipe, although in urban areas itmay be necessary to construct a discharge chamberfrom which water is pumped to the surface waterdrainage system. On sewage pipelines, dischargeshould be made to a watertight chamber, controlledby a valve at the end of the washout pipe or bereturned to a convenient gravity foul sewer. Therelevant water or drainage authority should beconsulted with respect to the allowable size andlocation of washout discharge.NOTE The gradient between air release valves and betweendrainage valves should not normally be less than 1:250 althoughin special cases a minimum gradient of 1:400 may be used.

17.4 Under pressure connections

These specialized fittings are used to take branchesfrom existing live pipelines. Several designs areavailable and the particular manufacturersrecommendations should be followed.

18 Joints18.1 General

Flexible joints are of proprietary design and themanufacturers guidance should be soughtregarding interchangeability. The gasket and pipe

joint should be in accordance with themanufacturers dimensions and tolerances. Thegasket should be of such size and shape that, when

jointed in accordance with the manufacturersinstructions, it provides a positive seal within themanufacturers range of maximum joint deflectionand spigot withdrawal, under all combinations of

joint and gasket dimensional tolerances and in therange of pressures likely to occur along the pipelineincluding, where applicable, pressures belowatmospheric.

18.2 Types of joint

18.2.1 Joint selection. The pipeline should either bedesigned with sufficient flexibility or be providedwith sufficient restraint to prevent thermalmovement from causing excessive stresses in thepipes, excessive bending or unusual loads at joints,and to prevent undesirable forces at or adjacent topoints of connection to equipment or supportingstructures, or at anchors, valves and branches.

Account should also be taken of the effects of groundmovement. The type of joint to be used should beselected from those described below and illustratedin Appendix A.


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18.2.2 Flexible non-anchored joints. Flexiblenon-anchored joints are either of a push-in form(type 1, see Appendix A) or a mechanical form(types 2, 3 and 4, see Appendix A).Such joints offer little or no resistance against spigot

withdrawal due to internal pressure and dynamicloading and should usually be anchored at changesof direction and at blank ends (see 26.3 ).NOTE For low pressure gas installations, undergroundanchorage may not be required.

18.2.3 Flexible self-anchored joints. Flexibleself-anchored joints are either of the push-in form(types 6 and 7, see Appendix A) or mechanical form(type 8, see Appendix A). At changes in direction,blank ends, etc. these joints are an ideal alternativeto the traditional concrete anchor block especially inareas where the latter is undesirable on technicalgrounds, e.g. very soft ground conditions, remote

areas, in busy streets, etc. Careful considerationshould be given to the number of anchorage pointsin order to achieve satisfactory anchorage usingself-anchoring joints. It is rarely satisfactory toanchor the fitting alone since this will only move thepoint of possible separation further along thepipeline. However, it is not normally necessary toanchor the entire pipeline and the manufacturer orother expert authority should be consulted to giveguidance on the number of joints which need to beanchored.NOTE Specific recommendations for gas pipelines are given inIGE/TD/3 [1].

18.2.4 Rigid non-anchored joints. Where connectionsare to be made to existing pipelines, which may bein imperial sizes, it may be necessary to use thetraditional lead-caulked joint(type 9, see Appendix A). This joint allows nodeflection or spigot withdrawal and it is essentialthat it be anchored if there is any possibility of jointseparation.18.2.5 Rigid anchored joints. Rigid anchored jointsare of the flanged design (type 10, see Appendix A).They give no provision for deflection but areself-anchored and, therefore, no external anchorageis required at changes in direction or at blank ends.Self-anchoring flange adapters(type 5, see Appendix A) obviate the need forexternal anchorage but offer limited resistance todeflection and should be supported to prevent sagunder the mass of the pipe and its contents. It isessential that flanged joints are tightened to apredetermined torque using clean bolts, lubricatedon all mating surfaces, to ensure that the designload is obtained. Advice on recommended torquesshould be obtained from the manufacturer.


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Subsection 4. Protection against corrosion

19 Pipes and fittings19.1 General

Pipes should comply with the requirements forcorrosion protection specified in BS 4772. In sizesDN 80 to DN 800 the pipes are required to be zinccoated externally prior to bitumen coatinginternally and externally. For sizes DN 900 toDN 1600 pipes are required to be cement mortarlined and coated externally with bitumen. Allfittings are required to be coated internally andexternally with a bitumen material. The bitumen tobe used should comply with BS 3416 type II orBS 4147 type 1.

19.2 Additional external protection

In naturally corrosive soils (usually water-loggedheavy clays and saline and peat marshescharacterized by an electrical resistivitybelow 40 m) additional external protection shouldbe provided, e.g. by the correct application of loosepolyethylene sleeving as specified in BS 6076.NOTE Guidance on the correct application of polyethylenesleeving is available from pipe manufacturers and WaterResearch Centre Information and Guidance Note No. 4-50-01 [4].In made-up ground containing industrial debris, orin natural soils containing large, sharp-edgedstones, shale or flints, the polyethylene sleevingmay be liable to mechanical damage duringbackfilling. Selected backfill should be used toprevent damage to polyethylene sleeving.Where there is a risk of electrical interferencecurrents, or in abnormally corrosive ground,consideration should be given to the use of a morerobust protective coating, such as bitumensheathing or protective tape, alone or with cathodicprotection, and advice should be sought frommanufacturers or other expert advisory body.

19.3 Additional internal linings

Where the contents of the pipeline are conducive totuberculation, the pipes should be cement mortarlined or protected by other suitable linings.

20 Joints containing steel componentsWhere steel is used for bolts, nuts and washers,slip-on couplings, or anchorage devices, protectionfrom corrosion should be provided.Protection can be afforded by packing a suitablemastic material over the components and theadjacent external surface of the pipe so as to form acontinuous layer with a smooth profile which cansubsequently be wrapped with a compatible

cold-applied tape (e.g. petrolatum-based orplastic-backed types, depending on the masticused). Care should be taken to ensure there are novoids between the mastic and the pipe componentsubstrate, nor between the tape and the mastic.

Alternatively, heat-shrinkable sleeves can beobtained for the protection of certain profiles,e.g. flanged joints, bolted flange couplings.


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Subsection 5. Transport, handling and storage

NOTE See BS 8010-1 for procedures to be followed before anywork is commenced. Part 1 details procedures andrecommendations for work on land which are common to all types

of pipelines.

21 GeneralPipes should be loaded and handled with reasonablecare in accordance with the manufacturersrecommendations and should not be dropped.

Although ductile iron pipes are not susceptible tobreakage by impact loading, bad handling can resultin damaged coatings or linings and, in severe cases,deformation of the spigot, which could affect thesealing of the joint.Particular attention should be paid to the following

to prevent damage to pipes or joint components:a) securing of loads on lorry or wagon;b) correct use of suitable handling equipment;c) correct stacking methods;d) proper storage of joint components.

22 Transport All pipes should be secured to the lorry or railwaywagon during transit to prevent movement. Themeans of securing should be designed to minimizedamage to the coating. The pipes may be loaded onto the vehicle in pyramid or straight-sidedformation.When pyramid loaded, the pipes in the bottom layershould be restrained by the use of profiled cradles orbroad wooden wedges secured to the vehicleplatform. The pyramid should be built by resting thepipes between pairs of pipes in the preceding layerwith the sockets in successive layers reversed.Straight-sided loading should only be used wherevehicles have purpose designed supports along thesides of the vehicle platform or where special cradlesseparating the layers are used, or where pipes arebundled.

23 Handling and storage23.1 Off-loading by crane

It is essential that pipe masses, type of stacking,outreach required and site conditions be taken intoaccount when determining the suitability of liftingequipment. The lifting machine should be of thetype which retains the load safely in the event of apower failure. Off-loading should be carried outsmoothly and without snatch.Where pipes up to and including DN 400 have beenbundled, it is essential that the bundles be

off-loaded using fork-lifts or cranes with slingsaround the complete bundle. It is essential thatbundles are NOT lifted by means of their retainingstraps.

When cranes are used for off-loading individualpipes, slings or lifting beams with purpose designed

padded hooks should always be used.23.2 Off-loading without crane

Where lifting gear is not available and the mass ofthe pipe permits (normally DN 250 max.),individual pipes should be off-loaded by rolling themdown a ramp formed of timber skids extending fromthe vehicle side to the ground. During thisoperation, suitable steadying ropes should be usedto prevent the pipes from rolling down at excessivespeeds and striking other pipes or objects on theground.

23.3 Stacking non-bundled pipes

23.3.1 General . Pipes being taken to a centralstockground for storage and held pending furtherdistribution should be arranged in stacks. Thestacking area should provide a firm foundation witha suitable approach road for vehicles. Stacks shouldbe arranged so as to provide safe vehicular andpedestrian access. During stacking and removaloperations, safe access to the top of the stack isessential. In bad weather conditions, when pipesurfaces may become slippery, consideration shouldbe given to the use of lightweight stagings placed ontop of the stacks. Pipes should be stacked on a baseof raised wooden battens atleast 100 mm thick 225 mm wide. The battensshould be positioned approximately 600 mm fromeach end of the pipe. The bottom layer of pipesshould be securely anchored. Three types ofstacking are recommended:

a) square stacking: suitable for pipes up to andincluding DN 400b) parallel stacking using timber: suitable forpipes of all sizes;c) pyramid stacking: suitable for pipes of all sizes.

23.3.2 Square stacking . Each tier of pipes should bepositioned with their axes at right angles to those ofthe preceding tier to form a stable and compactstack. The sockets of the pipes in each tier should beat the same end, except for the two end pipes whichshould be reversed to lock the tiers in position.

Alternatively, the sockets of alternate pipes in eachtier may be reversed. The pipes rest directly uponthose beneath and extra care should be exercisedwhen lowering the pipes into position to preventdamage to the protective coating.


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23.3.3 Parallel stacking using timbers . For thismethod of stacking, two timber battens of sufficient

strength should be placed across the pipes betweeneach tier, approximately 600 mm from the pipeends. The sockets of pipes in each successive tiershould be reversed and the battens should be ofsufficient thickness to avoid metal to metal contact.

An adequate number of chocks should be wedgedunder the outer pipes of each tier and nailed to thetimber bearers to ensure stability.NOTE Pipes may be rolled into position along the battens, thusfacilitating stacking or removal from the end of the stack.

23.3.4 Pyramid stacking . In pyramid stacks, eachpipe nestles between the two pipes immediatelybeneath it and care should be exercised when

lowering pipes into position. It is essential that theend pipes of the bottom tier be securely anchoredalong their length with chocks preferably fixed totimbers running the width of the stack. The axes ofall pipes should be in the same direction, and thesockets should be reversed in successive tiers.23.3.5 Stacking heights . The heights of stacksshould be determined by consideration of:

a) the stresses on the lowest layer of pipes in thestack;b) the total lift given by the available crane; andc) the facilites available to ensure stable stacking.

All these factors should be taken into considerationand the stacking heights should not exceed those inTable 3.

Table 3 Stacking heights

23.3.6 Pipes having special external protection .Wherever possible, pipes with special external

protections should not be stacked but should be laidout in a single layer and supported on the shoulderof the socket and the unprotected spigot end, so thatthe whole barrel is clear of the ground. If the spaceavailable is limited, then reduced stacking may bepermissible, in such circumstances themanufacturer should be consulted. Care should beexercised when handling such pipes to avoiddamaging the protection. They should be lifted byhooks engaging in the socket and spigot ends. Thehooks should be as wide as possible and padded withrubber to minimize damage to cement linings.Smaller sizes, up to DN 400, may be lifted with wide

fabric slings. Wire ropes or chain slings should notbe used.

23.4 Stacking bundled pipes

23.4.1 General . The stacking area should provide afirm foundation with a suitable approach road forvehicles. Stacks should be arranged to provide safevehicular and pedestrian access. Bundles areprovided with base timbers and these can be laiddirectly onto a good, level, hard-standing surface.The bundles should be stacked one on top of theother with the axes of pipes parallel.The maximum recommended stacking height on a

good, level, hard-standing surface is five bundles.However the maximum stacking height for anyparticular location should be determined by acompetent supervisor.23.4.2 Breaking down of pipe bundles . It is essentialthat bundles which have been stacked be lowered toground level before the straps are cut. Specialprecautions should be taken when cutting thestraps of the bundles and when removing pipes fromindividual tiers. The manufacturersrecommendations should be followed.

23.5 Stringing

Pipes should be wedged or pinned to preventaccidental movement.NOTE See also BS 8010-1.

Nominal size DN Maximum number of layers instack

80 18

100 16

150 14

200 12

250 10300 8

350 and 400 7

450 and 500 6

600 4

700 3

800 and above 2


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Subsection 6. Construction

24 TrenchingNOTE See BS 8010-1 for general considerations regarding

trenching.The width of trench should be as narrow aspracticable, taking into consideration the type ofnative soil and backfill and the compactionequipment required. Where mechanical compactionis required, the width of the trench should betypically pipe o.d. + 600 mm but may be increasedfor heavier equipment.Where mechanical compaction is not required, thewidth of trench should be typically pipeo.d. + 300 mm but may be reduced where narrowtrenching techniques are employed.

The trench bottom should be prepared to give aneven bed for the barrel of the pipe and to ensureproper alignment. The bed should be provided with

joint holes to ensure that the pipe rests on the barreland not on the socket.In rocky ground, the trench should be excavated atleast 100 mm deeper than normally required andthen made up to the required level by the addition ofwell compacted, selected bedding material orimported granular bedding.Where a change in direction is being made byutilizing the lateral deflection available fromflexible joints, the trench should be cut to givesufficient room for the joint to be made with thepipes in line, the pipe being deflected after the jointhas been made. Deflection of any as-laid joint shouldnot exceed 75 % of the maximum deflectionrecommended by the manufacturer(see Appendix A) to allow for subsequent movement.

25 Pipe inspection, repairs and cutting25.1 Inspection

Ductile iron pipes are not normally susceptible tohandling and transport damage but mishandlingcan damage protective coatings and linings or

bruise and deform jointing surfaces and may createovality. In the case of pipes to be used with aself-anchoring type 8 joint (see Appendix A), thepresence, at the spigot end, of the groove forretaining the circlip should be checked.

25.2 Repairs of damaged external coatings andlinings

25.2.1 Damage to concrete lining or zinc coatingshould be repaired in accordance with BS 4772.25.2.2 Coatings and linings . Damage should bemade good with a material which is compatible withthe original material and offers equivalentprotection.

25.2.3 Special external coatings and linings .Damaged coatings and linings should be made good.

The materials and method to be employed willdepend upon the material originally used and theprotection required and should comply with themanufacturers recommendations.

25.3 Cutting

25.3.1 General . Methods of cutting ductile iron pipesshould be selected from the following.

a) By hand or power operated hacksaw , usingblades having teeth at a pitch of 1 mm (24 teethper inch).NOTE This method is suitable for pipes up to DN 200.

b) By manually operated wheel cutter , withwheels specifically designed for use with ductileiron.NOTE This type of cutter is suitable for pipes up to DN 300.

c) By pipe cutting machine , using cutting tools ofthe simple lathe or milling saw type. A 7 frontrake is recommended for cutter heads inmachines using lathe type cutting tools.NOTE Pipe cutting machines are available throughout thediameter range and are usually driven mechanically, e.g. bycompressed air motor, although for pipes smaller thanDN 300 a hand operated windlass may be used.

d) By power driven abrasive wheel cuttingmachine , with abrasive discs fitted to suitablehand tools, usually driven by compressed air orsmall internal combustion engines. It isimportant that abrasive disc cutting equipment isspecifically designed for use with ductile ironpipe, that it is used by a competent operator andthat the disc type, size and spindle speed of theequipment are compatible.NOTE This is the most widely used method for cuttingductile iron pipes. It has the advantage of being suitable for allsizes, with no need for adjustment to suit pipe size or to attachmachinery to the pipe.

25.3.2 End preparation of cut pipes for jointing . Anyburrs or sharp edges left after cutting should be

trimmed off by filing or grinding.Where self-anchored joints of type 8(see Appendix A) are to be used, the cut end of thepipe may be grooved and chamfered on site bymeans of one of a number of proprietary lightweightcutting machines specially adapted for the purpose.Where joints of type 1 or 6 (see Appendix A) are tobe used, the cut ends should be chamfered by filingor grinding similar to the original spigot ends.


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For sizes up to and including DN 300 and for largersizes where the pipes are marked as being suitable

for cutting, the diameter will be within the tapetolerances given in BS 4772, but may be outside theovality tolerances given in BS 4772. Manufacturersguidance should be sought as to re-rounding. Otherpipes, when cut, may have tape diameters outsidethe tolerance and these should be ground ormachined to the tolerances given in BS 4772. Theground or machined area of spigot projecting out ofthe socket-face should be coated to give a similardegree of protection as the rest of the pipe, see 25.2 .

26 Laying, jointing and anchoring26.1 Laying

Pipes should at all times be handled with care inaccordance with the manufacturersrecommendations. Pipes should be lowered into thetrench with tackle suitable for the mass of the pipes.

A mobile crane or a well designed set of shear legsshould be used and the positioning of the slingchecked, when the pipe is just clear of the ground, toensure a proper balance. Where lifting equipment isnot available, small diameter pipes (normallyDN 250 max.) should be lowered by hand usingsuitable ropes.

All persons should vacate the section of the trench

into which the pipe is being lowered. All construction debris should be cleared from theinside of the pipe either before or just after a joint ismade. This can be done by passing a pull-throughalong the pipe, or by hand, depending on thediameter of the pipe. When laying is not in progress,a temporary end-closure should be fitted securely tothe open end of the pipeline. This may make thepipes buoyant in the event of the trench becomingflooded, in which case the pipes should be held downeither by partial re-filling of the trench or bytemporary strutting.

26.2 Jointing26.2.1 General . Jointing procedures will varyaccording to the type of joint being used.Basic conditions which should be ensured for alltypes of joint are:

a) cleanliness of all parts;b) correct location of components;c) centralization of spigot within socket; andd) strict compliance with the manufacturers

jointing instructions.

The inside of sockets and the outside of spigotsshould be cleaned for at least the insertion depth for

each joint. Glands and gaskets should be wipedclean and inspected for damage. Where lifting gearhas been used to place the pipe in the trench itshould be used to support the pipe and assist incentralizing the spigot in the socket. Where thepipeline is suspected to be subject to movement dueto ground settlement or temperature variation, asuitable gap should be left between the end of thespigot and the bottom of the socket.26.2.2 Jointing pipes laid on gradients . If pipes arelaid on steep gradients where the soil/pipe friction islow, care should be taken to ensure that no excessivespigot entry or withdrawal occurs. As soon as the

joint assembly has been made, the pipe should beheld in place and the trench backfilled over thebarrel of the pipe.Unless the gradient is 1:2 or steeper, anchorages arenot normally necessary. However, for these verysteep gradients, self-anchoring joints or anchorblocks at each socket are recommended.For pipelines laid above ground on steep gradients,self-anchoring joints should be used.

26.3 Anchoring

Unless an adequate length of the line is fitted withself-anchoring joints, external anchorage should beprovided at blank ends, bends, tees, tapers andvalves to resist the thrust arising from internalpressure and dynamic loading. Anchors and thrustblocks should be designed to withstand the forcesresulting from the internal pressure when thepipeline is under test, taking into account the safebearing pressure of the surrounding soil.Consideration should also be given to forces on thepipeline, when empty, and precautions takenagainst possible flotation. Where possible, concreteanchor blocks should be of such a shape as to leavethe joint area clear.

27 BackfillingNOTE See BS 8010-1 for general considerations regardingbackfilling, clearing-up and reinstatement.Wherever possible, in order to minimizemisalignment of the bed with resulting shear acrossthe joint, backfill material should not be placed on apipe until the succeeding pipe is laid and jointed. If

joints are to be individually inspected duringhydrostatic testing, it is not practicable to backfillthe trench completely. It is important, however, tobackfill over the barrel of each pipe and to compactthe backfill or take other such measures to prevent

movement of pipes during the testing processes.


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On pipes greater than DN 600 special attentionshould be given to the compaction of the backfill

material under the haunch of the pipe.In most cases tamped, selected excavated material,from the trench will be suitable for the backfill. Thematerial selected for backfill should exclude debris,organic material, frozen soil, large stones, rocks,tree roots or similar large objects. In instances ofexcessive depths, high vehicular loading orsuper-loading from buildings, etc. or of very poor soilproperties it may be necessary to import backfill(see also 19.2 ). The manufacturer or other advisorybody should be consulted where any doubt exists.


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Subsection 7. Cleaning, testing and commissioning

28 CleaningBefore a pipeline can be considered ready for serviceit should be cleaned internally as thoroughly aspossible to ensure that no foreign matter remainsinside the pipe. The first stage of the cleaningoperation, i.e. cleaning individual pipes during

jointing, should be performed in accordance with26.1 . Pigs of suitable design, e.g. polyurethaneswabs, may be used provided that the pipeline hasbeen constructed to allow the passage of such pigs.Where the pipeline is to be tested with water, thefilling and emptying of the pipeline may to someextent cleanse the line.

29 Testing29.1 General

All pipelines should be tested before being broughtinto service. The type of test will depend upon thefluid which the pipeline will eventually convey andmay be a hydrostatic test or a pneumatic test, orboth. The hydrostatic test is safer to carry out andcan be made more stringent as regards the strengthof a completed pipeline. It should be used whereverpracticable, but it has certain disadvantages whenapplied to pipelines designed to carry gases. Withthe exception of testing non-pressure pipelines atvery low pressures (100 mm water gauge),pneumatic testing is to be avoided, if possible,because of the hazards inherent in containing largevolumes of compressed air. However, there may beoccasions when hydrostatic testing is not possibleand air is the only medium available for applying atest pressure. For pneumatic testing of gas pipelinessee 29.3 .

29.2 Hydrostatic testing

29.2.1 General . The completed pipeline may betested either in one length or in sections; the lengthof section should be decided by considering:

a) the availability of suitable water;b) the number of joints to be inspected; andc) the difference in elevation between one part ofthe pipeline and another.

Where joints are left uncovered until after testing,sufficient material should be backfilled over thecentre of each pipe to prevent movement under thetest pressure (see clause 27 ).29.2.2 Initial procedure . It is prudent to begintesting any particular pipeline in comparativelyshort lengths and to increase the length of testsection progressively as experience is gained, untillengths of about 1.5 km or more are tested in onesection, subject to consideration of the length oftrench which it is permissible to leave open inparticular circumstances.

Each test section should be properly sealed off,preferably with special stop ends, designed for the

safe introduction and disposal of the test water andrelease of air, which should be secured by adequatetemporary anchors.The thrust on the stop ends should be calculated onthe full spigot external diameter and on the anchorsdesigned to resist it.NOTE It may often be economical to provide a concrete anchorblock which has subsequently to be demolished, rather than riskmovement of the stop ends during testing. Hydraulic jacks maybe inserted between temporary anchors and stop ends to take upany horizontal movement of the temporary anchors.

All permanent anchors (see 26.3 ) should be inposition and, if of concrete, should have developedadequate strength before testing begins. The sectionunder test should be filled with clean, disinfectedwater, taking care that all air is displaced throughvents at high points or by using a pig or a sphere.

After filling, the pipeline should be left at workingpressure for a period in order to achieve conditionsas stable as possible for testing. The length of thisperiod will depend upon many factors, such asmovement of the pipeline under pressure, thequantity of air trapped and whether the pipeline hasa cement mortar lining which absorbs water. Ifpressure measurements are not made at the lowestpoint of the section, an allowance should be made forthe static head between the lowest point and thepoint at measurement to ensure that the maximumpressure is not exceeded at the lowest point.29.2.3 Test procedure . Site hydrostatic testpressures should be in accordance with 13.4 .The pressure in the pipeline should be raisedsteadily until the site test pressure is reached in thelowest part of the section. This pressure should bemaintained, by pumping if necessary, for a periodof 1 h. The pump should then be disconnected andno further water permitted to enter the pipeline fora period of 1 h. At the end of this period, the originalpressure should be restored by pumping and the loss

measured by drawing off water from the pipelineuntil the pressure reached at the end of the test isreached again.The acceptable loss should be clearly specified andthe test should be repeated until this is achieved.The generally accepted loss for non-absorbentpipelines such as steel and iron is 0.02 L/mm ofnominal bore per kilometre of pipeline per 24 h perbar of pressure applied head (calculated as theaverage head applied to the section under test). Therate of loss should be plotted graphically to showwhen absorption is substantially complete.

A more stringent requirement may be necessary forpipelines carrying fluids other than water.29.2.4 Detection of leaks . If the test is notsatisfactory, the fault should be found and rectified.


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Section 7

Consideration should be given to leak detectionmethods such as:

a) visual inspection of pipeline, especially each joint, if not covered by the backfill;b) aural inspection, using a stethoscope orlistening stick in contact with the pipeline;c) use of electronic listening devices includingleak noise correlators which detect and amplifythe sound of any escaping fluid; actual contactbetween the probe and the pipe may or may notbe essential;d) use of a bar probe to detect signs of water in thevicinity of joints, if backfilled;e) introduction of a gas compound into the testwater, using a gas detection device to detect thepresence of any gas that has escaped through theleak.

Where there is difficulty in locating a fault, thesection under test should be subdivided and eachpart tested separately.NOTE A pneumatic test with an air pressure notexceeding 2 bar may be used to detect leaks in pipelines laid inwater-logged ground.

29.2.5 Final procedure . After all sections have been jointed together on completion of section testing, atest should be carried out on the complete pipeline

in accordance with 29.2.3 . During the test, all workwhich has not been subject to sectional tests shouldbe inspected.29.2.6 Disposal of water . It is important to ensurethat proper arrangements are made for the disposalof water from the pipeline after completion ofhydrostatic testing and that all consents which maybe required from land owners and occupiers, andfrom river drainage and water authorities havebeen obtained.NOTE With some liquids, notably oil and oil products, it may benecessary to provide temporary interceptors to prevent any oilbeing discharged with the water. In some cases, e.g. heavilychlorinated water, some treatment may be necessary before finaldisposal.

29.3 Pneumatic testing of gas pipelines

29.3.1 General . A pneumatic test should be carriedout to prove the tightness of joints rather than thestrength of the pipeline.NOTE. The air pressure to be applied will vary according tocircumstances.

29.3.2 Safety precautions during pneumatic testing .Pneumatic testing could in the event of failure, giverise to a serious explosion. During each test, it isimportant that all persons not engaged in the testoperations be kept away from the section of the

pipeline under test.

Persons engaged on pneumatic testing operationsshould remain in a safe place whilst pressure is

being raised and during the whole of the time thepressure is maintained. No approach should bemade for inspection or any other purpose until thepressure has been reduced to the maximum workingpressure.If these precautions are not possible or if hazards topersons and property are likely to arise duringpneumatic testing, then a hydrostatic test should beapplied first, in accordance with 29.2 .29.3.3 Test procedure . Reference should be made toIGE/TD/3 [1]. Ductile iron pipelines for conveyinggas should be pneumatically tested at not less thanthe maximum gas working pressure. The maximumpneumatic pressure applied should not exceed thatspecified for any particular joint or any otherpressure restriction that may be imposed as a resultof local conditions or regulations (see 14.3 ).29.3.4 Detection of leaks . If the pneumatic test is notsatisfactory the fault should be found and rectified.Consideration should be given to leak detectionmethods such as:

a) application of soapy water or similar solutionaround the joints;b) aural inspection using a stethoscope orlistening stick;c) use of electronic listening device;d) introduction of halogen gas into the pipelineand use of a suitable detector to indicate thepresence of gas outside the pipeline; ande) introduction of a distinctive odorant into thepipeline.

30 Commissioning30.1 General

The procedure for commissioning a completedpipeline will vary according to whether it has been

hydrostatically or pneumatically tested andwhether it is to convey a liquid or a gas.

30.2 Liquid pipelines

Pipelines intended to convey liquids are usuallytested hydrostatically and, therefore,commissioning consists of displacing the test waterfrom the line by the liquid to be conveyed. Visibledirt and debris should have been removed eithermanually or by the use of cleaning pigs beforetesting (see 26.1 and clause 28 ). Filling andemptying the pipeline with test water may also helpcleanse the line. Where air release and drainage

valves have been installed, the test water may bedrained and the pipeline refilled with the liquid tobe conveyed.


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If the pipeline is intended to carry potable water, itshould be thoroughly flushed with clean water,

where feasible. It should then be disinfected bycontact for 24 h with water containing atleast 20 mg/L of free chlorine, then emptied andfilled with potable water. The chlorinated watershould receive treatment to dilute the chlorine to anacceptable level before discharge to sewer orwatercourse. After a further 24 h, samples should betaken for bacteriological examination at a number ofpoints along the pipeline and at all extremities.The pipeline should not be brought into service untilthe water at each sampling point, having stood inthe pipeline for 24 h, has maintained a satisfactorypotable standard as described in DHSSReport 71 [5].30.3 Gas pipelines

Reference should be made to IGE/TD/3 [1]. Whenthe pipeline has been subjected to hydrostatic test,the water should be drained from the pipeline. Insome cases it may be found convenient toincorporate air release and drainage valves in theconstruction of the pipeline and to blank off thesefittings after the line has been emptied.

Air-propelled swabs may subsequently be used toassist in removing any remaining water.If the pipeline is intended to convey a flammable gasthen, when it is considered to be sufficiently dry, thepipeline should be purged by introducing a slug ofinert gas, such as nitrogen. The slug should be ofsufficient length to preclude the possibility of thegas to be conveyed coming into contact with the airin the pipeline.The gas to be conveyed should be admittedimmediately after the nitrogen slug at a carefullymaintained rate to ensure turbulent flow conditionsalong the pipeline. The gas should be turned on asthe nitrogen is turned off.Proper venting arrangements should be provided at

the end of the pipeline and should consist of:a) a vent pipe connected to the pipeline through avalved connection;b) a small, valved sampling connection;c) a pressure gauge connected to the pipeline; andd) a suitable detection apparatus to check thechange from air to nitrogen and from nitrogen togas or the change from air to gas where purgingis not required.

For gases that are lighter than air, the vent pipe(see item a) should be vertical and should terminate

not less than 2 m above ground level. For gases thatare heavier than air, the vent pipe should lead totemporary storage where any gas/nitrogen mixturecan be retained and disposed of later. For flammablegases, an efficient flame arresting terminal shouldbe fitted at the end of the vent pipe.When 100 % gas is being received either theregulated flow should be closed down and switchedto the normal operating route or the pipeline shouldbe closed down ready for use when required. In thelatter case, the pipeline should be closed downunder a positive pressure which should bemonitored regularly until the pipeline is broughtinto normal operating service.

All temporary connections used during the testing,purging and commissioning procedure should beclosed off and securely blanked before the pipeline isbrought up to full operating pressure.


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Appendix A Types of joint for ductileiron pipelines

A.0 IntroductionJoints are generally of a type using elastomericgaskets as a sealing medium. The most commonlyused types of joint are described in A.1 to A.10 . Theactual details may differ from one manufacturer toanother.The joint deflections stated are the maximumrecommended by the manufacturers and areintended to provide for changes in gradient andlevel, slow curves, the adjustment of angle at bendsand any subsequent movement. Deflection atinstallation should not exceed 75 % of the maximumrecommended and, where subsequent movement isanticipated, consideration should be given tofurther limitation of the installed deflection.

A.1 Push-in joints (type 1)NOTE See Figure 1.

Push-in joints are made on pipes having achamfered plain spigot at one end and a speciallyformed socket at the other. The seal is effected bymeans of a gasket placed within the socket before

jointing. Entry of the spigot into the socket throughthis gasket completes the joint. Little effort isrequired to complete assembly in the case of smallerpipes; tackle to joint larger pipes is supplied by themanufacturer.Push-in joints are available throughout the pipediameter range, DN 80 to DN 1600. They can bedeflected 5 in any direction for pipes of diameter upto and including DN 300 and 4 for pipes of diameterDN 350 and above, and can accommodateconsiderable axial movement.

A.2 Bolted mechanical joints (type 2)NOTE See Figure 2.

Bolted mechanical joints are made on pipes havinga plain spigot at one end and a specially formedsocket at the other. The spigot is entered centrallyinto the socket and the seal is effected by thecompression of a wedge-shaped gasket between aseating on the inside of the socket and the externalsurface of the spigot. Compression is achieved bymeans of a pressure gland and bolts passingthrough a circumferential flange cast integrally onthe face of the socket.Bolted mechanical joints are currently available forpipes in the range DN 80 to DN 600 and alldiameters of fittings DN 80 to DN 1600. The jointmay be deflected up to 4 in any direction and iscapable of considerable axial movement.

A.3 Slip-on couplings (type 3)NOTE See Figure 3.

Slip-on couplings are designed for use with plainend pipes. The coupling consists of a sleeve, at theends of which are wedge-shaped rubber gaskets andflanges held together by bolts. Tightening of thebolts compresses the gaskets between the sleeve andpipe to seal the joint.The coupling sleeve may have an internal rib(central register) which acts as a locating stop, butsleeves without this rib are supplied to facilitate theinsertion of closing lengths in a pipeline. Thecoupling includes steel components which should besuitably protected.

Figure 1 Push-in-joint (type 1)

Figure 2 Bolted mechanical joint (type 2)


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Slip-on couplings are currently available in the pipediameter range DN 80 to DN 1600 and special

couplings to connect pipes of different diametersand/or materials are available. Several designs areavailable and the manufacturers advice regardingdeflection and withdrawal should be sought.

A.4 Flange adapters (type 4)NOTE See Figure 4.

Flange adapters are designed to connect flangedpipe or any flanged fitting to plain-ended pipe. Theyconsist of a flange and sleeve piece, a wedge-shapedrubber gasket and a loose gland fastened to themain body by bolts. Tightening of the boltscompresses the gasket between the sleeve and pipe

to seal the joint. The flange joint is made usingstandard jointing procedures for flanged pipework.The adapter includes steel components whichshould be suitably protected.Several designs are available and manufacturersadvice regarding deflection and withdrawal shouldbe sought. Flange adapters do not provide theanchorage and rigidity of a flanged joint and shouldbe supported or anchored accordingly.

A.5 Self-anchoring flange adapters (type 5)NOTE See Figure 5.

Self-anchoring flange adapters are used to connect

pipes in the same way as type 10 flanged joints butincorporate special anchor segments. They consist ofa loose flange, bolts and one or more rubber seals,which carry anchoring segments. Tightening of thebolts seals both the flanges and between the pipeand adapter, and also forces the anchor segmentsinto contact with the pipe. The adapter is made ofductile iron.Self-anchoring flange adapters are available in therange DN 80 to DN 300. Being self-anchoring theyobviate the need for external anchorage but offerlimited resistance to deflection and require supportto prevent sag under self-weight, the mass of the

pipe and its contents.

Figure 3 Slip-on coupling (type 3)

Figure 4 Flange adapter (type 4)


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A.8 Self-anchoring bolted mechanical joints(type 8)

NOTE See Figure 8.This is a modified form of the type 2 boltedmechanical joint incorporating a ductile iron circlipwhich is located in a chamber or groove cast in thesocket and which registers with a groove speciallymachined in the spigot. This joint is used primarilyfor gas pipelines at pressures of up to 8 bar working.IGE/TD/3 [1] lays down working pressures andtrench conditions where this type of joint should beused in gas pipelines. When the circlip is fitted, the

joint becomes self-anchoring and obviates the use ofanchor blocks.This joint is available in the range of sizes DN 100to DN 450 excluding DN 350.

A special tool is required to dismantle the joint.The joint is capable of 2 angular deflection in anydirection.

A.9 Lead-caulked joints (type 9)NOTE See Figure 9.

Lead-caulked joints are not recommended for use innew installations. Their use should be restricted toconnections and repairs to existing pipelines whereno suitable alternatives are available.The lead-caulked joints are made on pipes having anenlarged socket at one end and a plain or beaded

spigot at the other. The spigot is entered centrallyinto the socket of the adjacent pipe and a quantity ofspun yarn compressed into the annulus until this isfilled to approximately half the socket depth. Moltenlead is poured into the remaining annulus and, aftercooling, is caulked using a suitable tool. Fibrous leadmay be substituted for molten lead.This joint allows no deflection or spigot withdrawaland it is essential that it be anchored if there is anypossibility of joint separation.

Figure 7 Self-anchoring tie-bar joint(type 7)

Figure 8 Self-anchoring bolted mechanical joint (type 8)


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A.10 Flanged joints (type 10)NOTE See Figure 10.

Flanged joints are made on pipes by welding,

screwing or integrally casting flanges onto the endof the standard pipe. The seal is usually effected bymeans of a flat rubber gasket compressed betweenthe flanges by means of bolts which also serve toconnect the pipes rigidly. Gaskets of othermaterials, both metallic and non-metallic, areavailable for special applications.

Appendix B Effect of non-metallicmaterials on water quality

When used under the conditions for which they aredesigned, non-metallic materials in contact with orlikely to come into contact with potable water shallnot constitute a toxic hazard, shall not supportmicrobial growth and shall not give rise tounpleasant taste or odour, cloudiness ordiscoloration of the water.

Concentrations of substances, chemicals andbiological agents leached from materials in contactwith water, and measurements oforganoleptic/physical parameters shall not exceedthe maximum values recommended by the WorldHealth Organization in its publication Guidelinesfor drinking water quality Vol 1Recommendations (WHO, Geneva 1984) or asrequired by the EEC Council Directive of 15 July1980 relating to the quality of water intended forhuman consumption (Official Journal of theEuropean Communities L229 pp 11-29), whicheverin each case is the more stringent.

Figure 9 Lead-caulked joint (type 9)

Figure 10 Flanged joint (type 10)


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NOTE 1 Requirements for the testing of non-metallic materialsin these respects are set out in the UK Water Fittings ByelawsScheme Information and Guidance Note No. 5-01-02,

ISSN 0267-0313 obtainable from the Water Research Centre,Water Byelaws Advisory Service, 660 Ajax Avenue, Slough,Berkshire SL1 4BG.NOTE 2 Pending the determination of suitable means ofcharacterizing the toxicity of leachates from materials in contactwith potable water, materials approved by the Department of theEnvironment Committee on Chemicals and Materials ofConstruction for use in Public Water Supply and SwimmingPools are considered free from toxic hazard for the purposes ofcompliance with this appendix. A list of approved chemicals andmaterials is available from the Technical Secretary of thatCommittee at the Department of the Environment, WaterDivision, Romney House, 43 Marsham Street, LondonSW1P 3PY.NOTE 3 Products manufactured for installation and use in theUnited Kingdom which are verified and listed under the UK

Water Fittings Byelaws Scheme administered by the WaterResearch Centre (address as in note 1) are deemed to satisfy therequirements detailed in this appendix.

Appendix C References

1. INSTITUTION OF GAS ENGINEERS.Recommendations on transmission and distributionpractice. Technical Document IGE/TD/3 . Secondedition, 1983.2. HYDRAULICS RESEARCH LTD. Charts for thehydraulic design of channels and pipes. Fifthedition, 1983.

3. HYDRAULICS RESEARCH LTD. Tables for thehydraulic design of pipes and sewers. Fourthedition, 1983.4. WATER RESEARCH CENTRE. Information andGuidance Note No . 4-50-01.5. DEPARTMENT OF HEALTH AND SOCIALSERVICES. The bacteriological examination ofwater supplies. DHSS Report 71 , 1982.

Appendix D Further reading

These documents are listed for information andguidance. The list should not be assumed to becomplete or exclusive. Where there are differencesthe advice of this standard should be followed or anengineers decision taken.TRANSPORT AND ROAD RESEARCHLABORATORY. A guide to design loadings for rigidpipes 3) . TRRL , 1983.WATER RESEARCH CENTRE AND WATER

AUTHORITIES ASSOCIATION. Civil engineeringspecification for the water industry. 1984.WATER RESEARCH CENTRE. Information and

Guidance Notes Nos. 4-21-01 and 4-51-01 .CONSTRUCTION INDUSTRY RESEARCH ANDINFORMATION ASSOCIATION. TrenchingPractice. CIRIA Report 97 .NATIONAL WATER COUNCIL. Water supplyhygiene. Occasional Technical Paper No. 2 .Manufacturers literature.

3) This document is for guidance on vehicular loading only.


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Publications referred to

BS 2494, Specification for elastomeric joint rings for pipework and pipelines.BS 3416, Black bitumen coating solutions for cold application.

BS 3692, ISO metric precision hexagon bolts, screws and nuts.BS 4147, Specification for bitumen based hot applied coating material for protecting iron and steelincluding suitable primers where required.BS 4190, ISO metric black hexagon bolts, screws and nuts.BS 432O, Metal washers for general engineering purposes.BS 4504, Flanges and bolting for pipes, valves and fittings. Metric series.BS 4622, Grey iron pipes and fittings.BS 4772, Specification for ductile iron pipes and fittings.BS 4865, Dimensions of gaskets for pipe flanges to BS 4504.BS 5150, Cast iron wedge and double disk gate valves for general purposes.BS 5152, Cast iron globe and globe stop and check valves for general purposes.BS 5153, Cast iron check valves for general purposes.BS 5155, Specification for butterfly valves.BS 5163, Double flanged cast iron wedge gate valves for waterworks purposes.BS 6076, Specification for tubular polyethylene film for use as protective sleeving for buried iron pipes and

fittings.BS 8010, Code of practice for pipelines .

BS 8010-1, Pipelines on land: general 4) .BS 8301, Code of practice on building drainage.CP 2005, Sewerage.CP 3009, Thermally insulated underground piping systems.

4) In preparation


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