HDPE WastePipe & Fittings

Technical ManualEffective 1st January 2007

Introduction

PPI commenced production of polyethylene pipe in 1979. Since then it has grown into the largest privately Australian owned producer of plastic pipe and fittings with factories in Brisbane, Adelaide, Perth, Renmark and New Zealand. During this time, PPI has gained an enviable reputation by applying local knowledge to local problems and for persistently challenging the highest quality and service standards.

PPI manufacture HDPE Waste Pipe for brand name suppliers servicing the HDPE Waste Pipe and Fittings market in Australia.

This manual has been produced to help the industry understand this relatively new piping system.

It should be used as a guide only and also with reference to the installation or special instructions provided by the fittings supplier.

All care has been taken to develop this technical guide for HDPE waste pipe and fittings systems. However, PPI cannot be held responsible for any design failures or installations that do not conform with the National Plumbing Code or other requirements of the

relevant statutory authority.

Copyright © 1997 by PPI Corporation Pty LtdAll rights reserved. No part of this manual may be reproduced without the prior written consent of PPI Corporation Pty Ltd.

PO Box 55, Geebung Queensland Australia 4034ABN 79 010 656 004

Benefits of HDPE Page 2

Joints Page 3

HDPE Installations Page 4

Welding Techniques Page 6

Connecting to Other Systems Page 7

Transport, Storage and Handling Page 13

What is Polyethylene? Page 14

Chemical Resistance Page 16

Index

Benefits of HDPE

PPI's High Density Polyethylene (HDPE) waste pipe and fittings have been designed to carry a large range of non-pressured waste materials for;

• Domestic soil waste

• Industrial soil waste

• Trade waste

• Sewerage

• Stormwater

• Civil drainage works

The characteristics of the HDPE waste pipe and fittings system lead to significant benefits in comparison to the tradional materials.

These benefits are;

• HDPE is resistant to a broad range of chemicals. It is the ideal choice for harch industrial waste (chemical resistance charts are provided at the back of this manual).

• HDPE is easier and faster to install as it is light and the joints can be made quickly. Installation time and money can be saved on every installation.

• It is the economic alternative to copper, cast-iron earthenware or pyrex glass.

• Alterations to a completed system are very simple. Mistakes are bad enough but at least with HDPE it doesn't take forever to get back on track.

• HDPE is impact resistant. It will bend to resist loads that split or dent other systems.

• HDPE will not corrode. The system has a long life.

• Nothing sticks to HDPE which means that it is more resistant to build up or scaling.

• HDPE will not crack due to soil movement.

• Roots will not penetrate a welded joint.

• HDPE does not give off toxic fumes during a fire. HDPE will burn so fire collars are required at fire walls and through concrete floors. It is reassuring to know that nobody will be harmed by the fumes which are usually the most dangerous part of a fire.

• HDPE has natural sound deadening properties which makes it the ideal choice for high rise apartments.

• HDPE welded joints will not break down over a period of time as there are no other materials or solvents involved.

• HDPE is no subject to electrolytic action and will therefore not interfere with other nearby systems or installations.

Page 3

Joints

There are 5 different types of joints with specific advantages for a variety of applications. Some of the joining techniques are different to the traditional waste pipe systems but they are surprisingly simple and easy to master with very little training of practice required.

Butt WeldA butt welded joint is the most common and space saving connection as it is safe, strong, economical and quick to make. It is a non-manipulative joint which can resist tensile stress and will not degrade over time as it does not require the introduction of other materials to form the joint. The butt weld is formed by fusing two ends together after they have been heated by a thermostatically controlled heat plate. Small diameters can be butt welded by hand whereas larger diameters require a machine to keep the correct alignment.

Electrofusion WeldThis method uses the socket type fitting with an internal heating element connected to surface terminals. An electrofusion weld is also a non-manipulative joint which can resist tensile stress and it will not degrade over time as it does not require the introduction of other materials to form the joint. The electrofusion weld is created passing low voltage electricity through the internal heating element, heating the fitting and the pipe and fusing them together. It give reliable long-lasting joints which are easy to make and are very popular in difficult constrictive situations.

Threaded CouplingThis type of joint is the most used in the plumbing industry. A threaded coupling forms a manipulative joint which is resistant to tensile stress. The joint is formed by inserting the pipe into the end of the threaded coupling. A coupling nut is then tightened to compress a ring against the outside of the pipe. These joints allow easy access and disassembly for future extensions.

Flanged JointsFlanged joining is generally used for industrial plants and for joining pipes of big diameters. It is a non-manipulative joint which can resist tensile stress. The joint is formed by butt welding a waste stub end to the end of the pipe. This retains the galvanised steel waste backing flange which can be bolted to another flange. A gasket is used between the two flanges to ensure an effective seal. Flanged joints allow HDPE pipes to be easily connected to other different materials, equipment and pumps.

Ring Seal JointsA ring seal is ideal for joining prefabricated sections or connecting dissimilar materials. An expansion joint is a special ring seal fitting with a longer body which allows for movement when the pipe expands or contracts due to termperature changes. A ring seal join is a manipulative joint which will not resist tensile stress. In both cases an elastromeric lip seal ensures a perfect joint.

Page 4

HDPE Installations

Installation Above GroundHDPE pipe that is used in sanitary design can be used above ground in:

• Single stack

• Single stack modified

• Fully ventilated

• Fully ventilated modified systems

• Other conveyancing systems

Pipe SupportsThe following table shows the recommended maximum support distance for HDPE waste pipes or elevated drainage pipes at normal working temperatures or subjected to short periods of steam or tempered hot water up to 95ºC.

In the case where the system is conveying constant high temperature discharge the use of additional pipe bands and support bars may be required.

All pipe work must be securely fixed to the building or structure and the pipe supports must be strong enough to support the installation.

The distance between the pipe and the structure should be ashort as possible to prevent high bending movement on the connecting rod.

Slope

Pipe Dia (mm)

Graded (m)

Vertical (m)

40 0.4 1.2

50 0.5 1.2

56 0.6 1.5

63 0.6 1.5

75 0.8 1.5

90 0.9 2.0

110 1.1 2.0

160 1.6 2.0

200 2.0 2.0

250 2.5 2.5

315 3.0 3.0

Two styles of supports are required;

• General pipe supports must support the installation but allow for thermal movement along the length of the pipe.

• Supports for the expansion joints must be rigid or braced so that the expansion joint is held stationary and the thermal movement of the pipe is taken up in the fitting.

Thermal MovementLike all materials HDPE will also expand and contract when the temperature changes. The predominant effect and the only one that needs to be considered in the design or installation of a HDPE system is the change in length.

A temperature increase will cause the pipe to increase in length and a decrease in temperature will cause the pipe to shorten.

HDPE has a linear coefficient of expansion of 0.2mm m-1 ºC-1, which means that one metre of HDPE pipe will expand by 0.2mm for every degree increase in temperature.

This is 20 times as much as steel, which has linear coefficient of expansion 0.01mm m-1 ºC-1. One metre of steel pipe will expand by 0.01mm for every degree increase in temperature.

The variation in length can easily be determined from the following formula;

∆l = L x λ x ∆t

where;

∆l is the change in length (mm)

L is the initial pipe length (m)

λ is the coefficient of expansion (mm m-1 ºC-1)

∆t is the difference between the lower and higher expected working temperatures (ºC)

In drainage systems it is evident that the temperature of the fluid conveyed varies considerably. For instance, the same type of pipe can be used for an outdoor rain pipe or for draining hot water from dishwashers or kitchen sinks.

In the first case the temperature may only fluctuate from 0 to 35ºC but in the second case, pipe which is normally at 15 to 25ºC can suddenly be required to drain water at 70ºC and over.

Similarly the pipes can be laid during winter with the temperature near 0ºC, or anywhere in between.

For all these reasons it is very important to calculate the length variantion due to the difference in the working temperatures. Remember that may be negative which means contraction rather than expansion.

Calculation ExamplesExample 1

Installation of an outdoor drainage pipe during summer.

Possible Winter Temp: – 10ºCSummer / laying Temp: + 35ºCPipe Length: 5m

Therefore:

∆t = –10 – (+35) = –45ºC

and

∆l = L x λ x ∆t

∆l = 5 x 0.2 x (-45) = –45mm

which is a contraction of 45mm.

Page 5

HDPE Installations

Example 2.Installation of a dishwasher drainage pipe for water at 70ºC.

Working Temp: 70ºCLaying Temp: 20ºCPipe Length: 20m

Therefore:

∆t = 70 – 20 = 50ºC

And:

∆l = L x λx ∆t∆l = 3 x 0.2 x 50 = 30mm

which is an expansion of 30mm

It is also reasonable to assume that the working termperature is 10 to 20ºC lower than the real calculated value as;

• vertical pipes are never completely full

• HDPE is a bad heat conductor

• drainage time can be relatively short

• a certain amount of air circulates in the pipe

Expansion Summary• Determine the lower and higher

working temperatures

• Calculate the difference in termperature

• Calculate the change in length

Expansion JointAn expansion joint is a special ring seal joint that has a long body to take up the movement in the pipe due to thermal expansion and contraction.

In most instances, it is possible to simply push the pipe into the centre of the body as it is sufficiently long enough to allow for the most common expansion conditions. It is advisable however to calculate the expansion rate until the concept is fully understood.

As a rule of thumb with graded pipe work an expansion joint should be installed at 6 metre intervals. In long runs it is often more convenient to install an expansion joint at the end of every length of pipe.

For the expansion joint to work it must remain stationary so it is very imporatant to mount each joint on a rigid or braced support.

For vertical stack work an expansion joint fixed at the base is normally required for each floor.

Bevelling the end of the pipe at approximately 20ºC and applying lubricant will usually assist installation.

Expansion joints are not required below ground as the ambient termperature is fairly stable and the fluid temperatures from many inlets have usually mixed and stabliised through the above ground pipework.

Fire Collar StopsHDPE does not give off toxic fumes during a fire but it will burn. Fire stop collars need to be fitted at every fire wall and floor penetration to prevent the spread of fire. They are readily available from reputable manufacturers and suppliers in sizes that suit HDPE.

Installation Below GroundPPI HDPE waste pipes with butt welded or electrofusion welded joints are very well suited to below ground applications.

A major benefit is that there are no weak points or connections as found with rubber ring joints or solvent glue used on other systems. Corrosion is also not an issue and HDPE is not subject to electrolytic action.

Butt welded or electrofusion welded joints are stronger than the pipe itself so there is no possiblity of infiltration by roots and there is no chance of leakage seeping into the surrounding soil or water table.

HDPE pipe and joints are flexible and very tolerant of ground movement. The chemical resistance properties also means that it is unaffected not only by the fluid inside but also by any aggressive soils on the outside.

The trench installation guide given below is satisfactory for the majority of installations.

• Provide a minimum of 100mm either side of the pipe

• The pipe bedding material needs to be a minimum of 100mm of sand to provide a continuous support along the entire length of the pipe.

• Side support between the trench wall and the pipe with hand compacted bedding material.

• The first 300mm of cover over the pipe should be of a material able to compact to as near as possible to the original ground conditions. The natural backfill may be used providing all rocks or other sharp objects have been removed. Do not use a machine compactor. Hand compact at 100mm intervals.

• Natural backfill can be used for the remainder of the trench. Machine compacting for this layer is permissible.

A more comprehensive guide is given in AS2033 "Installation Polyethylene Pipe Systems".

Topsoil Backfill

Compacted Pipe Overlay – 300mm

100mm min 100mm min

Compacted side support

Compacted Pipe Underlay – 100mm

Page 6

Welding Techniques

How HDPE is welded.Welding HDPE is very simple and is stronger than the pipe or fittings that are being joined.

The weld is achieved by heating the two surfaces to be joined until the material is "soft" and then bringing them into contact with each other and allowing them to cool.

The process is very clean and there is no naked flame, filler rods, flux or weld splatter associated with the traditional pipe welding techniques.

There are two welding processes;

• Butt Welding uses a heating plate to heat the ends of the pipe or fittings which are then brought together under pressure.

• Electrofusion Welding uses special socket fittings that are embedded with a heating element. The socket holds the pipe or fittings under pressure and the welding heat is generated by connecting a current that is timed and controlled by the Electrofusion Welder.

General Welding RulesThe following general rules should be followed for both butt welding and electrofusion welding.

• Maintain a clean and dry working area.

• Ensure that the pipes and fittings are clean and dry.

• Keep the welding plates clean.

• Check that the welding plates are set at a temperature of 210 ±5ºC.

• Ensure that all cuts are square.

• Remove the oxidised layer from all surfaces that form part of the weld.

• Follow the times and pressures outlined in the instructions supplied with the welders.

• Do not use water or compressed air to artifically cool the weld.

• Ensure that all electrical and site safety rules are followed.

Butt Welding EquipmentButt Welding can be performed by either Machine Butt Welding or Hand Butt Welding.

A Butt Welding Machine consists of a heating plate, a facing miller and set of clamps mounted on a spring loaded carriage. The pipe is held firmly during each operation which ensure the most accurate butt weld. It should be used wherever possible and is advisable for pipes greater than 75mm diameter.

Hand Butt Welding is performed on a heating plate which is mounted on a stand. There are no mechanical aides as the operator holds the pieces to be welded. It is the ideal method for confined areas.

Butt Welding ProcessThe butt welding process is simple but it is still advisable to undergo an approved training course and to follow the specific instructions supplied with each butt welding machine. A small investment in training or practice will;

• save time on-site

• ensure a better quality installation

• ensure that there are no problems to be called back to

• make your customer happy

The butt welding process is divided into several stages as shown in the diagrams and graph on the opposite page.

Preparation

It is important to remove the oxidised layer from ends of the pipe or fittings that are to be welded.

The machine butt welders have an electrical facing miller that also ensures the ends are square. A pipe cutter provides the neatest ends for hand butt welding but any method can be used provided the ends are left flat and clean.

Do not under any circumstances touch the ends after they have been cleaned as this may effect the weld quality.

Heating under Pressure

The first stage of heating is done under pressure and creates two separate rims or beads of molten plastic material. The pressure is usually referred to as the adaptation pressure. The size of the bead is a very good indication that the appropriate pressure and time has been applied.

Heating at Low Pressure

The pressure and time for the second stage of heating have been calculated to ensure that the ends are heated evenly and to the correct depth. Only a small amount of pressure is required to ensure that the ends maintain contact with the heating plate. The size of the bead should not change during this stage.

Heating Plate

Facing Miller

Clamps for Pipes or Fittings

Spring Loaded Carriage

Page 7

Welding Techniques

Machine Butt Welding Preparation

Butt Welding Process

Pres

sure

Time

5 6 7 8

Heat under Pressure(Adaptation Force)

Heat at Lower Pressure(Heating Force) Remove Heating Plate

Weld under Pressure(Welding Pressure)

Cooling(Do not cool artificially)

9

Warm up heating plate Shave under pressureRemove miller Keep ends clean

Do not touch

1 2 3 4P

ipe

Dia

met

er

(mm

)

Wal

l Th

ick

nes

s (m

m)

Ad

apta

tion

For

ce

(kg

f)

Hei

gh

t of

wel

d b

ead

af

ter

adat

atio

n t

ime

(m

m)

Hea

tin

g F

orce

(k

gf)

Hea

tin

g t

ime

(sec

)

Ch

ang

ing

tim

e (s

ec)

Tim

e to

rea

ch

Wel

din

g f

orce

(s

ec)

Coo

lin

g t

ime

(mm

)

40 3.0 4.1 0.5 0.1 45 5 5 4.1 6

50 3.0 6.4 0.5 0.2 45 5 5 6.4 6

56 3.0 7.5 0.5 0.2 45 5 5 7.5 6

63 3.0 9.8 0.5 0.3 45 5 5 9.8 6

75 3.0 9.8 0.5 0.3 45 5 5 9.8 6

90 3.5 14.0 0.5 1.0 45 5 5 14.0 6

110 4.3 21.0 0.5 1.0 43 5 5 21.0 6

160 6.2 44.0 1.0 3.0 61 6 6 44.0 9

200 6.2 56.0 1.0 4.0 61 6 6 56.0 9

250 7.8 89.0 1.5 6.0 78 6 6 89.0 11

315 9.8 141.0 1.5 9.0 98 7 7 141.0 13

Values of Force and Time for Butt Welding

Page 8

Welding Techniques

Remove Heating Plate:The time to remove the heating plate and bring the ends together needs to be kept to a minimum.

Weld Under Pressure & Cooling:The two ends are bought together and the welding force is gradually applied. The welding force is maintained for the times stated to ensure progrssive cooling of the weld. The weld should not be stressed in any way until this time has been reached and under no circumstances should the joint be artificially cooled with compressed air or water.

Machine Butt Welding InstructionsPre-welding CheckThe following simple precautions should be made before welding commences.

• Ensure that the site is suitable for welding.

• Ensure that the machine is placed on a stable surface located away from the wind.

• Make sure that the heating plate has reached the operating temperature before use.

• Be sure that the machine carriageway is free from any obstructions.

Making the Weld

• Select and fit the clamp inserts which match the size of the pipe or fittings.

• Check that the clamps and pipe supports are correctly aligned.

• Place the pipes in the machine clamps to protrude 30mm past the jaws.

• Use the PPI pipe stand to make sure that any lengths of pipe are supported securely.

• Place the miller between the two ends that are to be welded.

• Apply slight pressure to the milling disc and shave the surface until a constant running swarth strip of the full pipe wall thickness is produced.

• Remove the miller and slide the ends together and check the alignment. Adjust the clamps if necessary.

• Wipe machined surfaces with a clean, lint free cloth.

• Separate the two ends and place the heat plate between the two ends.

• Apply the adaptation and heating pressures.

• Release the pressure and remove the heating plate.

• Bring the molten pipe faces into contact with each other without any delay.

• Maintain the welding pressure for the time listed in the instructions.

• Leave the machine under tension by fixing the lever with the locking knob.

• Remember – Do not artifically cool the joint.

• Remove the joint from the machine.

Hand Butt WeldingHand butt welding is very similar to machine butt welding. The same principles apply with specific attention to the following.

• Be sure that the ends are flat and clean. Do not assume that the heating plate will compensate for any irregularities.

• Hold the pipes on either side of the plate so that they touch the heating plate evenly.

• Experience with Machine Butt Welding will give a "feel" for the forces to be applied.

• Judge the adaptation force by the size of the molten bead.

• Align the two ends evenly when applying the welding force. It is usually best to hold one piece firmly to prevent movement and then guide the other piece onto it.

• Remember – Do not touch the ends or articially cool the joint.

Page 9

30mm

Welding Techniques

Simple Weld TestsUse these simple weld test to prove that your weld samples are as strong as the pipe.

Proper care will avoid Weld Defects

Page 10

Crack

OverheatingLoading before cooling

Porosity

Poorly cleaned ends

Inclusions

Dusty and dirty environment

"Cold" Weld

Temperature too lowHeating time too shortHeating pressure too high

"Sinks"

Welding pressure too lowWelding time too low

Correct Excessive welding pressure Uneven heating Misalignment

Welding Techniques

Electrofusion WeldingPre-Electrofusion Check• Ensure that the worksite, pipe joint

and fusion machine are totally dry.

• Make certain that no other electrical appliances are being used in the immediate area. This especially applies to mobile phones and radios.

• The electrofusion welding machine must be used in conjunction with a safety voltage regulator when using a generator.

• Ensure all electrical safety procedures are followed.

• Ensure all site safety procedures are met.

Making the Electrofusion Weld• Cut the pipe ends square and remove

any burrs.

• Mark how far each pipe goes into the electrofusion coupling.

• Deoxidise any of the pipe surface that will be in contact with the electrofusion coupling. Use a scraper, emery paper or a light file.

• Deoxidise the inside of the fusion coupling with emery paper and clean.

• Insert the prepare pipes into the electrofusion coupling.

• Ensure that the pipes are pushed completely into the electrofusion coupling. Do not use the coupling to make up "length". The entire surface are is required to ensure a successful weld.

• Ensure that the joint is not under stress.

• Connect the electrofusion welder to the coupling.

• Initiate welding procedures as per manufacturers instructions as these vary depending on the size of the electrofusion coupling and the model of electrofusion welder.

• The welding cycle will be complete when the white external joint indicator on the electrofusion coupling turns black.

• Do not apply any stress to the joint until it has cooled. Allow 10 minutes for small fittings and up to one hour for large fittings.

• Do not cool the joint artifically.

• Do not perform another welding procedure on the same coupling. It is far safer to select another coupling if the welding process fails or is inhibited in some way.

Please Note:Any alterations to the power and fusion coupling cables are prohibited and all guarantee claims are void if the lead seals are removed.

Ritmo Electrofusion MachinesRitmo electrofusion machines are supplied in both automatic and manual models. Please read the instructions supplied with each machine and become familiar with the pertinent features prior to performing welds on an installation.

Page 11

Connecting to Other Systems

Connecting HDPE Waste Pipe to Earthenware Pipe

PPI HDPE Waste Pipe

PPI EarthenwareSocket Adaptor

Weld

EarthenwareRubber Ring

EarthenwarePipe or Socket

COMPATIBLE SIZES

HDPE EARTHENWARE

110 100

160 150

Connecting HDPE Waste Pipe to Copper or PVC Pipe

COMPATIBLE SIZES

HDPE COPPER / PVC

RING SEAL

PVC COPPER

50 40 U U

56 50 S U

75 65 U U

90 80 U U

110 100 S U

160 150 S N

PPI HDPE Waste Pipe

PPI Universal Ring Seal or Ring Seal for HDPE Pipe

PPI Ring Seal Adaptor

Copper or PVC Pipe

Weld

Connecting HDPE Waste Pipe to Cast-Iron Pipe

COMPATIBLE SIZES

HDPE CAST-IRON

110 100

160 150

PPI HDPE Waste Pipe

Cast-Iron Flange

Cast-Iron x HDPE/PVC Insert Rubber

Cast-Iron Pipe & Mechanical Socket

Page 12

U – Universal Ring Seal for PVC & Copper PipeS – Standard Rind Seal for HDPE PipeN – Not Available

Connecting to Other Systems

Cutting into an existing line is very easy with the HDPE Waste Pipe and Fittings system. The following example for Earthenware Pipe can be applied to any other pipeline.

• Dig a trench long enought to expose two collars and the pipe in between.

• "Smash" out one pipe being careful not to damage the ends of the remaining pipes.

• Insert the earthenware collar (one end only), the rubber rings and the earthenware socket adaptors.

• Measure the distance between the earthenware socket adaptors.

• Butt weld on earthernware socket adaptor to the junction.

• Butt weld the other earthenware socket adaptor to a length of pipe. Ensure that the pipe is slightly longer than necessary.

• Cut the pipe so that the total length from butt weld on the junction to the butt weld on the pipe is equal to the measurement taken previously.

• Mark the correct location of the electrofusion coupling on either side of the joint.

• Remove the centre stopper and slide the electrofusion coupling on either side of the joint.

• Fit both assemblies into the main line and slide the electrofusion coupling into position as indicated by the marks.

• Fuse together

This same process can also be used as a simple method to repair a break in an existing line of any material.

Cutting into an Existing Line with HDPE Waste Pipe

1. Butt Weld

2. Butt Weld3. Cut

Page 13

HDPE Waste Pipe and Fittings are very resilient but as with most systems, trouble free installations can be assured with just a little attention to the correct transportation, storage and handling techniques.

HandlingWhile handling the pipes or the fittings they must not be

• thrown

• scratched against hard surfaces

• dragged along the ground

as this may cause damage to surfaces which makes it difficult to fit together and increases the time required for cleaning.

TransportingWherever possible the pipe should be transported on a flat surface. Large bore pipe should be placed on the bottom of a stack. Small bore pipe can either be on top or inside larger pipe. Protection should be provided if chains are to be used to tie down the load. Always be aware of the transportation regulations especially in relation to lengths of pipes overhanding the vehile.

Storage and StackingPipes and Fittings must be placed on a flat surface to avoid deformities over a period of time. The maximum stack height for pipes must not be more than 2 metres whatever the diameter. Open storage must not be for long periods of time. It is recommended that pipe and fittings be placed under cover.

On-Site HandlingPipes stacked in small quanitites at work sites or along the route of work should be placed directly on a flat surface free of hard or sharp objects and where possible not exposed to direct sunlight.

Transport, Storage and Handling

Page 14

What is Polyethylene?

HistoryPolyethylene was first discovered at the ICI laboratories in the UK by E.W Fawcett and R.O.G Gibson, who found traces of polyethylene in the form of white powder obtained by polymerising ethylene at an extremely high temperature and pressure. In 1933, ICI were granted a patent and industrial production of Low Density Polyethylene commenced in 1938. This material was first used in the manufacture of household articles.

In the mid fifties, two new patents for polyethylene were registed by Professor Ziegler and the Phillips Petroleum Company. New industrial processes led to the manufacture of polyethylene with the same chemical composition but with a higher density using catalysts at low temperatures and pressures.

Over the years, further methods were introduced and imporvements made following reserch, experimentation and changing technical and commercial requirements. The result today is a highly reliable, long-lasting material which is so versatile that it can be used in a vast range of applications, such as fuel tanks, electric wire sheathing, gas pipelines, drainage and sewer systems, bottles, food containers and stretch film packing.

What is Polyethylene?Polyethylene is a thermoplastic resin obtained by polymerising ethylene (C2H4), an unsaturated hydrocarbon normally occurring as a gas.

The polymerisation process consists of linking ethylene molecules in long chains to give solid compounds called polymers.

The molecules forming polymers can be more or less ramified, close together or far apart and long or short.

These features determine the main properties of polyethylene, which are;

• Density (which depends on the distance between the molecules).

• Molecular weight (which depends on the length).

• Molecular weight distribution (which depends on the distance between and the length of the molecules).

Polyethylene is usually subdivided into three types:

• low density (915 – 925kg/m3)

• medium density (926 – 942kg/m3)

• high density (943 – 954kg/m3)

Low Density Polyethylene is characterised by a highly ramified structure, high density polyethylene is more linear, while medium density is somewhere in between.

Hydrogen

Carbon

Ethylene Molecule

Ethylene Gas

Polyethylene Polymer

Molecules – close together

Molecules – far apart

Page 15

What is Polyethylene?

The base resins also receive additive which further specify the final features of the materials and make it suitable for special applications and use in various manufacturing processes.

High density polyethylene with a very crystalline structure (only slightly ramified molecules very close together) is the type used for making drainage pipes and fittings.

It can safely be used in private and industrial buildings for discharging waste fluids not under pressure up to 95ºC from sanitary appliances, washing machines and dishwashers, large-scale kitchens and industrial plants and for draining aggressive fluids from chemical laboratories and technological processes (see table enclosed from compatibility with chemical agents.

The reasons for the rapid spread of this material for so many different applications are to be found in its properties, which are;

• high mechanical resistance

• flexibility

• shock resistance (even at low temperatures)

• resistance to corrosion

• easy laying

• high versatility

• high resistance to chemical agents

Compare to metal piping it is easier to connect, more flexible and more resistant to corrosion.

Compared to other plastics it has a wider temperature range –40ºC to +95ºC), greater flexibility and improved mechanical and shock resistance.

The only drawback is that it is not self-extinguishing which means that fireproof sleeving is required where subdivisions are required.

Polyethylene has a fairly low thermal conductivity (40 – 60 W/m K or 0.35 – 0.50 Kcal/h mºC) which protects it from sudden heat changes when drainage is discontinuous. It also has a linear expansion coefficient of:

λ = 0.2mm m-1 ºC-1

Polyethylene is an extremely long last-ing material with most pipe systems exhibiting a design life of greater than 50 years.

Fluid concentration cleassifications used in the chemical resistance charts are;

Sat. Sol. Saturated water solution prepared at 20ºC.

Sol. Diluted water solution, concentration over 10% unsaturated.

Dil. Sol. Diluted water solution, concentration less than 10% unsaturated.

W. Cone. Working concentration ie normal concentration industrial use.

Page 16

Chemical Resistance

Acetic Acid 10%Adipic Acid Sat. Sol.Allyalcohol 96%Alum. Sol.Aluminium Chloride Sat. Sol.Aluminium Fluoride Sat. Sol.Aluminium Sulphate Sat. Sol.Ammonia (gas) 100%Ammonia (liquid) 100%Ammonia (solution) Dil. Sol. Ammonium Chloride Sat. Sol.Ammonium Fluoride Sol.Ammonium Nitrate Sat. Sol.Ammonium Sulphate Sat. Sol.Ammonium Sulphide Sol.Antimonous (III) Chloride 90%Arsenci Acid Sat. SolBarium Carbonate Sat. Sol.Barium Chloride Sat. Sol.Barium Hydroxide Sat. Sol.Barium Sulphate Sat. Sol.Benzoic Acid Sat. Sol.BeerBorax Sat. Sol.Boric Acid Sat. Sol.Butane (gas) 100%Butanol 100%Calcium Carbonate Sat. Sol.Calcium Chlorate Sat. Sol.Calcium Chloride Sat. Sol.Calcium Hydroxide Sat. Sol.Calcium Hypochlorite Sol.Calcium Nitrate Sat. Sol.Calcium Sulphate Sat. Sol.Carbon Dioxide (dry) 100%Carbon Monoxide 100%ChlorineChloroacetic Acid (mono) Sol.Citric Acid Sat. Sol.Copper (II) Chloride Sat. Sol.Copper (II) Nitrate Sat. Sol.Copper (II) Sulphate Sat. Sol.Cycloexanol 100%Dextrin Sol.1.4 Dioxane 100%Fluosilicic Acid 40%Formaldehyde 40%Formic Acid 50%Formic Acid 90-100%Glucose Sat. Sol.Glycerine 100%

GlycolGlycol 100%Glycolic Acid Sol.Hydrobromic Acid 50%Hydrobromic Acid 100%Hydrocyanic Acid 100%Hydrochloric Acid 100%Hydrochloric Acid Conc.Hydrofluoric Acid 4%Hydroquinon Sat. Sol.Hydrogen 100%Hydrogen Peroxide 30%Hydrogen Sulphide 100%Iron (II) Chloride Sat. Sol.Iron (III) Chloride Sat. Sol.Iron (III) Nitrate Sol.Iron (II) Sulphate Sat. Sol.Lactic Acid 100%Magnesium Carbonate Sat. Sol.Magnesium Chloride Sat. Sol.Magnesium Hydroxide Sat. Sol.Magnesium Nitrate Sat. Sol.Maleic Acid Sat. Sol.MilkMolasses W. Conc.Mercury 100%Mercury (II) Cyanide Sat. Sol.Mercury (II) Chloride Sat. Sol.Mercury (I) Nitrate Sol.Methanol (see Methyl Alcohol)Methyl Alcohol 100%Nickel Chloride Sat. Sol.Nickel Nitrate Sat. Sol.Nickel Sulphate Sat. Sol.Nitric Acid 25%Oxalic Acid Sat. Sol.Phenol Sol.Phosphoric Acid (ortho) 50%Photographic Developers Work Conc.Potassium Bicarbonate Sat. Sol.Potassium Bichromate Sat. Sol.Potassium Bisulphate Sat. Sol.Potassium Bisulphite Sol.Potassium Bromate Sat. Sol.Potassium Bromide Sat. Sol.Potassium Carbonate Sat. Sol.Potassium Cyanide Sol.Potassium Chlorate Sat. Sol.Potassium Chromate Sat. Sol.Potassium Ferricyanide Sat. Sol.Potassium Ferrocyanide Sat. Sol.

Potassium Fluoride Sat. Sol.

Potassium Phosphate ortho)

Sat. Sol.

Potassium Hydroxide 10%

Potassium Hydroxide Sol.

Potassium Nitrate Sat. Sol.

Potassium Perchlorate Sat. Sol.

Potassium Permanganate 20%

Potassium Persulphate Sat. Sol.

Potassium Sulphate Sat. Sol.

Potassium Sulphide Sol.

Propionic Acid 50%

Salicylic Acid Sat. Sol.

Silver Acetate Sat. Sol.

Silver Cyanide Sat. Sol.

Silver Nitrite Sat. Sol.

Sodium Benzoate Sat. Sol.

Sodium Bicarbonate Sat. Sol.

Sodium Bisulphite Sol.

Sodium Bromide Sat. Sol.

Sodium Carbonate Sat. Sol.

Sodium Chlorate Sat. Sol.

Sodium Cyanide Sat. Sol.

Sodium Ferricyanide Sat. Sol.

Sodium Ferrocyanide Sat. Sol.

Sodium Fluoride Sat. Sol.

Sodium Phosphate (ortho) Sat. Sol.

Sodium Hydroxide 40%

Sodium Hydroxide Sol.

Sodium Hypochlorite 15% of Chlorine

Sodium Nitrate Sat. Sol.

Sodium Nitrite Sat. Sol.

Sodium Sulphate Sat. Sol.

Sodium Sulphide Sat. Sol.

Sulphur Dioxide (dry) 100%

Sulphurous Acid 30%

Sulphuric Acid 10%

Sulphuric Acid 50%

Tannic Acid Sol.

Tartaric Acid Sol.

Tin Chloride (II) Sat. Sol.

Tin Chloride (III) Sat. Sol.

Urea Sol.

Urine

Water

Wine & Spirits

Yeast Sol.

Zinc Carbonate Sat. Sol.

Zinc Chloride Sat. Sol.

Zinc Oxide Sat. Sol.

Zinc Sulphate Sat. Sol.

Table of fluids which can be conveyed through HDPE Waste Pipe & Fittings.No Internal Pressure, Temperature up to 60º and no Mechanical Stress.

The Chemical Resistance Charts are intended as a guide to the suitability of HDPE Waste Pipe and Fittings for various conditions. No guarantee can be given that the result will be correct in every case as it is diffult to define the actual operating conditions.

Page 17

Chemical Resistance

Acetaldeyde 100% Dioctyl-phthalate 100% Oleic Acid 100%

Acetic Dioxide 100% Ethanol (see ethylic alcohol) Oxygen 100%

Amylacetate (l-penthanol acetate) 100% Ethylic Alcohol (ethanol) 40% Phosphoric Acid (Ortho) 95%

Amyl Alcohol (l-penthanol) 100% Ethyl Acetate 100% Phosphorus Trichloride 100%

Aniline 100% Furfuryl Alcohol 100% Picric Acid Sat. Sol.

Benzaldehyde 100% Glacial Acetic Acid over 96% Potassium Hypochloride Sol.

Benzine (Aliphatic Hydrocarbons) 100% Heptane 100% Propionic Acid 100%

Butyric Acid 100% Hydrogen Peroxide 90% Pyridine 100%

Cyclohexane 100% Hydroflouric Acid 60% Sulphuric Acid 98%

Chromic Acid 20% Lead Acetate Sat. Sol. Triethanolamine Sol.

Chromic Acid 50% Mineral Oils

Decaline 100% Nicotinic Acid Dil. Sol.

Table of fluids which can be conveyed through HDPE Waste Pipe & Fittings.No Internal Pressure, Temperature up to 20ºC and No Mechanical Stress.

Aqua Regia HC1/HNO3=3/1 Chloroform 100% Nitric Acid 100%

Bromium (liquid) 100% Cresylic Acid (methyl-benzoic) Sat. Sol. Ozone 100%

Bromium (dry steam) 100% Fluorine 100% Sulphur Dioxide 100%

Carbon Sulphite 100% Fuming Sulphuric Acid (oleium) Thionyl Chloride 100%

Carbon Tetrachloride 100% Methylene Chloride 100% Toluene 100%

Chlorine (gas) Dry 100% Nitric Acid 50% Trichloroethylene 100%.

Chlorine Water Sat. Sol. Nitric Acid 75% Xylene 100%

Table of fluids unsuitable for conveyance in HDPE Waste Pipes or Fittings

Page 18

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