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Polybutene-1

Pipe Extrusion Guide

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DisclaimerUnless otherwise agreed in writing, Basell disclaims any warranties with respect to theapplication of the information herein, its products or the safety or suitability thereof, or resultsobtained, whether express or implied, including, without limitation, any implied warranty ofmerchantability or fitness for a particular purpose and/or any other warranty. Buyers andusers must determine the results to be obtained from the application of the information andthe safety and suitability of the products for their own purposes. Buyers and users assume allrisk, responsibility and liability whatsoever for any and all injuries (including death), losses ordamages to persons or property arising from the application of the information or use ofproducts, whether or not occasioned by seller’s negligence or based on strict product liabilityor principles of indemnity or contribution. Basell neither assumes nor authorises any personto assume for it any liability in connection with the use of the information or products. Underno circumstances shall Basell be liable for special, consequential or incidental damages.The information provided in this document is provided as a service to polybutene-1 pipecustomers and is based on general considerations, best estimates, practical experience andknow-how collected over several years including other sources than Basell. It is intended foruse only as general information for the production of unaltered PB 4237, PB 4235 and PB4201 type materials. Although specific values may be given here they should be taken asguidelines only and may not be applicable for all systems, equipment and material grades tothe same extent. The information provided is intended only for use as a starting point for theprocessing of Polybutene-1 pipes since modifications may be required in order to optimisefor each particular customer, line or application.The information contained in this document may not be applicable for any type of pipe orsystem that utilises other material including all co-extrusion processes.

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Table of contents

1. Description of PB-1 52. Properties of PB-1 pipe materials 10

2.1 Rheology 102.2 Mechanical properties 112.3 Impact resistance 132.4 Compression set 132.5 Abrasion and wear resistance 132.6 Creep behaviour 13

2.6.1 General 132.6.2 Creep performance at uniaxial load 152.6.3 Practical consequences of creep 15

2.7 Pipe pressure performance 172.7.1 Quick burst 172.7.2 Creep rupture strength 172.7.3 Flammability 20

3. Pipe extrusion of PB-1 203.1 General extrusion techniques 213.2 Extrusion equipment 22

3.2.1 General considerations 223.2.2 Feeding system 223.2.3 Screw configuration 223.2.4 Melt pump 233.2.5 Breaker plate and screen pack 233.2.6 Melt temperature and pressure sensors 243.2.7 Die head 243.2.8 Pipe sizing 253.2.9 Materials of construction 283.2.10 Pullers and coilers 283.2.11 Cutters 28

3.3 Tooling 283.3.1 General considerations 283.3.2 Tooling estimation scheme 293.3.3 Tooling for small and medium size pipe 34

3.4 Large diameter PB-1 pipe 363.4.1 General considerations 363.4.2 Equipment 363.4.3 Physical properties 36

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3.4.4 Tooling for big pipe 383.5 Grinding and reprocessing 393.6 Troubleshooting 40

3.6.1 General procedure 403.6.1.1 Evaluation procedure 1 403.6.1.2 Evaluation procedure 2 413.6.1.3 Evaluation procedure 3 41

3.6.2 Miscellaneous problems 423.6.2.1 Melt sticking at pre-sizing water

chamber faceplate or sizing sleeve 423.6.2.2 Difficulty increasing rate of extrusion 423.6.2.3 Longitudinal lines in pipe 423.6.2.4 Pipe is not round (ovality) 433.6.2.5 Poor appearance of pipe surface

(outside and inside) 433.6.2.6 Elongation at break values below

minimum 433.6.2.7 Processing water quality, pressure and

temperature 433.6.3 Lot to lot variability in PB-1 pipe production 44

3.6.3.1 Symptoms 443.6.3.2 Possible causes – Extrusion process 443.6.3.3 Possible causes – Raw material 44

3.6.4 PB-1 pipe extrusion troubleshooting cross reference 454. Annex: List of standards relevant for PB-1 pipes 47

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1. Description of PB-1Polybutene-1 (PB-1) is a thermoplastic polymer obtained by polymerisation of 1-butene usingstereospecific Ziegler-Natta catalysts belonging to the family of polyolefins (Fig. 1). Due to itssimilar structure the properties resemble mostly those of polypropylene (PP) but because ofthe longer side chain there are some considerable differences. PB-1 is compatible with PPbut not with PE.

PB-1 is a highly isotactic, partially crystalline homopolymer of high molecular mass. Highlyisotactic means that nearly all C2 side chains are attached to the same side of the molecule.PB-1 must not be confused with the rubber-like polyisobutene (PIB) (Fig. 2).

PB-1 crystallises upon cooling from the melt. During crystallisation the polymer chains fold tothree-dimensional order in small regions, the crystallites. These crystallites are connected bytie-molecules and chain entanglements so that a single PB-1 molecule typically contributesto the structure of many crystallites. This physical network is the key for excellent mechanicalproperties of PB-1 pipe grades. The crystallites form superstructures, the so-calledspherulites. The typical degree of crystallisation of Basell PB-1 pipe grades is about 50 %.The exact value of crystallinity as well as the size of crystallites and spherulites both dependstrongly upon cooling conditions.

— C — C —

H H

H CH2

CH3

n

l l

l l

l

Polybutene-1

n

— C — C —

H H

H CH3

l l

l l

Polypropylene

— C — C —

H H

H H n

l l

Fig. 27: Sc

Polyethylene

Fig. 1: Structure of various polyolefins

Fig. 2: Polybuten-1 is not Polyisobutene

C CCCC

C

CC

C CCC

C

C

C

C

CC

C

C

C

C

CC

Butene-1

PolyButene-1PB-1

Isobutene

PolyIsoButenePIB

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The crystallisation rate of PB-1 is considerably lower than PE or PP. Upon solidification fromthe melt PB-1 crystallises first to an 11/3-helix in a metastable tetragonal modification calledform II which is kinetically favoured. In this stage PB-1 is a rather soft, mechanically weakmaterial. Over several days the material hardens by transforming into form I which is a 3/1-helix in hexagonal unit cell and which is thermodynamically favoured. This crystallinetransformation can be observed by differential scanning calorimetry, or DSC, as shown inFigure 3.

Fig: 3: Transformation of crystalline form II -> I of PB 4237 measured by DSC

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The transformation of form II to form I depends strongly on ambient temperature andpressure as demonstrated in Fig. 4. At atmospheric pressure (1 bar) the maximum rate oftransformation occurs around 20 °C but drops significantly by increasing or decreasing thetemperature. If ageing is performed at lower or higher temperatures than 20 °C only the timeto achieve final properties is longer: the final performance of the material itself is not affected.

As can be taken from Fig. 4, too, the crystalline transformation can be shortened from a fewdays to only a few minutes by application of hydrostatic pressure of up to 2 kbar using asuitable autoclave. Only in this final stage after termination of ageing PB-1 achieves its excellent hightemperature mechanical strength which for pipe and piping system producers make thematerial a preferred candidate for all hot water applications.

Fig. 4: Dependence of transformation of form II -> I of PB-1on ambient temperature and pressure

1 bar

500 bar

1.200 bar

1.500 bar

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Tab. 1: Characteristics of important crystalline forms and amorphous phase of PB-1

Crystalline Form Helix type Crystal type Melt temperature Density

I 3/1 twin hexagonal 125 – 135 °C 0.950 g/cm³

II 11/3 tetragonal 110 – 120 °C 0,900 g/cm³

amorphous 0,870 g/cm3

Provided the material is appropriately processed, pipe systems made of Basell PB-1 meet orcomfortably exceed all national and international standards relevant for pipe applications. PB-1 combines the well-known properties of typical polyolefines, e.g. good chemicalresistance, easy weldability and low noise emission, with a unique combination ofoutstanding creep resistance, excellent high temperature stress rating and high flexibility.The most prominent features of PB-1 pipe grades are:– high strength also at higher temperatures,– excellent creep resistance,– low modulus and high flexibility,– little noise transmission,– good weldability,– strong wet abrasion resistance,– resistant to most chemicals.In principle, as a thermoplastic material, PB-1 is also recyclable.Basell Polybutene-1 is currently available in 3 pipe grades:

Tab. 2: Available PB-1 pipe grades and their application

Grade Strength class Typical application

PB 4237 grey PB 140 Hot and cold water heating and plumbing

PB 4235 ivory PB 140 Underfloor and radiator heating

PB 4201 black PB 140 Cold water transport

Basell Polybutene-1 pipe grades are supplied as fully stabilised and coloured ready-to-usepelletised compounds.The main properties of Basell PB-1 pipe grades are summarised in Table 3.

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Tab. 3: Typical properties of Polybutene-1 Homopolymer Resins for Pipe Applications

MATERIAL PROPERTIES (a) METHOD (b) UNIT PB 4201 PB 4235 PB 4237

PHYSICAL PROPERTIES

Melt flow rate MFR 190°C/2.16 kg ISO 1133 dg/min 0,35 0,35 0,35

Density ISO 1183 g/cm3 0,928 0,939 0,939

Hardness Shore D ISO 8608 - 53 53 53

MECHANICAL PROPERTIES (c)

Tensile strength at yield ISO R 527 MPa 20,4 20,4 20,4

Tensile strength at break ISO R 527 MPa 36,5 36,5 36,5

Elongation at break ISO R 527 % 330 330 330

Flexural Elastic Modulus ISO 178 MPa 530 530 530

Notched Impact Strength at 20°C ISO 180 kJ/m² no break no break no break

Notched Impact Strength at 0°C ISO 180 kJ/m² 40 40 40

THERMAL PROPERTIES

Melting point (Form I) DSC (d) oC 130 130 130

Vicat Softening Temperature ISO 306 (A50) oC 120 120 120

Coefficient of liner thermalexpansion

ASTM D696 cm/cm/oC 1.3 x 10-4 1.3 x 10-4 1.3 x 10-4

Thermal conductivity (20oC) ASTM C 177 W/mK 0.19 0.19 0.19

Glass transition temperature DMTA (d) °C -16 -16 -16

SPECIFIC CHARACTERISTICS

Environmental Stress Cracking(50°C / 10 % Igepal C0630 solution)

ASTM D 1693 h 15000, no failure

Wet abrasion(sand slurry test, 23°C, 100 h)

% 1

Suitability for potable applications variousEuropeanwater qualitystandards

- approvedfor coldwatersupply

notsuitable

approvedfor hotand coldwatersupply

Colour - - Black Ivory Grey

a) Values shown are averages and not to be considered as product specifications. These values may shift slightly as more data isaccumulatedb) ASTM test methods are the latest under the current procedures. All specimens are prepared by injection (ASTM 2146)c) Tests performed on compression moulded specimens which were conditioned 10 days at 20°C.d) DSC = Differential Scanning Calorimetry

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2. Properties of PB-1 pipe materials

2.1 RheologyDuring processing, the rheological behaviour of PB-1 in its molten state plays an importantrole. Processing characteristics like die swell and melt strength are determined by therheology of the material. Also the heat generated by shear within the extruder is mainlygoverned by rheology.

As for most other polymers the rheological behaviour of PB-1 is very non-Newtonian, too.This means that the melt viscosity will depend strongly upon the shear stress experiencedduring processing. In Fig. 5 the shear viscosity is plotted against shear stress for somepolyolefins of similar MFR. As demonstrated in Figure 5, PB-1 is more sensitive to shear thanother polyolefins. The practical consequence is that PB-1 needs less extruder drive powerbecause of its lower viscosity at processing conditions.The relationship between shear stress and shear rate is given by the definitiion of viscositywhich is

rateshearstressshearityvis �cos

Shear stress (Pa)

1e+3 1e+4 1e+5 1e+6 1e+7

Shea

r vis

cosi

ty (P

as)

1

10

100

1000

10000

ca. 1000 s -1

ca. 100 s -1

LDPE

PB-1

shear rate

processing zone

PP

LLDPE

Figure 5: Shear viscosity vs. shear stress

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Polybutene-1 can be extruded, injection moulded and compression moulded as required bythe particular application. For all Basell PB-1 grades, there is a one-to-one relationshipbetween the melt flow rate (MFR) and the steady state viscosity at a given shear stress level,as illustrated in Figure 6. When plotting viscosity values as a function of MFR, straight linesfit to the data points in a double logarithmic graph. The sensitivity is highest at small shearstresses, the slope of the line being equal to –1,16, and slightly decreases with increasingstress: the slope decreases until –1,04 at 20 000 Pa shear stress (about the stress levelcorresponding to conditions used for measuring MFR) and –0,77 at 80 000 Pa shear stress(approximately corresponding to processing conditions). At even higher shear stress or shearrate levels the slope further decreases.Using Figure 6, it can be calculated that 10% difference in MFR value corresponds to 12%difference in viscosity at low shear stress and to 8% at high shear stress. 20% difference inMFR would correspond to 19% and 13% difference in viscosity, respectively.

2.2 Mechanical propertiesPB-1 is a partially crystalline polymer with high isotacticity and consequently high crystallinity.Generally, the crystalline part determines a number of intrinsic characteristics of the polymer.These include density, stiffness, hardness, creep resistance, abrasion resistance,temperature resistance and chemical resistance. On the other hand, the amorphous partinfluences other properties like mechanical strength, impact resistance, environmental stresscracking resistance and compression set properties.

Melt flow rate (g/10min)

10 -1 10 0 10 1 10 2

� (Pas)

10 1

10 2

10 3

10 4

10 5Black: zero shear plateauRed: 20.000 PaBlue: 80.000 Pa

Slope = -1,16

-1,04

-0,77

Shear stress

Figure 6: Viscosity (at different stress levels) as a function of MFR at 190ºC.Homopolymer (pipe grades)0,75 % Ethylene2,2 % Ethylene Copolymers (specialty grades)5,5 % Ethylene

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As shown in the model depicted in Figure 7, the crystalline layers in PB-1 are connected byentangled tie-molecules. These tie molecules reside in the amorphous part. Because of thehigh molecular mass a large number of tie-molecules is generated and the relatively longC2H5 side groups prevent extensive slipping of entanglement chains. These two factors makethe bonds between adjacent crystallites very stable. The crystalline lamellae form sphericalsuperstructures, which are called spherulites. A strong 3-dimensional network of entangledcrystallites is formed.

The peculiar tensile behaviour of PB-1 is based mainly on these chain entanglements. PB-1does not show the typical necking behaviour; instead it tends to support the load while itcontinues to stretch. This is sometimes referred to as “ductile with work-hardening”*.However, depending on the preparation of the test specimen and the conditions ofmeasurement, PB-1 may exhibit a very little yielding (see Figure 8).

* Turner, S., Mechanical Testing Of Plastics, 2nd Ed, Longman Inc. New York, p.133, 1983

Entangledmolecules

AmorphouspartCrystalline

parts

Figure 7: Chain entanglements between crystalline domains

Strain

other polyolefins

Stress

PB-1

�s

Figure 8: Tensile behaviour of PB-1 vs. other polyolefins

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2.3 Impact resistancePB-1 has excellent impact toughness. The IZOD notched impact strength (ISO 180) of PB-1is classified “no break” at room temperature. The material retains its flexibility even attemperatures below freezing point which strongly facilitates installation during cold seasons.The glass transition temperature determining the ductile / brittle transition of PB-1 lies atapprox. –16°C.

2.4 Compression setThe compression set of PB-1 is remarkable. PB-1 homopolymers are very flexible and softmaterials. However, because of its network of strongly entangled crystallites it exhibits anexcellent elastic recovery even though it is not cross-linked. Typically, the compression set at23°C is ca. 55 %, and at 70°C ca. 64 %, when tested in accordance with ASTM D395-89,method B.

2.5 Abrasion and wear resistancePB-1 has an excellent wet abrasion resistance, when tested in sand/slurry type conditions asshown in Figure 9. It performs as well as UHMW-PE which is well known for its outstandingabrasion and wear resistance. Therefore, pipes made of Basell PB-1 resins can also be usedfor transport of slurry, e.g. in the mining industry. In dry conditions, however, PB-1 behavessimilarly to conventional polyolefins.

2.6 Creep behaviour

2.6.1 GeneralAll thermoplastic polymers show viscoelastic behaviour, i.e. their mechanical propertiesdepend not only on stress and temperature but also on time. A particular, very importantfeature of viscoelastic materials is creep which means that the deformation of such materialsat given temperature and load increases as a function of time. Figure 10 shows the timedependence of elongation at constant temperature and load of PB-1 compared to otherpolyolefins. This excellent creep performance is maintained even at elevated temperaturesas shown in Figure 11.

Figure 9 : Sand-Slurry abrasion resistance of polyolefins

0

1

2

3

4

5

6

UHMW-PE PB-1 HMW-HDPE HDPE PP

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0

8

16

24

32

10 10 10 10 10

PE-HD

PE-X

PPPP-Co

-2 0 2 4 6

Time [h]

Elon

gatio

n [%

]

PB-1

Fig. 10: Creep behaviour of polyolefins in uniaxial tension at 23 °C / 8 MPa

100000

2

4

6

8

0,1 1 10 100 1000

13,80 MPa @ 23C

3,45 MPa @ 23C

3,45 MPa @ 60C

6,60 MPa @ 60C

Elon

gatio

n [%

]

Fig. 11: Creep performance of PB-1 at elevated temperature and stress

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2.6.2 Creep performance at uniaxial loadTwo different experiments can be performed: retardation measurements in which the changeof deformation � �t� at constant stress � �.const�� is measured and relaxation experiments inwhich the change of stress � at constant deformation � �.const�� is monitored.

As a result of retardation experiments the creep modulus can be obtained according to theequation

Creep modulus � �� �t

tEc�

�

� (1)

This measurement can be performed in bending (flexural creep by three-point loading)according to ISO 6602 or in tension (tensile creep) according to ISO 899. Since in flexuralbending defects of the outer fibre zone may disturb the result tensile creep is more reliablebecause of its uniform stress at whole cross section.It has to be taken into account that the measured value of creep modulus depends on the

level of stress.

2.6.3 Practical consequences of creepThe creep performance / stiffness ratio of PB-1 is similar to engineering polymers like TPU,PA11 or PA12 as shown in Figure 13.

Fig. 11: Creep modulus of PB-1 compared to other polymers at elevated temperatures

App

aren

t mod

ulus

(MPa

)

0

400

1 10 100 1000Time (hours)

PP homopolymer at 60°C and 2.75 MPa

nylon 12 at 80°C and 2 MPa

PB-1 at 85°C and 5.4 MPa

63 D copolyester at 100°C and 5.5 MPa

300

200

100

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Translated into pipe applications creep means 'blowing up' the pipe under constant pressureover time, i.e. increasing the diameter and at the same time decreasing wall thickness asillustrated in Figure 14, which leads to lower pressure performance at longer time. Theexcellent creep properties of PB-1 mean that the problem of creepis reduced to a minimum,even in hot water piping applications.

0

500

1000

1500

2000

2500

3000

POM

PPHDPE

LDPE

TPO

PA11/12 PB-1 TPU

PA6/66

Creep Resistance

Stiff

ness

[MPa

]

Figure 13: Stiffness vs. creep resistance of various polymers

Fig. 14: Change of pipe dimensions and burst due to creep (schematic)

Creep

(Constant pressure over time)

Burst

(Further maintenanceof pressure)

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For calculating finished parts the properties obtained from long-term mechanical experimentsare divided by a safety or design factor depending on application. Examples for such designfactors can be found in relevant pipe standards like ISO 15876.

2.7 Pipe pressure performance

2.7.1 Quick burstSince final mechanical strength of PB-1 is only achieved after transformation of form II ->form I the quick burst performance of pipes depends on ageing time, too, as demonstrated inFig. 15. Although 90 % of the final value is achieved after 5 days there is still some additionalincrease in quick burst and overall pipe performance even after months. However, an ageingtime of 5 days is sufficient to meet all application requirements and the pipe is ready to use.

2.7.2 Creep rupture strengthMore important than instantaneous strength like quick burst is the long time performance ofPB-1 pipes up to and, for safety reasons, above the upper service temperature since PB-1 isintended for long-term use at elevated temperature and pressure. For most heating andplumbing applications an expected lifetime of 50 years and more is required. A fulldescription of pipe performance as a function of time, temperature and pressure can be donevia creep rupture strength diagrams according to ISO 9080 as shown in Figures 16 - 18 forPB 4237, PB 4235 and PB 4201.

Fig. 15: Quick burst stress of PB 4237 pipes at 95 °C as a function of ageing time(Ageing done at 23 °C)

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

10,00

2 3 4 5 6 7 8 9 10 15 20

Time (days)

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Based on these diagrams a classification according to ISO 12 126 can be done. Startingpoint is the evaluation of creep rupture curves according to the Standard ExtrapolationMethod (SEM) as described in ISO 9080. This evaluation yields for the hoop stress at 20 °Cand 50 years lifetime– the expected Long-Term Hydrostatic Strength (LTHS) and– the 97,5 % Lower Probability Limit (LPL).This LPL hoop stress is classified according to the Renard 10 (R 10) number scheme asdefined in ISO 3, which is a division of a logarithmic decade in 10 equal steps1 – 1,25 – 1,6 – 2 – 2,5 – 3,2 – 4 – 5 – 6,3 – 8 – 10. Note: For extrapolated hoop stresses above 10 MPa the Renard 20 (R 20) number scheme

is used, which divides the logarithmic decade in 20 equally spaced steps and thusyields a finer separation of MRS classification.

The calculated LPL hoop stress at 20 °C is then degraded to the next lower R 10 or R 20number. The result is the Minimum Required Strength (MRS). Final estimation of the MRSclass of current Basell grades is in progress. Preliminary data indicate that Basell PB-1 pipegrades will achieve at least a LPL hoop stress of 14 MPa. As a result of this, all currentBasell PB-1 grades belong to MRS class PB 140.

Fig. 16: Creep rupture strength of PB 4237

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Fig. 17: Creep rupture strength of PB 4235

Fig. 18: Creep rupture strength of PB 4201

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Besides the determination of the MRS classification of the material creep rupture stressdiagrams can also be used to evaluate the expected lifetime at any temperature and stresscombination given.2 From the dimensional independent parameter hoop stress thecorresponding pressure can be calculated according to the equation:

edep�

��

�

20�

with p (bar): pressure� (MPa): hoop stresse (mm): wall thicknessd (mm): outer diameter

or by defining the Standard Dimension Ratio (SDR)

edSDR � ->

120�

�

�

SDRp �

For practical purposes most often a safety or design factor of between 1,25 and 2 isconsidered in addition.A complete list of operational pressures dependent on application classes, pipe dimensions,temperatures, lifetimes and design factors can be taken from relevant pipe standards, e. g.ISO 15876 or DIN 16989.

2.8 Flammability As other polyolefins, polybutene-1 is a material with normal flammability. Therefore, itbelongs to building material class B2 according to DIN 4102-1.Polybutene-1 can be ignited by an open flame and continues to burn even after removal ofthe ignition source. Because of the generated heat the material melts with burning drips. Theignition is favoured by sharp edges and becomes easier for lower wall thickness.Typical combustion products are carbon monoxide, carbon dioxide and water but nocorrosive or environmental harmful residues occur.For installation in buildings the use of suitable fire protected insulation materials like e.g.rockwool may be required as regulated by relevant local standards or other fire protectionregulations.

3 Pipe extrusion of PB-1Generally, PB-1 pipe materials can be extruded with standard extruder screws and die headsdesigned for polyolefins without major problems. As outlined in the previous section PB-1crystallises relatively slowly in a kinetically favoured form II yielding a very soft product. Upontransformation to the thermodynamically stable form I the excellent properties of PB-1 pipeare achieved. At 20 °C this ageing completes to more than 90 % within 5 days, but continuesincreasingly slowly later on. Even after months and years there is still some additionalageing. Because of this unique crystallisation and ageing behaviour some precautions duringcalibration and cooling of pipe processing have to be considered. The dimensions of freshpipe have to be chosen slightly bigger to account for the shrinkage occurring during ageing.The storing conditions during ageing have to be controlled carefully in order to obtain good

2 In case of different temperatures or pressures a combined lifetime can be estimated using Miner’sRule as described in ISO 13 760 which describes the cumulative load resulting from additivity of allindividual loads at each particular temperature / stress combination.

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quality final pipe. The following guidelines could help to acquaint the processors with thehandling characteristics of this unique material and the processing conditions required.

3.1 General extrusion techniquesThe recommended processing melt temperature and melt viscosity of Basell polybutene-1pipe compounds are very similar to other polyolefins, in particular to low and medium densitypolyethylene. The optimum melt temperature should be between 180 and 200 °C. Use ofhigher than recommended melt temperatures can result in sticking of the extruded pipe in thesizing sleeve or presizer face plate or even in the extruder itself leading to problems inpurging the extruder. Lower than recommended melt temperatures may cause excessivemachine direction (MD) orientation resulting in poor pipe quality which may lead to reducedcreep rupture performance and premature failure upon bending during installation of pipes.Depending on line and screw speed and screw design some additional shear heat may begenerated leading to higher melt temperatures than set at the end of the die. Table 4 showsa typical temperature profile of extruder and die zones.

Tab. 4: Typical extrusion temperature profile*

Extruder Die Melt

Zone 1 2 3 4 1 2 3 4 5 6

Temp 175 175 180 180 180 180 180 180 180 185 190

Slight inevitable changes in MFR among different batches of PB-1 can be corrected veryeasily by simply adjusting the melt temperature accordingly. As a rule of thumb an increaseof MFR (190/2,16) of 0,1 corresponds to a decrease in melt temperature of approx. 10 °C. Anexample of corresponding MFR / melt temperature combinations is given in Table 5.

Tab. 5: Change of melt temperature due to MFR variation

MFR (190/2,16) 0,25 0,30 0,35 0,40 0,45

Melt temp. (°C) 202 196 190 185 181

By using a melt pump adjustments of melt temperature due to MFR variations can beavoided in most cases.As initially extruded polybutene-1 crystallises slowly into the phase II form, a soft, lowmodulus material. Upon ageing, polybutene-1 will change crystalline form within several daysto phase I, a stiffer, higher modulus product exhibiting the final desired properties.The slow crystallisation rate of polybutene-1 requires direct water cooling prior to surfacecontact. A spray ring that provides a water film for quenching and lubricating the pipe surfacewithout causing water marks should be used. In addition to water quenching it isrecommended to use a water seal to presize the pipe to maintain uniform sizing and processstability.Due to the relatively slow crystallisation rate of PB-1 and individual characteristics ofprocessing extruders various customers may use somewhat different conditions to producePB-1 pipes. Some have found that starting with a lower melt temperature facilitates fastercrystallisation from the melt and thus allows for easier pipe extrusion. For other customersthe trade off between better processability obtained with lower melt temperatures and the

* These temperatures are presented only as a guideline and should not be considered

optimum for all extruders.

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decrease in certain physical properties, like higher orientation in machine direction asmeasured by elongation at break, is not acceptable. Generally, melt temperatures between 180 °C and 200 °C combined with cooling watertemperatures between 10 °C and 12 °C for spray ring, presizer and cooling baths mayprovide the best balance of pipe processability and physical properties for extrusion of smallpipes of sufficiently high line speed.

3.2 Extrusion equipment

3.2.1 General considerationsAny extruder suitable for processing of polyolefins can be used for extrusion of polybutene-1pipe as well. Depending on size of pipes to be produced the appropriate size of extruder hasto be chosen. For pipe sizes up to 25 mm O.D. an extruder having a maximum throughput of120 - 150 kg/h will be sufficient. Depending on the design of the screw and feeding zone thisis typically achieved with extruders having a screw diameter of 45 – 60 mm. For bigger pipesup to 110 mm O.D. a maximum throughput of 250 – 300 kg/h is recommended. In this casescrew diameters up to 90 mm may be used. Length-to-diameter (L/D) ratios of 24 or greaterare recommended to achieve sufficient plasticisation.Relatively low temperatures are applied to process polybutene-1 resins; however, heatersand controllers capable of efficient operation up to 260°C are desirable. The extruder barrelshould be divided into at least three, preferably five, independently controlled heating zones,each equipped with its own thermocouple and temperature indicating controller.Barrel air or water cooling systems are suitable for polybutene-1 pipe extrusion as long asadequate temperature control is achieved. Effective air cooling, however, might beacceptable. Water cooling of the throat section of the barrel should be used to preventbridging and to increase throat-bearing life. Screw cooling and forced feeding are notrequired.Any of the drive systems normally employed for polyolefins may be used; however, goodspeed regulation (recommend ± 1 %) is essential. In contrast to other polyolefins, apolybutene-1 screw has a shallower feed zone and therefore requires higher screw speed(RPM) for maximum throughput. Polybutene-1, having a lower heat of fusion than low-density polyethylene (LDPE) requires less total energy per kilogram to process.

3.2.2 Feeding system To increase throughput a grooved feeding zone can be used which has to be water cooled toensure proper feeding and prevent blocking of the screw by partly molten pellets. Gravimetricfeeding systems are recommended to have constant, uniform material supply. By using adryer adsorbed moisture can be removed from pellets which otherwise may cause voids inpipe walls.

3.2.3 Screw configurationSeveral commercial screw designs perform well with polybutene-1. These includeconventional 2- or 3-stage screws as well as barrier type screws as shown in Fig. 19. Inorder to increase melt homogeneity the screw design may contain shear mixing sections,e.g. Maddox type. Tooth type mixing section are less suitable because they may introduceregions with higher residence time. A screw designed for polyethylene or polypropylene mayalso be acceptable.When purchasing an extrusion screw for the production of polybutene-1 pipe or tubing, themost sensible approach would be to consult an extrusion screw manufacturer. Consideringindividual requirements of the customer, the extrusion screw manufacturer will typically runrheology curves at different shear rates on the materials to be processed and willrecommend a screw profile based on data generated by such experiments.

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3.2.4 Melt pumpA melt pump, fitted to the particular extruder and processing conditions is stronglyrecommended because freshly extruded polybutene-1 pipe is extremely soft and thus verysensitive to even minor throughput changes which may result in surging and a concomitantunacceptable variation in pipe wall thickness and diameter. Output or melt pressurevariations should be kept below 1 %. This will increase melt output and pipe extrusion rates(typically by at least 10 %), stability and allow for increased flexibility of the process. Inaddition to that the sensitivity of extrusion against variations of melt viscosity is greatlyreduced.

3.2.5 Breaker plate and screen packA breaker plate and screen pack is recommended. Breaker plate holes should bestreamlined for flow. Stainless steel screen packs containing a 20, 80, 40 mesh screens or aDutch weave having similar mesh size are recommended to develop adequate back-pressure for good mixing. Although the screens also act as a filter in the event foreignmaterial is inadvertently introduced in the feed, precautions should be taken to avoidcontamination. Resin feed stock and boxes of regrind should be kept closed wheneverpossible. As a further precaution, the use of a hopper magnet is suggested.

Fig. 19: Screw design: Standard 3-zone vs. barrier screw (Source: Fa. Battenfeld)

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Note that the deliberate addition of processing aids, masterbatches or other additionalmaterial to the polybutene-1 being processed may invalidate the codes and standards aswell as the relevant water authority approvals to which the material as supplied hasconformance.

3.2.6 Melt temperature and pressure sensorsThe extruder should be equipped with sensors for continuously monitoring temperature andpressure of the melt during extrusion. The melt temperature cannot be estimated from barreltemperatures since it may deviate considerably from the latter due to heat generated byshear, which varies with screw design, speed, and resin viscosity.The temperature sensor should be located downstream of the breaker plate. In order toobtain a more accurate measurement and to minimise the effect of any heat transfer from theheated metal surfaces, the temperature sensor should protrude into the melt stream. The tipof the sensor should extend at least 3 mm from the wall, but not further than the centerline ofthe flow channel.Extruder discharge pressure or head pressure should be monitored, preferably using atransducer type pressure gauge before and behind the melt pump, respectively. The use ofpressure gauges provides information about the uniformity of extrusion conditions,continuous and sufficient melt supply and will detect such problems as surging. A furtherpressure sensor in front of the breaker plate will function as a safety device indicatingclogging of the screen pack and, thus, prevent serious barrel overpressure. Normally, typicalextrusion pressures for Basell polybutene-1 resins are low (80 – 120 bar).

3.2.7 Die headThe required pipe or tubing diameter and wall draw-down ratios depend upon extrusion rateand desired pipe size. Draw-down ratios of 5-20 % are typical, with larger profiles being atthe upper end. Use of greater than recommended draw-down ratios can lead to poor qualitypipes and high machine direction orientation. Appropriate tooling incorporating therecommended draw-down ratios for corresponding processing conditions is shown in thetooling section of this manual. Extrusion with inadequate draw-down ratio will result in difficulty in maintaining pipedimensional control and quality.

Fig. 20: Basket Mandrel Die (Source: Fa. Battenfeld)

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The optimum land length / annular gap (L/D) ratio also varies with line speed and pipe size.In general, (for pipe and tubing of 50 mm SDR 13.5 size and smaller), an L/D ratio of at least8/1 is recommended to promote uniform extrudate and quality piping at economical rates ofextrusion. Larger pipe sizes are less critical.Minimum disruption to material flow is desirable at this point avoiding formation ofpronounced flow lines. Of the various die types available, the Basket Mandrel die shown inFigure 20 provides for the least interruption of material flow and therefore results in a morehomogeneous material flow and pipe wall. However, other die design types like the spidermandrel die can be used as well provided a suitable temperature profile avoids formation ofweld lines which may cause premature failure of pipes.

3.2.8 Pipe sizingBecause of its very low crystallisation speed compared to other polyolefines polybutene-1pipes require some special measures during cooling and calibration. As shown in Figure 21,a spray ring and a pre-sizing water well are used before entering the usual calibrator formingthe outer diameter of the pipe.

Immediately after having left the die head the polybutene-1 tube is quenched by means of aconical water film sprayed onto the pipe surface. The opening angle of this spray film shouldbe approx. 45 degrees. A water head pressure of 2,5 – 3,0 bar at the spray ring with thevalve open is typically used. Care must be taken to avoid damage of pipe surface byexcessive water pressure or non-uniform spray pattern. Besides cooling this water film also

Fig. 21: Precooling and calibration section of a polybuten-1 pipe line (schematic)

SPRAYEDWATER

WATER WELL /PRESIZING CHAMBER

SIZINGSLEEVE

MOLTEN PIPE

DIEMELT

PRESIZINGFACEPLATE

SIZING SLEEVEFACEPLATE

SPRAY RING VACUUMCHAMBER

WATER

- 27 -

'lubricates' the outer pipe surface and thus prevents sticking of the still molten tube at theentrance of the water well faceplate.In addition to this immediate quenching, a water well equipped with a water seal faceplatehaving an entry angle of 40 to 45 degrees and a land length not greater than 0,8 mm shouldbe provided to maintain uniform sizing and process stability. The water seal faceplate dia-meter depends on extrusion rates and tubing size. However, the seal ID should not be lessthan 7 % greater than the fresh tubing. The correct size is achieved when there is only asmall gap (< 0,5 mm) between pipe surface and bore of water well faceplate. Typically, thewater well is supplied with cooling water from the bottom having an overflow at its top side.Ideally, the water supply should be set in order to just balance the loss of water through thegap between pipe surface and bore of faceplate. If these conditions are met, this results in aslight, steady overflow of water.Generally, vacuum sizing is recommended for processing of polybutene-1 pipe. The vacuumsizing sleeve diameter should be 2,5 - 3 % greater than the in-line "fresh" tube diameter. Theeffective land length of the sleeve depends on extrusion rates being longer for higher linespeeds. The sizing sleeve geometry for polybutene-1 differs somewhat from otherpolyolefins. A greater entry angle and sufficient length are required because of lowercrystallisation rate of PB-1.At least for smaller pipes (up to 50 mm diameter) disc type calibrators are preferred.However, barrel type sizing sleeves containing holes or slits can be used provided their innersurface is not smooth but finely rifled to prevent sticking of the pipe at the metal surface. Thekey aim is to minimize the contact area between polybutene-1 and the metal surface of thesizing sleeve in order to prevent sticking.Spray rings and pre-sizing chambers are not typically used in the production of polybutene-1tube in sizes over 70 mm diameter, however, it has to be checked whether a spray ring mayhelp to maintain processing stability.Polybutene-1 generally requires much lower vacuum levels than other polymers because ofits slow rate of crystallisation and low modulus. Very stable operation is achieved at vacuumlevels as low as 40 – 80 mbar. It is therefore recommended that the sizing tank incorporatesvacuum gauges calibrated in mbar. Only gauges providing a very stable vacuum should beused. In addition to that split vacuum tanks are preferred which allow to set 2 or 3 differentvacuum levels along the pipe to increase dimensional stability and facilitate dimensionalcontrol.Contoured rollers are usually required to support PB-1 pipe in order to minimise pipe ovalityfor all pipe sizes. These rollers should be spaced every 0,5 m within the vacuum and coolingtanks and have to be installed below the pipe for spray cooling and above the pipe for floodcooling. The rollers in the vacuum tank should have the same inside diameter as the inside

Fig. 22: Contoured roller

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diameter of the sizing sleeve. The rollers in the cooling tanks should be 4 – 5 % larger thanthe maximum fresh tubing radius to minimise out-of-roundness because of the very softfreshly extruded polybutene-1 pipe. In addition to this the rollers should have a land length ofapprox. 10 mm. For 75 m pipes and larger the radius should conform to the radius of thefresh tube. The first roller should be located approximately 50 – 75 mm from the sizingsleeve exit to maintain proper sizing and reduce distortion. A schematic drawing of a typicalcontoured roller is shown in Fig. 22.The contoured rollers can be made of any plastic material with sufficient stiffness and wetabrasive resistance such as polyethylene, polypropylene or nylon. Care should be taken toensure that there is no significant friction of the roller bearings. Figure 23 gives a typicalexample of a contoured roller.

The cooling tanks should be sized to have a length of 1 meter for each meter per minute ofline speed. Spray cooling can be used as well as underwater cooling. Note that improperdesign or water pressure of spray dies may give rise to water markings on the pipe surface.Gaskets used to seal cooling tanks should be wide enough and made of very soft material in

Fig. 23: Contoured roller for PB-1 pipe extrusion

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order to avoid too much friction. Excessive friction will give rise to extra pulling force whichcan cause pipe pulsation.A processing water temperature of 10 – 12 °C is recommended.

3.2.9 Materials of constructionIn the molten state, Basell polybutene-1 resins are not corrosive to metals. Therefore, ageneral purpose grade steel typically used for plastics processing is adequate for extruderbarrel and screw, melt pump, adapters, head and dies.Chrome plating of the extrusion dies is not required. They should be medium polished only,(0,3 µm surface roughness). Chrome plated or highly polished surfaces can favour "stick-slip”behaviour of the extrudate.The screw flight lands should be Stellite or surface hardened to prevent wear of the screwand to maintain the proper screw-barrel clearance. Chrome plating of the screw is notnecessary.Pre-sizer and calibrator faceplate can also be made from brass.

3.2.10 Pullers and coilersA continuous type puller with soft foam pads is recommended. The use of cleated pullersmay be acceptable if the pads are constructed of soft rubber (i.e., Shore A hardness -approximately 10) and do not present a discontinuity to the profile surface upon contact.Hard cleated pullers are not recommended since they will cause severe distortion of theinitially soft polybutene-1 product. Tire type pullers are not recommended since inadequatecontact is present that results in slippage. Also, excessive pressure causes profile flattening.Pullers may be pneumatically loaded but should be adjusted mechanically.The coiling diameter should be as large as practical to provide the optimum in finishedproduct dimensional quality. The coiling tension should be as low as possible to avoidstretching. The minimum coiling diameters for polybutene-1 profiles and tubing aredependent upon diameter and wall thickness. It is recommended to maintain a coilingdiameter of at least 40 times the pipe diameter, but not be less than 700 mm. Upon suitablerecoiling in the opposite direction after ageing almost straight polybutene-1 pipe can beobtained on unwinding.During installation of polybutene-1 pipe bending diameters lower than 12 times the pipe dia-meter should be avoided to prevent excessive stress on outer pipe surface. It isrecommended to use the highest bending ratio possible during application.

3.2.11 CuttersFor the production of small pipe up to 25 mm at higher line speeds (12 m/min and more) theuse of fly wheel cutters is recommend to provide sufficiently fast cutting. For lower linespeeds guillotine type or planetary saw cutters are acceptable, too. Since fresh polybutene-1pipe is very soft, cutter blades should be sharpened or replaced regularly.

3.3 Tooling

3.3.1 General considerationsTooling dimensions to be used for extrusion of polybutene-1 pipe depend strongly onprocessing parameters like line speed, water temperature, melt temperature, etc. Otherimportant factors for estimating correct tooling dimensions are pipe shrinkage duringprocessing and subsequent ageing (form II-> form I transformation) as well as OD and wallthickness draw down ratio, i.e. ratio between die and freshly extruded pipe dimensions.These parameters in turn depend on pipe size.

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3.3.2 Tooling estimation schemeThe following example demonstrates steps required for evaluating tooling dimensions for agiven SDR 11 pipe of 20 mm (+ 0,3 mm) outside diameter (OD) and a wall thickness of 1,9(+ 0,3 mm).Estimates provided in this example are based on calculations, premises and best estimatesas well as practical experience. They are intended only as starting point guidelines for theproduction of polybutene-1 pipe of sizes below 40 mm OD. Some modifications may berequired in order to optimise tooling for each particular line as well as for each particular setof processing conditions.All dimensions are in millimeters.

Step 1: Determination of average freshly extruded (form II) outside diameter (OD-II)and mid-wall thickness (wall-II) of pipeFirst of all the dimensions (OD and wall thickness) of the aged pipe have to bedefined. For this example of 20 x 1,9 mm pipe nominal values are: OD (OD-I) is 20mm with a tolerance of + 0,3 mm whereas wall thickness (wall-I) is 1,9 mm +0,3mm.

� �� �factorshrinkODtoleranceODIODIODIIOD ���

�

���

� �� 1

2

OD-II Estimated mid-outside diameter of fresh(form II) pipe 20,5

OD-I Desired nominal outside diameter of aged(form I) pipe 20,0

OD tolerance Tolerance (+) of outside diameter of agedpipe +0,3

OD shrink factor Estimated outside diameter shrinkage factor(premise) for actual pipe size 0,017

� �� �factorshrinkwalltolerancewallIwallIwallIIwall ���

�

���

� �� 1

2

Wall-II Estimated mid-wall thickness of fresh(form II) pipe 2,07

Wall-I Desired nominal wall thickness of aged (formI) pipe 1,9

Wall tolerance Tolerance (+) of wall thickness of aged pipe +0,3

Wall shrink factor Estimated shrinkage factor (premise) foractual pipe size 0,010

- 31 -

Step 2: Determination of die inside diameter (DID)

Fresh pipe size (OD-II): 20,5Percent OD draw down ratio desired: 4,5 %Inside diameter of die (DID) is 4,5 % larger than outside diameter of freshly extruded(OD-II) pipe.

� �045,01 ���� IIODDID

DID Estimated inside diameter of die 21,4

OD-II Estimated mid-outside diameter of fresh(form II) pipe 20,5

OD draw down ratio Estimated OD draw down ratio required(premise) 4,5 %

Step 3: Determination of die gap (DG)

Fresh mid-wall thickness (wall-II) of pipe: 2,07Percent fresh (wall-II) draw down ratio desired: 10 %Die gap (DID) is 10 % thicker than mid-wall thickness of freshly extruded (wall-II)pipe.

� �100,01 ���� IIwallDG

DG Estimated die gap (die opening) 2,28

wall-II Estimated mid-wall thickness of fresh (formII) pipe 2,07

wall draw down ratio Estimated wall draw down ratio required(premise) 10 %

Step 4: Determination of outside diameter of pin (POD)

Inside diameter of die (DID): 21,4Die gap (die opening): 2,28

DGDIDPOD ��� 2

POD Estimated outside diameter of pin 16,9DID Estimated inside diameter of die 21,4

DG Estimated die gap (die opening) 2,28

- 32 -

Step 5: Determination of die land length (LL)

The length of the parallel zone at the end of the die divided by the width of dieopening or die gap (DG) should equal 10. This ratio is abbreviated L/D.Deviations from estimated land length can be tolerated as long as die swell and pipesurface remain acceptable.

DLDGLL ��

LL Estimated land length 23DG Estimated die gap (die opening) 2,28

L/D Ratio of length of parallel zone of die to diegap (premise) 10

Step 6: Determination of inside diameter of sizing sleeve (SSID)

Fresh outside diameter (OD-II) of pipe: 20,5Percent processing shrinkage: 3%

Inside diameter of sizing sleeve (SSID) is 3 % larger than fresh pipe size (OD-II).

� �030,01 ���� IIODSSID

SSID Estimated inside diameter of sizingsleeve 21,2

OD-II Estimated mid-outside diameter of fresh(form II) pipe 20,5

Processing shrinkage Ratio of inside diameter of sizing sleeve tooutside diameter of fresh pipe (premise) 3 %

Step 7: Determination of sizing sleeve length (SSL)

Inside diameter of sizing sleeve (SSID): 23Desired ratio of sizing sleeve length to its inside diameter is 5/1.This estimates only the approximate length of the sizing sleeve. Depending oncooling intensity and line speed the actual length required may be somewhat longeror shorter.

5�� SSIDSSL

- 33 -

SSL Estimated length of sizing sleeve 106SSID Estimated inside diameter of sizing sleeve 21,2

Sizing sleeveL/D ratio

Ratio of inside diameter of sizing sleeve tooutside diameter of fresh pipe (premise) 3 %

Step 8: Determination of inside diameter of water well (presizer) faceplate (WSID)

Fresh outside diameter (OD-II) of pipe: 20,5

Inside diameter of water well faceplate (WSID) is 13 % larger than fresh pipe size(OD-II).

� �130,01 ���� IIODWSID

WSID Estimated inside diameter of water well(presizer) faceplate 23,2

OD-II Estimated mid-outside diameter of fresh(form II) pipe 20,5

Faceplate size ratioRatio of inside diameter of water wellfaceplate to outside diameter of fresh pipe(premise)

13 %

Step 9: Determination of inside diameter of water spray ring (SRID)

Inside diameter of die (DID): 21,4

Inside diameter of water spray ring (SRID) is 50 % larger than inside diameter of die(DID).

� �50,01 ��� DIDSRID

SRID Estimated inside diameter of spray ring 32DID Estimated inside diameter of die 21,4

Spray ring size ratio Ratio of inside diameter of spray ring toinside diameter of die (premise) 50 %

The inside diameter of the water spray ring is not very critical. As long as anadequate conical spray pattern is achieved at the pipe surface and there is nocontact between pipe and spray ring even differently sized spray rings can be used.In some cases, it may be possible to use the same spray ring to produce severalsizes of pipe having similar outside diameters.

- 34 -

Very important is the distance between spray ring and water well faceplate (typically50 – 120 mm) as well as the distance between spray ring and die (typically 30 – 80mm). By adjusting these distances, for which the values in brackets may serve asguideline, the effective die swell of the pipe can be adjusted.Although spray rings for pipe sizes of outside diameter greater than 63 mm are notabsolutely necessary their use may improve the quality of the pipe surface.

Step 10: Estimate length of pre-sizing water chamber

The pre-sizing water chamber is usually constructed from a tube or pipe with aninside diameter sufficiently greater than the pipe to be extruded. The preferredmaterial for this tube would be a transparent plastic allowing the user to look into thechamber. The chamber has an inlet with a valve on the bottom in order tocontinuously add small amounts of water. A hole should also be present on top ofthe chamber to allow excess water to exit the chamber which during normal pipeproduction should be completely filled with chilled water (10 – 12 °C). This pre-sizingwater chamber is connected to the front of the vacuum tank and has a water seal(pre-sizing faceplate) attached at the other end. The distance between vacuum tankand water seal (pre-sizing faceplate) is the pre-sizing water chamber length. Thefunction of the pre-sizing water chamber is to enhance the cooling of the slowlycrystallising molten polybutene-1 tube and to pre-size the melt before final sizingtakes place in the sizing sleeve. In order to correctly optimise the length of thischamber, it is necessary to know the line speed of pipe production. The length of thepre-sizing water chamber typically ranges from 50 to 125 mm being the longer thehigher the line speed is.

Line speed Estimated length of pre-sizing water chamber

3 m/min 50 mm

10 m/min 75 mm

17 m/min 100 mm

23 m/min 125 mm

The above mentioned estimates are valid for production of pipe sizes with anoutside diameter of up to 63 mm only. Pre-sizing water chambers are not typicallyused for extrusion of big pipes.

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3.3.3 Tooling for small and medium size pipe

These tooling dimensions and drawings are based on calculations, premises and bestestimates as well as practical polybutene-1 pipe experience. They are intended only asguidelines or starting points to assist in the production of polybutene-1 pipe. Somemodifications may be necessary to optimize production for each particular system or whenprocessing conditions like melt temperature, water temperature, line speed, draw down ratio,etc. deviate from these estimates.

The production rate (line speed) estimates given in Tab. 6 are for experienced users and canonly be achieved if the line used is suitably equipped to meet the needs for PB-1 extrusion.In addition to that it requires thorough understanding and developing sufficient expertise ofPB-1 processing behaviour.

A

B

C D

G

H

FE

Sizing sleeve

Pre-sizingfaceplate

Pre-sizing chamber(Water well)

Vacuum tank

Spray ring

50 – 80 mm100 – 210 mm

Fig. 24: Schematic drawing of tooling for small PB-1 pipe

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Tab. 6: Tooling dimension recommendations for small and medium size pipe

Tooling Diagramletter 12 x 1,3 16 x 1,5 16 x 2 17,9 x 2 20 x 1,9 21,9 x 2 25 x 2,3 27,9 x 2,5 32 x 2,9 63 x 5,8

Fresh pipeO.D. 12,3 16,4 16,4 18,3 20,5 22,4 25,6 28,6 32,7 64,4

Fresh wallthickness 1,46 1,67 2,17 2,17 2,07 2,17 2,54 2,74 3,15 6,24

Die I.D. A 12,6 16,9 16,9 19,0 21,4 23,5 26,8 29,8 35,2 72,8

Land length B 15 18 24 24 23 24 28 30 35 69

Pin O.D. C 9,5 13,2 12,1 14,2 16,9 18,7 21,2 23,8 28,3 59,1

Sizing sleeveI.D. D 12,7 16,9 16,9 18,9 21,2 23,2 26,5 29,6 33,9 66,7

Sizing sleevelength E 200 200 200 200 200 180 150 150 180 300

Pre-sizerfaceplate I.D. F 13,9 18,5 18,5 20,7 23,2 25,4 28,9 32,3 37,0 72,8

Pre-sizerlength G 120 120 110 100 100 90 80 75 70 50

Spray ring I.D. H 20 25 25 30 35 35 40 50 60 120

Line speed(m/min) 20 20 18 16 16 14 11 9 8 3

Pipe dimensions according to ISO 15876-2All dimensions in mm

- 37 -

3.4 Large diameter PB-1 pipe

3.4.1 General considerationsAs the size of pipe increases, the line speed and die swell typically decreases and the needfor spray rings and pre-sizing chambers becomes less apparent or beneficial to the extrusionprocess.Because the material will typically spend only a fraction of a second in the sizing sleevewhen producing 16 mm pipe at 18 m/min, it is necessary to pre-cool and pre-size the pipe tofacilitate the crystallisation and sizing process. When producing 160 mm pipe, the line speedis substantially reduced to about 0,6 m/min only. At that rate the material exits the die withmuch less die swell and could be subjected to surface cooling in the sizing sleeve for up to25 seconds. The tooling calculations and premises that are used for smaller diameter pipewill not work with larger pipe sizes.

3.4.2 EquipmentAlthough larger extruders with increased output and/or lower line speeds are required theuse of a melt pump is also recommended for large polybutene-1 pipe. Since pre-sizing waterchambers are typically not used for large pipe the sizing sleeve will be closer (80 – 150 mm)to the die in order to maintain proper sealing of the vacuum tank. The use of a spray ring isnot as important as for small pipe but can be helpful for big pipe, too, in order to enhancelubrication of the extrudate upon entering the sizing sleeve.For production of big pipe higher draw down ratios of 20 % or more are typically used.Because of higher wall thickness extended downstream cooling length is required despitemuch lower line speed used for large pipe extrusion, e.g. approx. 15 m for 110 x 10 mm pipeproduced at 1,3 m/min. Preferred cutter type is a travelling or planetary saw with bladecooling to provide proper pipe cuts. Mostly straight pipes are produced. However, if coiledpipe is required, heavy duty coilers have to be used.

3.4.3 Physical propertiesBecause of the much slower cooling speed of thick walled pipe a gradient of morphologicaland hence physical properties across the pipe wall becomes more prominent and makes thepipe more brittle and less flexible. As a result lower elongation at break will be achieved bothin machine and transverse direction. A typical picture of obtained spherulite size distributionacross pipe wall thickness is shown in Figure 25. By reason of the relatively fast cooling thespherulites at the outer surface are much smaller than at the slower cooled pipe inside. Inaddition to this there is an amorphous skin at the very outer pipe surface. As a consequenceof this, elongation at break of thick walled pipe is considerably lower than that of thin walledpipe and shows a gradient across the pipe wall becoming even lower towards the innersurface. If available, inside cooling of the pipe could help a lot to improve this situation and toget a more uniform spherulite morphology across the wall with an amorphous skin at theinner surface, too. A schematic drawing of internal cooling is given in Fig. 26.

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Fig. 25: Spherulite morphology across pipe wall

Crystal rich regionBigger spherulites

More amorphous regionSmaller spherulites

Fig. 26: Schematic drawing of inside cooling during pipe extrusion

Air or water inlet

Sizing sleeve

Vacuum tank

Insulation

Cooling tube with sprayholes (0,5 – 1 mm) Extension tube

Polymermelt

Solidified melt (pipe)

- 39 -

3.4.4 Tooling for big pipe

Tab. 7: Tooling dimension recommendations for big pipes

Tooling Diagramletter 110 x 10 125 x 11,4 160 x 14,6

Fresh pipe O.D. 112,7 128,1 164,0

Fresh wall thickness 11,0 12,6 16,2

Die I.D. A 134,7 153,7 203,3

Land length B 120 140 180

Pin O.D. C 110,6 126,0 167,7

Sizing sleeve I.D. D 116,7 132,6 169,7

Sizing sleeve length E 180 200 250

Line speed (m/min) 1,3 1 0,6

Pipe dimensions according to ISO 15876-2All dimensions in mm

CA

D

Sizing sleeve

B

Vacuum tank

E

Fig. 27: Schematic drawing of tooling for big PB-1 pipe

- 40 -

3.5 Grinding and reprocessingWhile Basell does not recommend any particular type or style of grinder or granulator for usewith polybutene-1, some general information on this type of equipment can be provided.Since polybutene-1 is a relatively soft, low modulus material with a somewhat low softeningpoint temperature, some precautions have to be considered. The material has a tendency todeform or smear instead of being cut in a clean uniform manner. This is partly due to heatgeneration in the grinder or granulator caused by friction of the grinder blades trying to cutsoft material.Generally, the longer polybutene-1 is aged after processing and the cooler the material iskept during regrinding, the easier it will be to cut it. While most heavy duty grinders will beable to handle polybutene-1, the following recommendations may help to make grindersperform more efficiently.1. The grinder should have sufficient motor power to handle the volume and heat

generation during grinding the material without burning up or seizing the motor.2. The grinder cutter blades should be kept sharp at all times to reduce frictional heat

generation.3. The mesh size of the sieves should be chosen accordingly in order to prevent large

particles to pass through and assure that the regrind material is of uniform size that theextruder can reprocess.

4. Sometimes the performance of the grinder can be improved by removing some of thecutter blades in order to reduce frictional heat generation during the grinding process.

5. Grinders with cooling options for cutter blades (chilled water or forced air) can be abenefit.

6. The main purpose of a polybutene-1 grinder is to produce a clean material of smalluniform size (approx. 3 – 5 mm) that can be readily fed into the extruder and processedin a consistent manner. Particle size of regrind and size of virgin pellets should match inorder to avoid melt inhomogeneity caused by inconsistent feeding.

7. Check MFR and OIT of regrind. MFR of regrind should match that of virgin material asclose as possible to avoid extrusion instabilities due to different melt viscosity. OITshould remain above specification limit in order to make sure that no significant loss ofstabiliser has occurred.

8. Careful drying of regrind and virgin material is recommended to avoid problems causedby moisture.

9. During collection of scrap and regrinding precautions should be taken to avoidcontamination.

10. Based on current experience and best estimates not more than 10 % regrind should beused with not less than 90 % virgin material in order to avoid too much loss ofperformance and oxidative stability. These percentages are based on current experienceand best estimates without giving any guarantee or accepting any liability.

The above mentioned considerations are valid only for pure polybutene-1 material.Regrinding of barrier pipe is not considered.

- 41 -

3.6 Troubleshooting

3.6.1 General procedureFirst of all existing outside diameter and wall thickness variations of pipe have to bequantified. Then the root cause for excessive dimensional variations should be determined.This evaluation process of the pipe extrusion line can be done by segregating the system inthe following three sub-systems:1. Extruder / Adapters / Screen pack changer / Melt pump / Die2. Vacuum control / Cooling system3. Puller / CutterThe procedure should start with isolation and evaluation of the sub-system most suspectedto contribute to the problem.All sensors, gauges, transducers and thermocouples of the three sub-systems involved haveto be calibrated.Before taking samples of pipes of approx. 1m length the extruder should be allowed tostabilise for at least 45 min after final adjustment to achieve target dimensions for theparticular pipe size. At least 50 pipe samples should be collected.Pipe dimensions should be measured on each individual sample at least 5 days afterproduction and measuring on a particular series should be completed within three days. Theoutside diameter is measured using a periphery tape with an accuracy of � 0,05 mm. Thewall thickness is measured using a spring-loaded micrometer with rounded ball ends at aminimum distance of 20 mm from the end with an accuracy of � 0,02 mm. At least eightseparate measurements should be taken at 45 ° angles around the pipe wall in order todetermine the minimum value. Using all individual dimensions collected, minimum,maximum, mean value and standard deviation of outside diameter and wall thickness shouldbe calculated.In addition to this dimensional check of the finished pipe there are some more toolingevaluations to be considered:a. The shape of the water film of the spray ring should be conical with an angle of 40 – 50 °

and centered at the pipe.b. Between pre-sizing water chamber faceplate and pipe there should be a small gap of not

more than 0,5 mm. Bigger gaps will result in increased loss of cooling water andinconsistent water supply while contact between pipe and faceplate will cause sticking ofthe pipe leading which can lead to pulsation.

c. Inappropriate pre-sizing chamber length or wrong sizing sleeve diameter itself will resultin mismatch of pipe outside diameter and sizing sleeve inside diameter giving rise tosticking of pipe at sizing sleeve entrance if pipe diameter is too large or loss of vacuum ifpipe diameter is too small.

d. Tooling dimensions like pre-sizing chamber faceplate and length as well as sizing sleevediameter will depend strongly on processing parameters like melt temperature, coolingwater temperature, vacuum, line speed, etc.

3.6.1.1 Evaluation procedure 1:The feed throat cooling system should be checked to assure that there are no obstructionsand sufficient cooling is provided to the feed throat.Systems utilising melt pumps should optimise differential pressure between melt pump input(suction) pressure and output (discharge) pressure. The pressure difference between thesetwo points is typically maintained at approx. 70 bar, the discharge pressure being higher than

- 42 -

the suction pressure. Differences in material and processing conditions can affect theoptimum differential pressure setting. In systems without melt pump screen packs or barriersin die head or adapter are normally used to develop head pressure. In these systems typicalpressures are between 70 – 140 bar.a. The output consistency of the extruder should be evaluated at the rate (extruder speed)

desired for the particular operation. This procedure should determine the amount ofmaterial fluctuation attributable to the extruder:

b. The extruder should be run using standard barrel and die temperature profile at thedesired output rate until processing parameters reach equilibrium, usually 30 min, andthe material is pumped on the floor.

c. After 30 min of operation samples of material should be collected using a spatula to cutaway material from the die at 15 second intervals.

d. Sample collection can be terminated after 10 min or 40 samples. The individual samplesare weighed with an accuracy of � 1 g and minimum, maximum and fluctuations arecalculated.

Optimisation of this system can be done by appropriate adjustment of the temperature profileof barrel and die. Melt output consistency (surging) should be less than 1% when using amelt pump and can increase up to 10 % without melt pump (depending on material, screwconfiguration and temperature profile.A re-evaluation may be required whenever the material, screw or rate of extrusion ischanged. Normal wear of screw and barrel may also call for re-evaluation of the system inorder to maintain low levels of surging.

3.6.1.2 Evaluation procedure 2:This describes the evaluation procedure of the vacuum control and water cooling system foradequate pressure and temperature control and consistency.a. Each vacuum compartment should be isolated from the other compartments (if the

vacuum sizing system is equipped with multiple sizing compartments). Front and backopenings are to be sealed with tape or other sealant.

b. A small hole should be punched in the tape or sealant and the system should be run attypical operating conditions for 15 min with vacuum, temperature and pressure recordedevery 10 seconds.

c. Steps a. and b. are to be repeated for all vacuum compartments.d. By plotting results against time the control consistency of this sub-system is obtained.Optimisation of this system could require repair or replacement of pumps, pump seals, va-cuum valves or gaskets.

Typical vacuum, temperature and pressure control is � 2% of set point.

3.6.1.3 Evaluation procedure 3:This describes the evaluation procedure of the puller and cutter system consistency.a. The puller should be operated at typical or desired speed for 15 minutes.b. A sufficiently long pipe is to be inserted at the entrance of the puller.c. The pipe should be marked at exactly the same location at 10 seconds intervals. This

must be done with a high degree of precision. Alternatively a pipe cutter can be usedthat automatically cuts at specific time intervals with the same precision.

d. By measuring the distance of markings or actual length of pipes cut differences in lengthindicate puller consistency.

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Optimisation of this sub-system could require re-calibration of the puller motor control,physical inspection of the mechanical linkage system that conveys motor speed to pullerbelts or slipping of the pipe as it is being pulled through puller belts. Possibly puller beltsneed to be replaced or puller belt pressure has to be adjusted.If a pipe coiler is used in the system, it should be checked that the coiler is not pulling thepipe through the puller belts. Eventually coiler tension has to be reduced. Besidesinconsistency in pulling this could cause dimensional variations of pipe during processing aswell as deformation (ovality) of pipe after it exits the puller.

3.6.2 Miscellaneous problems

3.6.2.1 Melt sticking at pre-sizing water chamber faceplate or sizing sleeve– Inconsistent extruder output can cause stick / slip appearance of material entering the pre-

sizing chamber or sizing sleeve because during the higher volume output phase thematerial will stick or build up at those points.

– Spray ring and pre-sizing chamber water temperature and pressure are not optimised (10– 12 ° C temperature and 3 bar pressure) or water temperature or pressure shows toomuch fluctuation.

– Position of spray ring with respect to die and / or pre-sizing chamber not optimised.– Diameter and / or entrance angles of pre-sizing chamber faceplate and / or sizing sleeve

not optimised.– Increase length of pre-sizing chamber to allow for more melt cooling before pipe is sized.– Incorrect vacuum level.

3.6.2.2 Difficulty increasing rate of extrusion– Extruder should be capable of delivering consistent output at desired rate while operating

at approx. 80 % of maximum throughput.– Puller should be capable of delivering consistent speed at desired rate while operating at

80 % of maximum rating.– Downstream water cooling length (1 m of cooling bath incl. vacuum tank for every m/min

of line speed) and downstream water cooling temperature (10 °C – 14 °C) should beadequate (temperatures of 10 °C – 12 °C are recommended at spray ring and pre-sizingwater chamber).

– The pre-sizing water chamber length may need to be increased (in 5 mm increments) aswell as inside diameters of pre-sizer faceplate ( in 0,5 mm increments) and sizing sleeve(in 0,2 mm increments).

3.6.2.3 Longitudinal lines in pipe– Burrs or scars on die, pin or sizing sleeve.– Deposit on die / pin surface or sizing sleeve.– Spider design not optimised, i.e. spider legs too wide or too cold.– Contamination in die / pin or spider area causing polymer to flow around contaminated

particle resulting in flow line.– Tooling not optimised (die / pin land length typically between 10 – 20 L / D).– Polymer melt temperatures too low (typically between 180 °C – 200 °C).– Insufficient back pressure in die / spider area (typically between 110 – 140 bar).

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3.6.2.4 Pipe is not round (ovality)– Puller / haul-off belts are too hard (typically sponge type or soft rubber of Shore A

hardness - approximately 10).– Compression of puller belts on pipe is too strong.– Cross-section of puller belt or belt pads not V-shaped.– Downstream water cooling length or cooling water temperature is not sufficient, i.e.

cooling length too short or water temperature too high, to cool pipe adequately beforeentering the puller / haul-off belts so that puller belts can deform the pipe after processing.

– No contoured rollers or rollers of wrong shape; typically a new set corresponding to thepipe size produced should be used, i.e. half-circle shaped approx. 5 % larger than thefresh outside diameter of the pipe with a land length of about 10 mm. Rollers should bespaced at 0,5 m intervals starting from the sizing sleeve along the entire length of thevacuum and cooling bath.

– Sizing sleeve or vacuum tank gaskets are not of correct size.– Pipe coiling tension is too high.

3.6.2.5 Poor appearance of pipe surface (outside and inside)– Burrs or scars on inside or outside of die / pin or sizing sleeve.– Contamination of material, e.g. size, composition and cleanliness of regrind.– Check proper shape of spray ring pattern and water temperature (10 °C – 12 °C).– Check screen pack integrity, cleanliness and mesh size (typically approx. 80 – 100 mesh).– Moisture in extruder (from feed throat cooling condensation or on pellets.– Temperature profile of extruder and die can be increased in order to get more shiny pipe.

3.6.2.6 Elongation at break values below minimum– Extrusion rate too high.– Too strong extension of pipe or draw-down ratio too high.– Polymer melt temperature too low (typically between 180 °C – 200 °C).– MFR of polymer too low (can be compensated by higher melt temperature.– Check proper shape of spray ring pattern and water temperature (10 °C – 12 °C).– The pre-sizing water chamber length may need to be increased (in 5 mm increments) as

well as inside diameters of pre-sizer faceplate ( in 0,5 mm increments) and sizing sleeve(in 0,2 mm increments).

– Vacuum level too high (typically 40 – 80 mbar).

3.6.2.7 Processing water quality, pressure and temperature– Dirty, contaminated (high mineral content) water could clog lines, pumps and spray ring

and thus produce erratic flow.– Water system treatments like rust inhibitors, pump lubricants, etc. that come into contact

with pipe during processing are not recommended.– Water pressure and volume (flow) should be adequate and consistent (particularly at

spray ring and vacuum tanks) in order to maintain effective and uniform cooling andappropriate vacuum sizing.

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3.6.3 Lot to lot variability in polybutene-1 pipe production

3.6.3.1 Symptoms– Pipe outside diameter (O.D.) varies from original target or fluctuates during production.– Pipe wall thickness varies from original target or fluctuates during production.– Melt pressure or temperature at inlet to die varies upon feeding of new lot of material.

3.6.3.2 Possible causes – Extrusion process– Process water temperature or pressure changes or fluctuates during processing (seasonal

changes or poor control).– Material feed temperature or pressure changes or fluctuates during processing (seasonal

changes or inconsistent control, i.e. cold / hot material from warehouse, improper drying,partial obstructions in feed throat, throat cooling temperature changes, condensation ofmoisture in feed section, etc.).

– Extrusion temperature profile or melt temperature varies from original setting duringproduction (heater bands or controllers malfunction, inaccurate or malfunctioningtemperature sensors, shear temperature changes due to screw or barrel wear, etc.).

– Extruder speed changes due to inconsistent motor speed control.– Line speed (extrusion rate) varies during production (haul-off control inconsistent, haul-off

belts worn, hardened or inconsistent contact / compression on pipe, etc.).

3.6.3.3 Possible causes – Raw material– MFR (melt viscosity) of material changes between lots– Pellet density, shape or size changes between lots– Pellet count (volume) of material changes between lots– Variation of moisture/volatile content between lots– Bulk density of material changes between lots– Homogeneity of additive distribution changes between lots

Note: Basell PB-1 pipe grades are produced on a state-of-the-art polimerisation plant to atight specification under a system certified to EN ISO 9002. The current productspecification includes upper and lower limits on MFR, pellet size, moisture/volatilecontent and other important material properties.

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3.6.4 PB-1 pipe extrusion troubleshooting cross reference

Potential problem Possible cause

1. Extruder surging � Wrong temperature profile

� Extruder speed (RPM) too high

� Insufficient back pressure

2. Poor vacuum control � Extruder surging

� Stick-slip in sizing sleeve

� Poor water flow through vacuum tank

� Wrong size of vacuum tank gaskets

3. Wrong pipe O.D. � Wrong tooling

� Wrong vacuum

� Wrong pre-sizing water chamber dimensions

� Wrong spray ring position

� Wrong melt temperature

� Wrong line speed

4. Pipe bambooing � Extruder surging

� Variable vacuum

� Clogged vent port in pin

� Wrong pre-sizing water chamber dimensions

� Wrong pre-sizing water chamber faceplate angle

� Wrong melt temperature

� Wrong size of cooling bath gaskets

� Wrong spray ring position

� Wrong spray ring pattern

� Die swell too high

� Sizing sleeve too small

5. Wrong wall thickness � Wrong tooling

� Wrong draw down ratio

� Wrong extruder speed

� Wrong puller speed

6. Poor pipe concentricity � Poor die / pin adjustment

� Poor die design

� Wrong puller speed

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7. Oval pipe � Non-contoured rollers

� Puller compression / tension too high

� Coiler tension too high

� Wrong size of cooling bath gaskets

8. Flow lines � Burrs or scars in pin / die, pre-sizer faceplate orsizing sleeve

� Melt temperature too low or wrong die temperatureprofile (spider lines)

� Land length too short

� Contamination of material

� Insufficient back pressure in die

9. Crease lines � Die gap too large (too much material)

� Vacuum too low (pipe collapse)

10. Poor surface � Burrs or scars in pin / die, pre-sizer faceplate orsizing sleeve

� Wrong spray ring pattern or water pressure

� Volatiles (moisture)

� Dirty product

� Dirt in screen packs

� Melt temperature or line speed too low or too high(melt fracture)

11. Water spots � Wrong spray ring pattern or water pressure

� Wrong position or water pressure of spray dies invacuum tank

12. Voids in pipe � Voids / volatiles in pellets

� Surface moisture (condensation of water) on pellets

13. Melt sagging � Melt temperature too high

� MFR too high

� Wrong tooling

� Tooling in wrong position

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4. Annex: List of standards relevant for PB-1 pipes

Characterisation of material

ISO 1133 Plastics - Determination of the melt mass-flow rate (MFR) and themelt volume-flow rate (MVR) of thermoplastics

ISO 1183 Plastics – Determination of density of non-cellular plastics

ISO 8986 Plastics - Polybutene (PB) moulding and extrusion materials - Part1: Designation system and basis for specification; Part 2:preparation of test specimens and determination of properties

ISO 11357-6 Plastics - Differential scanning calorimetry (DSC) - Part 6:determination of oxidation induction time

ISO FDIS 16770 Plastics – determination of environmental stress cracking (ESC) ofpolyethylene (PE) – Full-notch creep test (FNCT)

Pipe related standards

ISO

ISO 161 Thermoplastics pipes for the conveyance of fluids – Nominaloutside diameter and nominal pressure

ISO 497 Guide to the choice of series of preferred numbers and of seriescontaining more rounded values of preferred numbers

ISO 1167 Thermoplastics pipes for the conveyance of fluids - Resistance tointernal pressure - Test method

ISO CD 2505 Thermoplastics pipes - Longitudinal reversion - Test methods andparameters

ISO 3126 Plastics piping systems – Plastics piping components –Measurement and determination of dimensions

ISO 4065 Thermoplastics pipes – Table of wall thickness

ISO 4433 Thermoplastics pipes – Resistance against chemical fluids -Classification

ISO 6259 Thermoplastics pipes - Determination of tensile properties

ISO 6964 Polyolefin pipes and fittings – Determination of carbon blackcontent by means of pyrolytic degradation – Test method andrequired values

ISO CD 7686 Plastics pipes and fittings - Opacity - Test method

ISO 8795 Plastics piping systems for the transport of water intended forhuman consumption - Migration assessment - Determination ofmigration values of plastics pipes and fittings and their joints

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ISO 9080 Plastics piping and ducting systems - Determination of long-termhydrostatic strength of thermoplastics materials in pipe form byextrapolation

ISO 9967 Thermoplastic pipes – Determination of creep behaviour

ISO 9969 Thermoplastic pipes – Determination of ring stiffness

ISO/TR 10358 Plastics pipes and fittings - Combined chemical-resistanceclassification table

ISO 10508 Thermoplastics pipes and fittings for hot and cold water systems

ISO 11922 Thermoplastics pipes for the conveyance of fluids - Dimensions andtolerances

ISO 12162 Thermoplastics materials for pipes and fittings for pressureapplications - Classification and designation - Overall service(design) coefficient

ISO 12230 Polybutene (PB) pipes - Effect of time and temperature on theexpected strength

ISO 13477 Thermoplastic pipes for the transport of fluids – Determination ofresistance against rapid crack propagation – Laboratory test atsmall pipe samples (S4)

ISO 13478 Thermoplastic pipes for the transport of fluids – Determination ofresistance against rapid crack propagation – Practical test (FST)

ISO 13479 Thermoplastic pipes for the transport of fluids – Determination ofresistance against crack propagation – Test method for slow crackpropagation of notched pipes (notch test)

ISO 13760 Plastics pipes for the conveyance of fluids under pressure - Miner'srule - Calculation method for cumulative damage

ISO 15494 Plastics piping systems for industrial applications - Polybutene(PB), polyethylene (PE), polypropylene (PP) - Specifications forcomponents and the system

ISO FDIS 15876-1 - 7(formerly known as EN12319)

Plastics piping systems for hot and cold water installations -Polybutylene (PB) – Part 1 - 7

ISO DIS 16871 Plastics piping and ducting systems - Method for exposure to direct(natural) weathering

ISO FDIS 18553 Method for the assessment of pigment or carbon black dispersionin polyolefin pipes, fittings and compounds

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CEN

EN 496 Plastics piping and ducting systems - Plastics pipes and fittings -Measurement of dimensions and visual inspection of surfaces

EN 578 Plastics piping systems - Plastics pipes and fittings - Determinationof the opacity

EN 712 Plastics piping systems - End-load bearing mechanical jointsbetween pressure pipes and fittings - Test method for resistance topull-out under constant longitudinal force

EN 713 Plastics piping systems - Mechanical joints between fittings andpolyolefin pressure pipes - Test method for leaktightness underinternal pressure of assemblies subjected to bending

EN 743 Plastics piping and ducting systems - Thermoplastics pipes -Determination of the longitudinal reversion

EN 806 Specification for installations inside buildings conveying water forhuman consumption

ENV 852 Plastics piping systems for the transport of water intended forhuman consumption - Migration assessment - Guidance on theinterpretation of laboratory derived migration value

EN 921 Plastics piping systems - Thermoplastics pipes - Determination ofresistance to internal pressure at constant temperature

EN 1056 Plastics piping and ducting systems - Plastics pipes and fittings -Method for exposure to direct (natural) weathering

EN 1264-4 Floor heating - Systems and components - Part 4: Installation

EN 1420 Influence of organic materials on water intended for humanconsumption - Determination of odour and flavour of water in pipingsystems

EN 12107 Plastics piping systems - Injection-moulded thermoplastics fittings,valves and ancillary equipment - Determination of long-termhydrostatic strength of thermoplastics materials used for injection-moulded piping components

EN 12293 Plastics piping systems - Thermoplastics pipes and fittings for hotand cold water - Method of test for the resistance of piping systemsto thermal cycling

EN 12294 Plastics piping systems for hot and cold water - Method of test forleaktightness under vacuum

EN 12295 Plastics piping systems - Thermoplastics pipes and fittings for hotand cold water - Method of test for resistance of piping systemsunder pressure cycling

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EN 12873 Influence of materials on water intended for human consumption -Influence due to migration

DIN and other German standards and guidelines

DIN 4102-1 Brandverhalten von Baustoffen und Bauteilen – Teil 1: Baustoffe –Begriffe, Anforderungen und Prüfungen

DIN 4726 Warmwasser-Fußbodenheizungen und Heizkörperanbindungen -Rohrleitungen aus Kunstsstoffen

DIN 4727 Rohrleitungen aus Polybuten für Warmwasser-Fußbodenheizungen- Besondere Anforderungen und Prüfung

DIN 16831-1 - 7 Rohrverbindungen und Formstücke für Druckrohrleitungen ausPolybuten (PB) - PB 125 - Teile 1 - 7

DIN 16887 Prüfung von Rohren aus thermoplastischen Kunststoffen;Bestimmung der Zeitstand-Innendruckverhaltnis

DIN 16888-1 Bewertung der chemischen Widerstandsfähigkeit von Rohren ausThermoplasten; Rohre aus Polyolefinen

DIN 16889-1 Bestimmung der chemischen Resistenzfaktoren an Rohren ausThermoplasten; Rohre aus Polyolefinen

DIN 16968 Rohre aus Polybuten (PB); Allgemeine Anforderungen und Prüfung

DIN 16969 Rohre aus Polybuten (PB) - PB 125 - Maße

DVGW W 270 Technische Regel - Arbeitsblatt – Vermehrung vonMikroorganismen auf Materialien für den Trinkwasserbereich –Prüfung und Bewertung

DVGW W 534 Technische Regel - Arbeitsblatt - Rohrverbinder undRohrverbindungen

DVGW W 542 Verbundrohre in der Trinkwasser-Installation; Anforderungen undPrüfungen

DVGW W544 Technische Regel - Arbeitsblatt - Kunststoffrohre in derTrinkwasser-Installation; Anforderungen und Prüfungen

ASTM

D 2581 Standard specification for polybuylene (PB) plastics moulding andextrusion materials

Australia / New Zealand

AS/NZS 2642.1-3 Polybutylene pipe systems - Polybutylene (PB) pipe for hot andcold water applications – Part 1 - 3

AS/NZS 3500 National plumbing and drainage code

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AS/NZS 4020 Testing of products for use in contact with drinking water

Japan

JIS K 6792 Polybutene (PB) pipes for water works

Korea

KS M3363 Polybutylene (PB) Pipes

Phillipines

PNS 152 Specification for Polybutylene (PB) Pipes for Potable Water Supply

Spain

UNE 53415-1 - 4 Plastic piping systems for hot and cold water installations -Polybutylene (PB) – Part 1 - 4

Thailand

TIS 910-2532 Polybutylene (PB) pipe and tubing for drinking water services

UK

BS 6920 Suitability of non-metallic products for use in contact with waterintended for human consumption with regard to their effect on thequality of the water