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Polyethylene Water Systems
Technical Guide
Technical Guide Content
04: Introduction
06: Polyethylene Systems
10: Quality Control
12: Product Details
14: Characteristics & Properties
20: Design & Performance Testing
25: Product Information
26: Fittings Range
28: Jointing
35: Testing & Commissioning
36: Installation
42: Handling & Storage
46: Health & Safety
Wavin Plastics Limited is part ofthe 1.7 billion (NLG) WavinGroup of companies. As agroup, Wavin operates intwenty-six countries, making itone of the largest converters ofplastic, the largest manufacturerof plastic pipe systems and thelargest industrial re-cycler ofplastics world-wide. UKHeadquarters are located inChippenham, where WavinPlastics Limited is the leadingplastics pipe systemsmanufacturer for the Building,Utility and Civil markets.
04
Welcome to Wavin
Wavin was founded in 1955 byJohann Keller, Managingdirector of the Overijssel WaterCompany. Today the WavinGroup employs over 4500people in 26 countries inEurope and South East Asia andworks closely with over 40licensees all over the worldincluding Japan, the UnitedStates and South America.
Wavin Plastics occupies a 26-acre site on the outskirts ofDurham City, employing over140 people in the production of
polyethylene and PVC-u pipesystems for the UK waterindustry, the agricultural marketand the world-wide gas market.
Wavin Plastics pursues a policyof continuous development andinvestment. This has resulted ina major re-organisation of themanufacturing site, which nowhouses what is almost certainlythe longest, most modern andtechnologically advancedpolyethylene plant in Europe.This enables Wavin Plastics tooffer pipe in long straight
lengths up to 18 metres, as wellas coils and drums up to 770metres in length. With aninvestment of 1.4 million, thenew layout incorporates thelatest equipment from materialconveying through extrusion tofinished product handling,storage and despatch. Inaddition to the facilities atBrandon, applied research,technical support and productdevelopment are undertaken atthe Wavin Advanced Centre forResearch and Developmentin Holland.
Flying the flag in Europe
05
High Performance Polyethylene(HPPE) with a strengthclassification, PE100, whichrefers to a pipe which has aminimum 50 years strength of10Mpa. This enables operationat pressures up to 16 bar for anSDR 11 pipe or 10 bar for anSDR 17 pipe. Further details onthe properties of these materialsare given in the Design andPerformance section of thisguide.
Wavin offers a choice of twomaterials:-
Medium Density Polyethylene(MDPE) with a strengthclassification, PE80, whichrefers to a pipe which has aminimum 50 years strength of8Mpa. This enables operation atpressures up to 12.5 bar for anSDR 11 pipe, 8 bar for an SDR17 pipe.
Polyethylene pipe systems offerthe water engineer manybenefits:-
✪ Cost Saving with faster,easier installation
✪ Limited or no dig installation
✪ Maintenance free design life
✪ Corrosion resistance
✪ Suitability for renovation,lining and insertion
✪ No requirement for end loadrestraint for fusion weldedsystems
✪ Fully fused jointing ensuringwater-tight system
✪ Flexibility, allowing forground movement
Polyethylene Systems
06
Medium densitypolyethylene (MDPE)
High performancepolyethylene (HPPE)
07
PE100
100 hrs Log Time Hrs 50 yrs
Log
Str
ess
MP
a
PE80
6
8
10
12
14
6
8
10
12
14
Figure 1. Material Classification
The WavinSure system is arange of blue MDPE (PE80) pipeand fittings suitable for use withbelow ground potable water.
The system meets therequirements of BS 6572:1985 for sizes up to andincluding 63mm, for use atpressures up to 12 bar. Sizes90mm and above meet therequirements of WIS 4-32-17 (pipe), 4-32-14 and 4-32-15(fittings). This system allows foruse at pressures up to 12.5 bar.
Details of the product rangecan be found in the WavinPolyethylene Potable WaterSystems Product Selector.
The Wavin SupaSure system isa range of blue HPPE (PE100)pipe and fittings suitable foruse with below groundpotable water.
The system meets therequirements of WIS 4-32-17(pipe), 4-32-14 and 4-32-15(fittings).
The material’s higherperformance characteristicsenable pipe systems to operateat pressures up to 16 bar.
WavinSureMDPE (PE80)
Wavin SupaSureHPPE (PE100)
Polyethylene Systems
08
Wavin TSHPPE (PE100)
The Wavin TS system is a co-extruded 2 layer pipe which hasan exterior layer of extremelytough polymer and an innerlayer of standard PE100material.
The system meets therequirements of WIS 4-32-17,for use at pressures up to 16bar.
Wavin TS’ superior performancecharacteristics provides greatersecurity against abrasion,notches and scoring when usedin adverse installationconditions.
The WavinBlack system is arange of black MDPE (PE80)pipe and fittings suitable for usewith above ground potableand below ground non potablewater.
The system meets therequirements of BS 6730:1986 for sizes up to andincluding 63mm, for use atpressures up to 12 bar. Sizes90mm and above meet therequirements of WIS 4-32-17 (pipe), 4-32-14 and 4-32-15 (fittings). This system allowsfor use at pressures up to12.5 bar.
The WavinJet system is a rangeof black HPPE (PE100) pipe and fittings suitable for use with above ground potable and below ground non potable water.
The system meets theperformance requirements ofWIS 4-32-17, 4-32-14 and4-32-15 (fittings).
The material’s higherperformance characteristicsenable pipe systems to operateat pressures up to 16 bar.
Details of the full product rangecan be obtained from the WavinSales Office.
WavinJetHPPE (PE100)
WavinBlackMDPE (PE80)
09
WIS 4-32-14Specification for PE80 and PE100 electrofusion fittings fornominal sizes up to andincluding 630mm.
WIS 4-32-15Specification for PE80 and PE100 spigot fittings and drawnbends for nominal sizes up toand including 1000mm.
WIS 4-32-17Specification for PE80 andPE100 blue and blackpolyethylene pressure pipes,nominal sizes 20mm to 630mmfor pressurised water supplyand sewerage duties.
WIS 4-32-03Specification for bluepolyethylene (PE80) pressurepipe for cold potable waternominal sizes 90mm to1000mm for underground orprotected use.
WIS 4-32-09Specification for blackpolyethylene (PE80) pressurepipe for cold potable water orsewerage, nominal sizes90mm to 1000mm forabove ground use.
WIS 4-32-13Specification for blue higherperformance polyethylene(PE100) pressure pipe, nominalsizes 90mm to 1000mm forunderground or protected usefor the conveyance of waterintended for humanconsumption.
Wavin also manufacture bluepolyethylene pipes up tonominal size 63mm for belowground use for potable water toBS 6572 : 1985 under aKitemark Licence issued by BSI.
Black polyethylene pipes up tonominal size 63mm for aboveground use for cold potablewater are manufactured to BS6730 : 1986 under a KitemarkLicence issued by BSI.
All Wavin products aremanufactured and tested undera Quality Management Systemthat is third party certificated bythe British Standards Institutionagainst the requirements ofBS EN ISO 9002 : 1994.Wavin Plastics Ltd. is a firm ofassessed capability under theBritish Standard Institution (BSI)scheme (Registration Number
FM 00217) for the manufactureand supply of pipe and fittingsconforming to the WaterResearch Centre (WRc)Engineering Specifications.
The Registered Firm Approvalcovers the manufacture andsupply against the followingspecifications:
Quality Control
10
Wavin operate a policy ofcontinuous improvement.Additional approvals, therefore,may be added to those detailed.Up to date information isalways available from theTechnical Services Helpdesk.
Wavin has continuallymaintained a commitment toquality and currently holds BSIKitemark Licences for thefollowing products:
BS 4962 : 1989Plastic pipes and fittings for useas subsoil field drains.
BS 5255 : 1989Thermoplastic waste pipe andfittings.
BS EN 1401-1 : 1998PVC-u pipe systems for nonpressure underground drainageand sewerage.
BS EN 7291 Parts 1&2 : 1990Thermoplastic pipes and fittingsfor hot and cold water fordomestic supply.
WIS 4-31-08 : 2001Oriented Polyvinyl Chloride(PVC-0) pressure pipes forunderground use.
Additionally Wavin havesupplied polyethylene pipe andfittings to British Gas since1975 and have maintained theirapproval status up to andincluding 500mm SDR 11 pipein PE80 and PE100.
11
Nominal Bore (ID) mm
SDR
11 17 21 26
20 15.25 • • •
25 20.3 • • •
32 25.8 • • •
50 40.4 • • •
63 50.9 • • •
90 72.9 78.7 81.0 •
110 89.1 96.3 99.0 •
125 101.2 109.5 112.5 •
160 129.6 140.3 144.0 147.4
180 145.9 158.0 161.9 165.8
225 182.4 197.3 202.4 207.4
250 202.8 219.6 224.9 230.4
280 227.1 245.9 251.9 258.0
315 255.6 276.6 283.4 290.3
355 288.1 311.5 319.4 327.6
400 324.6 351.2 360.0 368.7
450 360.1 395.2 404.9 414.8
500 406.3 438.9 449.9 460.9
560 454.7 493.9 503.7 516.3
630 511.5 553.1 566.8 580.8
PipeDiameter(mm)
Wavin Polyethylene PipeSystems are manufactured fromPE80, commonly known asMedium Density Polyethylene(MDPE) and PE100, HighPerformance Polyethylene(HPPE) and can be used forboth pressure and non-pressureapplications. Wavin have beenmanufacturing polyethylenepipe systems since the early
1970’s and since then havebeen at the forefront ofmaterials and manufacturingtechnology. This has resulted inWavin becoming the leadingplastics manufacturer in Europe.
Polyethylene is now anestablished pipeline materialfor water, gas and industrialuses and provides a cost
effective, reliable pipe systemwith excellent properties suchas corrosion resistance,chemical resistance andflexibility.
Wavin Polyethylene PipeSystems are available fornumerous applications and arecolour coded, following NJUGguidelines for each specific use.
Product Details
12
✪ Light Blue/Dark BlueBelow ground potable waterpipework
✪ BlackBelow ground pressure andnon-pressure foul waterpipework
Above ground potable water pipework
Above ground industrial pipework
✪ YellowBelow ground gas systems,up to 5.5 bar
✪ OrangeBelow ground gas systems,up to 7 bar
Figure 2. Pipe Dimensions.
The Standard DimensionalRatio (SDR) is used to describethe relationship between pipediameter, wall thickness andtherefore the pressure rating ofthe pipe.
The relationship between thepipe OD and wall thicknessremains constant for all pipesizes for a given pressure rating,and can be expressed in thefollowing equation.
SDR = Pipe Outside Diameter (Minimum)
SDR = Pipe Wall Thickness (Minimum)
eg: SDR 11 = 25022.8
13
Standard DimensionalRatio (SDR)
All Wavin Polyethylene pipeproducts are marked fortraceability in accordance withNational or InternationalStandards and the followinginformation is repeated at metreintervals along the pipe.
Pipe Marking Details:✪ Date of manufacture✪ Machine No.✪ Pipe Diameter✪ Shift No.✪ Product Standard✪ Company Identification✪ Material Grade✪ Sequential metre marking✪ SDR✪ Nominal Pressure rating
PipeMarking
250mm (O.D)
Wall Thickness22.8mm
Figure 3. SDR - Relationship betweenpipe O.D. and wall thickness.
Polyethylene has an extremelylow co-efficient of friction andtherefore has significantadvantages over other pipematerials for the transportationof abrasive slurries and in itsresistance to abrasion.
WavinBlack polyethylene pipehas been used extensively forpumped slurry applications overmany years and has been usedfor power station fly ash, chinaclay slurry, quarries and sandslurries. Field use andlaboratory testing has shown
that the performance of PEexceeds metallic pipe systems.This coupled with its flexibility,lightweight and ease ofinstallation makes it the idealchoice for abrasive slurryapplications.
The external effects of abrasivebackfill materials have only anegligible effect on PE. Wherepipe has been damaged by asharp object and the cut orgouge exceeds 10% of the pipewall thickness, the damagedsection should be cut out and
Characteristics & Properties
14
AbrasionResistance
Polyethylene is a tough materialand generally is resistant to theeffects of the UK climate.WavinBlack PE systems aremanufactured with a carbonblack additive which gives fullprotection against UV radiationand is therefore perfectlysuitable for use above ground.
WavinSure PE systems forbelow ground water use areintended for short term aboveground storage only and shouldnot be stored in excess of 12months, unless specificprotection is provided. Forfurther information please referto the Handling and Storagesection of this guide.
Weather Resistance
PROPERTY UNITS PE80 PE100
Density Kg/M3
Blue 944 Blue 950Black 949 Black 959
Poisons Ratio – 0.4 0.4
Melt Flow Rate@ 2.16 Kg Load g/10 min 0.2 <0.15@ 5 Kg Load g/10 min 1.0 <0.5
Tensile Strength@ Yield MPa 18 23
% Elongation@ Break % >600 >600
Modulus ofElasticity MPa 700 1000
Softening Point °C 116 124Brittleness Temp °C <-70 <-100
Coefficient ofLinear Expansion °C
-11.5 x 10
-41.3 x 10
-4
ThermalConductivity W/M °C 0.4 0.4
replaced. For further advicecontact the Wavin TechnicalServices Helpdesk.
Site practices in the UK do notgenerally allow pipe laying tocontinue below 0˚C, howeverthere may be instances duringinstallation or pipeline operationwhere temperatures below 0˚Care encountered.
The mechanical properties ofPE, operating pressure and
impact resistance aremaintained at temperatures aslow as -60˚C and therefore themoderate UK wintertemperatures do not pose anyparticular problems to theperformance of PE pipe.
Polyethylene is a particularlylow thermal conductor and willdelay the freezing of waterwithin the pipe. Where thewater does become frozen, theflexibility of PE and its ability toexpand without rupture ensuresthe security of the pipeline.
Low TemperatureUsage
Figure 4. Material Properties Table.
15
suitable, Wavin have developed‘Trigon’ – a multi-layered barrierpipe specifically for carryingpotable water throughcontaminated land. The WavinTrigon system consists of threelayers; an inner polyethylenecore pipe which is approved fortransporting potable water,followed by a layer ofaluminium which acts as abarrier, and an outer sheath ofpolyethylene which is markedwith distinctive brown stripesfor easy identification.
Please contact the WavinTechnical Services Helpdesk forany further information.
The exceptional resistance of PEto chemical attack is wellknown and generally there areno naturally occurring groundconditions which affect thematerial.
Polyethylene does not corrode,rot, pit or lose its mechanicalstrength properties throughelectrical or chemical reactionswith backfill soils.
Polyethylene does not, undernormal operating conditions,support the microbiologicalgrowth of algae, bacteria orfungi, nor is it affected by theseconditions.
Polyethylene may be affected bycertain chemicals and care mustbe exercised when consideringre-development of old industrialbrownfield sites.
Where soil conditions areunknown or known to beharmful, a soils analysis shouldbe carried out to determine anylikely contaminants.The harmful chemicals can begrouped into 3 main types:
✪ Oxidisers, eg very strong acids
✪ Cracking Agents, eg detergents
✪ Solvents, eg hydrocarbons (petrol, oil)
The degree of resistance to anychemical is dependent onconcentration, temperature andthe working pressure, all ofwhich may have an effect onthe lifetime of the pipeline. The effects may be detrimentalto the pipes strength orpermeate the pipe wall causingtainting of the potable watersupplies.
Where pipework is to be laid insuspect conditions, eg:brownfield sites and petrolforecourts, expert advice shouldbe sought before installingpolyethylene. If conditions aresuch that the use ofpolyethylene would not be
Chemical Resistance
PIPE EXPANSION/CONTRACTION (mm)
PIPE 5˚c 10˚c 15˚c 20˚c 30˚c 40˚cLENGTH (M)
1 0.75 1.5 2.25 3.0 4.5 6.02 1.50 3.0 4.50 6.0 9.0 12.05 3.75 7.5 11.25 15.0 22.5 30.08 6.0 12.0 18.0 24.0 36.0 48.010 7.50 15.0 22.5 30.0 45.0 60.015 11.25 22.50 33.75 45.0 67.5 90.020 15.0 30.0 45.0 60.0 90.0 120.050 37.5 75.0 112.5 150.0 225.0 300.075 56.25 112.5 168.75 225.0 337.5 450.0100 75.0 150.0 225.0 300.0 450.0 600.0150 112.50 125.0 337.5 450.0 675.0 900.0200 150.0 300.0 450.0 600.0 900.0 1200.0
Expansion &Contraction
securely anchored to preventpipe pullout.
With below ground installationsnew pipelines should beallowed to stabilise to ambienttemperatures before making thefinal tie-in connections, partialbackfilling of the pipe will assistin minimising the effects ofdirect sunlight.
Figure 5. The expansion and contraction of PE pipe in mm for a temperaturevariation range over pipe lengths up to 200 metres.
Polyethylene has a co-efficientof linear expansion ofapproximately 1.5 x 10 -4˚C -1
which is approximately 10times greater than metallicpipes. Expansion is animportant factor which shouldtherefore be considered in the
design of pipelines where asignificant variation intemperature is expected,particularly above groundpipework.
For design purposes pipeexpansion can be morepractically understood if weconsider the expansion as1.5mm/10˚C/ m. In above
ground installations carefulconsideration should be givento the positioning of supportbrackets and anchor points andthe use of fully end load bearingjoints. Where possibleexpansion and contraction maybe accommodated at changes ofdirection. Where non-end loadbearing fittings are used it isimportant that such fittings are
MDPE (PE80) has a minimumrequired strength (MRS) derivedfrom a 50 year extrapolated97.5% lower confidence limit of8 MPa and HPPE (PE100) has aMRS of 10 MPa. TheHydrostatic Design stress for
Polyethylene is a poorconductor of electricity anddoes not suffer from electrolyticcorrosion when in contact withmetal components (valves etc)or when connected into existingmetal pipelines.
As a non-conducting material PEshould not be used for theearthing of electrical equipmentnor can it be used as aconductor for frost protectionsystems. Similarly PE should notbe used where there are highlevels of static electricity,eg. in mines.
Polyethylene under normal
both materials is determined byapplying a safety factor of 1.25.The design life for the WaterIndustry requires a minimumlife of 50 years, therefore thedesign stress for PE80 andPE100 is as follows:
operating conditions isimpermeable to gas and is usedalmost exclusively for NaturalGas and LPG gas systems. PEpipework for potable water canbe laid in close proximity to PEgas mains following the NJUGrecommendations for pipeseparation distances. Thepresence of naturally occurringgas, such as is found in landfillsites, similarly has no effect onPE pipework.
PE80 and PE100 polyethylenematerials are very tough and itis difficult to initiate brittlefailure, even in the laboratoryon pipework at very low
PE80 = 5 MPa PE100 = 8 MPaPolyethylene pipe pressurerating is generally referred to inbar; 1 bar is approximatelyequivalent to 10.2 metre head.A harmonised UK Polyethylene
temperatures. Failure is typicallyof a ductile nature andextensive testing has shownRCP failure will not occur in apipeline full of liquid. Onlywhen air is present at levelsgreater than 10% is RCP likely,and with modern PE materialsany crack is arrested veryquickly.
Therefore under normaldistribution mains conditions,RCP failure is most unlikely. Forfurther information contact theWavin Technical ServicesHelpdesk.
Polyethylene is known to be
Pressure Pipe specification hasbeen developed alongsideISO/CEN working groups. Thetable below gives the pressureratings and SDR’s for PE80 andPE100 pipe.
extremely durable in normal useand it is not uncommon forpipes to be scratched andscuffed during handling andinstallation, particularly with re-habilitation methods such as slip lining and mainsbursting.
This sort of typical site damagewill have no adverse long-termeffect on the pipe provided thedamage does not exceed 10%pipe wall thickness. If thedamage is greater than 10% thepipe should not be used.Further details on Rapid CrackPropagation and NotchSensitivity can be found in theDesign and Performance sectionof this guide.
16
PE80 PE100
DIAMETER SDR MAX WORKING SDR MAX WORKINGPRESSURE (BAR) PRESSURE (BAR)
20(mm) 9 12.5 • •
25-63(mm) 11 12.5 • •
90-315(mm) 11 12.5 11 16
17.0 8 17.0 10
26 5 26 6
355-630(mm) 11 11.5 – 8 11 16
17.0 8 – 5 17.0 10
26 5 – 3.5 26 6
PressureRating
Electrolytic Reaction/Electrical Conduction
Permeability
Rapid CrackPropagation
NotchSensitivity
Characteristics & Properties
Figure 6. Pressure Rating
Pipe sizing and pressure dropcan be determined using theFlow Charts overleaf. These arebased on the Colebrook - WhiteFormula. Using the requireddesign flow rate (l/sec) thefollowing data can bedetermined:
✪ Pipe Diameter (mm)✪ Frictional Head Loss
(m/1000 metres)✪ Flow Velocity
(m/sec)
Determining the pressure dropin fittings is more complex.However, using a simpleformula to give an equivalentincrease in pipe length,pressure drop can be carriedout using the following formula;
L = F x ID where L = equivalent pipelength in metresF = Fittings constantID = Internal diameter ofthe fitting
Polyethylene pipe has anextremely smooth bore givingexceptionally good flowcharacteristics. As polyethyleneis non-corrosive and maintainsits smooth bore throughout itslifetime there is no deteriorationin its hydraulic performance.
Polyethylene pipe is classed ashydraulically smooth and thehydraulic frictional co-efficientsused for design purposes are asfollows:✪ Colebrooke - White
Ks 0.003 mm✪ Hazen Williams C = 150
All pipelines carrying water orslurries will see pressure lossesdue to the friction between theliquid and pipe wall. These aregeneral losses due to fluid flow.In addition there are pointlosses caused by fittings in the system.
17
BEND FITTING F
90˚ Elbow 0.030
45˚ Elbow 0.015
90˚ Tee (straight through) 0.020
90˚ Tee (side branch) 0.075
90˚ Long Radius bend 0.020
45˚ Long Radius bend 0.010
Polyethylene is a thermoplasticmaterial and a loss in strengthoccurs with increasingtemperature. The maximumoperating pressure for anyspecific pipe is based upon a 50year design life at 20˚C. Anyincrease above 20˚C will resultin a reduction in the maximum
allowable operating pressure orlifetime or possibly both.Polyethylene pipe systemsshould not be operated above60˚C. The following chart gives the reduction factors to be applied to the maximumoperating pressures at 20˚C.
If the temperature falls within this range the life expectancy of the pipecan be affected.Please contact the Wavin Technical Services Helpdesk for further details.
Operational Pressures forElevated Temperature Use
FlowCalculations
FittingsFormula
HydraulicProperties
20
% R
atin
g
50
100
25 30 35 40 45 50 55
Operating Temperature ˚C
9182
7363
4636
55
Figure 7. Pressure Reduction Factors for PE Pipe at Elevated Temperatures
Figure 8. Fittings Constant
18
PLEA
SE N
OTE:
TH
IS D
IAG
RA
M I
S F
OR
WA
TER
AT 1
5˚C
, A
ND
UTIL
ISES A
RO
UG
HN
ESS F
AC
TO
R (
ks)
OF 0
.003m
m
FLO
W D
IAG
RA
M F
OR
WA
VIN
PO
LYETH
YLEN
E P
IPE S
IZES 2
0m
m T
O 3
15m
m
19
PLEA
SE N
OTE:
TH
IS D
IAG
RA
M I
S F
OR
WA
TER
AT 1
5˚C
, A
ND
UTIL
ISES A
RO
UG
HN
ESS F
AC
TO
R (
ks)
OF 0
.003m
m
FLO
W D
IAG
RA
M F
OR
WA
VIN
PO
LYETH
YLEN
E P
IPE S
IZES 9
0m
m T
O 1
000m
m
Although a polyethylenepipeline, like any other pressuresystem, is primarily designed totake the wall stresses producedby the internal pressure of thesystem, it is important toconsider other potential loadingconditions. This is particularlytrue if full benefit is to be madeof the flexibility of the system inthe use of modern installationtechniques.
For example, in close-fitinsertion or moleploughoperations there is a tendency
to score the outside diameter ofthe pipe. Therefore it isessential to ensure that the pipehas sufficient resistance to thegrowth of cracks that couldarise from these externalnotches. This and many otherpotential hazards are taken intoaccount in the design andperformance testing of theWavin range of polyethylenewater systems to ensure thatthey have a long andmaintenance free service lifeunder design operatingconditions.
The burst pressure ofpolyethylene pipe is timedependent and therefore it isnecessary to define the strengthof the material at a referencelifetime.
The lifetime chosen for thisreference value is 50 years - itshould be noted that this doesnot mean that the pipeline willfail after 50 years, as the varioussafety factors that areincorporated into the design
mean that the actual lifetimewill be many times greater.In order to generate the burststrength of the material at 50years, a number of pipesamples are pressure tested tofailure at lifetimes between 10and 10,000 hours. The resultsof these tests are graphically ornumerically analysed to obtainthe minimum required strength(MRS) at 50 years. A graphicalrepresentation of this process is shown in Figure 9.
Design & Performance Testing
GeneralInformation
Design forInternal Pressure
20
10 Log Time Hrs 10,000 50 yrs
Log
Str
ess
MRS
MP
a
Figure 9. Hydrostatic Pressure Test Curve
In addition to a sound designphilosophy, it is also necessaryto work to a rigorous QualityAssurance testing scheme if thishigh level of performance is tobe maintained in day-to-dayproduction. This is best carriedout under a third partycertification scheme where anexternal body regularly checkstest procedures and productperformance.
This provides the end user withcomplete assurance of qualityfor the product range.
At the present time the Wavinrange of polyethylene watersystems are manufactured andtested in accordance with WaterIndustry or British Standards.However, discussions arecurrently taking place within thevarious European Committeesto develop the CENspecifications and certificationschemes.
The views expressed in thissection represent the currentthinking within these EuropeanStandards Committees.
Within the CEN and ISOStandards, it is recommendedthat the MRS value is basedupon the 97.5% lowerconfidence limit obtained byregression analysis, inaccordance with the methodoutlined in ISO / DTR 9080.2.
Within the Wavin range ofpolyethylene water systems,two basic polymers are
included – Medium DensityPolyethylene (MDPE) and HighPerformance Polyethylene(HPPE).
MDPE has a minimum requiredstrength of 8MPa and isdesignated PE80 while HPPEhas a minimum requiredstrength of 10MPa and isdesignated PE100 as shownin the following table.
diameter and wall thickness ofthe pipe by the formula:
SDR = Dt
Therefore:σ = P (SDR - 1)
2 or P = 2σ
(SDR - 1)
If this equation is applied topolyethylene pipe systems it ispossible to calculate theallowable operating pressure(PFA) as shown below:
PFA = 2 x MRS(SDR - 1) α
where:α = minimum design factorThis equation gives the stress in
MPa. For conventional use, andto express the pressure in barrating, the value in MPa ismultiplyed by 10. For example:
For PE80:PFA = 2 x 8 x 10
(SDR - 1) x 1.25
= 128 (SDR - 1)
For PE100:PFA = 2 x 10 x 10
(SDR - 1) x 1.25
= 160 (SDR - 1)
21
TYPE MRS
PE80 8.0
PE100 10.0
Figure 10. MRS Classification at 20˚C
Within the classification systemdeveloped at ISO/CEN, therehas also been considerablediscussion of the application ofdesign factors that should beused to determine the allowableoperating pressures (PFA) of aparticular plastic pipe system.This design factor is applied toaccount for any ‘unknown’loading or environmentalconditions.
The classification group hasrecommended minimum valuesonly, which allow the pipelineengineer to use additionalfactors if difficult conditionsexist (eg surge, elevatedtemperature or poor groundconditions).
For polyethylene pipelinesystems, the recommendeddesign factor is 1.25, whichenables the allowable operatingpressure to be calculated foreach system using Lame’sformula for thick walled pipes:
Hoop stress: σ = P (D - t)2t
where:σ = Hoop stress MPaP = Max. operating
pressure barD = Outside Diameter mmt = Wall thickness mmTherefore: σ = P D - 1
2 t
Now the Standard DimensionalRatio (SDR) is related to the
)(
20
% R
atin
g
50
100
25 30 35 40 45 50 55
Operating Temperature ˚C
9182
7363
4636
55
In calculating the operatingpressure, it is normal to roundup or down the values to thenearest useful pressure classshown in the table on the right.
It should be noted that theabove represent the maximumoperating pressures for the
pipeline and additionalconsideration may causeengineers to reduce theoperating pressure to a lowerlevel. For example, on largediameter PE80 pipelines whererapid crack propagation may beof concern (please refer to thesection on Fast Fracture).
Many materials may beextremely strong in laboratorytests but when they are notchedor scored in handling they canbecome very brittle. The classicmaterial in this category isglass, which is brittle enough tosnap along a defined line whenit is lightly scored. When laying
When operating a pipelineabove 20˚C, it is important toallow for the reduction in thestrength of the material atelevated temperatures. Withinthe ISO TC 138 SC5 committeesome work has been carried outto establish the relationshipbetween the maximumoperating pressure and theoperating temperature of thepipeline.
Their recommendations aregiven in Figure 12.
pipelines it is common for thepipe surface to become lightlyscored.
This is particularly true whenthe pipe is being inserted intoan existing main, or wheretrenchless laying methods arebeing used. In order to ensure
that brittle failure will notdevelop in the short or longterm from these surfacenotches, it is usual to carry outelevated temperature pressuretests on notched pipe samples.It should be noted that this testis only used within the UK,although discussions are now
taking place within ISO/CENcommittees for a wideradoption of these tests.
In practice, during installation itis recommended that pipe withnotches up to a maximum of10% of the wall thickness canbe used.
NotchSensitivity
22
PRESSURE CLASS (BAR)
TYPE SDR 11 SDR 17 SDR 26
PE80 12.5 8.0 5.0
PE100 16 10 6
Figure 11. Pressure Class for Polyethylene Systems
Figure 12. Pressure Reduction Factors for Polyethylene Pipe at Elevated Temperatures
TEST CONDITIONS
Type Notch Depth Temp˚C Stress (MPa) Life (hrs)
PE80 20% 80 4.0 170
PE100 20% 80 4.6 170
Figure 13. Test Conditions for Polyethylene Systems
Design & Performance Testing
If the temperature falls within this range the life expectancy of the pipe can beaffected.Please contact the Wavin Technical Services Helpdesk for further details.
23
For virtually all materials it ispossible for a dynamic crack togrow along the pipe lengthprovided that sufficient energyis available to overcome thematerial’s resistance to crackgrowth. Fractures of this typehave travelled many kilometresin welded steel pipelines andare only arrested by a valve orother pipeline fittings.
Over the past 10 yearsconsiderable test work has beencarried out to investigate therelevance of this mode of
fracture to polyethylenepressure pipelines. The conclusions of this workmay be summarised as follows:
✪ Crack propagation cannot occur if the pipeline is full of water. However, if the pipeline contains 10% or more air then propagation can occur.
✪ Cracks will not propagate through fittings including flanges or electrofusion couplers. Therefore the
crack will be limited to one pipe length in these cases.
✪ Crack propagation cannot occur in small diameter pipelines and therefore only large pipelines need be considered:PE80 - pipe diameter 250mm or above.PE100 - pipe diameters above 500mm.
✪ The critical pressure at which rapid crack propagation will occur is
FastFracture
Pipe Dia
Crack Propagation
Crack Arrest
PE80
PE100
250mm 500mm
24 BAR
Pre
ssu
re
Figure 14. Critical Pressure Curve for Polyethylene Pipe
dependent upon the pipe material and the pipe diameter. (see Figure 14).
If, in a particular scheme, it isimportant to design againstrapid crack propagation, themaximum working pressuresgiven in figure 14 should beused. For information on thesuitability and maximumoperating pressure of WavinPolyethylene systems outsideof the information given, pleasecontact the Wavin TechnicalServices Helpdesk.
✪ Yield StrengthPE100 23 N/mm2
PE80 18 N/mm2
✪ Linear Thermal Co-efficient of expansionPE80 1.5 x 10 -4˚C-1PE100 1.3 x 10 -4˚C-1
This equates to the followingmore useful terms:✪ PE80 0.15mm/m/˚C✪ PE100 0.13mm/m/˚C
(eg for 1 metre of PE80 pipe itslength increases 0.15mm forevery 1˚C rise in temperature).
Continuous performance testsare carried out on Wavinpolyethylene pipe systemsduring manufacture. These are:
TENSILE TESTSTest specimens from pipeproduction are tensile tested todetermine the yield strengthand elongation at break. Typicalminimum results giveelongation at more than 600%.
DELAYED BURST TESTFor PE80 pipe, samples taken atregular intervals are subjectedto a circumferential wall stress
of 12 MPa for a period of onehour at 20˚C. The pressure issteadily increased until the pipebursts, and it must be at astress greater than 16MN/m2.For PE100 the same test iscarried out at a wall stress of12.5 MPa for 100 hours.
ELEVATED TEMPERATURE TESTSamples from all production ofpipe from PE80 material arenotched to 20% of wallthickness at four points aroundthe circumference andsubjected to a wall stress of4.0MPa (8 bar for SDR 11) at
80˚C for a minimum period of170 hours, to establishcomparative performancetrends in relation to theresistance of the system tofailure by stress cracking. For PE100 material, the notchedpipe is subjected to a wallstress of 4.6MPa (9.2 bar forSDR 11). The purpose of thistest is to monitor the stresscrack resistance of the systemand to ensure that crack growthdoes not occur in less than therequired test life represented bythe test.
AdditionalDesign Details
Quality AssuranceTesting
24
In designing any pipelinesystem, it is necessary toconsider other factors that mayinfluence the performance ofthe pipe. In most cases,sufficient data will have been
gathered to provide formaldesign recommendations, but in other situations adviceshould be sought from theWavin Technical ServicesHelpdesk.
Other designConsiderations
Design & Performance Testing
Product Information
PipeLengths
Pipe up to and including180mm diameter is supplied ineither straight lengths or ascoils, 250mm diameter pipeand above is supplied in straightlengths. Straight pipe issupplied in bundles supportedby wooden timbers.
Coils of up to 100 metres inlength are available in pipe sizes90mm – 180mm (see figure15.) These coils offer the benefit of areduced number of jointscompared to straight lengthsand are particularly useful inconstricted urbanenvironments.
Special attention must be givento handling these coils; detailsare given in the Handling andInstallation sections of thisguide.
25
FREE STANDING COIL DIMENSIONS
Nominal Length Width Width Internal Internal External ExternalDia. (mm) (M) (mm) (mm) Dia. (mm) Dia. (mm) Dia. (mm) Dia. (mm)
SDR 11 SDR 17 SDR 11 SDR 17 SDR 11 SDR 17
90 50 280 280 1800 2500 2300 2900100 370 370 1800 2500 2800 3000
125 PE 80 100 510 510 2500 2500 3200 3200
125 PE 100 100 510 510 2500 3000 3200 3700
180 100 600 600 3000 3000 4000 4000
Free StandingCoils
LOOSE COILS PER LOAD
Pipe 50M 100MDiameter Coils Coils
20 mm 450 40025 mm 400 40032 mm 300 25050 mm 100 4063 mm 100 4075 mm 35 4090 mm SDR 11 40 2090 mm SDR 17 28 20125 mm 15 12180 mm SDR 11 8 6
StandardCoils
Drums of pipe up to 770metres in length are available indiameters 90mm, 125mm and180mm. Figure 18 gives somedetails. Drums are ideal forrural applications withtrenchless laying techniques,reducing the number of jointsand utilising the flexible natureof polyethylene.
DrumLengths
COIL DIMENSIONS
Nominal Length Width External NominalDia. (mm) (M) (mm) Dia. (mm) Dia. (mm)
20 25 85 840 78050 130 860 780100 150 900 780150 165 920 780
25 25 110 855 78050 140 880 780100 180 930 780150 205 955 780
32 25 130 876 78050 165 908 780100 200 972 780150 245 1004 780
50 25 160 1400 130050 260 1450 1300100 280 1550 1300150 280 1650 1300
63 25 190 1436 130050 255 1489 1300100 380 1562 1310150 400 1625 1310
DRUM LENGTHS
Pipe LengthDiameter (M)
90 mm 770
125 mm 440
180 mm 220
Coils of 50 and 100 metrelengths are available in pipesizes up to and including180mm. 150 metre coils areavailable up to and including75mm. Figure 17 gives detailsof the coil dimensions. Othercoil lengths may be availableupon request.
Straight pipe can be supplied inlengths of up to 18m. This is ofparticular benefit for pipediameters of 250mm and abovefor which coils of pipe are notavailable. Details on handlingand transportation are given inthe Handling section of this
guide. To optimise space,export shipping standardlengths are 5.8m (20’containers) and 11.65m (40’containers), and are nested(smaller diameter inside largerdiameter) where possible.Longer lengths are available
dependent on site location andaccess. Please contact TechnicalServices for details.
StraightLengths
Figure 15. Free Standing Coil Dimensions
Figure 16. Loose Coils per Load Figure 17. Coil Dimensions Figure 18. Drum Lengths
For information regarding 110mm, 140mmand 160mm please contact Wavin TechnicalServices Helpdesk.
PuppedFittings
ElectrofusionFittings
Electrofusion Fittings areavailable for use with Wavinpolyethylene systems. Thesesocket fittings consist of aninjection moulded polyethylenebody with an integral heatingelement. Some of the fittingsavailable are shown right.
Details on jointing usingelectrofusion fittings are givenin the Installation section of this guide.
Fittings Range
Pupped fittings are available inall ranges in sizes above 63mm.These fittings comprise of aninjection moulded centre bodywith 500mm length of pipe(pups) butt welded to it as astandard. These fittings areprimarily designed for buttfusion, but can also be usedwith electrofusion couplers.The illustrations (right) showsome of these fittings.
26
Wavin polyethylene spigotfittings are available in allranges. These fittings (shownright) are completely injectionmoulded and and are designedfor use with electrofusionfittings.
SpigotFittings
DrawnBends
Wavin offer a range of longradius drawn bends in allranges, in sizes 90mm andabove. These fittings involve aspecified length of polyethylenepipe pulled to a defined angleand are suitable for use withbutt fusion and electrofusioncouplers. Drawn bends areavailable in 90˚, 45˚, 22.5˚ and 11.25˚ angles as standard.
For details of the full range of polyethylene fittings, please consult the Wavin Potable Water Product Selector.
MitredFittings
A range of mitred (orsegmented) fittings are availableto supplement the range ofpupped fittings. These fittings(shown right) are manufacturedfrom pipe using a computercontrolled automatic butt fusionmachine, and are available insizes 63mm and above.
27
Both Butt Fusion andElectrofusion use specialistequipment to carry out fieldjointing. Modern machinedevelopments now providetotally automatic jointing,eliminating the risk of operatorerror and providing a full recordof joint history for QualityAssurance of site welding.
Machinery can be eitherpurchased or hired from
manufacturers and detailedproduct literature is availabletogether with familiarisationcourses to ensure correct use of the machinery.Operatives should howeverreceive full training. Courses areprovided by the WTI (WaterTraining International), andtraining is available from Wavineither at its Durham basedCustomer Training facility or atthe customers premises.
Jointing
28
ButtFusion
Polyethylene pipe systems arerelatively simple to joint andinstall. Two jointing methodsare available to cater for thecomponents that are used tobuild an operational system.
✪ Fusion Welded Joints
a) Butt Fusion b) Electrofusion
✪ Mechanical fittings
GeneralInformation
Butt Fusion jointing involves thefusing together of two pipeends in a specialist machinewhich prepares the pipe ends,heats them and brings themtogether under pressure to forma homogeneous weld. The joint is fully end loadresistant and is at least asstrong as the parent pipe.
With Butt Fusion it is essentialonly similar grades of PE arewelded, eg:
PE100 – PE 100 ✓PE100 – PE80 ✗
and similar SDR’s are used, eg:SDR 11 – SDR 11 ✓SDR 11 – SDR 33 ✗
Reference should be made tothe Water Industry SpecificationWIS 4 - 32 - 08, Issue 2, 1994,which details all site fusionwelding methods and coversthe single and dual pressuremethods. Dual pressurewelding was introduced as aresult of investigations into jointquality by the WRc and thisprocedure should be used forall pipes with a wall thicknessgreater than 20mm. Due to thelow pressures involved in thedual pressure procedure, onlyfully automatic machines shouldbe used; manual machines maystill be used for single pressureButt Fusion jointing.
FusionWelding
29
EquipmentRequired
✪ Butt Fusion machine, inclusive of trimmer, heater plate and hydraulic pump.
✪ 110v Generator, fuel✪ Welding Tent/Base board✪ Pipe support rollers✪ Clean water, lint free cloths✪ External de-beading tool✪ Bead gauge✪ Pipe end covers✪ Indelible marker pen✪ Pipe cutting tools
✪ Ensure the pipe ends are clean and if necessary, wash with clean water and dry.
✪ Cut the pipe ends square and clamp securely in the B/F machine.
✪ Align and level the pipes with pipe support rollers.
✪ To prevent cooling of the heater plate blank off the free pipe ends.
✪ Trim the pipe ends until a continuous shaving is seen from each pipe end.
✪ Remove loose shavings and importantly, do not touch the prepared pipe ends.
✪ Close the clamps and check for good alignment of the pipe ends, the allowable mismatch is; 90mm-315mm pipe, 1 mm 355mm-630mm pipe, 2 mm Re-trim if mismatch is greater than these values.
✪ Open and close the clamps, noting the gauge pressure to close the clamps - This is
the drag pressure. The fusion (jointing) pressure is obtained by adding the drag pressure to the hydraulic ram pressure given on the machine data plate.
✪ Place the heater plate in the machine, checking it is clean and undamaged and up to temperature, 225˚C - 240˚C.
✪ Close the clamps and apply the previously determined pressure until a bead of 2-3mm is formed.
✪ Reduce the pressure in the system to between 0 and drag, the heat soak time commences. Ensure the pipes maintain contact with the heater plate.
✪ Upon completion of the heat soak time, remove the heater
plate and close the clamps immediately, (within 10 seconds).
✪ Maintain the required fusion (jointing) pressure for the specified cooling period.
✪ Remove the joint & allow to cool for a similar period.
✪ Clearly mark the joint and bead for identification with an indelible pen.
✪ Check the joint is free from any contamination, and check the bead widths meet the specified limits and are uniform.
✪ Remove the external bead and twist in several positions. If the bead splits at any position the joint should be cut out and re-made.
Procedures ofManual Butt Fusion
✪ If the heater plate requires cleaning this should be done when the plate is cold. The plate can be washed with clean water and lint free cloth and dried thoroughly. Isopropanol may be used to remove any oil or grease.
✪ Washing the heater plate
may not remove very fine dusty particles, therefore at the start of each welding session a dummy weld should be carried out for pipes up to 180mm in diameter. For pipe sizes greater than 180mm, two dummy welds should be
maintain the required minimum ambient temperature for welding.
✪ Electrofusion "wet wipes" should not be used after the pipe ends have been trimmed, if any contam-ination does occur the pipe ends should be re-trimmed.
30
Additional Notesfor Butt Fusion
made. An actual joint need not be made, the dummy weld can be aborted at the end of the heat soak period. Pipe offcuts may be used.
✪ In very cold conditions, below 5˚C, additional space heating must be provided in the fusion welding tent to
Electrofusion
Electrofusion fittingsincorporate an electrical heating element which is energised viaan E/F control box to heat theelements.
When the fitting is energisedthe material next to itbecomes molten and in turncauses the pipe surfaceto melt, resulting in a moltenpool of material fusingthe materials of fitting and pipe.Once cooled this produces afully fused and leak free joint.
Details of electrofusionprocedures are given in WIS 4-32-08, Issue 2, 1994 and reference should be madeto this document for furtherguidance.
Jointing
onto the pipe.The correct tooling must be used for each style of saddle.
A number of manufacturersproduce E/F control boxes andthe ancillary tooling required. The correct tooling must beused to ensure consistentlyreliable joints and this may beeither purchased or hired fromthe tooling manufacturer ortheir agents. The site
31
Automatic &Manual Fittings
Many manufacturers now offerAutomatic and Manual fittingsand it is important to ensure theE/F control unit is compatiblewith the fittings being used.Most control units can beoperated in both Automatic and Manual mode.
Two styles of saddle fittings areavailable;✪ stack loaded saddles✪ under clamp saddles
Both styles provide a serviceconnection to polyethylenemains and differ only in themanner they are clampedduring fusion.
Stack loaded saddles are locatedwith a stack loading tool whichdelivers the force requiredduring fusion through the stackof the fitting, whereas, withunderclamp saddles the jointingforce is provided by a clampdevice, located beneath thefitting and pulls the fitting down
Saddle Fittings(Tapping Tees)
FusionIndicator
FusionZone
ColdZones
ElectrofusionFitting DesignThe design of an E/F fitting iscrucial to its performance and isdependent on the position andpitch of the heating coil. The heat distribution should be consistent throughout thefusion cycle and over the full
fusion area. The melt must beadequately controlled within thehot and cold zones to ensure afully welded, homogeneousjoint. The different zones of anE/F fitting are shown in Figure 19.
Figure 19. Cross section through an Electrofusion Coupler
equipment should include:✪ E/F control unit✪ 110 volt generator✪ 3 - 3.5 KVA for 39.5 volt
fittings✪ 6 - 7 KVA for 80 volt fittings✪ Jointing shelter✪ Pipe scraping tool, including
mechanical scrapers for pipe end preparation and hand scrapers for saddle joints
✪ Pipe cutting tool✪ Marker pen, solvent wipes,
lint free cloths/paper towels
EquipmentRequired
32
the entire pipe surface over the marked area in a continuous ribbon of material if possible.
NOTE: Do not touch thecleaned scraped surface.
Mechanical scrapers arepreferred over hand scrapers asskill and practice is requiredwith hand scraping and can bequite time consuming for larger
diameter pipes.✪ Remove the fitting from its
bag, check it is clean and undamaged, and assemble onto the pipe ends clearly marking the depth of entry with a marker pen.
✪ Securely clamp the joint assembly with the appropriate clamps.
✪ Attach the control unit leads, check the generator has sufficient fuel and
✪ Pipe ends must be cut square and de-burred.
✪ If necessary clean the pipe ends with clean water and dry.
✪ Clearly mark the depth of entry, plus 25mm, around the pipe circumference. Use the fitting as a guide, without removing from its sealed bag at this stage.
✪ Using the mechanical pipe-scraping tool, remove
commence the fusion cycle following the control unit instructions for the type of fitting being used.
✪ Check the melt indicators have risen, these indicate the fitting has been energised and has completed a fusion cycle.
✪ Allow the joint to cool for the required time, full fusion details are given on each fitting.
Principles ofEF Jointing
pipe straightening tooling should be used to assist in the process.
✪ Do not extend control unit leads to the fittings and ensure the lead between generator and control unit is not excessive as an unacceptable power drop can be created.
✪ Jointing must always be carried out in dry and dust free conditions.
✪ Do not use rasps/files or abrasive sheets to prepare pipe ends.
✪ Always use the correct clamps for jointing.
✪ When jointing coiled pipe, additional re-rounding and
✪ For live connections, tapping into the water main should be carried out after all joints have cooled for a minimum of 30 minutes.
✪ Where E/F couplers are to be used for repair situations the existing main should be completely dry with no running water.
✪ If the fusion cycle stops in mid-cycle first check for any control unit faults. Check for fuel. If the fault can be rectified, welding can re-commence providing the joint has cooled to ambient temperature and the fusion time is re-set for a further full cycle.
Additional Notesfor Electrofusion
Jointing
33
FlangedJoints
There are numerousmanufacturers of compressionfittings suitable for use withpolyethylene pipe, they are allbased on the same designprinciple where an elastomeric
ring seal is compressed betweenpipe and fitting. Some fittingsrequire the use of pipe boreinserts to provide sufficientrigidity for the compressionseal to be effective.
Mechanical JointsCompression Fittings Replacement Pipe“o” Ring
Pipe Stiffeners
One of the simplest and earliestmethods for connecting PE pipeto valves, hydrants and existingpipe materials is to use apolyethylene stub flange. Stub flanges are supplied pre-fabricated with either spigot orpupped pipe lengths and steelbacking ring, drilled to suitmetric PN16 flanges. Otherflange drillings are availableupon request.
As polyethylene pipe is sized onthe O.D. and Ductile Iron, forexample, is sized by its internalbore, allowances must be madefor differences in pipe bore anddiscrepancies in correspondingmating flanges. This occursmore with larger diameter pipesand a flange converter will berequired in these instances toensure compatibility of pipe bores.
Figure 20. Cross Section through an Elastomeric Ring Seal
TYPICAL BOLTING TORQUES (PE TO PE)
Pipe Nominal Bolts Torque (nm)
Diameter Flange ± 10%
63 (mm) 50 (mm) M16 x 4 3590 (mm) 80 (mm) M16 x 8 35125 (mm) 100 (mm) M16 x 8 35180 (mm) 150 (mm) M20 x 8 60225 (mm) 200 (mm) M20 x 12 80250 (mm) 250 (mm) M24 x 12 100315 (mm) 300 (mm) M24 x 12 120355 (mm) 350 (mm) M24 x 16 150400 (mm) 400 (mm) M27 x 16 200450 (mm) 450 (mm) M27 x 20 250500 (mm) 500 (mm) M35 x 20 300
Where a change in pipe bore isnot acceptable, a steel flangeconverter can be used tomaintain a clear bore, thediagram below shows a typicalflange configuration for a450mm PE stub flange to a400mm D.I. flange.
34
FlangeConvertor
Jointing is straight forward andthe following guidelines can be used.✪ Ensure the mating flange
faces are clean and free from damage.
✪ Select the appropriate size and grade of gasket for the application.
✪ Align both flange faces before bolting up. Ensure thepipes/components are
aligned and do not impose any bending stresses on the joint.
✪ Jointing compounds are not necessary.
✪ Use only clean undamaged nuts, bolts and washers of the correct size.
✪ Ensure the gasket is aligned and centred before bolting .
✪ Assemble the joint and finger tighten all nuts / bolts
and progressively tighten all bolts in a diagonally opposing sequence as follows, using a torque wrench:• 5% of final torque• 20% of final torque• 50% of final torque• 75% of final torque• 100% of final torque
✪ For evenness of tightening it is advisable to use two
operators for flanged joints larger than 180mm diameter.
✪ If practical, final torquing up should be repeated after the joint has relaxed for 1 hour.
✪ It is important the joint is tightened evenly and in sequence to ensure a leak free joint, this is as important as the use of recommended final torque values.
Stub FlangeJointing Procedure
400m
m
450m
m
450m
m
Figure 23. Standard Stub Flange Joint
450m
m
400m
m
450m
m
Figure 22. Flange Convertor
Jointing
Figure 21. Typical Bolting Torques
35
✪ Upon reaching the test pressure, the test section is isolated.
✪ Pressure loading time is used as the base reference point, (t1).
✪ A correction factor, 0.4tL, is used to calculate ratios (N), this accounts for the pipeline beginning to relax during the pressurisation period.
✪ Take a first reading of pressure P1 at t1 where t1 is equal to the pressureloading tL.Corrected value = t1ct1c = t1 + 0.4tL
✪ Take a second reading of pressure P2 at a decay time of 7tL this is time t2.Corrected value = t2ct2c = t2 + 0.4tL.
Calculate N1 = log P1-log P2log t2c-log t1c
For a pipeline without leaks, N1should be:a) 0.08 to 0.10 for pipes
without constraint (eg sliplined, or not backfilled)
b) 0.04 to 0.05 for pipes with compacted backfillIf the resultant values are significantly less than those specified, this indicates that there is too great a volume of air in the pipeline. This air must be removed before a re-test can be satisfactorily carried out.
✪ Take a further reading of pressure P3 at a decay time of not less than 15tL, this is time t3.
t3c = t3 + 0.4tLCalculate Nz= log Pz - log P3
log t3c - log t2c
The ratio N2 should again be asthose identified above. The testsensitivity can be increased byextending the value of t3.
✪ If an unacceptable leak is indicated, all mechanical joints should first be checked, followed by checks on any Butt or Electrofusion joints.
✪ If a further test is necessary, a period of at least five times the first test period should elapse before re-testing. This allows the pipeline to recover from the previous pressurisation.
✪ Upon the successful completion of a test, the remaining pressure in the pipeline should be released slowly.
Following successful pressuretesting all new mains, lined or re-furbished, should becommissioned in the followingmanner and in accordance withany local requirements:
✪ Cleaning and/or swabbing of the main
✪ Filling and sterilisation✪ Flushing and/or neutralisation✪ Refilling the main✪ Bacteriological sampling✪ Acceptance certification✪ Introduction of the main into
service
TestProcedure
CommissioningProcedure
PE pipe systems should bepressure tested up to amaximum of 1.5 times the ratedpressure of the pipe. However,for practical purposes it is usual and may only benecessary to pressure test up to1.5 times the pipeline workingpressure.
✪ Test in sections of 1000 metres or less.
✪ Pipework should be backfilled, with joints left exposed at the
engineers discretion.✪ Pipework must not be tested
at temperatures in excess of 30˚C.
✪ Air valves should be placed at all high points in the system.
✪ Data loggers with pressure transducers should be used to provide a precise analysis of the pressure test data and can provide the engineer with an early indication of any leakage.
✪ For on site calculations a pocket calculator is sufficient.
TestPressures
Test SectionPreparation
Testing & Commissioning
Site PressureTesting
The traditional testingprocedure used for mostpipeline materials throughoutthe Water Supply Industry isgiven in BS CP 312 : Part 3 :1973 : Section 10.These procedures are generallyintended for linearly elasticmaterials, eg ductile iron and
steel, and are not suitablewithout modification for viscoelastic materials such aspolyethylene. Pipemanufactured from suchmaterials exhibit creep andstress relaxation. With a PE pipesealed under a test pressure,there will be a reduction in
pressure (pressure decay) dueto the visco elastic (creep)response of the material.This will occur even in a leakfree system. This pressuredecay is non-linear in anunrestrained pipe. In view ofthis characteristic the WRc havedeveloped a pressure test which
accounts for the effects of creepand stress relaxation. The fulltest procedure with detailedbackground data is given in theWRc "Manual for PolyethylenePipe Systems for Water SupplyApplication", 1994. For furtherguidance reference should alsobe made to the manual.
Pressure
Pipe
Figure 24. Test Pressure Curve
Wavin PE80 and PE100polyethylene pipe systemsprovide a cost effective andsimple to install pipe system.
Polyethylene is a thermoplasticmaterial resulting in alightweight, flexible pipe, whichis totally corrosion resistant andleak free with proven fusionwelded and mechanical
jointing methods.
The following notes give ageneral guidance into the use ofPE, and should be read inconjunction with the WRC"Manual for Polyethylene PipeSystems for Water SupplyApplications, 1994 and BS COP312, Parts 1 and 3 PlasticPipework".
Excavation and disposal ofwaste spoil are major factors inpipe installation. Landfill taxesare becoming a significant costand environmental factors areforcing Engineers to look at newinstallation methods tominimise the disruption andamount of waste spoilgenerated.
The current practice in the UKis to lay service pipes at 750mmcover and mains at 900mmcover, measured from the pipe crown.
The width of the trench shouldbe the minimum of pipe O.D.plus 250mm to allow for thecorrect compaction of sidefill.The location of cables and pipesfrom other utilities should beidentified prior to excavation
and generally at least 3 pipelengths should be excavatedprior to pipe installation toallow for obstructions to be avoided.
Polyethylene may in someinstances be laid directly ontothe trimmed trench bottomwhere the soil is uniform, finegrained and free from largestones and flints.
In other cases the trench shouldbe excavated to a depth toallow for a minimum 100mmbed of gravel, crushed stone orcoarse sand. A sand/gravel mixis also acceptable, provided thegravel is less than 20mm in size.
Further details on bed and fillmaterials are given inWIS 4-08-01.
One of the key strengths ofpolyethylene is its ability to befusion welded, either by Butt orElectrofusion. This results in acontinuous, flexible pipe stringwhich can be easily snaked intopre-dug trenches. Where siteconditions permit welding canbe very easily carried out aboveground. Polyethylene lendsitself to a number of minimum
dig and no-dig techniques,many of which were developedspecifically around PE pipesystems, eg:✪ Narrow Trenching✪ Ploughing✪ Moling✪ Pipe Bursting✪ Slip Lining✪ Folded PE, lining systems✪ Directional Drilling
Installation
BuriedPipework
ConventionalOpen Cut Trenching
36
Imported or selectedbedding & backfillmaterial
300mm
Marker Tape
Min900mm
100mmPipe OD +250mm
As dugmaterial
Figure 25. Typical Open-Cut Trench Detail
As discussed earlier a numberof techniques have beendeveloped to maximise thebenefits of using polyethylene,these techniques are brieflydiscussed below.
A modification of traditionalopen-cut trenching. Usingeither narrow backhoe bucketsor chain trenchers, trenches100mm wider than the pipebeing installed are excavated.Coiled, drummed or pre-weldedpipe strings can be quicklyinstalled. Significant savings canbe achieved through reductionsin less excavated spoil, less
imported fill materials andreduced labour.
Developed from agriculturalmachines laying land drainage,these machines are used forlaying cross-country waterand gas pipelines.
Pipes are laid with littledisruption to the land which is quickly reinstated toagriculture. Pipe is installedcontinuously through a hollowplough with bed & surroundmaterial plus marker tapeinstalled simultaneously as required.
37
Backfilling
InstallationTechniques
PloughingTechniques
NarrowTrenching
ShallowCover
Lessthan900mm
150mmMin
Trench Width +300mm
Figure 26. RecommendedProtection for Shallow Pipes
Polyethylene is a flexiblematerial and can deform underload without damage. It ishowever, important that anydeformation is minimised andthat the placement of thecorrect sidefill and initial backfillmaterials is carried out correctlywith adequate compaction.A minimum 100mm cover
should be placed above thecrown of the pipe, with heavycompaction equipment notbeing used with less than300mm cover. Backfilling canthen proceed in 300mm layers.Trench reinstatement inHighways is covered in theNRASWA "Specification for theReinstatement of Openings in
Highways", 1992. This code wasintroduced with the aim that allhighway reinstatement iscompleted as soon as possibleto a consistent prescribedperformance criteria.
Trench backfilling shouldcommence as soon as possibleafter pipe laying to give the pipe
protection from damage fromobjects possibly falling into thetrench. To protect the pipefrom potential futureinterference damage it is goodpractice to install a marker tape300mm above pipe crown.Marker tapes can also include a tracer wire to allow futureidentification of the pipeline.
There may be situations wherepipes cannot be laid at therecommended depths of cover.In these situations for highways or traffic areas thepipe should be protectedby placing a 150mm thickreinforced concrete bridgingslab above the pipe. A 150mmthick granular cushion shouldbe placed between the pipecrown and concrete, figure 26 details the typicalapplication.
InstalDrilling Rig Pipeline
WashoverPipe Barrel
Reamer
Pipeline
Swivel Joint
Drilling Rig
WashoverPipe
BarrelReamer
Pipeline
Moling has become anestablished no-dig method forthe installation of smalldiameter service pipes andmains, and can give significantcost savings over open-cuttrenching. Excavation is limitedto launch and reception pits andmoling is ideally suited for roadcrossings and installationsunder expensive paved areasand gardens where open-cuttrenches would be verydisruptive.
Note: The presence of otherservices should be establishedprior to moling.
The impact mole is an air drivenpercussion tool, which drives aborehole and usually pulls anew polyethylene pipe directlyin behind it.
The technique can also be usedon carriageways in a techniqueknown as "pipe stitching" wherepipe is installed from pit to pit.
This technique has also becomean established installationmethod for PE pipe and is usedfor road, rail and river crossingswhere open-cut work would beusually impracticable andprohibitively costly.
The hole is bored by eitherhigh-pressure liquid jets or withdrill bits, and fully steerablesystems are available bymonitoring transmitters in thecutting head.
The operation involves drilling asmall diameter ‘pilot’ holebeneath the obstacle and thefinal hole size is achieved byprogressively back reaming upto the diameter required. The PE pipe (coil or pre-weldedstring) is finally pulled throughon the last pass. Experiencedcontractors are necessary withthis technique to ensure the PEstring is not over stressed onthe final pull through.
Moling
Pipe Bursting
DirectionalDrilling
38
Figure 28 Typical Directional Drilling Operation
Figure 27. Typical Bursting Operation
This is an ever-increasingmethod of re-habilitating anexisting pipeline where a non-structural lining method wouldbe unacceptable. With pipebursting the existing pipe iscracked open and the new PEpipe is drawn into the holecreated, and provides either a
size for size replacement pipeor by use of reamers theoriginal main can be upsized.
The present day hydraulicbursting tools are capable ofcracking out both pipes andfittings in very demandingsituations, and further
adaptations are now capable of splitting ductile iron and steelmains.
With this technique, damage toadjacent utilities plant ispossible and therefore care isrequired in the planning andoperation of bursting.
Drilling Rig
WashoverPipe
Drill PipeDrill Bit
Installation
lationA number of methods areavailable for the structural liningofexisting pipes, maximising theoverall cost savings of usingthe existing ‘hole in theground’.
Two methods rely on physicallyreducing the outside diameterof the liner pipe to provide aclearance gap for insertion.Both work by either passing thepre-welded pipe through rollersor a reducing die. The pipe iseither re-expanded using waterpressure or allowed to recovernaturally when the winch loadhas been removed.
Wavin have developed andpatented their own re-habilitation method based onreducing the liner pipe O.D. byphysically deforming the pipeinto a ‘C’ shape. This productwhich is factory formed isknown as ‘Compact Pipe’ and isavailable in a range of diametersand SDR’s .
For further details on CompactPipe please contact ourTechnical Services Helpdesk.
For pipelines, which are stillstructurally sound and requirerehabilitation for leakage orwater quality problems, thinwall PE liners can provide thesolution. With SDR’s of 33 - 61the pipe is either factory or siteformed into a folded profile toreduce its diameter for ease ofinstallation into the existingmain.
Lengths of up to 700m can bepulled in, in one operation, andwhen in place the folded pipe isreverted with mains water, toform a close-fitting liner.The technique is particularlyeffective on small diametermains, 3 - 12" diameter, withthe full system comprisingtermination fittings and ferruleconnections.
One of the major benefits of PEis its flexibility and this can beutilised to full advantage forburied pipework. Gradualchanges of direction up to11.5˚ can normally beaccommodated by the pipe
itself, without the need foradditional fittings and the costsof jointing.
The accepted rule of thumb forWavin PE pipe systems (warmconditions for SDR 11 pipe) is, Bend radius = 15 x pipe O.D.
For colder weather and SDR 17pipe a safe bending radius is 25x pipe O.D.In very cold wintertemperatures this increases to35 x pipe O.D. Where thinnerwalled SDR 26 and SDR 33pipes are being used thesevalues should be increased by 50%. Fittings and pipe jointsshould not be included in bentpipe sections; formed bendsand elbows should be usedinstead to prevent unduestresses in the pipeline.
For future location of PEpipelines and in line with goodpipe laying practice, thesimplest and most economicalmethod is to lay a marker tape/mesh which incorporates a
tracer wire. This should beinstalled 300mm above the pipecrown and also providesprotection from any future thirdparty damage.
A key feature of a welded PEpipeline is that it is a fully endload resistant system and thrustblocks are not required atchanges of direction/diameteror branches, providingsignificant time and costbenefits to the total installedcost of the system. It should beremembered that anyconnection to a non-end load-bearing fitting will requireanchorage to prevent pipe pull-out.
Where heavy ancillary plant isinstalled on a PE pipeline,provision should be consideredfor concrete support. Thisshould provide support both forthe dead weight and resist anyturning movements underoperating conditions, eg. valvesand hydrants.
Close FitInsertion Methods
39
Thin WallPolyethylene Liners
PipeBending Pipe
Detection
Pipe Anchorage &Thrust Blocks
The insertion of a smallerdiameter PE pipe, slip-lining,into an existing pipeline is oneof many no-dig techniques forre-habilitation of ageingpipelines.
With slip-lining there isinevitably a reduction in pipe
bore, although this can beminimised by thorough cleaningof the old main and choosingthe largest possible pipe size forinsertion.
The smaller bore is alsocompensated for by the greatlyimproved flow characteristics of
polyethylene and in many casesthe higher operating pressurecapability of the new pipe.Pressure grouting of the annulargap provides structuralrehabilitation of the existingpipe and reinforces the overallstrength of the new pipe.Grouting may also offer a more
economical total installation byallowing the use of a thinnerwalled PE pipe. Considerationshould be given to theresistance of the pipeline togrouting pressures and this willbe dependent on pipe SDR andovality (especially coiled ordrummed pipe).
Slip Lining
PERMISSIBLE GROUTING PRESSURES FOR PE PIPES
Deformation 0% 1% 3% 6%SDR Permissible Grouting Pressure (KN/M2)
33 13 12 10 726 27 25 20 1517 96 88 73 5911 417 383 317 242
Figure 29. Permissible Grouting Pressures Figure 30. Typical Slip Lining Operation
Pipe entry into rigid concrete orbrickwork structures needs totake account of a number ofdesign factors and shouldinclude:✪ Differential settlement.
This can usually be accommodated by the
flexibility of the pipe itself and by incorporating a flexible annular seal to the pipe sleeve through the structure.
✪ Watertight seal. The protective sleeve should provide both a watertight
seal to the structure and to the PE pipe passing through the sleeve.
✪ In some situations PE pipe may be connected tothe structure by a rigid flanged joint. To prevent undue stresses through
movement and settlement, support can be provided by a reinforced concrete plinth. The plinth should extend one pipe diameter or 300mm (min) from the flange face, with pipe straps bolted to the plinth.
Pipe Entryinto Structures
Where polyethylene pipe is tobe installed above ground,WavinBlack PE systems shouldbe used, providing protectionagainst the effects of ultra-violet. Where blue PE systemsare specified, the pipe requiresprotection against exposure to sunlight.
As polyethylene is a flexiblepipe material, adequate pipesupport must be provided toprevent sagging. Pipe supportsshould be designed to supportboth the pipe weight and itscontents and also accommodatethe weight of any heavy fittings,valves etc. The pipe brackets,
straps or plinths should haveflat surfaces, and be 0.5 x pipeO.D. or 100mm min wide(whichever is the greater) andhave non-abrasive surfaces toprevent damage to the pipe.The support and bracketingdesign should allow for thestresses generated from thermalmovement and if, for aestheticreasons pipe deflection isunacceptable, continuous pipesupport should be provided.
The above table givesrecommendations for maximumsupport spacings for pipe full ofwater at an ambienttemperature of 20˚C or below.
At temperatures of 40˚C andabove, continuous support isrequired. Above groundpipework should ideally beinstalled at or near themaximum operatingtemperature. The pipe willtherefore be in its expandedstate when installed.
As the pipeline cools, anycontraction will be resisted bythe pipe clamps, and when re-heated to its normal operatingtemperature, pipe saggingbetween supports will beminimised. Polyethylene is agood insulation material(thermal conductivity 0.4
w/m˚C) and will help preventor delay the freezing of the pipecontents.
The pipe itself will not fail if thecontents do freeze as PE cansafely expand to cater for theincreased volume. It is,however, good practice foroperational reasons to insulatepipework to prevent freezingand to ensure that theinsulation is waterproofed.Pipework should be protectedfrom possible impact damageand provision should be madefor draining down horizontalpipe runs at low points in the system.
Above GroundInstallation
40
ABOVE GROUND PIPEWORK, MAX. SUPPORT SPACINGS (M)
Pipe SDR 11 SDR 17 SDR 26Diameter (mm)
32 0.60 • •63 0.80 • •90 0.95 0.80 •110 1.00 0.90 •125 1.15 1.00 •160 1.40 1.30 1.20180 1.50 1.40 1.30225 1.80 1.60 1.50250 2.00 1.80 1.70315 2.25 2.10 1.90355 2.75 2.50 2.30400 3.00 2.75 2.50450 3.25 3.00 2.80500 3.50 3.20 3.00560 3.75 3.50 3.20630 4.00 3.70 3.40
Installation
Figure 31. Maximum Support Spacings for Above Ground Pipework.For availability of pipe sizes above 630mm, please contact theWavin Sales Office.
41
Polyethylene is resistant to mostnaturally occurring groundcontaminants. However, thegreater use of previouslydeveloped land (brownfieldsites) is resulting in a greaterpotential exposure to harmfulcontaminants.
The main concern for potablewater pipework is the risk oflong term mechanical damageto the material and of moreimportance, the contaminationmay cause water qualityproblems, taste and odour, dueto permeation through the pipewall. Former industrial sitespose the greatest problem.Development of the following
sites should be carefullyassessed:
✪ Coal workings, including coking and town gas production.
✪ Chemical works✪ Gas works✪ Paint and varnish works✪ Wood plants (preservatives)✪ Landfill sites✪ Garages/petrol stations
Where there is a known risk ofcontamination, professionalguidance should be sought onsoils analysis to identify therange and degree ofcontaminants. The analysis canthen be used to determine the
suitability for polyethylenepotable mains and services andwhether suitable protection canbe provided.
In some instances wherecontamination is negligibleprotection can be given with aclean sand/granular surroundand a heavy gaugepolyethylene membrane liningto the trench. If conditions aresuch that the use ofpolyethylene would not besuitable, the ‘Trigon’ barrierpipe has been developedspecifically for carrying potablewater through contaminatedland. Further guidance isavailable from the WavinTechnical Services Helpdesk.
ContaminatedGround
Pipe, whether bundles, coils orloose pipe must be stored in amanner which is both safe andwhich keeps the product freefrom damage. Pipe ends inparticular should be protected,as distortion or damage maycause difficulties in jointing.
Pipe and fittings should bestored away from risk ofdamage from exhausts andother heat sources. Care isrequired to avoid any contactwith solvents and oils, eg.spillage from site diesel tanksand exhausts.
Pipe and large fabricated fittingscan be stored externally for up
to a year. However for longerterm storage cover should beprovided to avoid UV damage.Electrofusion fittings should bestored under cover and keptdry. Fittings packaging must bekept intact up to the point of use.
Individual pipes should bestacked on level ground, free ofstones and sharp objects, withtimber batten supports at 1mcentres. The pipe can be storedin pyramid fashion up to 1mhigh and should be securelystaked to avoid collapse. See Figure 32.
Pipe strung out on site shouldbe protected from damage, egconed off or within a barriersystem and pipe end capsshould be left in place toprevent the ingress of dirt,vermin etc.
Wavin polyethylene pipesystems are tough and relativelylight and easy to handlealthough they can be damagedby sharp objects throughscoring or gouging.
Therefore it is important thatpipe and fittings are handled
sensibly and with care, for theoperatives safety as well as forthe protection of the pipe and fittings.
Pipes and fittings should not bedropped or thrown fromvehicles, or dragged acrossrough ground which may cause
scoring. Pipe with scoring inexcess of 10% of wall thicknessshould be clearly marked asdamaged and discarded.
Polyethylene is unaffected byfreezing conditions. Pipe can,however, become very slipperyand extra care should be
exercised during handling andinstallation. In general allprotective packaging shouldremain in place as long aspracticable before use.
All packaging should bedisposed of sensibly accordingto the requirements of the site.
Handling & Storage
GeneralPrinciples
Storage
LoosePipes
42
Figure 32. Loose Pipe Storage
Pipe bundles should be storedon level ground and can bestored up to 3m high.
Small diameter coils, which arefilm wrapped and delivered on
pallets, should remain on thepallet and stored on flat grounduntil required. Individual filmwrapped coils should be storedflat on level ground. Againensure there are no large stonesor sharp objects, which maydamage the pipe.
Free standing coils (FSC’s) up to180mm diameter canpotentially cause injury ifhandled in the wrong manner,therefore FSC’s should bestored flat on battens up to amaximum of 2.5 metres high.Timber battens should also be
placed between coils to enablefork truck access or for slingingpurposes.
43
BundledPipe
Small DiameterCoils
Free StandingCoils
Transport
Pipe should be transported on aflat bed vehicle, which is freefrom any sharp objects, nailsetc. Full loads direct from thefactory can be offloaded with avehicle mounted Hi-Ab craneand are often delivered direct to site.
Pipe bundles should beoffloaded by crane or forktruck. With crane offloading thebundles can be lifted with wideband slings; chains, hooks orsteel rope should not be used.
Fork truck and side loaderoffloading should be carried outby trained operators only; care
is required to avoid damage bythe metal fork blades.
Free standing coils (FSC’s) aredelivered on dedicated cagedvehicles and off-loaded by Hi-Ab crane. They should behandled on site by fork truckor crane with slings for liftinginto the trailer/dispensers.
FSC’s are banded in individuallayers to allow the pipe to bedispensed in a safe andcontrolled manner; particularcare should be taken with pipeends so that they are securedwhen pipe is released from the coil dispenser.
SafetyNote
44
Handling & Storage
FSC’s contain a great deal ofstored energy and should behandled by trained operativesonly, with the correctdispensing and handlingequipment.
In addition to FSC’s Wavin alsooffer drummed pipe, whichprovide longer lengths of pipe,eg up to 220m of 180mm pipe.
Drums are delivered direct tosite on a low loader and arenormally dispensed direct fromthe vehicle by pulling off with aJCB for example. Drums give an
economical option for long piperuns and our Field Engineers areavailable to advise on theoptimum use of drums.
Electrofusion fittings should bestored under cover and keptdry, fittings should be keptboxed and in their sealed bagsup to the point of use.
Larger diameter fabricatedfittings can be stored externallyfor up to 1 year. However theymust be stored to avoiddamaging the pipe ends, as this
may cause problems in jointing. As with pipe, fittings should notbe stored close to heat sourcesor exhausts or where there maybe a risk of contamination fromchemicals, solvents and oils.
All small diameter pipe 20 -32mm are film wrapped andpalletised, individual coilsshould be cut from the pallet asrequired. Pipe should bedispensed from the centre ofthe coil as required, with thepipe end plug being replaced toprevent the ingress of dirt.
Drums
FittingsInformation
Small DiameterCoils
45
Wavin have been involved inthe manufacture and supply ofplastics pipe systems to theWater Industry for 45 years andwith polyethylene pipe productsfor over 25 years.
At all stages in the supply chain,
from manufacturing through totransport and delivery to thecustomer’s site, Wavin arecommitted to the safety of allpersonnel involved in thehandling of their products, andactively promote safe practicesthroughout all of its operations.
Polyethylene is classified aschemically unreactive andregarded as being biologicallyinert. Ingestion of PE in anyform should, however, beavoided.
PE is not considered to be askin irritant. However, whencutting or scraping PE, dustparticles may cause eyeirritation and appropriateprotective eyewear should be used.
PE does not release harmfulfumes at normal ambienttemperatures. Inhalation of PEdust can irritate the respiratorysystem and where possiblecutting or scraping operationsshould be carried out in well-ventilated areas.
Polyethylene will melt at 120 -135˚C and above 300˚C willdegrade to produce carbondioxide, carbon monoxide,water and small amounts of
various hydrocarbons andaldehydes. These gases mayignite and provide heat toaccelerate the process.Burning, molten droplets ofmaterial may be released whichcould ignite adjacent materials.
Avoid inhalation of smoke orfumes as the combustion of PEmay release toxic materials.Do not allow PE dust particlesto accumulate as in extremecircumstances there can be arisk of dust explosion.All electrical equipment should
be carefully sited and earthed,likewise with the siting of anypotential heat sources.In the event of fire, any fireextinguisher may be used,powder extinguishers are veryeffective in quenching flames.
Water sprays are especiallyeffective in rapidly cooling anddamping down a fire but arenot recommended.
Health & Safety
Ingestion
FireHazards
Inhalation
PhysicalContact
46
47
Polyethylene pipe and fittingsshould be handled inaccordance with instructions inthe Handling Section of thisguide and also in accordancewith the instructions in the WRcPolyethylene Manual.
Particular care should beobserved when handling largediameter pipe and fittings andduring cold frosty weather.Appropriate safety clothing andequipment should be used at alltimes when handling PE pipesand fittings.
When handling or dispensing
coils or drummed PE pipeextreme care should be taken,especially with 90mm diameterand larger pipe where a coil-dispensing trailer must be used.
Operatives should beadequately trained andexperienced in the use of largediameter coiled pipe.
Fusion welding of PE pipe andfittings produces molten PE andwill adhere strongly to skin ifallowed to come into contactand cause severe burns.Protective gloves should beworn during the jointing
process and when handling hot equipment.
Jointing should always becarried out in well-ventilatedareas. Fusion weldingprocedures produce smallquantities of fumes andinhalation of fumes should beavoided or minimised.
The Electrofusion jointingprocess can cause the ejectionof molten material if the jointassembly is incorrectly carried out. Operatives shouldwear safety gloves and gogglesduring jointing and avoidstanding directly over the joint area.
Polyethylene is biologically inertand is not considered to bedangerous to the environment.
Waste polyethylene material canbe reprocessed into new pipeproducts or other products andthere is a growing market forsuch waste materials.
For further details on re-cyclingof waste polyethylene pleasecontact the Wavin TechnicalServices Helpdesk.
Handling
SafetyCaution
Safetyin Jointing
Environment
Wavin Plastics Limited,Parsonage Way,Chippenham,
Wiltshire,SN15 5PN.
Sales:T. (01249) 766600F. (01249) 443473Technical:T. (0191) 3780841F. (0191) 3781380
www.wavin.co.uk
Issue no. 03 September 2001. All information contained in this Technical Guide is given in good faith. The user should, however, check that the product is suitable for purpose, in the application forwhich it shall be used. Please ensure compliance with all health and safety requirements. Whilst continuing its programme of continuous development, Wavin Plastics Limited reserves the right to
modify or extend any published information without any prior notification. No responsibility can be accepted for any error, omissions or incorrect assumptions.
