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Contract2 ProposedMembranePlantatChangiWaterReclamationPlant

G1.2 i

Cygnet/172365_2011C2_G1.2 Pipework.docx

GENERALSPECIFICATION

G1.2 PIPEWORK

CONTENTS

G1.2 PIPEWORK.............................................................................................................................. 3

G1.2.1 General..................................................................................................................... 3

G1.2.2 ReferenceStandards.................................................................................................. 4

G1.2.3 Material,WorkmanshipandWeldingStandards........................................................ 6

G1.2.3.1 HydraulicTestingofPipesatPlaceofManufacture.................................................... 7

G1.2.3.2 ProtectionofSteelPipesinTransit............................................................................ 7

G1.2.3.3 Delivery..................................................................................................................... 7

G1.2.3.4

Storage

......................................................................................................................

8

G1.2.3.5 ExaminationofSteelPipesPriortoInstallation.......................................................... 9

G1.2.3.6 RepairofPipeLiningsandSheathing.......................................................................... 9

G1.2.4 SubmissionsbytheContractor................................................................................. 10

G1.2.4.1 DrawingsandData.................................................................................................. 10

G1.2.4.2 ConsignmentNotes................................................................................................. 10

G1.2.4.3 RecordstobeKept.................................................................................................. 10

G1.2.4.4 TestCertificates....................................................................................................... 11

G1.2.4.5 MethodandProgrammeofPipelineConnections,TestingandCleaning................... 11

G1.2.5 PipeworkMaterials................................................................................................. 11

G1.2.5.1 Introduction............................................................................................................ 11

G

1.2.5.2

Steel

Pipework

........................................................................................................

11

G1.2.5.3 InternallyLinedSteelPipes...................................................................................... 12

G1.2.5.4 DuctileIronPipesandFittings.................................................................................. 13

G1.2.5.5 CastIronSoilPipesandFittings................................................................................ 14

G1.2.5.6 PolyvinylChloride(PVC)Pipes................................................................................. 14

G1.2.5.7 PE100PolyethylenePipes........................................................................................ 15

G1.2.5.8 VitrifiedClayPipes................................................................................................... 15

G1.2.5.9 StainlessSteelPipesandFittings.............................................................................. 15

G1.2.5.10 FibreglassReinforcedPlastic(FRP)Pipes.................................................................. 16

G1.2.6 PipeCutting............................................................................................................. 17

G1.2.7 ClosingLengths........................................................................................................ 17

G1.2.7.1 General................................................................................................................... 17

G1.2.7.2

Steel

Pipes

...............................................................................................................

18

G1.2.8 InternallyLinedFittings........................................................................................... 18

G1.2.8.1 RetainingRingsforInternallining............................................................................ 19

G1.2.9 Jointing.................................................................................................................... 19

G1.2.9.1 General................................................................................................................... 19

G1.2.9.2 InstallationProcedure............................................................................................. 21

G1.2.9.3 SpigotandSocketJoints.......................................................................................... 22

G1.2.9.4 FlangedJoints.......................................................................................................... 22

G1.2.9.5 MechanicalCouplings,FlangeAdaptersandExpansionJoints.................................. 23

G1.2.9.6 Welding................................................................................................................... 25

G1.2.10 AccesstoInteriorofPipelines.................................................................................. 29

G1.2.11 InstallationofUndergroundPipes............................................................................ 29

G1.2.11.1 General................................................................................................................... 29

G1.2.11.2 SteelPipes............................................................................................................... 30

G1.2.11.3 InstallationofPE100PolyethylenePipes.................................................................. 31

G1.2.11.4 InstallationofSolventWeldedThermoplasticsPipes............................................... 31

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G1.2.11.5 InstallationofValves............................................................................................... 31

G1.2.11.6 BeddingtoPipes...................................................................................................... 32

G1.2.12 ProtectionGeneral................................................................................................ 34

G1.2.12.1 CleaningandPriming............................................................................................... 34

G1.2.12.2 ExternalProtection.................................................................................................. 35

G1.2.12.3 ExternalWrapping................................................................................................... 37

G1.2.12.4

Polyethylene

Sleeving

..............................................................................................

38

G1.2.12.5 FusionBondedEpoxyCoating.................................................................................. 38

G1.2.12.6 InternalProtection................................................................................................... 38

G1.2.12.7 ProtectionofPipesandValvesinChambers............................................................. 41

G1.2.12.8 PaintingPipeworkaboveGround............................................................................. 42

G1.2.13 PipeSupports.......................................................................................................... 42

G1.2.13.1 Workmanship.......................................................................................................... 42

G1.2.13.2 Handling.................................................................................................................. 42

G1.2.13.3 PipeSupportsforExposedPipeworkwithinBuildings.............................................. 43

G1.2.14 InspectionandTesting............................................................................................. 45

G1.2.14.1 SpecialistInspectionandTesting.............................................................................. 45

G1.2.14.2 InspectionatTimeofInstallation............................................................................. 46

G1.2.14.3

Inspection

Prior

to

Water

Testing

.............................................................................

46

G1.2.14.4 CleaningPipelines.................................................................................................... 46

G1.2.15 TestingPipelinesGeneral...................................................................................... 47

G1.2.15.1 ProcedureforPressureTesting................................................................................ 48

G1.2.15.2 TestingGravityPipelines.......................................................................................... 51

G1.2.16 FlushingandSterilizationofPipelines...................................................................... 52

G1.2.17 Design,InstallationandBuildinginofPipework....................................................... 53

G1.2.18 WorkinsidePipelines............................................................................................... 53

G1.2.19 DangersofFloatation............................................................................................... 53

G1.2.20 PipelinesintheSameTrench................................................................................... 54

G1.2.21 AnchorandThrustBlocks......................................................................................... 54

G

1.2.22

Pipelines

Built

Into

Structures

..................................................................................

55

G1.2.23 InstallationofPipelinesotherthanBuriedPipelines................................................ 55

G1.2.24 ConnectionsbetweenDifferentPipeMaterials........................................................ 56

G1.2.25 ConnectingtoExistingPipelines............................................................................... 56

G1.2.26 PluggingofDeadEnds.............................................................................................. 57

G1.2.27 CablesSharingPipelineTrenches............................................................................. 57

G1.2.28 MarkerTapeforBuriedServices.............................................................................. 57

G1.2.29 RouteMarkerPosts................................................................................................. 57

G1.2.30 RepairofFusionBondedEpoxyCoatings.................................................................. 58

TABLEG1.2.2:MAXIMUMSPACINGBETWEENPIPESUPPORTSFOREXPOSEDSTEEL,DUCTILE IRON

ANDCOPPERPIPES............................................................................................................................ 45

TABLEG

1.2.3:

MAXIMUM

SPACING

BETWEEN

PIPE

SUPPORTS

FOR

UPVC

PIPES

...............................

45

TABLEG1.2.4:MARKERTAPE............................................................................................................ 57

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Contract2 ProposedMembranePlantatChangWaterReclamationPlant________________

G1.2 3


G1.2 PIPEWORK

G1.2.1 General(a) The term pipework shall include all necessary supports, saddles, slings,

fixing bolts and foundation bolts required to support the pipes and

associatedequipment.

(b) Pipeworkinbuildingsshallbearrangedanddesignedsoastofacilitatetheerection, painting in situ and dismantling of any section for maintenance

andtogiveaconstantanduniformflowoffluidwithaminimumheadloss.

Where steel pipework is used, the number of flanges shall be kept to a

minimumandthelengthofeachunitofpipeworktakenintoconsideration

theeaseofhandling,installationandgeneralappearanceofthecompleted

pipe system. Positions of flanges shall take into account any necessary

concretepipesupportsorthrustblocks.Flangesshallnotbecastintofloors

orwallsandshallbelocatedsuchthattheycanbereadilydismantled.

(c) Water velocities in the gravity main shall be less than 1m/s. Watervelocitiesinthesuctionbranchofapumpshallnotexceed1.5m/sandthedischargebranchshallnotexceed2.5m/s.

(d) Flexiblejoints/mechanicalcouplingsshallbeprovidedwherenecessarytofacilitate removal of Plant and/or to allow for differential settlement of

building structure. Flexiblejoints/ mechanical couplings shall be provided

with tie bolts or other means to transfer longitudinal thrust along the

pipeworkasawhole.Pipesupportsshallnotbeusedtoabsorbthrust. All

valves, flowmeters, static mixers that cannot easily be removed for

maintenanceshallbeprovidedwithflangeadapterstomaketheirremoval

and replacement easier. Flange adapter may only be omitted with the

approvalof

the

SO.

(e) In general, all pipes and fittings up to and including 100 mm in diametershallbemanufacturedeitherinsteelorinuPVCunlessotherwiseshownon

theDrawingsorrequiredaspartofapackageplant.

(f) Wheresteelandcastflangesarematedtogether,thesteelflangeshallbemachinedoveritsfullfaceafterweldingtoitsrespectivepipeiscompleted.

Wherever possible standard fittings shall be used in preference to

fabricatedorspecialfittings.

(g)

Facilities

shall

be

provided

for

draining

the

pipe

system

and

releasing

air.

Thedrainedfluidshallbepipedtoanapproveddischargepoint.

(h) Wherever possible, heavy equipment such as valves, strainers and otherdevicesmounted inthepipeworkshallbesupported independentlyofthe

pipestowhichtheyconnect.

(i) Unlessotherwisespecified,flangesshallconformtoBSEN1092andshallbedrilled in accordance with the appropriate pressure designation but

generallynotlessthanPN16.

(j) Whereapipepassesthroughareinforcedconcretewall,retainingwallorissubject

to

thrust,

it

shall

incorporate

apuddle

flange,

which

shall

conform

tothedimensionsstatedinBSEN1092butshallremainundrilled.

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(k) Vertical pipework may be supported on duckfoot bends mounted on thecivil structure. When used, duckfoot bends shall be bolted to the civil

structure.

(l) SpecificrequirementsforchemicalpipeworkarespecifiedintherespectivesectionoftheSpecification.

(m) Excavationandrefillingofpipetrenchesshallbecarriedout inaccordancetoSectionsG3andP3oftheSpecification.

(n) Further requirements specific to external protective coatings of pipeworkaregiveninSectionG1.5.

(o) Further requirements specific to pipework and valves for air conditioningandfirefightingsystemsaregiveninSectionG7.0.

G1.2.2 ReferenceStandards

(a) Unless otherwise specified and approved by the S.O., pipelines andpipework shall comply with the relevant Singapore Standards and the

ReferenceStandardslistedbelowwhereapplicable:

Standard Subject

BS65 Specification for Vitrified Clay Pipes, fittings

andDucts

BS437 Cast iron spigot and socket drain pipes and

fittings.

BSEN124 Gully tops and manhole tops for vehicular

andpedestrian

areas.

BS534 Steelpipes,jointsandspecialsforwaterand

sewage.

BSEN295 Vitrified Clay Pipes, Fittings and Pipe Joints

forDrainsandSewers

BS1154 Naturalrubbercompounds

BSEN1982 Copperalloyingotsandcopperalloyandhigh

conductivitycoppercastings.

BSEN1561 Flakegraphitecastiron.

BSEN6811 Elastomeric seals forjoints in pipework and

pipelines.

BS

2633

Class

I

arc

welding

of

ferritic

steel

pipework

BS2971 ClassIIarcweldingofcarbonsteelpipework

BSENISO35061,2,3 Mechanical properties of corrosion resistant

steelfasteners.

BSEN122011,2,3,4 Plastic piping systems for water supply:

Polythene.

BS3416 Bitumenbasedcoatingsforcoldapplication.

BSENISO1452 Plastic piping systems for water supply

unplasticizedpoly(vinylchloride)

BS3506 uPVCpipeforindustrialuses

BS3600 SpecificationforDimensionsandmassesper

unit length of welded and seamless steel

pipesand

tubes

for

pressure

purposes

BSEN102161 Seamless nonalloy steel tubes for pressure

purposes

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BSEN102171 Welded nonalloy steel tubes for pressure

purposes

BSEN10300 Bitumen based hot applied protective

coatings

BS4190 ISO metric black hexagon bolts, screws and

nuts.

BSENISO4320 Metal washers for general engineering

purposes,metricseries.

BSEN10029,BS7668 Weldablestructuralsteels.

BSEN10921,3 Circularflangesforpipes,valvesandfittings:

Steelandcopperalloy.

BSEN15151 Flangesandtheirjoints bolting

BS45151&2 Welding of steel pipelines on land and

offshore

BSEN545 Ductile iron pipes and fittings for water

application.

BSEN598 Ductile iron pipes and fittings for sewage

application.

BSEN

1514

Part

1to

4

Dimensionsof

gaskets

for

pipe

flanges

to

BS

EN1092.

BSEN1171 Castirongatevalves.

BSEN12334 Castironcheckvalvesforgeneralpurposes.

BS5292 Jointingmaterialsandcompounds.

BSEN1796 Glass reinforced plastics (GRP) pipes and

fittingsforuseforwatersupplyorsewerage.

BS5500 Unfiredfusionweldedpressurevessels

BS2782 11 General requirements for dimensions and

pressure ratings for pipe of thermoplastics

materials.

BS5911 Precast concrete pipes, fittings and ancillary

products.

BS6076 Tubular polyethylene film for use as

protectivesleevingforburied ironpipesand

fittings.

BSEN122021,2,3 Blue polyethylene pipes up to nominal size

63forbelowgrounduseforpotablewater.

BS6956 JointingofMaterials

BS7079:Part0 Preparationofsteelsubstrates.

BS8010:Parts1&2 Code of Practice for pipelines: Pipelines on

land

API5L Linepipes

API

5LS

Spiral

welded

line

pipes

API1104 Standard for welding pipelines and related

facilities

ASTMC582 Standard Specification for ContactMolded

Reinforced Thermosetting Plastic (RTP)

LaminatesforCorrosionResistantEquipment

ASTMD2310 Standard Classification for MachineMade

Fiberglass (GlassFiberReinforced

ThermosettingResin)Pipe

ASTMD2996 Standard Specification for FilamentWound

"Fiberglass" (GlassFiberReinforced

ThermosettingResin)Pipe

AWWAM11

Steel

pipe

design

and

installation

AWWAC208 Dimensions for Fabricated Steel Water Pipe

Fittings

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AWWAC213 Fusionbondedepoxycoatingforinteriorand

exteriorofsteelwaterpipelines

WIS*43202 Polyethylene pressure pipe for cold potable

water(undergrounduse).

WIS*43203 Polyethylene pressure pipe for cold potable

water(fornominalsizesgreaterthan63).

WIS*43204 Polyethylenefusionjointsandfittingsforuse

withcoldpotablewaterpressurepipes.

WIS*43206 Polyethylene electrofusion couplers and

fittings

WIS*43208 Fusion jointing of polyethelene pressure

pipeline systems using PE80 and PE100

material

WIS*45201 Polymericanticorrosion(barrier)coatings

WIS*45201A Polymeric anti corrosion (barrier) coatings

amendments

(* WRC (UK) Water Treatment Specifications, previously called

InformationandGuidanceNotes)

(b) Thislistisnotintendedtobeexhaustive.Thesestandardsforequipmentormaterialsprovidedaspartoftheworksmaybeapplicabletotheapproval

oftheS.O.

G1.2.3 Material,WorkmanshipandWeldingStandards(a) All pipes, flanges, fittings supplied shall be supplied with manufacturers

guaranteetoensurethesuitabilityofthesuppliedmaterialfortheintended

use.

(b) Material inspectionbeforerollingshallbecarriedouttocheckagainstMillCertificatessubmitted.Thisshallincludedeterminationofcountryoforigin,

manufacturer, physical inspection, checking of thickness and visual

inspectionofedgesforlamination.

(c) As a control on weld quality, the Contractor shall carry out and submitradiographs for 3% of all butt welds for the S.O.'s clearance. The S.O. will

advise the Contractor where he requires the radiographs to be taken.

Radiographsshallbetakendailywheneverweldingofpipesandspecials is

inprogress.Theclearanceandacceptanceoftheseradiographsshallbe in

accordancewithAPIStandard1104unlessotherwisedirectedbytheS.O.

(d) Weld defects shall include cracks, leaks, laminations, lack of completepenetration, lack of complete fusion, dents exceeding one eighth of the

specifiedwallthicknessandundercuttingorreductioninpipewallthickness

adjacenttoaweldexceeding0.5mmindepth.

(e) Slag inclusions and gas pockets or voids considered to be minorimperfectionsmaybeacceptedifthemaximumsizeanddistributionsdoes

notexceedthelimitsshowninSection9ofAPIStd5LorSection7ofAPIStd

5LS.

(f) Whereradiographicexaminationrevealsdefects inthewelds,theS.O.willeither reject the length of pipe containing such defects or will permit the

Contractortocarryoutrepairsandtosubmitradiographsofsuchrepairsfor

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G1.2 7


clearance. Lengths of pipe containing defects in welds after repair will be

liabletoberejected.

(g) Ifdefects inweldsarefound ina lengthofpipeorfitting,theweldsofthepipesandfittingsimmediatelybeforeandafterthedefectivepipeorfitting

intheproductionlineshallberadiographeduntiltheS.O.issatisfiedthatall

the welds are considered satisfactory. The cost of such radiographs and

radiographsofrepairedweldsshallbebornebytheContractorandshallbe

includedintheContractratesandshallnotformpartofthe3%ofallwelds

specifiedinapreviousparagraphofthisClause.

G1.2.3.1 HydraulicTestingofPipesatPlaceofManufacture(a) All pipes shall be hydraulically tested at the place of manufacture in

accordance with Section 5 of API Standard 5L or API Standard 5LS as

appropriate. Full test pressures shall be maintained for at least 3 minutes

during

testing

at

the

factory

and

automatic

pressure

recorders

must

beinstalledonhydraulictestingmachines.

(b) Any pipe which fails to withstand the hydraulic test pressure or whichexhibits signs of porosity shall be deemed not to comply with this

SpecificationandshallberejectedunlessotherwisedecidedbytheS.O.

(c) Unless otherwise specified, physical testing of the pipes shall also be inaccordance with Section 4 of API Standard 5L or API Standard 5LS as

appropriate.

(d) Allthepipessuppliedshallbetestedfortheintendedoperatingconditions,pressure/

vacuum,

at

the

manufacturers

place

and

acertificate

stating

the

suitabilityshouldbeissued.

G1.2.3.2 ProtectionofSteelPipesinTransit(a) Allsteelpipesshallbeprotectedpriortodespatchfromthemanufacturer's

works. All flanges shall have wooden discs bolted on. All other ends of

pipes and fittings shall be protected against impact damage and entry of

foreignmatter. Theprotectionshalltakeintoaccounttheenduseintended

for

the

pipes

and

whether

or

not

the

final

protection

has

been

completed.

(b) Pipes and fittings shall be wrapped or cushioned so that no load is takendirectlyontheexternalcoating.

G1.2.3.3 Delivery(a) TheContractorshallsubmittotheS.O.advancenoticesofallconsignments

of steel pipes. Every consignment shall be accompanied by a detailed

deliverynotewiththeitemnumberofeachpipeorfitting.

(b) TheContractorshalltakedeliveryofandoffloadpipes,valves,andprecastmanholesectionswhichheisrequiredtoprovide,attimesandatlocations

or storageareas on or about the Site to be arranged by him with his

suppliers,subjecttotheapprovaloftheS.O.. Anysuchlocationorstorage

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area which does not form part of the Site shall be arranged for by the

Contractorathisownriskandexpense.

(c) After pipes, valves and precast manhole sections have been delivered toandoffloadedatdeliverylocationsasaforesaid,theContractorshallmake

all arrangements for subsequent transport and handling on or about the

Sitetothepointof installation, includingwherenecessary,anymovement

intoandoutoftemporarystorage.

(d) TheContractorshall inspectallpipes,valvesandprecastmanholesectionsupondeliveryfromthemanufacturerandshallnotealldamaged,brokenor

otherwiseunsatisfactoryitemsandshalltakeimmediatestepstorectifyor

replace such broken or damaged or unsatisfactory items. Items with

damagedfusionbondedepoxycoatingsshallbetreatedinaccordancewith

therequirementsofSectionG1.5oftheSpecification.

G1.2.3.4 Storage

(a) TheContractorshalltakeintotemporaryprotectivestorageallpipes,valvesandprecastmanholesectionsnotrequiredforimmediateinstallationinthe

Works or, inthecaseofpipesand precast manholesections, for stringing

outalongthepipelineroute.

(b) Valves shall be stored under cover until they are required for installationand particular care shall be taken for the protection of any associated

electricalormechanicalequipment.

(c) TheContractorshallpreparepipestorageyardsatlocation(s)asdirectedbythe

S.O.

on

Site

at

which

the

steel

pipes

and

fittings

shall

be

delivered.

The

areasshallbeclearofvegetationand levelledoffandtheContractorshall

constructandmaintainadequatetemporaryaccesstothestorageyard(s).

(d) TheContractorshallprovideatnoextracosttotheEmployer,timberpiecestokeepallstoredpipes,clearoftheground. TheContractorshallmaintain

thestorageyardsinaconditionsatisfactorytotheS.O.untilcompletionof

theWorks.

(e) Pipesinstorageshallbelaidonwedgedtimberbearerssoastobeatleast75mm clearof the ground;steel pipes shall be stacked in one layer only,

other

pipes

may

be

stacked

up

to

three

pipes

high,

if

suitable

protective

packingisplacedbetweenthelayers. Topreventdamagetothesheathing

ofpipeswhicharesheathedwithbitumenthebearersshallbepositionedat

theunsheathedendsofthepipes.

(f) The period between taking delivery of a pipe and the completion of itsinstallationshallbekeptto aminimum and in thecase of steelpipesthis

periodshallnotexceedsixmonths. Anyperiodduringwhichthepipesare

strungoutalongthepipelinerouteorplacedalongsidetheWorksawaiting

installation shall also be kept to a minimum. Jointing parts and materials

shallinanycasebestoredundercoverasforvalves.

(g) Subject to the foregoing and to any restrictions of the duration oftemporary occupation of parts of the Site, pipes may be strung out along

the pipeline route prior to installation providing that any necessary

temporaryfencinghasfirstbeenerected.

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G1.2.3.5 ExaminationofSteelPipesPriortoInstallation(a) All pipes and specials shall be thoroughly brushed through, cleaned and

carefullyexaminedforcracksandflaws,bothinternallyandexternallyprior

tolaying. Materialsfoundtobedamagedinanywayshallbeshowntothe

S.O.whowillgiveinstructionsregardingremedialworkorotherwise.

(b) Whereendstobejointedbyweldingaretobecoatedwithensisoilattheplaceofmanufacture.Theendsshallbethoroughlycleanedwiththeensis

oilremovalpriortowelding.

(c) The ends of pipes and specials shall be wire brushed if necessary andthoroughlycleanedtoremovealltracesofrustanddirt.

(d) Should any pipe or specials be found to be damaged, it shall be excludedfromtheworkuntilrepairshavebeencarriedouttothesatisfactionofthe

S.O. Ingeneral,nopipeshallbe laid ifanendhassuffereddistortionfrom

the circular and a mechanical coupling or socket cannot be fitted or, if

damage

to

the

internal

and/or

external

protection

has

not

beensatisfactorilyrepaired.

G1.2.3.6 RepairofPipeLiningsandSheathing(a) Only specially competent and skilled men shall be employed to carry out

repairworktodamagedliningsandsheathing.

(b) Small cracks and flaws in the internal mortar lining of steel pipes andspecialsmay,withthepriorapprovaloftheS.O.andiftheyareaccessible,

berepaired

on

Site.

Such

cracks

may

be

repaired

by

cutting

out

a9mm

x9

mmdovetailedkeyandmakinggoodwithasemidrymortar(proportion1

partcementto2partscoarsesand)welltampedintothegroove,andcured

by keeping it damp for 7 days. Alternatively, small cracks may be caulked

withepoxyresinfiller.

(c) The external sheathing of steel pipes and specials shall be made goodwherever the steel has been exposed or the thickness of the coating

seriouslyreducedbydamage,orwherethecoatingdoesnotadheretightly

to the steel. Where the steel has been exposed, all rust and dirt shall be

removedcarefullybywirebrushingorotherwise,andwhenperfectlyclean

and

dry,

a

coat

of

approved

special

quick

drying

primer

applied

before

refettling. Small stones which may have become embedded in the

sheathing shall be picked out and the coating refettled by heating locally

with a blow lamp and smoothing over with a fettling knife. Additional

externaljointingmaterialshallbeaddedwherevernecessary.

(d) All defects to linings and sheathings shall be made good to the entiresatisfactionof the S.O. Where, in S.O.s opinion, the damage is such that

satisfactory repairs on Site will not be practicable, e.g. when damage or

cracking isextensive and/or inaccessible, the pipes or specials in question

shall be either returned to the factory for repairing properly or replaced

completely. TheContractorshallberesponsible ineithercaseforallcosts

involved

in

this

respect

and

for

any

delays

to

construction

work

thereby

caused. The compound used for repairing sheathings shall be compatible

withthesheathingmaterialandshallbeapprovedbytheS.O.

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G1.2 10


G1.2.4 SubmissionsbytheContractorG1.2.4.1 DrawingsandData

(a) Submissions which the Contractor is required to make in relation topipelinesinclude,whererelevant,thefollowing:

(i) Typicaldrawingsofstandarditems.(ii) Detaildrawingsofspecialitems.(iii) Manufacturer's calculations, catalogues and data sheets including

pressure/temperatureratingsforpipes,fittingsandjoints.

(iv) Forsteelpipes,drawingswithdescriptionsoutliningthemethodofformingpipesandspecials instandard lengthsfromsteelsheetor

strip.

(v) Welding procedure details including plant, method, number ofruns, weld materials, air testing of joints and names and

qualificationsofwelders.

(vi) Contractor'scalculationsforpipeandfittingdesign(vii) Full details of internal and external protection and lining systemsincludingmethodofapplication,materials,curing,etc.(viii) Evidence of compliance with requirements for materials,

substances and products in contact with water which is to be

suppliedfordrinking.

(ix) Methodofboxingoutforandbuildingpipesintostructurewalls.(x) Methodsofcontroloflineandlevelofpipelineduringinstallation.(xi) Methodsforpipehandling,installationandbackfill(xii) DetailsofContractor'spipesupports

G1.2.4.2 ConsignmentNotes

The Contractor shall forward to the S.O. advanced notices of all consignments.

Everyconsignmentshallbeaccompaniedbyadetaileddeliverynotewiththe item

numberofeachpipeorfitting.

G1.2.4.3 RecordstobeKept(a) TheContractorshallkeepdetailedanduptodaterecords ina formtobe

approved

by

the

S.O.

of

all

pipes

and

valves,

showing

the

quantities

of

each

type,sizeandclasswhichhavebeen

(i) orderedduringthecourseoftheWorks;(ii) deliveredduringthecourseoftheWorks;(iii) declaredondeliverytobefaultydamagedordeficient;(iv) usedintheWorks;(v) brokendamagedorlostduringthecourseoftheWorks.

(b) EachweektheContractorshallprovidetheS.O.withanuptodatecopyofthe above records. In the case of steel pipes, the Contractor shall also

recordtheBillofQuantitiesitemwise.

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G1.2 11


G1.2.4.4 TestCertificates(a) TheContractorshallforwardtotheS.O.beforedespatch,certificatesfromthe

manufacturerstoshowthatpipesandvalveshavebeentestedandcomplywith

theappropriateStandard(s).

(b) The Contractor shall forward to the S.O. copies of the certificates of all weldtestscarriedoutonsteelpipework.

G1.2.4.5 MethodandProgrammeofPipelineConnections,TestingandCleaning(a) The Contractor shall submit for the approval of the S.O., details of his

proposed methods and programme for pipeline connections to existing

pipelines,testing,swabbing,disinfectionandcleaning(includingdetailsoftest

andcleaningequipment).

G1.2.5 PipeworkMaterialsG1.2.5.1 Introduction

(a) ThisSectionisspecifictothematerialrequirementsforpipework.(b) Pipework shall be manufactured to the specification given hereunder and

shall be provided by the Contractor except as specified otherwise. The

particulartype,sizeandclassofpipesandvalvesforeachpartoftheWorks

shall

be

as

specified

or

as

described

on

the

Drawings

or

in

the

Bills

of

Quantities.

G1.2.5.2 SteelPipework(a) Pipes shall be specified by nominal diameters inaccordancewith BS 3600

Table1.

(b) CarbonsteelpipesshallbeinaccordancewithBSEN10216orBSEN10117asapplicable.

(c) CarbonsteelfittingsshallcomplywithBSEN10253 1.(d) WeldingshallbecarriedoutinaccordancewithBS2633Class1arcwelding.

Allweldersshallbetestedbyanindependentinspectionauthorityandshall

satisfy the requirements of BS EN 287 1. Current and valid welder test

certificates shall be provided by the Contractor for approval by the S.O.

priortocommencementofsitewelding.TheS.O.mayrejectanyproposed

welder on the basis of incompetence at any time during the

implementationoftheWorks.

(e) Steel pipework fittings shall be fabricated in accordance with BS 534.WheredimensionsfortherequiredfittingsarenotgiveninBS534,AWWAStandardC208for"dimensionsoffabricatedsteelwaterpipefittings"shall

beused.

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G1.2 12


(f) All fabrication and corrosion protection shall be carried out at themanufacturer'sworks. LiningsandcoatingsshallcomplywithSectionG1.5

ofthisSpecification.

G1.2.5.3 InternallyLinedSteelPipes(a) Steel pipes shall be manufactured, except where stated otherwise

hereunder,inaccordancewithAPISpecification5LorAPISpecification5LS.

MaterialforpipesshallbecarbonsteelplatetoGrade43AofBSEN10029

or better with a minimum lower yield stress of 275 N/mm2

for plate

thickness up to 16 mm and 265 N/mm2 for plate thickness greater than

16mmandupto40mm,andshallbesupplied in plateor strip formas of

appropriateforthemethodofpipemanufacture.Thepipesshallbeformed

bytheautomaticsubmergedarcprocess,witheitheralongitudinalseamor

a spiral seam at the option of the Contractor. With the method of

manufacture decided upon, the relevant standard will then apply i.e. API

Specification5L

for

longitudinal

seam

pipe

or

API

Specification

5LS

for

spiral

seampipe.TheAPIstandardsshallbereferredtohereunderasStd5L/Sand

shall be deemed to apply to all pipe sizes, including those whose outside

diameter(OD)fallsoutsidetheupperlimitcoveredbythestandards.

(b) TheContractorshallprovidealadleanalysisofthesteelusedforthepipesin accordance with Clause 7.1 of BS 4360:1986. Check analyses of the

finishedpipeshallbetakeninaccordancewithClause7.2ofBS4360:1986

and Clause 3.4 of Std 5L/S. In case of dispute, the methods of chemical

analysisshallbeinaccordancewithBSHandbookNo.19.

(c) Unless otherwise specified, thickness of the steel plates and the finishedoutside

diameters

of

the

pipes

shall

be

as

shown

in

the

following

table:

Table1.2.1:SteelPlatesThicknessandFinishedOutsideDiametersofPipes

NominalSize

(mm)

*Thicknessof

steelplate(mm)

Thicknessof

concretelining

(mm)

Outside

diameterof

pipe(mm)

2200

2000

1900

1800

1700

16001500

1400

1300

1200

1100

1000

900

800

750

700

600

500

450

400

300

15.9

15.9

15.9

12.7

12.7

12.712.7

12.7

12.7

12.7

12.7

12.7

9.5

8.0

8.0

6.0

6.0

6.0

6.0

6.0

6.0

25

25

25

25

25

2525

25

25

19

19

19

19

19

19

13

13

13

13

13

10

2216.2

2020

1911.3

1746.3

1720

1549.41520

1422.4

1320

1244.6

1120

1016

933.5

825.9

762

667.2

610

506.9

457

406.4

326.0

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G1.2 13


NominalSize

(mm)

*Thicknessof

steelplate(mm)

Thicknessof

concretelining

(mm)

Outside

diameterof

pipe(mm)

250

200

150

100

6.0

6.0

6.0

6.0

10

10

6

6

273

222.0

170.0

118.0

* The above thickness of steel plates shall not be subject to any

negativetoleranceforacceptancepurpose.

(d) Thethicknessofpipesused forbranchpipeworkoffthemainpipelinesorforuseinformingfittingsshallbethegreatestofthefollowing:

(i) The thickness necessary to provide the same outside diameter towallthicknessratiospecifiedforstraightpipes;

(ii) TheminimumthicknessshowninTable6.2ofStd5LorTable6.1ofStd 5LS for pipes of the appropriate diameter (or the nearest

equivalenttherein);

(iii) Thethicknessdeterminedtobenecessary inthedesignoffittingsasshownontheDrawings.

(e) Standard length straight pipes shall be manufactured with not more thanthreecircumferentialjointsandwithaneffectivelengthasshownbelow:

Finishedinternaldia(mm) StandardLength(m)

2100to2250 9

450to2050 10

Below450 6

(f) The allowable tolerance on standard length pipes shall be 150 mm. Inaddition a number of straight pipes of half the standard length pipes and

trulycircularstandardstraightpipesshallbesupplied.Allstandardandhalf

lengthpipesshallhaveendsformedasspecifiedbelowforjointscapableof

angularrotation.Trulycircularstandardstraightpipesrequired forcutting

purposesshallbetrulycircularthroughoutthelength.

(g) Allpipeswhethermanufacturedwitha longitudinalorspiralseamshallbesubjectedtonondestructivetestingofseamweldsandskelpandwelds in

accordancewithSection9ofStd5LorSection7ofStd5LSasappropriate.

G1.2.5.4 DuctileIronPipesandFittings(a) PipeworkandfittingsshallcomplywithBSEN545forwaterserviceandBS

EN598forsewageapplication.

(b) Flangesshallbeeithercastorwelded,orscrewedondependentupontheclass designation of pipe required. Flanges shall be Type PN16 unless

otherwisestated.

(c) Except where indicated otherwise, all socket and spigot pipes and fittingsandflangedpipesandfittingsshallbetothestandardclassdesignation(K9,

K12andK14).

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G1.2 14


(d) PipeworkshallbehydrostaticallytestedtoBSEN545andBSEN598andamanufacturer'scertificatesubmittedtotheS.O.

G1.2.5.5 CastIronSoilPipesandFittings(a) For socketless cast iron piping systems, the pipe and fittings shall be in

accordance with BS EN 877. Thejoints shall be heavy duty coupling, with

neoprene sealing sleeve, 304 stainless steel shield, and stainless steel

clamping bands, or boltedcast iron coupling withstainlesssteelbolts and

neoprenegasket. Couplingsshallbeclampedtype.

(b) Unless otherwise specified, socketless cast iron piping systems shall beappliedtobuildingsanitarydrainpiping,wastepiping,ventpiping,building

storm drain piping, and clear water waste piping at all locations except

whereburied.

(c)

Supports

shall

be

provided

at

every

hub

and

change

of

direction

of

pipe.

(d) Forsocketandspigotcastironpipingsystems,thepipeandfittingsshallbeinaccordancewithBS416:Part1.Thejointsshallberubbergasketed,push

ongasketsconformingtoBS416:Part1.

(e) Unlessotherwisespecified,socketandspigotcastironpipingsystemsshallbe applied to building sanitary drain piping, waste piping, vent piping,

buildingstormdrainpiping,andclearwaterwastepipingatalllocations.

G1.2.5.6 PolyvinylChloride(PVC)Pipes

(a) cPVCpipeworkforwaterserviceshallcomplywiththerelevantlatestASTMstandards. Piping shall comply with ASTM D1784 and ASTM F441. Fittings

shall comply with ASTM F439 for socketweld type and ASTM F437 for

threadedtype.JointsshallbesolventsocketweldedtoASTMF493,except

forconnectionstovalvesandequipment where futuredisassemblingmay

berequired.FlangesshallcomplywithBSEN1092PN16.Boltingandnuts

shallbeaccordingtoBSENISO3506.Teflontapeshallbeusedforthreaded

connection.

(b) UnplasticisedPVCpipes,jointsandfittingsfordrainsshallcomplywiththerelevant

provisions

of

BS

4660

or

BS

EN

1401

1.

(c) Unplasticised PVC pipes used as cable ducts shall comply with BS3506ClassE.

(d) Solvent cements forjointing unplasticised PVC pipes shall comply with BSENISO1452.ForpipesandfittingscomplyingwithBS4660,solventcement

mayalternativelycomplywithBS6209.

(e) All uPVC pipes for sewerage purposes shall comply with BS3506 andBS2782 11,andshallhaveaminimumsustainedpressureratingof12bar.

(f) ScrewedconnectionstometalcomponentsshallbemadewithproprietaryirontouPVCadaptorfittings.

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G1.2 15


(g) Where flangedjoints are required, full face uPVC flanges and galvanisedmildsteelbackingringsshallbeused.

(h) WhereuPVCpipeworksystemsconnecttosteelmains,theofftakepointsshallbe isolatedbymeansofgatevalvestoBSEN1171orBS5163.Other

valvesinuPVCpipeworksystemsshallbeasspecifiedunderSectionG1.3or

as specifically approved by the S.O with regard to function, location and

operatingconditions.

(i) Pipework shall be supported in accordance with manufacturer'srecommendations and adequate provisions shall be made for thermal

expansionandcontraction.

G1.2.5.7 PE100PolyethylenePipes(a) PE100 polyethylene pipes and fittings for pressure pipelines shall be in

accordance

with

specifications

issued

by

WRC

as

Water

IndustrySpecifications(previouslycalled InformationandGuidanceNotes)43202,

43203 and43204. Themanufacturer shall beresponsible for all testing

andqualityassuranceproceduresandbecoveredbyathirdpartycertificate

scheme all in accordance with these standards. Pipes exceeding 90 mm

nominaldiametershallnotbesuppliedincoils.Pipesuptonominalsize63

shallfurthercomplywithBSEN122022.

(b) The Contractor shall ensure that all PE100 polyethelene pipes and fittingsforthermalfusionjointingtoformanindividualpipelineorpipelinesystems

shallbesuppliedbyonemanufacturer,unlesstheS.O.approvesotherwise.

Electrofusioncouplingsareexemptedfromtherequirementbutmustbeof

atype

approved

by

S.O.

and

shall

incorporate

pins

which

pop

up

to

confirm

thatoptimummeltpressurehasbeenachieved.

(c) Mechanicaljointsshallbecompletewithliners.

G1.2.5.8 VitrifiedClayPipes(a) Vitrified clay pipes and pipeline fittings shall comply with the relevant

provisionsofBS65orBSEN295

(b) Vitrifiedclaypipesshallbeofnormaltypewithflexiblemechanicaljoints.

G1.2.5.9 StainlessSteelPipesandFittings(a) StainlesssteelpipesandfittingsshallgenerallybeSS316Linaccordancewith

ASTM standards. The grades of pipes to be used shall be selected to suit

mediahandledandpressuresencounteredintheapplication.TheContractor

is

responsible

for

proposing

suitable

grades

for

the

consideration

of

the

Employer.Alltheproposedfittingsshallalsobeofthesamematerialasthe

pipes. Special care shall be taken whilejoining different grades of stainless

steelmaterials.Theweldingelectrodesandproceduresshallbesubmittedto

theS.Oforapprovalpriortocommencementofwelding.

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G1.2 16


(b) For welding of stainless steel pipes and fittings, appropriate electrodes andqualifiedweldersshallbeused.

(c) The manufacturerof the pipesand fittings shall bewellexperienced in thisfieldandshouldhavemanufacturedpipessimilarinsizesandpressureratings

forsimilarapplicationas inthisplant.TheContractorshallprovideproofof

thisalongwiththetender.

(d) The manufacturer shall be responsible for all testing and quality assuranceprocedures and be covered by a third party certificate scheme all in

accordancewiththesestandards.

(e) Where thin walled stainless steel pipe and fittings are used, prefabricatedpipe spools including all welded fittings shall be pickled and passivated

beforeshippingtoworkslocation.Flangedconnectionsshallbeprovidedat

pipespoolswherepassivatingofinteriorandexteriorfieldbuttweldsisnot

possibleduetopipesizeorotherphysicalrestraints.

G1.2.5.10 FibreglassReinforcedPlastic(FRP)PipesItem Size Description

Pipe AllSizes Fibreglassreinforcedplastic,helicallywound,

conformingtoASTMD2310Type1,vinylester

resin,TypeCglassmonofilamentsurfacingmat

and/orDynelorganicfibresyntheticsurfacing

veilorapprovedequal.Constructedin

conformancewithASTMD2996.

UVProtection:Addtothewaxcoat.

Fabrication AllSizes Interiorsurfacingveilshallbe250to

500micronsthick.Matlayersshallberesinrich,

fullywetted,1.3mmminimumthickness.

Onelayerveilandtwomatlayersbelland

spigot,buttandwrapandflanged.

Ratings Fibreglassreinforcedpipe,fittings,andflanges

shallberated690kPaasspecifiedinASTM

D2310.

Minimumcontinuous

strand

glass

filament

(coatedwithresin)wallthicknessforpipeareas

follows:

50to150mm

200mm

250mmto

300mm

350mm

400mmto

450mm

500mm

600mm

4.75mm

6.35mm

7.95mm

9.50mm

11.10mm

12.70mm

14.30mm

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G1.2 17


Item Size Description

Joints 50mmto400mm

Greaterthan

400mm

Adhesivebondedtaperedbellandspigot.Butt

andwrap.

Flangedatvalvesandequipment.

Fittings Allsizes Fittings:ASTMC582andD2996.Surfaceveiland

matlayers

same

as

specified

above

under

Ratings.

Bendsshallbelongradius.

Structuralbodyoffittingsshallbefilament

woundorbuiltupwithalternatelayersof

wovenrovingandchoppedstandmat.Filament

woundfittingsshallbesamethicknessas

specifiedaboveunderFabrication.

Flanges AllSizes Fibreglassreinforcedplastic,flatfacedand

drilledBSEN10921PN16.

Bolting

Boltingmaterial

shall

be

A4

70

per

BS

EN

ISO3506.

NutmaterialshallbeA270perBSENISO3506.

Washershallbesamematerialasbolt.

Gaskets FlatFaceFlanges:Ethylenepropylenerubber

(EPR),3mmthick,fullfaced.

Colour Addpigmenttothefinallayeronlyofexterior

surfacingresintolightlytintthesurface,butnot

obliteratelaminatequality.Coloursareas

follows:

Green

G1.2.6 PipeCuttingWhere it is necessary to cut pipes to provide closing lengths or for laying pipe

specialsorintherepairofdamagedorchippedpipes,thecuttingshallbeneatlyand

accuratelyperformedsoasto leavetheendofthepipetrulynormaltotheaxisof

thepipe.

G1.2.7 ClosingLengthsG1.2.7.1 General

(a) The use of closing lengths shall be avoided by laying the pipes in acontinuous length. Pipes which are required to be cut to form closing

pieces inanyportionofthepipelineortoterminate inmanholesorother

partsoftheWorksshallnotbecutuntilafteralladjacentpipeshavebeen

installedand

jointed.

Pipes

for

closing

lengths

shall

be

cut

to

allow

a20

mm

gapbetweenadjacentpipeends.

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G1.2 18


(b) TheContractorshalldeterminethelengthofeachclosingpieceandtheendof the pipe shaped up and trimmed so as to ensure an accuratejoint or

terminationasthecasemaybe.Anydamagetosheathingcoatingorlining

shallbemadegood.

(c) Pipes terminating in manholes and the like shall except where otherwisespecified be cut so that the end of the pipe is flush with the face of the

structureintowhichitisbuilt.

(d) The closing joints in pressure pipelines shall be made with detachableflexiblecouplingswithlocatingplugs.

(e) TheContractormayarrangeathisownriskforcutstobeperformedbythepipesupplier.

G1.2.7.2 SteelPipesWhereclosinglengthsarerequiredtheContractorshallusethespecial'sized'pipes

forcuttingtotheexactlengthsrequired.Thesesteel'sized'pipesmanufacturedtruly

circular along their full length shall be marked by two longitudinal bends in paint

along each pipe. Closing lengths shall be located as near to access openings as

possiblesoastoenableinternalandexternalweldingatjointstobecarriedout.

G1.2.8 InternallyLinedFittings(a) All bends, tees and other fittings shall be prefabricated and testedby the

pipemanufacturer

in

accordance

with

Section

4of

BS

534.

(b) Fittings shall be formed from completely lined and hydraulically testedstraight pipes as specified unless otherwise approved by the S.O., with

suitable rubber spacers inserted during the lining operation. The coating

and liningonthestraightpipesshallthenbecutbackfromtheendstobe

weldedorcutforasufficientdistancetoensurethatnomaterialwhich is

intendedtoremainpartofthecoating/liningisdamagedoraffectedbythe

weldingorcuttingprocess.

(c) Weldingshallbeofastandardequaltothatspecifiedforstraightpipes.Allbutt

welds

shall

be

subjected

to

a

100%

radiographic

test.

All

fillet

welds

shall be subjected to air tests where appropriate and to 100% magnetic

particletests.

(d) Branchesofteesshallbemadefromthesamematerialasthemainbody.(e) The Contractor shall design and reinforce steel fittings to withstand the

specified pressure test and to enable self support in accordance with the

methods contained in the American Water Works Association (AWWA)

Steel Pipe Design Manual, BS 5500 or by other methods approved by the

S.O.WhenusingtheAWWAM11method,thetestpressureforfittingsshall

beoneandaquartertimesthedesignpressureandwhenusingtheBS5500

method,the

test

pressure

shall

be

the

"standard"

test

pressure

determined

in accordance with Clause 5.8.5 of BS 5500. The design pressure shall be

takenasatleastoneandahalftimesthespecifiedworkingpressureorthe

specifiedpipelinetestpressure,whicheveristhegreater.

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G1.2 19


(f) Prior to fabrication of any fitting, the Contractor shall have obtained theS.O.'sapprovalofthecalculations,drawingsandfabricationproceduresfor

thatfitting.

(g) Theoutsidediameterofspecialsshallconformtotheoutsidediametersofthestandardstraightpipes.Theendsofplainendedspecialsshallbetruly

circular and shall conform to the tolerances required for the fitting of

mechanicalcouplingsandflangeadaptors.

(h) Ring girders shall be provided to conform with details shown on theDrawings. They shall be supplied complete with all accessories. Metallic

partsaretobedescaledtosecondqualitystandardinBS7079andpainted

with two pack polyamide cured epoxy zinc phosphate primer with 75

micronsminimumdryfilmthickness.

G1.2.8.1 RetainingRingsforInternalliningAll flanged pipe ends, flanged branches and plain ends for use with mechanical

couplingsorflangeadaptorsshallhavea6mmsteelretainingringweldedintothe

bore of the pipe flush with the end of the pipe after which the ring shall be shot

blastedtoSA2toBS7079followedbyappropriatecoatingSystemasspecifiedin

SectionG1.5.Theradialthicknessoftheringsshallbesimilartothethicknessofthe

concreteliningandshallnotbelessthan6mm.

G1.2.9 JointingG1.2.9.1 General

(a) Pipejoints shall be in accordance with Section 3 of BS 534 as describedbelowwiththeamendmentsstated.

(i) Pipes jointed in the trench or above ground shall have sleevewelded (spigot and socket) joints of the hemispherical type in

accordancewithClause13.6ofBS534unlessotherwiseshown.

(ii) Forchangesinpipegradeordirection,thejointsmayhaveangulardeflections

up

to

5

degrees

provided

that

the

joint

design

is

suitableandwillallowthetoleranceforweldingtobemaintained.

Theminimumoverlapofpipeendsatmaximumdeflectionshallbe

fourtimesthepipethickness

(b) Forspigotandsockettypejointsofthe hemisphericaltype,themaximumangulardeflectionshallbe2degrees.

(i) Buttweldedjointsmaybeusedasanalternativetosleeveweldedjoints for pipes to bejointed outside the trench subject to the

approvaloftheS.O..

(ii) Detachable flexible couplings shall be used where specified orwhereshownontheDrawings.

(iii) FlangejointsshallbeusedwhereshownontheDrawings.

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G1.2 20


(iv) Welding collars in accordance with Clause 23 of BS 534 shall beusedforjointingcutpipesorclosinglengthsintrench.

(c) Spigot and socketjoints shall be of the hemispherical sleeve type with aminimum penetration of the formed ends as specified below. Thejoint

designshallprovideforthecontactsurfaceofthespigotendandthesleeve

endtobeformedtothesamesphericalradiuswhichshallnotbelessthan

50%oftheoutsideofthebarrelofthepipeforthehemisphericaltype.

(d) Pipestobeused in conjunction withweldedcollars, mechanicalcouplingsorflangeadaptorsshallbesuppliedwithplainends.

(e) Sleeve weldedjoints shall have external fillet welds on pipes of 710 mmoutsidediameterandunderbutshallhavebothinternallyandexternalfillet

weldsonpipeswithanoutsidediametergreaterthan710mm.

(f) The gap between sleeve and spigot at any weld location for internal andexternal welds on Type 3joints (i.e. hemispherical) shall nowhere exceed

1.5mm

whether

the

joint

is

deflected

or

not

and

the

average

gap

around

thecircumferenceofanyweldshallnotexceed1mm.

(g) The minimum penetration of the spigot into the socket shall not be lessthanfourtimesthepipethicknessandthisoverlapshallbeobtainedatthe

maximumdeflectionof2degrees.Atzerodeflectiontheminimumoverlap

shall be the minimum penetration as specified above increased by such

allowanceasisnecessarytoensurecontactbetweenthespigotandsocket

overthespecifiedmaximumamountofangulardeflectionatthejoint.

(h) Pipeendsofthehemisphericaltypeshallbe formedbyhydraulicpressingusing a full circle die or expanding former capable of forming ends

consistently

to

a

constant

spherical

contact

surface

throughout

the

pipe

productionrun.

(i) Fillet welds shall be strength welds having a throat thickness of not lessthan0.7timesthepipethickness.Buttweldsshallbefullpenetrationwelds

havingathroatthicknessofnotlessthanthepipethickness.

(j) Theinternalsurfaceofsleevesandtheexternalsurfaceofthespigotsshallbegroundsmoothalongthelongitudinalfusionweldsforadistanceof150

mm(measuredalongthepipeaxis)fromtheendofthepipeineachcase.

(k)

The

external

surface

of

the

plain

ended

pipes

intended

for

collar

or

mechanicallycouplingjointsshallbesimilarlyprepared.Plainpipeendsfor

use with mechanical couplingjoints shall conform to the requirements of

themanufacturerofthemechanicaljoint.

(l) For large pipes where man access is possible, welded collars shall beprovided forjointing cut pipes or closure pieces by means of internal and

externalfilletwelding.Theminimumlengthofeachcollarshallbe250mm

and the collar thickness shall be 1.5 mm greater than the equivalent

standardstraightpipethickness.Weldingcollarsmaybeprovidedassingle

split collars with temporary bolts and lugs. Split collar ends shall be

prepared for butt welding in the same manner as plain ends of pipes

prepared for butt welding. Collars shall make close contact around the

circumferencesof

both

pipes

connected

and

the

gap

between

the

ends

of

a

split collar after tightening shall not exceed 3 mm. The tolerances of the

collarshallbesuchthatnowhereshallthegapbetweenthe insidesurface

of the collar and the outside surface of the pipe at fillet weld locations

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G1.2 21


exceed the tolerances permitted for spigot and socketjoints. The overlap

ontheweldedcollaroneachpipeshallnotbelessthan75mm.Collarjoints

shallnotberequiredtotakeanydeflection.

(m) Allweldedsleeveandcollarjointsshallbeprovidedwithtwotappedholesspacedat90degreesapartonthecircumference.Theyshallbeofnot less

than6mmdiameterandshallbeprovidedwithmatchingplugstofacilitate

theairpressuretestingoffieldwelds.Thesetappedholesshallbe located

withintheend30mmofthesocketsandshallbeclearedofweldingruns.

(n) EndspreparedforbuttweldingshallbesubjecttomanufacturingtolerancesinaccordancewithTable6.3ofAPIStandard5LorTable6.2ofAPIStandard

5LS.

(o) Plain ends for use with mechanicaljoints or flange adaptorjoints shall betruly circular with a diameter tolerance of 1 mm over a distance of 225

mmfromthepipeends.

(p) Pipes to be used for closing lengths shall be correctly sized over their fulllengthsothataccuratealignmentforsplitcollarjointscanbeobtained.Allsuchpipesshallbeclearlymarked.

(q) ThejointsforuPVC,GRPandPE100polyethelenepipesshallbemadeusingmechanical type or solvent welding or thermofusion techniques. The

method ofjointing shall be to the approval of the S.O. The pipes shall be

laidandjointedstrictly inaccordancewiththemanufacturer's instructions

andshallconformtoCP312.

G1.2.9.2 InstallationProcedure

(a) BeforemakinganyjointtheContractorshallensurethattheinteriorofeachpipeorfittingiscleanandthatitremainsclean.Immediatelybeforestarting

ajoint the Contractor shall clean the end of each pipe to bejointed and

shallpreparetheendsforjointingasnecessary.Allmechanicaljointsshall

be cleaned and have their coating made good before assembly in

accordancewiththecoatingmanufacturer'srecommendations.

(b) The Contractor shall use only the properjointing parts as specified andobtained from the suppliers of pipes or fittings. All joints shall be

assembled and tightened and shall be made only on pipes which comply

dimensionally and have been prepared in accordance with the

manufacturer'sinstructions.Alljointsshallbecapableofpassingthetestfor

individualjointsandforthecompletedpipelineasspecified.

(c) Detachable flexible couplings shall be installed where detailed on theDrawings. Thejointsshallbeassembledandtightened inaccordancewith

the manufacturer's instructions. Where shown on the Drawings,

longitudinal movement of pipesjoined by mechanical couplings shall be

restricted by a steel work harness approved by the S.O. After installation

the harness shall be cleaned and painted with two coats of bituminous

paintbeforewrapping.

(d) WheretheDrawingsshow,ortheS.O.requires,achangeofdirectiontobeachievedbythedeflectionofaflexiblejointofanykind,thedeflectionshall

not exceed 50% of the design value for the size and type of joint as

recommendedbythemanufacturer.

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G1.2 22


(e) Boltsforflangedorothermechanicaljointsshallshowtwothreadsclearofthenutaftertightening.

(f) Stainless steel nuts and bolts shall be lubricated before assembly with anantigallinglubricant.Nutsshallbetightenedtothetorquesrecommended

bythejointmanufacturer.Torquesshallnotexceedvalueswherethereisa

riskofgalling.

(g) Aftereachjointhasbeencompleted,anyprotectiveorothercoatingshallbemadegoodandanyliningshallbecompletedasspecifiedordetailedon

the Drawings without delay. Any metaljoint which is not already coated

shallbecleanedandpaintedwithtwocoatsofbituminouspainttoBS3416

(excludingClause10).

G1.2.9.3 SpigotandSocketJoints(a)

In

jointing

iron

spigot

and

socket

pipes

and

specials

with

Tyton

or

Stantyte

typeflexiblejointstheContractorshalltakeaccountofthemanufacturer's

recommendations as to the methods and equipment to be used in

assembling thejoints. In particular the Contractor shall ensure that the

spigot end of the pipe to be jointed is smooth and has been properly

chamfered, that the rubber ring is correctly positioned in the socket and

thatthetwopipesareaccuratelyinline,beforethejointismade. Afterthe

joint has been made the Contractor shall ensure by the use of a suitable

feeler gauge that the rubber ring is evenly seated in its correct final

position. The rubber rings and any recommended lubricant shall be

obtainedonlythroughthepipesupplier.

G1.2.9.4 FlangedJointsG1.2.9.4.1 General

(a) Allflangesshallbeofsteel,weldedtothepipebytheelectricarcprocessorother approved method. They shall conform in all respects with the

requirements of BS EN 1092 or PD 5500 unless otherwise specified. They

shall be of the raised face type and shall be truly faced over their whole

width. Bolt holes shall be drilled off centre lines, truly in line end to end

withthelongitudinalaxis.Allflangesshallberatedfor16bar(PN16)unless

otherwise specified. All flanges shall be adequate to withstand test

pressuresforthefittingstowhichtheyareattached.

(b) Therequirementforboltholestobedrilledoffcentremustalsobetrueforflangesonequipmenttowhichthepipeflangesareconnected.

(c) Allmaterialsrequiredforuseinthemakingofflangedjointsincludingnuts,bolts, washers andjoint gaskets shall be supplied by the Contractor. Joint

gaskets shall be contained within the bolt pitch circle and shall be made

from4.5mmthickrubbertoBS1154ClassY3reinforcedwithtwolayersof

fabricinaccordancewithBS5292.Eachboltshallbesuppliedandinstalled

withanut

and

two

washers

(one

on

either

side

of

the

flanges

to

be

joined)

andeachboltshallbeofsufficientlengthtoshowtwothreadspastthenut

whensoinstalled.

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G1.2 23


(d) Test certificates for the flange material shall be provided to the S.O. ThefinishonflangejointsurfacesshallbeinaccordancewithBSEN1092.

(e) BlankflangesshallbedesignedandsuppliedbytheContractor foranendloading equivalent to the rating pressure of the flange. Lifting eyes or

handlesandairreleasecocksshallbeprovidedasnecessary.

(f) Thrustflangesshallbeweldedtotheoutsidesurfaceofpipeworkandshallbedesignedtowithstanda longitudinalforceequaltothe loadingapplied

toablankflangeofequivalentdiameter.

(g) TheContractorshallberesponsible forcheckingandensuringthatmatingflanges are compatible in all cases, includingwhereconnectionsare to be

made to existing pipe flanges and to equipment provide as part of the

Works.

G1.2.9.4.2 Installation

(a) When assembling flangedjoints the rubberjoint ring may be fastened tothe bolts with cotton thread. The use ofjointing paste, adhesive tape or

greasewillnotbepermitted. Theboresofabuttingpipesorfittingsshallbe

concentricwiththejointgasketpositionedcentrally;nojointmaterialisto

beleftprotrudingintothebore.Allnutsshallfirstbetightenedbyhandand

nutsonoppositesidesofthejointcircumferenceshallthenbealternately

andprogressivelytightenedwithaspannersoastoensureevenpressureall

round thejoint. Care shall be taken to see that thejoint rings remain in

positionundistortedwhiletheboltsaretightened. Forprecisetightening,

presettorquewrenchshallbeused.

(b) Flanged joints located in chambers shall be painted with two coats ofbituminous epoxy paint but flanges which will be subsequently buried in

trenchandnotencasedinconcreteshallbecarefullywrappedwith'Denso'

tape as manufactured by Winn and Coales Ltd., or similar approved

material.Whereflangedpipe istobeburied,the pipemanufacturerssafe

workingbendingmomentvaluesshallnottobeexceeded.

G1.2.9.5 MechanicalCouplings,FlangeAdaptersandExpansionJointsG1.2.9.5.1 General

(a) Mechanicalcouplingsforjointingplainendedpipesshallbeofanapprovedmake, capable of maintaining a watertight joint over a range of axial

movement between the pipe ends of at least 80 mm and with up to 3

degreesangulardeflectionbetweenthelongitudinalaxesofthepipes.

(b) Where mechanical couplings are used to take up the settlement instructures,theyshallbeprovidedinpairs.

(c) Flange adapters forjointing plain ended pipes to fittings shall be of anapproved

make

capable

of

maintaining

a

watertightjoint

over

a

range

of

axialmovementofatleast25mmandanangulardeflectionofnotlessthan

oneandahalfdegrees.

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G1.2 24


(d) Expansionjoints shall be provided to conform to details as shown on thedrawing.Theyshallbesuppliedcompletewithallaccessories.

(e) Mechanical couplings, flange adapters and expansion joints shall beprovidedwithtierodswherevernecessary.Pipesupportsshallnotbeused

to absorb thrust. Where tie rods are necessary, the rods shall be of the

samediameterastheflangebolts.Flangeadapters,whichrequiretierods,

shallbeofsuitabledimensionstoallowthetierodsnottointerferewiththe

body of the flange adapter. Cutting or grinding of flange adapter to allow

installationoftierodsshallnotbecarriedout.

(f) Allnecessarycouplers,jointrings,nuts,boltsandwashers,etc.requiredforcompletingjoints shall be supplied by the Contractor. All bolts, nuts and

washershallbehotdipgalvanisedinaccordancewithBSENISO1461.

(g) Couplings shall be supplied with or without a central register or locatingplugs as required. The central collar shall be at least 1.5 mm thicker than

theequivalentstandardpipethickness.

(h) Every coupling, flange adapter and expansion joint shall be capable ofwithstandingwithoutleakagethepressurerequiredfortheworkshydraulic

testofthesectionofpipelineinwhichitwillbeincorporated.Thepressure

rating shall be clearly stamped on all couplings and adapters. The rubber

jointringsshallbeType1toBSEN6811havingahardnessrangeof4565

degrees measured in accordance with BS 903 and tensile stressstrain

propertiesdetailedinTable3correspondingtotherelevanthardness.

(i) AllmetallicpartsaretobeshotblastedtoSA2toBS7079andprotectedwithtwocoatsofapprovedtwopackepoxybasedcoatingunlessotherwise

stated. Theenamelshallbetaintfree,nontoxicandchlorineresistant.

(j) Allweldingprotrusionshallbemachinefinished.Mechanicalcouplingsandflangeadaptorsshallbehydraulictestedattheplaceofmanufactureonein

everyfiveforeachsizeofcouplingandadaptor.

(k) Everyexpansionjointshallbehydraulictestedattheplaceofmanufacturepriortodelivery.

G1.2.9.5.2 InstallationofFlexibleMechanicalCouplingsforIronorSteelPipes(a) Mechanical couplings and flange adaptorsjoints shall be installed in strict

accordance with the instructions given by the manufacturer and to the

S.O.'s approval. In particular the Contractor shall render the end of each

pipe perfectly smooth so as to allow thejoint sleeve to slide freely and

wherenecessaryshallrecoatthepipeendswithtwocoatsofquickdrying

bituminoussolution.

(b) Beforejointing,theendsofeachpipeshallbewirebrushedtoremoveanyprotective material adhering to the coating, together with any

protuberances which may have been caused by rubbing of the packing

materialandalsoberemovedallrustatexposedplacesduetostrippingof

thebitumastic

coating.

The

ends

shall

then

be

recoated

with

aquick

drying

solutionsoastoproduceasmoothcoatofuniformthickness.

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G1.2 25


(c) Oncompletionofthejointthesurfacesofthecouplingandadaptorshallbepaintedwithaquickdryingprimerandanexternalsheathingmouldformed

toenclosethecouplingandendsoftheadjoiningpipes. Thisworkshallbe

carriedoutbyspeciallycompetentandskilledmeninstrictaccordancewith

theinstructionsgivenbythemanufacturer.

(d) Theprimerandsheathingmaterialcompatibletothesheathingmaterialonthepipesandthemouldboxesandfunnelsrequiredtoformtheprotective

mouldandwhitingusedforliningthemouldboxespriortoeachpourshall

besuppliedbytheContractor,whoshallalsosupplythenecessaryboilers

to heat the sheathing material to the application temperature. The

ContractRatesformakingcouplingandadaptorjointsshallcoverallcostsin

complyingfullywiththerequirementsofthisClause.

(e) Mechanical couplings and flange adaptors located in chambers shall bepainted with two coats of approved bituminous epoxy enamel unless

otherwisespecified.

G1.2.9.5.3 GasketsforFlexibleJoints(a) Gaskets forjoints shall be obtained from the manufacturer of the pipe or

joint.

(b) Jointgaskets shall complywiththe relevant requirements ofBSEN6811,shallbeofamaterialsuitableformakingalongtermflexiblesealbetween

the pipes and shall be resistant tomechanical, chemical or bacteriological

attack leading to deterioration of the flexible seal. Joint gaskets shall be

entirelycompatiblewiththemediabeingconveyedbythepipeline.

(c) Lubricantsusedduringjointingshallhavenodeleteriouseffectsonthejointrings,pipesorpipecoating.

G1.2.9.6 WeldingG1.2.9.6.1 General

(a) Wherethesteelpipesaretobejointedbywelding itshallbebymeansofan

internal

and

an

external

circumferential

electric

arc

weld

at

each

joint.

(b) Welded joints in trench shall generally be of the parallel short sleeve,spherical spigot and socket type with a circumferential full strength fillet

weld both internally and externally. Welding gap tolerances shall be as

specified. Full strength fillet welds shall have a throat thickness not less

than0.7timesthethicknessofthepipetobewelded.

(c) Whereprejointingofstraightrunsofpipeoutsidethetrench ispermittedby the S.O., full penetration butt welds executed by manual or automatic

procedures to the approval of the S.O. may beadopted. Butt welds shall

haveathroatthicknessnotlessthanthethicknessofthepipewall. During

welding,

the

pipe

ends

shall

be

securely

held

by

an

approved

method

ensuringacorrectanduniformrootgap.

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G1.2 26


(d) Beforeplacingthepipestogethertheportionofthesocketsandspigotstobeweldedshallbecleanedtoabrightmetallic finish,thespigotendshall

thenbeplacedinthesocketandforcedinsidesothatthesphericalsurfaces

areincontactandthatthegapbetweenthepipesattheendofthespigotis

nowhere greater than 1.5 mm. For longitudinally welded pipes, the

longitudinalweldsonadjacentpipesshallbeatleast15ooutofline. Details

ofthesocketandspigotweldedjointareshownontheDrawings.

(e) Wherepipes aretobejointedbyaweldedcollarjoint,thepipeendsandthecollarshallbecleanedtoabrightmetallicfinish. Thecollarshallthen

beplacedcentrallyoverthetwoendstobejointedsothatthegapbetween

thepipeendsshallbeabout25mmfromthecentrelineofthecollar. The

endofeachpipeshallbeweldedtothesleevecollarusingcircumferential

fullstrengthfilletweldsbothinternallyandexternally. Whereasplitcollar

is used, the two halves shall be drawn together by tie bolts until the gap

betweenthemislessthan3mm. Thefourcircumferentialweldsshallthen

be made, after which the tie bolts shall be removed and the longitudinal

seambetweenthecollarpieceswelded. Thetieboltlugsshallthenbecut

offand

the

attachment

points

smoothed

before

the

welds

are

tested.

(f) All parts to be welded shall have scale, slag, loose rust, paint and otherforeignmatter removedbymeans ofa mechanicalbrush andshall be left

clean and dry immediately before welding. All scale and slag shall be

removedfromeachweldrunwhenitiscompletedbeforeweldingoverany

previouslydepositedweldmetalandpriortoairtesting.

(g) AllweldsshallbesubjecttoinspectionbytheS.O.andshallcomplywiththerequirements of Clauses 9 and 11 of BS EN 1011 for freedom from

undercutting,fusionpenetrationandsoundness.

(h) After completion of welding at eachjoint, magnetic crack detection testsshall be carried out on all fillet welds made and 100% radiographic

examinationcarriedoutonallbuttweldsmade. TheContractorshallmake

allthenecessaryarrangementapparatusandequipmentandaspecialistto

carryoutthetest.AllsuchtestsshallbecarriedoutbytheContractorinthe

presenceoftheS.O.Wherebuttjointsarebeingweldedmechanically,the

S.O. may permit the proportion of weld radiographically examined to be

reducedto20% ifandwhenandas longashe issatisfiedwiththeresults

being obtained. The standard of acceptability of welds shall be in

accordance with API 1104 Section 6. Where necessary, welds shall be

repairedinaccordancewithSection10ofAPI5L. Weldrepairsshallnotbe

made

more

than

once

at

any

position

on

the

joint.

(i) TheanalyticaltestreportsinduplicateshallbesubmittedtotheS.O.threedays after the test. Therepaired weldsshallberadiographedagain atno

extracosttotheEmployer.

G1.2.9.6.2 WeldingProcedure(a) Weldingofjoints intrenchforsteelpipesshallbecarriedoutmanuallyby

the metalarc process complying generally with the requirements of BS

4515.

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G1.2 27


(b) Before starting the welding of pipe joints on Site, The Contractor shallsubmit fortheS.O.'s approval details of the plant, methods andmaterials

heproposestouse,includingthefollowingdetails:

(i) Make,typeandgaugeofelectrodes(ii) Size,shapeandnumberofrunsinweldedjoint(iii) Directionofwelding(iv) Currentstrength(v) Arrangementsforairtesting(vi) Welderscertificates.

(c) The Contractor shall make test specimens on pipes of the same size andthicknessesasthepipelinestobewelded. Thesepipesshallbesuppliedby

the Contractor. Thejoints shall be tested in the presence of the S.O. for

eachprocedureproposed inaccordancewiththerequirementsofClause7

ofBS4515.

(d) Only procedures approved in writing by the S.O. shall be adopted in thewelding

of

the

pipelines,

and

change

from

one

procedure

to

another

will

notbepermittedwithoutsubmittingthenewprocedureforretesting.

G1.2.9.6.3 WeldersandWelderPerformanceTests(a) OnlythemosthighlyskilledweldersshallbeemployedontheWorks,and

everywelderbeforecommencinganyjointweldingshallpreparespecimens

for testing in accordance with Clause 7 of BS 4515 for each welding

procedure proposed by the Contractor. Every welder shall be tested in

accordancetoClause8ofBS4515. TheContractorshallberesponsiblefor

thepreparation,

setting

up,

provision

of

specimen,

all

necessary

equipment

andmaterialsforthetestingofweldingpersonnel.

(b) The S.O. will advise the Contractor in writing which welders pass theperformance qualification test. Welding shall be carried out only by

weldersapprovedbytheS.O.andeachweldershall identifyhisownwork

bymeansofastencilledmark.

(c) TheContractorshallmaintainanuptodatelistofweldersapprovedbytheS.O.and,iforderedbytheS.O.,heshallremovefromtheapprovedlistany

welderwhoseworkmanship,asdemonstratedbytheresultsofairpressure

and/or

other

tests

and

visual

inspection

of

individual

welded

joints,

is

in

the

S.O.'sopinionbelowtherequiredstandard.

G1.2.9.6.4 AirTestingofWeldedJoints(a) Aftereachjointhasbeenweldeditshallbeairtestedinthepresenceofthe

S.O.

(b) Atappedhole,notlessthan6mmdiameter,shallbeprovidedinthespigotend of each pipe as specified elsewhere, into which a suitable pressure

gaugeshall

be

fitted

for

purposes

of

the

test.

An

air

pressure

of

17

bar

shall

thenbepumpedintotheannularspacebetweenthespigotandsocketand

thepumpdisconnected. Inthecaseofsplitcollarjoints,atappedholeshall

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G1.2 28


be provided at each end of the collar and each side of thejoint shall be

pressurised.

(c) If no drop in pressure occurs over the ensuing period of ten minutes, thetest shall be deemed successful subject to careful visual inspection for

leakage during the test. If the test pressure is not maintained for ten

minutes,thepositionoftheleakshallbedeterminedusingsoapsolution.

(d) All defects in the weld shall be cut back and rewelded as directed by theS.O.andthetestreapplieduntilsuccessful.

(e) Thetappedtestholesshallbethensealedoffwithweldingintopositionthethreadedscrewplugaftereachjointhasbeensatisfactorilytested.

(f) The Contractor shall provide all necessary gauges, pumps, etc, for the airtesting.

(g) Therequirementsofthisclauseshallnot limittheContractor'sobligationsin

achieving

satisfactory

results

in

the

tests

on

completion

as

prescribed

later.

G1.2.9.6.5 ThermalFusionJointingEquipment(a) Alltoolingandequipmentusedforthermalfusionjointingshallbeoftypes

in accordance with Employer/ British Gas Standards and shall include all

equipment necessary to cut, plane and clean, clamp, heat and align pipe

andindicateorcontroltemperaturesandheatingandcoolinginaccordance

withEmployer/BritishGasStandards.

(b) Fusion tools and heating plates shall be electrically heated andthermostaticallycontrolledwithanyhandlesorbracketsmadeofmaterial

havingelectricalinsulatingpropertiesconformingtoBS2559:Part3foruse

with230Va.c.or ifmadeofwoodtheyshallconformtoBS3823:Part1.

Thetoolorplateshallbeearthedthroughthegenerator.

(c) A thermometer shall be fitted and shall have a green zone indicating thecorrectfusiontemperaturerangeforPE100polyethelenemarkedwiththe

appropriate code. Thermometers shall be suitably protected from

mechanical damage, shall be replaceable and shall be accurate to 3C

within

the

fusion

temperature

range.

If

an

alternative

temperatureindicating system is used the plate shall have provision for inserting a

suitableconventionalthermometer.

(d) Thewattageoftheheaterelementsshallbesuchthattherequiredsurfacetemperaturerange isreachedwithin15minutes instillairandatambient

temperaturesof20C5C.

(e) TheinputleadsshallconformtoBS6500Table7orotheragreedstandards.(f) The temperature control system (thermostat) shall be flameproof in

accordancewithBS4683:Part2.

(g) Hydraulicramsusedtoalignpipeendsandbringthemtogethershalleachhave independentpressuregauges. Eachgauge shallhavea performance

certificate indicatinganydeviations intruetoactualreadings issuedbyan

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G1.2 29


independent tester not less than one month prior to its use. The

certificatesshallbemadeavailabletotheS.O.,togetherwithdatarelating

thehydraulicpressureofthemachinetothetotalforceappliedtothepipe.

G1.2.10 AccesstoInteriorofPipelines(a) Pipesprovidedwithcablepassholesshallbelaidsoastoprovidepassholes

positioned on top of the pipelines in excess of 600 mm in diameter at

intervalsofapproximately60m. Whenapasshole isno longerrequired,

thescrewplugshallbereplacedandweldedtothepipeexternallyandthe

internalandexternalprotectionsystemsshallbemadegoodovertheplug

andholidaytested.

(b) TheContractorshallrecordthelocationofallcableholepassesandensurethecorrectsealingthereof.

G1.2.11 InstallationofUndergroundPipesG1.2.11.1 General

(a) Trenchexcavationandbackfillingshallbecoordinatedwiththeconstructionof the pipeline as a whole so as to ensure expeditious completion of the

wholeoperation.

(b) Trench excavation and backfill shall be carriedout in accordance with therequirementsforEarthworksinthisSpecificationand,wherenototherwise

specified,in

accordance

with

Section

4of

BS

8010:

Part

1.

The

minimum

depth of cover above pipelines shall normally be 1000mm, the depth of

coverbeingmeasuredfromoriginalgroundleveltothetopofthebarrelof

thepipe. Anypipelinewithlessthannormalcovershallbesurroundedwith

atleast150mmofconcreteunlessotherwiseinstructed.

(c) Thelinesandlevelsofthepipelineandthepositionsofthebends,junctionsandotherfittingswhichareshownontheDrawingsmaybeadjustedbythe

S.O. as necessary before construction of a particular section commences.

The pipeline shall be accurately installed to the lines, levels, grade and

positionssetoutbytheContractorfromdatasuppliedtohimbytheS.O.so

that

the

barrel

of

the

pipe

shall

be

continuously

supported

throughout

its

lengthbythebottomofthetrenchorbybeddingmaterialasspecified.

(d) TheContractorshallsubmitfulldetailsofthemethodsheproposestouseforcontroloftheaccuracyofpipelaying. Siterailsshallbeusedtocontrol

the accuracy of pipelaying unless the S.O. directs otherwise. Where sight

rails are used, they shall be fixed and maintained at each change of

gradient,andatasmanyintermediatepointsasmaybenecessary,butnot

more than 35m apart. Sightrails shall be clearly painted in contrastin

c2_g1.2 - pipework

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