Effast Tech Manual

8/2/2019 Effast Tech Manual

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Effast PVCu and ABS

High performance PVCu and ABS Pressure Pipe Systems

DECEMBER 2008EFF-TM2-IND


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Eff ast fr om Polypipe is a well establ ished brand name

that is recognised throughout both t he industri al

process market and const ruction industr ies for i ts

market-leading range of thermoplasti c pipework

systems suit able for use wi th in i ndustrial app lications.The company now provides these components to

customers all over the world and leads the way in the

research and development of advanced new solut ions

that satisfy the specifi c needs of the market .

Polypipe, wit h it s large UK based manuf acturing

capabilities, has developed Effasts comprehensive

product port fol io such that it now o ff ers a proven and

effective solut ion t o virt ually any requirement. No

matt er what t he project, t he Eff ast range can off er the

perfect combination of pressure pipe fi t t ings, ball,

butterfl y, diaphragm and actuated valves, compression

joint s, adaptors and other fi t ti ngs.

Normally available in both metric and imperial

dimensions these products are suit ed t o many

dif ferent commercial appl icat ions in such areas as

food and beverage processing, chemical manuf acture,

water t reatment and agriculture.

Outstanding performance and reliability have come

to represent the hallmarks by which Polypipes Eff ast

products are recognised. With these products also

carrying BSI Kite Mark accredit ation and conforming

to various other European standards they can be

specifi ed w it h complete confi dence.

Dedicated t o support ing it s customers at every stage

the company also complements its products and

systems with a full technical information and support

service, while a nationw ide distri but ion net work

means that products are readily available, even when

needed next day.

For fu rther in fo rmation please see our contact

details on the back cover of this brochure.

Effast


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Contents

Effast

Introduction to plastics 4 - 6

Material selection 7 - 11

Pressure and temperature relationships 12 - 17

Select ion of pipeline systems 18 - 22

Pipeline system design 23 - 27

Sto rage, handling and installat ion 28 - 35

Methods of joint ing 36 - 40

Pipe and fi t t ings dimensions 41 - 43

Guide to chemical resistance 44 - 79

Dimensions, uni ts and conversion tables 80 - 81


4/844

Table 1.1 Monomers

Monomer name Formula Structure Polymer

Propylene C3

H6

Polypropylene

PP

Vinyl

C2H

3R

R can take manyforms (Including H,when it becomes

ethane).

Polyvinyl Chloride

PVC

Styrene C8H

8

PolystyrenePS

Introduction to plastics

1.1 Plastics: Polymers and mersPlasti cs are a group of engineering materials, belonging to

the larger family of polymers. Polymers are oft en

chain molecules and commonly t wo and t hree-dimensional

networks of repeating mer units, hence

poly-mers . The basic str ucture in p last ics is based on

carbon (C) and hydrogen (H); a range of other atoms

including chlorine (Cl), nitrogen (N), fl uorine (F) and

silicon (Si) may be present depending on the polymer.

The simplest C-H polymer is based on C2H

4(ethylene)

monomer f ormed int o chains of polyethylene (C2H2)n in

wh ich the monomers are linked end-on.

1.3 Macromolecule typesPolymer molecules are conventionally thought of as long

chains, but side br anches or cross-link ing between chains

can occur. The lat ter can pr oduce a 2-D or even a

3-D network, w ith propert ies such as Youngs modulus

increasing w ith the extent of the cross linking.

Putting this cross linking in place can be used to harden and

stiffen polymers; vulcanisation of rubber achieves this.

The structure of the molecular chains wil l determine how

closely they wi ll nest together and how crystalline

the result ing po lymer is.

1.4 Bond types and properties

Polymer molecules are held t ogether by t wo types of

bonds:-

Primary, covalent bonds between t he atoms in the chain

molecules. These are high strength bonds and can only be

broken irreversibly by hi gh t emperatures.

Secondary, hydrogen or van der Waals bonds, between

chain molecules. These bonds are easily broken down by

heating but r eform on cooling

1.2 Common monomers and polymers

Beyond the simplest common group above, there are a

number of others, some of which are easily recognisable by

name from t he polymers whi ch they make up.

Table 1.1 show s examples of monomers, their st ructu re,

and the result ing po lymer.

H C3H

3

C1

C2

H H

H H

C C

H Hn

H R

C C

H H

H H

C C

H H

H H

H HH

H CH2

C

Linear

Side-branched

Cross-linked


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1.4.1 Thermoplast ic plast icsThese consist of covalentl y bon ded chain mol ecules, perh aps

with some side chains, held in a solid by secondary bonds.

Heating sof tens and melt s th ese materi als, wh ich can be

remoulded and shaped; cooling allows them to hold a new

shape w hen t he secondary bonds refor m. Hence

thermoplastics can be recycled, although excessive heat will

break dow n the chains and change the material irr eversibly.

1.4.2 Thermosett ing plast ics

These mater ials consist of 2-D or 3-D net wo rks of heavily

cross linked chain molecules. The bonding is principally

prim ary covalent, so heati ng on ly serves to ult imat ely

dest roy t hem. Thermosets are not recyclable, so when

hardened, thermosets cannot be melted, deformed or fused.

Thermosets are usually reinforced w it h fi lling mater ials such

as glass fi bre, carbo n or t ext ile fi bres. Resins used in this case

include the following: -

Phenol ic resin (PF)

Polyester resin (UP)

Epoxy resin (EP)

1.4.3 ElastomersLike thermosets, these materials contain large amounts of

cross linking between chains. The progr essive st raigh tening

under t ension o f these long and convolut ed chains provides

the reversible elastic behaviour of these materials.

Elastomers resume their no rmal shape after being d istor ted

and also retain t heir elasticity at low t emperature.

Elastomers cannot be melted, f used or reshaped although

some thermoplastic elastomers have been developed.

Typical examples of elastomers are eth ylene propylene

rubber (EPDM), nit rile r ubber (NBR) and fl uorinerubber (FPM).

1.5 Structure of plastics PVCu,

ABS and PP

PVCu stands for unplasticised PVC. Polyvinyl chloride is

produced by polymerizati on of the monomer, vinyl chloride

as show n. PVCu is a hard plasti c that is made sof ter and more

fl exible by the addit ion o f p last icizers, the most w idely used

being pht halates.

ABS (acrylon it ril e but adiene styrene C8H

8C

4H

6C

3H

3N)

n

is a copolymer made by polymerizing styrene and

acrylonit rile in t he presence of polybutadiene.

The propor tions can vary from 15% t o 35% acrylonit rile,

5% t o 30% but adiene and 40% t o 60% styrene. The result is

a long chain of polybutadiene criss-crossed with shorter

chains of polystyrene-co-acrylonit rile. The nit rile groups from

neighbour ing chains, are polar and at tract each ot her

binding t he chains together w ith secondary bonds. Therefore

ABS is str onger than pu re pol ystyrene. The styrene group

gives the plastic a shiny, impervious surf ace wh ilst t he

butadiene, provides resilience even at low temperatures.

ABS can typicall y be u sed between -40 C and +60 C.

PP (polypropylene) is an addit ion polymer made fr om t hemonomer propylene, unusually resistant to many

chemical solvents, alkalis and acids and exhibit s a level o f

crystallinity intermediate between that of low density

polyethylene (LDPE) and high density po lyethylene (HDPE).

PPs Youngs modulus is also intermediate. Less tough than

LDPE, it is much less brittle than HDPE. This allows

polypropylene to be used as an alternat ive to engineering

plast ics, such as ABS. Polypropylene has very good resistance

to fatigue. The way in which the propylene group repeats

dow n t he chain det ermines crystallin it y and hence a lot of

properties of PP can be engineered at the polymerisation

stage, using pressure, temperature and type of catalyst to

cont rol t he structure as show n below.

Polyvinyl chloride

polymer

H H H H

C C C C

CI H CI H

Vinyl chlori de

monomer

H H

C C

CI H

CH2

N

Acrylonitrile

CH2

Styrene

CH2

H2C

1,3-butadiene

H H H H H H H H

C C C C C C C C

CH3

H CH3

H CH3

H CH3

H

CH3

H H H CH3

H H H

C C C C C C C C

H H CH3

H H H CH3

H


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Introduction to plastics

1.6 SynthesisOil, natural gas, coal and cellulose (vegetable in origin) are

the raw material sources from which plastics can be made.

When oil i s refi ned it is broken down by distil lation and

separated int o gr oups according t o evaporation rate. Gas

heads the group, f ollow ed by benzene, petroleum, gas oil and

fi nally t he bit umen residues. Benzene (used in t he producti on

of plastics) in its raw state is further subjected to the process

of heat cracking, which eff ectively breaks it down int o

ethylene, propylene, butylene and other hydrocarbons. These

are then modifi ed by using po lymerisation , polycondensation

or polyaddition processes to produce the required group o fplast ics.

1.6.1 Polymerisat ion

This is the most common of the processes used in plast ic

synthesis. In po lymerisation the basic molecules

(the monomers) are lined up to make macromolecular chains.

In t urn these macromolecular chains are aligned in their

entirety (no separation of by-product or other material) to

produce the plastic. Polyvinyl chloride (PVC), polypropylene

(PP) and polyethylene (PE), along wi th ot her p lasti cs are all

produced by pol ymerisation.

1.6.2 Polycondensat ionPolycondensat ion separates the by-products such as wat er or

acids fo rmed duri ng t he process whi le aligning both like and

unlike monomers, to produce macromolecular chains such as

polyamides and resins.

1.6.3 Polyaddit ion

Polyaddition is the creation of macromolecules from

molecules which are disimilar. During the process the

by-products are included and not subjected to separation.

Epoxide resins are produced in t his manner.

Table 1.2 Polymer groups

Plastics

Thermoplastics Thermosets Elastomers

AMORPHOUS(Random, unorganised molecular structure)

Vinylchlorides and Styroles

Polystyrene (PS)

Polycarbonate (PC)

Polyvinyl Chloride (PVC)

Acrylonitrile Butadiene Styrene (ABS)

SEMI-CRYSTALLINE(Partially ordered molecular structure)

Polyolefines

Polyethelene (PE)

Polypropylene (PP)

Polybutylene (PB)

RESINOUS POLYMER CHAINS(Hardener cross-linked on polymer chains)

Thermosets are usually reinforced by

using a filling material such as glass,

carbon or textile fibre producing:-

Glass-Fibre Plastic (GFK)

Carbon-Fibre Plastic (KFK) Carbon-Fibre Phenolic Resin (KF-PF)

Glass-Fibre Epoxy Resin (GF-EP)

ELASTIC PLASTICS(Synthetic and natural rubbers)

Natural Rubber (NR)

Latex

Synthetic Caoutchouc

Ethylene Propylene Rubber (EPDM)

Nitrile Rubber (NBR)

Chloroprene Rubber (CR)

Fluorine Rubber (FPM)

Silicone Rubber (SIR)

Thermally reversible They don't melt

Jointing by Chemical Welding Jointing by Fusion Welding Not suitable for jointing

Thermoelastomers

Thermoelastomers have similar properties to a thermoset, but

with almost the same hardness as the base thermoplastic.

i.e. Cross Linked Polyethelene (PEX).


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Material selection

2.0 Material selectionThere are a number of propert ies of engineering pl astics

which are key in making selection decisions. The range of

intrinsic physical properties largely depends on molecular

chain lengt h, molecular mass, crystallin ity, the proport ion of

primary bonds and the amount of cross linking .

The key properties and their relevance are detailed here:

2.1 General propert ies

Density (Mg/m3)

This represents the mass of a given volume, polymers havethe lowest density of all classes of engineering materials.

Energy content (MJ/kg)

The energy liberated during the combustion of the

substance.

Recycle fraction

Thermoplasti cs can be recycled, hi gher fr acti ons indicate

a more environmentally sensitive material. Thermosets

cannot be recycled, but may be dow n cycled by

incorporating t hem as a particulate fi ller in ot her

materials.

2.2 Mechanical propert ies

Youngs modulus or modulus of elasticity (GPa)

This modulus is a measure o f the materials resistance to

elastic defor mation . For t wo component s of the same

shape and size, a higher Youngs modulus will give a higher

sti ff ness of component .

Elastic limit (MPa)

Material can sustain certain stress due to axial loading

wit hout permanent def ormat ion. This is know n as Hookes

Law and is limited t o t he point know n as the Elasti c limit,

beyond which the material will not retain its original shape

if loading increased.

Tensile strength (MPa)

This is defi ned as the maximum load carried by the

component acting on the area of cross-section.

Poissons ratio

When a compo nent is placed in t ension, it s elast ic response

wil l be an increase in length , combined w ith a reduction in

cross sect ion (it gets longer and thinner). Poissons ratio is

a ratio of the narrowing (lateral) strain t o t he lengthening

(longit udinal) strain. As a number, typically around 0.4

fo r p last ics.

Hardness, VickersThis is the standard method for measuring the hardness of

materials; the surf ace is subjected to a standard pressure

fo r a standard lengt h of time by means of a pyramid

shaped diamond. Vickers Hardness is oft en g iven as a

hardness number rather t han a st ress.

Fracture toughness (MPa.m)

A measure of the ability of a material to withstand impact

and is not t he same as strength. A tough mat erial is the

opposite of a brittle one; an ideal material would be

strong and tough.

Ductility (%)The strain or proportional elongation at fracture. Higher

values imply a more ductile material. Ductilit y may be

quoted as a simple ratio e.g. 0.1 = 10%.

2.3 Thermal properties

Specific heat (J/kg.K)

A measure of the amount of energy required to raise the

temperature of a mass of material through a specifi ed

temperature. This propert y becomes import ant i n an

application w here sto rage or release of thermal energy is

an issue w ith higher values indicative of a material w hich

could store more heat.

Thermal expansion coefficient (mm/m.C)

This is the r ate of expansion o r contraction due t o a

change in t emperature and w hilst the un its of mm/m.C

seem quite small, this can lead to serious stresses in

materials which are constrained and experience

temperature changes. Where plastics are joined to other

materials of very different thermal expansion coeffi cients,

this difference can lead to stresses at the joint or

interface.

Thermal conductivity (W/m.K)Indication of the t ransfer of heat through the material.

Higher values indicate a material wh ich allows the

passage of heat more readily. Lower values imply a better

insulating material.

2.4 Elect rical propert ies

Dielectric constant

A dielectric material is a substance that is a poor

conductor of electr icity, but an effi cient support er of

electrostatic fi elds.

Resistivity (Ohms.m, in the range 1013 )The surface resistance of a plastic is, as the name

suggests, the resistance to t he fl ow of elect rical current

over i ts surf ace.


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Material selection

2.5 Selection of plastics for pipe systemsIn order to select the most suit able material f or a pipe system

the fol low ing f acto rs need to be addressed: -

The medium or fl uid conveyed and it s chemical composition

Operating pressure

Operating temperature

These factors are interlinked and only when all are addressed

can the correct materi al be selected. In addit ion t o t he above

it is necessary to be familiar with the characteristics of the

material f or t he pipe system.

Picture supplied courtesy of Sterling Hydrotec.

Table 2.1 Comparative properties of PVCu, ABS and PP

Property PVCu-Rigid ABS High Impact PP Homopolymer

General

Composition (CH2-CH-CI)

n(CH

2-CH-CH

2--CH-CN-C

6H

4)n

(CH2-CH-CH

3)n

Density (Mg/m) 1.35 to 1.55 1.03 to 1.07 0.90 to 0.92

Energy Content (Mj/kg) 85 to 106 85 to 120 90 to 110

Recycle Fraction 0.15 to 0.25 0.45 to 0.55 0.25 to 0.35

Mechanical

Young's Modulus of elasticity (GPa) 2.2 to 3.5 2.1 to 2.8 1 to 1.6

Elastic Limit (MPa) 35 to 52 40 to 45 28 to 33

Tensile Strength (MPa) 30 to 70 45 to 48 25 to 40

Compressive Strengh (MPa) 55 to 60 55 to 60 40 to 45

Ductility 0.1 to 3 0.06 to 0.07 1 to 2

Endurance Limit (MPa) 27 to 31.2 24 to 27 15.4 to 18.2

Fracture Toughness (MPa.m) 1 to 2 2.3 to 2.6 1.9 to 2.1

Hardness Vickers 10.6 to 15.6 5.6 to 12.2 9.3 to 11.2

Poisson's Ratio 0.38 to 0.43 0.38 to 0.42 0.4 to 0.45

Thermal

Normal Service Temperature (C) 0 to 60 -40 to 60 -10 to 110

Thermal Expansion (mm/m.C) 0.055 to 0.095 0.070 to 0.100 0.080 to 0.150

Specific Heat (J/kg.K) 1000 to 1100 1500 to 1510 1920 to 2100

Thermal Conductivity (W/m.K) 0.24 to 0.26 0.17 to 0.24 0.16 to 0.24

Electrical

Dielectric Constant 3.1 to 3.2 2.8 to 3.3 2.26 to 2.4

Resistivity (1013 ohm.m) 3.16 to 10 6.31 to 15.8 10 to 1000


9/849

Plastic pipe systems have certain advantages when compared with metal pipe systems and the following

illust rates some of these advantages: -

Lightweight

Easier t o handle. Density range 0.9 - 1.8 g/cm

Elastic properties

Good impact resistance. Good bend stress resistance.

Heat loss

Plasti cs provide good

insulation and are poor

heat conductors.

Chemical stability

Good chemical resistance to a broad range of

materials conveyed.

Low temperature operation

Plastic pipelines can accommodate

ice expansion and t haw w ith out

damage.

Corrosion resistance

Plastic does not corrode, whereas many metals combine with

oxygen and corrode or rust.

Thermal expansion

Plasti cs expand much more than steel, as th ey are more

affected by thermal change.

Electrical conductivity

Plasti cs do not conduct electr ical

charge and t here is no electrolytic

reaction as wit h metals.

Smoother surface finish

Plastic pipes unlike metal pipes are not prone to

encrustat ion of lime-scale, etc; and t herefore w ill have

smaller pressure losses.

Colours

Plastic can be made in many permanent colours aiding

colour-code identifi cation and eliminati ng t he need for

paint maintenance.

SLURRY

Abrasion resistance

Plasti c is more resistant than

steel due to i ts lower fr ictional

characteristics.


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Material selection

2.6 Effast pipe system plastic materials2.6.1 Polyvinyl chloride (PVC)

Polyvinyl chloride, an amorphous thermoplastic is suitable for

injection moulding and extruding (i.e.reshaped with heat),

making it ideal for t he manufacture of pipes, fi tt ings and

valves. It can be heat welded or solvent cemented (chemically

welded). It can also be recycled and reprocessed. PVC in it s

natural stat e is a strong semi ri gid mat erial and is denot ed in

it s abbreviat ed form as PVCu or PVCuH where t he u

ident ifi es th e product as unp lasti cized and H as high impact.

PVCu pipes and fi tt ings are widely used wi th in t he Pot able

and Wastew ater t reatments industr ies. During t hemanufacturing process certain additives may be used to

enhance it s processabili ty and perf ormance characterist ics: -

Stabilizers:

Normally calcium or ti n based, provide p rot ection against

the adverse effects of heat degradati on and ult raviolet

(UV) radiation. Polymers used by Effast meet the

requirements of the many international regulatory bodies

governing the food and potable water industries.

Pigments:

These are colou rs that may assist in use ident ifi cation and

ease of maintenance.

Lubricants:

Are used to aid extrusion and the release of moulded

products from mould cavities.

These additives typically make up less than 5% of the

fi nished PVC component s mass. PVC pipe and fi tt ings can be

used in appli cations that require: -

Environment al resistance to aggressively caust ic or

acidic media

Good abrasion resistance

Operat ing temperat ure range: 0C to +60C

Solvent welding

2.6.2 Acrylonit ril e bu tadiene styrene (ABS)

Acrylonit rile but adiene styrene, an amorphous thermoplastic

is suitable for injection moulding and extruding

(i.e. reshaped wit h heat), making it suitable for the

manuf acture o f pipes, fi tt ings and valves. It can be solvent

cement ed (chemically welded). It can also be recycled and

reprocessed. ABS comprises a styrene and acrylonitrile

copolymer li nked t o po lybutadiene. The constit uents can be

changed in proportion and engineered to provide particular

propert ies required f or di ff erent appl ications such as the

cont ainment and conveyance of pot able wat er, slurri es

and chemicals.

ABS, being non-toxic, complies wi th the toxicolog ical

requirements of the British Plastics Federation/British

Industrial Biological Research Association (BIBRA) Code of

Practice for fo od usage 45/5.

ABS can be used in appli cat ions that requ ire: -

Good chemical resistance

Good abrasion resistance

Good material strength and hi gh impact resistance

Operating temperature range: -

- 40C to +60C- Suitable for low temperature usage

Solvent welding

2.6.3 Polypropylene (PP)

Polypropylene, a semi-crystalline thermoplasti c is suit able

for injection moulding and extruding (i.e. reshaped with

heat), making it suitable for the manuf actu re of pi pes,

fi ttings and valves. It can also be recycled and reprocessed.

Polypropylene is produced by polymerising propylene along

wit h a catalyst and ot her addit ives. The material can be

produced in eit her homo-polymer form (PP-H) and bl ock orrandom copolymers (PP-B or PP-R). Polypropylene is

adversely affected by UV radiati on and pipelines that are

installed ou tside or in direct sunligh t should be prot ected by

insulatio n o r p rot ective coating. Polypropylene is suit able

for use with foodstuffs, potable and ultra pure waters, as

well as wit hin the pharmaceutical and chemical industr ies.

Polypropylene can be used in applications that require: -

Environmental resistance to most organic and

inorganic chemicals

Good material strength and fat igue resistance

Operati ng t emperat ure range -10C to +110C

Fusion welding


11/8411

2.7 Specific environmental factorsfor pipe systems

2.7.1 Flammabi lit y

Mat erial fl ammabilit y can be measured by the Limiting

Oxygen Index (LOI) as defi ned under BS 2782 method

141 or ASTM 2863. Materials are assessed and given an

index number that refl ects their combustion characteristics.

For example materials wit h an index: -

Under 21, will support combusti on in air at ambient room

temperat ure (+15C)

Above 21, will not sustain combustion

Above 25, will burn onl y when there are extreme heat

condit ions i.e. where there is direct high temperatu re heat

applied (blowtor ch, etc.)

Plasti cs have a wide range of LOI and t he fo llow ing t able

demonstrates the LOI fo r d iff erent p lasti cs and it s effects

regarding fl ammabilit y and toxicity: -

Table 2.2 Flamabil ity properties

Thermoplasticmaterial

LOI Flammability Fumes' toxicity

PVCu 46 - 49 Self Extinguishing High

ABS 18 - 20 Burns Low to medium

PP 16 - 18 Burns Low to medium

2.7.2 Ultra violet light (UV)

The majorit y of p lastics when exposed to ult ra violet light

(present in sunligh t) w ill suffer degradation or loss of

properties to varying degrees. All plastics should be

prot ected and th is can be achieved by eit her lagging the

pipe where exposed or by painting with a weatherproof

wat er based paint.

2.7.3 Hot climat esApplications in hot climates should ensure storage and

installation to allow for thermal expansion, deformation

and degradati on due to excessive UV radiation or thermal

exposure.

2.7.4 Disinf ectants

Disinf ectant s are ant i-microbial agents in eit her an alcohol

or aqueous based solut ion, w ith detergent s to help spread

the agents th rough their str ong capillary actio n. The various

compositions of disinfectant s wil l have widely diff ering

eff ects on pl asti cs. It i s str ong ly advised when using p last ics

fo r a pipe system, that confi rmati on of compati bilit y wit h

the material should be sought from the disinf ectant

manufacturer.

Instr uctions for solvent cementing j oint s must be fo llow ed

rigidl y to avoid t he capillary acti on of solut ions.

The following table summarises certain thermoplastics for

use in d isinf ectant operating environment s: -

= Yes = No

* PVCu systems rated at 10 bar or above can only be used in

th is applicatio n when operated at 6 bar.

2.7.5 Electrostat ic charge

Plasti c pipe systems are not suit able f or electr ically conductive

applications. The build up of electrostatic charge may result

in a potentially explosive condit ion and in or der to avoid

such a situation t he foll owing guidelines must be followed: -

Stop electrostatic charge accumulating: By wrapping a

metallic earthing t ape fi rmly around t he pipecircumference or along the length of the pipe system or

painti ng t he pipe w ith a metalli c based, solvent

free, electr ically conducti ve paint.

Disperse the electrical charge: By ionizing the atmosphere,

increasing humidit y to over 65% or using an ant istat ic

hydroscopic soap.

2.7.6 Compressed air

Plasti c pipelines fo r compressed air appli cat ions can be

subject to damage from t he presence of oil, addit ives and

related vapour s. These contaminates should be removedfrom t he system t hrough fi ltrati on and t raps to ensure clean

and dry air.

The following table summarises certain thermoplastics for

use in compressed air systems: -

Table 2.3 Disinfectant suitability

Thermoplastic materialMaximum operating

pressure (bar)Suitability for

disinfectant use

PVCu 6 *

ABS NA

PP NA

PE and PVDF 10

Table 2.4 Compressor suitability

Thermoplastic materialSuitability as

compressed airlineEffects from

compressor oil

PVCu Poor suitability* Can become brittle

ABS Suitable Limited resistance

PP Unsuitable Drastically shortened life

PE and PB Very suitable Good resistance

* PVCu should only be used where t he air pressure does

not exceed 3 bar or t he applicati on is an open ended

dispersion system.


12/8412

Pressure and temperature

The required duration of operation for a given w orking

pressure and t emperature must be taken in to account when

plann ing a plastic pipe system. Pressures that can be

sustained f or a short time at a certain t emperature may not

be sustainable at a higher w orking temperature; or even at

the same pressure and t emperature should the wor king

durat ion o f the system be extended. It is possible t o w ork

out the maximum permitted working pressures at different

temperatures and the associated safety factors wit h t he

use of regression graphs. Safet y facto rs are used t o ensure

that plastic pipeline systems can operate under stress for theirgiven lifet ime wit hout damage or failure and is described as

the ratio between the maximum allowable circumferential

stress which a system can absorb and its operating stress.

Where P Permissible operat ing pressure (bar)

C Safet y facto r (see table 3.1)

20 Propor tionality constant

Circumferential stress (MPa), taken from

regression charts (3.1, 3.2 and 3.3) at t he end o f

this chapter.

e Pipes wall thickness (mm) D Pipes outside diameter (mm)

Note that fi tt ings and other component s, wit h the same

pressure rat ing as the pipe, are normally t hicker w alled and

therefore the lowest common denominator of wall thickness

(e) shou ld be used.

Table 3.1 Safety factors for thermoplastics (C)

Thermoplastic material

PVCu metric PVCu imperial ABS metric ABS imperial PP-H metric

Safety factor* 2.5 2.1 2.1 2.1 2.1

3.0 Pressure and temperature relationshipThe follow ing fo rmula is used to calculate t he permissible

working pressure for a pipeline system: -

* Safet y factors are based on 50 year expected li fe at 20C, wi th water.

The higher t he wor king t emperature of a plastic pipe system, t he lower wil l be the wor king pr essure that can be sustained

within the system, please refer to tables 3.2 to 3.5

(PN10) for 3 mm wall thickness

and

(PN10) for 3 mm wall thickness

and

(PN16) for 4.7 mm wall thickness (PN16) for 4.7 mm wall thickness

Worked example 3.1

Calculate the maximum operating pressure for a pipe system

wi th t he foll owing specifi cation :-

Mat erial type: PVCu

Intended operating lif e: 20 years

Maximum operat ing temperat ure: 20 C

Pipe dimension s: 63 x 3 mm and 63 x 4.7 mm

Solu t ion

Factor of safety C= 2.5 (from table 3.1).

Wit h li fe span 20 years and t emperat ure t = 20 C fi nd = 27

(from chart 3.1).

The fo rmula f or det ermining the operating pressure is used:-

Worked example 3.2

Calculate the maximum operating pressure for a pipe system

wit h the foll owing specifi cation :-

Mat erial type: PVCu

Intended operating lif e: 20 years

Maximum operat ing temperat ure: 30 C

Pipe dimensions: 63 x 3 mm and 63 x 4.7 mm

Solu t ion

Factor of safety C= 2.5 (from table 3.1).

Wit h li fe span 20 years and t emperat ure t = 30 C fi nd = 22

(from chart 3.1).

The fo rmula f or det ermining the operating pressure is used: -


13/8413

Table 3.2 Temperature and pressure relationship for pipes, PVCu imperial

Class C Class D Class E

Temperature (C) bar psi bar psi bar psi

0 9.0 130 12.0 174 15.0 217

20 9.0 130 12.0 174 15.0 217

30 8.1 117 10.8 156 13.5 195

35 7.2 104 9.6 139 12.0 174

40 6.3 91 8.4 121 10.5 152

45 5.4 78 7.2 104 9.0 130

50 4.0 58 5.4 78 6.7 97

55 2.7 39 3.6 52 4.5 65

60 1.3 18 1.8 26 2.2 31

Table 3.4 Temperature and pressure relationship for pipes, ABS imperial

Class C Class D Class E

Temperature (C) bar psi bar psi bar psi

-40 9.0 130 12.0 174 15.0 217

-20 9.0 130 12.0 174 15.0 217

0 9.0 130 12.0 174 15.0 217

20 9.0 130 12.0 174 15.0 217

30 8.1 117 11.3 163 13.5 195

40 6.3 91 8.5 123 10.5 152

50 4.5 65 6.3 91 7.5 108

60 2.7 39 3.8 55 4.5 65

Table 3.3 Temperature and pressure relationship for pipes,PVCu metric

Pipe pressure rating (bar)

Temperature (C) PN10 PN16

0 10.0 16.0

20 10.0 16.0

30 8.0 12.8

35 7.1 11.8

40 6.4 10.2

45 5.1 8.2

50 4.4 7.0

55 3.3 5.2

60 2.6 4.1

Table 3.5 Temperature and pressure relationship for pipes,PP-H metric (PN10)

Pipe pressure rating (bar)

Temperature (C) 50 Years 25 Years 10 Years 1 Year

20 10.0 10.6 11.0 12.3

40 6.2 6.6 6.9 8.0

60 3.8 4.1 4.3 5.2

80 - 1.6 2.0 3.5

95 - - 0.9 2.3110 - - - 1.6


14/84


15/8415

Solu t ionFrom table 3.3 for PVC at 20C, the pressure rat ing is 10 bar.

From tab le 3.6 for PVC at 20C, the permissible circumferent ial

stress = 10 MPa.

Hence

Scan also be calculated by:

alternatively:

It is recommended t hat i f the allowable negat ive pressure

(Pe) is less than 1 bar then the pipeline system will not sustain

vacuum. (1 bar = 0.98 Atmospheres.) Different thermoplastics

have diff erent operat ing t emperatures under a vacuum and

maximum installation temperatures must be observed, as

shown in table 3.7: -

Worked example 3.4

A PVCu pipe (PN10) operates under t he fo llow ing condit ion: -

Pipe out side diamet er: 110mm

Intended service lif e: 10 years

Safet y facto r: 2

Modulus of Elasti city 2200 MPa

Poissons Rat io 0.4

Determine the collapsing p ressure and det ermine whether t he

vacuum pressure can or can no t be sustained,

for t wo cases: -

Pipe wal l th ickness: 5.3mm

Pipe wal l th ickness: 3.0mm

Solu t ion

The collapsing pressure i s given by: -

(a) For e = 5.3mm, the collapsing and the vacuum pressure are

calculated: -

Therefore t he pipe w ill sustain t his condit ion,

asPe is greater t han 1.

(b) For e = 3mm, the collapsing and the vacuum pressure

are calculated: -

This pressure i s low er t han 1 b ar; hence the pipe system can

not support this condition.

3.3 Maximum working conditions for

negative pressureThe design safety factor for negative

pressure is 2.

Pipeline systems operat ing below atmospher ic pressure

(1 bar) are subjected to vacuum or negative pressure

and wil l tend t o collapse radially inwards due to t he

greater outside pressure.

The collapsing pressure can be shown by the following

formula: -

Where Pc Collapsing pressure (bar)

20 Propor tionality constant

E Modulus of elast icity (MPa) (See table 2.1)

Poissons ratio (See table 2.1)

e Pipe w all t hickness (mm)

D Pipe out side di ameter (mm)

C Safet y factor = 2 (Design safety f acto r f or

negat ive pressure)

The maximum allowable negative pressure (Pe) is obtained

from the collapsing pressure (Pc) and safety

factor (C) with: -

Table 3.7 Maximum installation temperatures forvacuum conditions

Thermoplastic material Maximum temperature under vacuum (C)

PN10 PN16

PVCu 40 60

ABS 60 60PP 80 80

+ +


16/8416

Pressure and temperature

100

504030

20

10

Load duration (hours)

Circum

ferentialstress(MPa)

1

0.10.1 1

20C30C40C

50C60C

10 100 103 104

1 5 10 25 50

Years

105 106

Chart 3.1 Life regression for PVCu

100

504030

20

10


Circu

mferentialstress(MPa)

1

0.10.1 1

20C30C

40C50C

60C

10 100 103 104

1 5 10 25 50Years

105 106

Chart 3.2 Life regression for ABS


17/8417

100

504030

20

10


Circum

ferentialstress(MPa)

1

0.10.1 1

20C30C40C

50C60C

70C80C

95C120C

10 100 103 104

1 5 10 25 50

Years

105 106

Chart 3.3 Life regression for PP-H


18/8418

Selection of pipeline systems

4.0 Pipeline system selectionPipeline system selection is usually based on a number

of parameters: -

The eff ect of working condit ions such as pressure,

temperat ure and t he fl uid carried as described in

chapter 3.

Flow rate of the fl uid usually governs the pipe size.

The relationship between the pipe size and the pressure

rating is show n in t ables 4.1 to 4.4 for the dif ferent types

of thermoplast ics; t hese tables also include pr essure

rat ings for pi pe fi t ti ngs and valves.

Table 4.1 PVCu (imperial sizes) pressure ratings -fittings, valves and pipes

Product Size - inchesPressure rating at 20C

psi bar

Fittings

Solvent cement - 6 217 15

8,10 and 12 130 9

Threaded /8 - 4 145 10

Union - 2 174 12

3 - 4 145 10

Flange Blanks

1 - 2 232 16

2 - 4 145 10

5 - 6 87 6

Valves

Ball/8 - 2 232 16

2 - 4 145 10

3 Way ball - 2 145 10

Diaphragm - 2 145 10

Butterfly 3 - 5 145 10

6 87 6

Knife gate 1 - 4 36 2.5

Check/8 - 2 232 16

2 - 3 145 10

Wafer check2 - 6 145 10

8 87 6

Pipes

Class E - 6 217 15

Class D 1 - 6 174 12

Class C 2 - 12 130 9

Class TThreading andmachining only

/8 - 2 174 12

Table 4.2 PVCu (metric sizes) pressure ratings -fittings, valves and pipes

Product Size - mmPressure rating at 20C

bar psi

Fittings

Solvent cement16 - 160 16 232

200 - 315 10 145

Metric solvent xBSP adaptor

16 x /8" -110 - 4"

10 145

Valves

Ball16 - 63 16 232

75 - 110 10 145

Diaphragm 20 - 63 10 145

Butterfly 90 - 140 10 145

160 6 87

Check16 - 63 16 232

75 - 90 10 145

Pipes

PN rated 16 - 315 10 and 16 145 and 232

Table 4.3 PP-H (metric sizes) pressure ratings -fittings, valves and pipes

ProductSize - mm(inches)

Pressure rating at 20C

bar psi

Fittings

Socket fusion 16 - 110 10 145

Valves

Ball union end/socket fusion

20 - 63("- 2")

10 145

Ball union end/threaded BSP

(" - 2") 10145

Butterfly

90 - 140(3" - 5")

10 145

160 - 225(6" - 8")

6 87

Check20 - 63

(" - 2")10 145

Pipes

PN rated 16 - 110 10 145


19/8419

Table 4.4 ABS (imperial sizes) pressure ratings -fittings, valves and pipes

ProductSize - inches

(mm)

Pressure rating at 20C

psi bar

Fittings

Solvent cement

- 4 217 15

5 - 6 174 12

8 145 10

Threaded BSP /8 - 3 145 10

Union - 2 174 12

3 - 4 145 10

Flange Blanks

1 - 2 232 16

2 - 4 145 10

5 - 6 87 6

Valves

Ball

/8 - 2(16 - 63mm)

232 16

2 - 4(75 - 110mm)

145 10

Check

/8 - 2(16 - 63mm)

232 16

2 - 3(75 - 90mm)

145 10

Pipes

Class E /8 - 4 217 15

Class D 6 174 12

Class C 1 - 8 130 9

Class TThreading andmachining only

/8 - 2 174 12

4.1 Valve selection

Valve select ion is based upon a number of key paramet ers: -

The primary valve body material is selected along wit h

the material best suit ed fo r t he pipe system.

Thereafter valve selecti on will depend on the propert ies

of the conveyed medium and the valve characteristics

themselves, as show n i n t able 4.5.

The compati bilit y of the seal material to the conveyed

medium within the known operating parameters must

be confi rmed, which can be determined by reference

to the valve seal behaviour in table 4.6.

Addit ionally, valves have another import ant characteristic

known as torque rating which is very important in

actuated applications. Charts 4.1 to 4.6 show the

tor que-valve diameter rat ing f or t hree types of valves.

Table 4.5 Valve select ion

Valve features Ball valve Butterfly valve Diaphragm valve

Standard seal EPDM, FPM EPDM, FPM EPDM

Flow Full Restricted Restricted

Flow adjustmentLimited,not positive

Good,positive

Good,positive

Frictionalpressure loss

Low Medium High

Behaviourwater hammer

Fair Limited Limited

Table 4.6 Valve seal behaviour

Seal features Ball valve Butterfly valve Diaphragm valve

Liquid, particlefree

Good Good Good

Liquid,particulate orcrystal forming

Limited, needsregular cleaning

Good, but needsoccasionalcleaning

Good

Liquid, viscous Good Limited Limited

Gases Good Good Limited


20/8420


Chart 4.3 Torque for industrial ball valve PP

35

30

25

20

15

10

5

0

16 20 25 32 40Pipe diameter (mm)

Tor

que(Nm)

50 63 75 90

Chart 4.2 Torque for industrial ball valve PVCu and ABS

35

30

25

20

15

10

5

0

20 25 32 40 50

Pipe diameter (mm)

Torque(Nm)

63 75 90 110

Please note: Some 75mm ball valves are based on90mm bodies and thus have a higher tor ques rating.

Chart 4.1 Torque for economy ball valve PVCu

70

60

50

40

30

20

10

0

16 20 25 32 40

Pipe diameter (mm)

Torque(Nm)

50 63 75 90

110

Please note: Some 75mm ball valves are based on90mm bodies and thus have a higher tor ques rating.

Torque charts for ball valves


21/8421

Chart 4.5 Torque for butterfly valve PP

70

80

90

60

50

40

30

20

10

0

90 110Pipe diameter (mm)

T

orque(Nm)

140 160 225

Chart 4.4 Torque for butterfly valve PVCu

35

30

25

20

15

10

5

0

90 110Pipe diameter (mm)

Torque(Nm)

125 140 160

Torque charts for butterfl y valves


22/8422


Chart 4.6 Torque for diaphragm valve PVCu

12

10

8

6

4

2

0

20Pipe diameter (mm)

Torque(Nm)

25 32 40 50 63

Torque chart for diaphragm valves


23/8423

Pipeline system design

Worked example 5.1(a) What size of PVCu pipe should be used if the volumetric

fl ow rate is 10 l/s and t he fl ow velocity is rest ricted t o

3m/s?

(b) What is the ef fect of using a smaller or larger size pipe

to do t he job? Take pipes of external diameters and w all

thicknesses as: -

(i) D = 50mm and e = 1.8mm.

(ii) D = 75mm and e = 2.2mm respectively.

Solu t ion

(a) The pipe int ernal diameter f ormula is used:-

(b) In case the suppliers do not have the exact diameter

determined above (65mm), let us examine two opt ions: -

(i) When the fl ow area is decreased to 50mm

diameter, then the velocity wil l increase as

shown by the Continuity equation in terms

of velocity: -

This is clearly over t he recommended design limit

of 3m/s for fl ow velocity of liquids in thi s pipeline

system and is not advisable.

(ii) When t he fl ow area is increased to 75mm

diameter, then the velocity will decrease as shown

by the Continuity equation: -

This fl ow velocity is lower than the maximum

recommended value of 3m/s and is therefor e

acceptable. Remember t hat low er fl ow velocity

means propor t ionately low er pressure losses,

therefore, always go f or t he next size up if your

calculated size is not available.

5.2 Flow regimes in pipeline system

Flow regimes in a pipe were classifi ed by Osborne Reynolds

(in the early tw entiet h century) into t hree categories: -

Laminar: Where the fl ow behaves in an orderly mannerrunnin g in parallel stream lines.

Turbulent: Where the fl ow st reams are inter linked.

Transient: An intermediate condit ion where the fl ow

is neither Laminar nor Turbulent.

This chapter describes the design calculati ons for a plastic

pipeline system by using t he fo llow ing criteria: -

Pipeline diameter for a given fl uid fl ow rat e

Frictional and pressure losses of t he system

Pumping power requirement

Pressure transient s (i.e. wat er hammer)

The above parameters are shown and worked examples are

provided to demonstrate the calculation

procedure for each aspect.

5.1 Pipe diameter calculation

Pipeline sizing is a thr ee-way relati onship betw een the

int ernal pipe fl ow area (A in m), the fl ow velocity

(u in m/s) and the volumetr ic fl ow rate (Q in m/s) as

given by: -

Where t he cross-sect ion of the pipes int ernal fl ow

area (A) is

The above relationship can be expressed in terms of the

internal pipe diameter (din m): -

If t he fl ow rate is expressed in lit res per second (l/s), then the

pipe diameter (mm) relation can be simplifi ed t o: -

Note t hat t here are tw o f actor s wh ich infl uence the selecti on

of fl ow velocity: -

In order to avoid increasing pressure losses due to f ricti on,

if the pipe int ernal diameter is reduced the fl ow velocit y

should be proport ionately reduced.

Noise generat ion increases rapid ly wi th velocity,

especially fo r gas fl ow applications and t he follow ing

limit ing velociti es are accepted f or the general design

of pipeline systems: -

Table 5.1 Noise limiting flow velocities inplastic pipeline systems

Medium carried Maximum velocity (m/s)

Liquid under suction 1

Liquid under delivery 3

Gas 25

mmu

Qd 65

3

1053 . 86 53 . 86 = ==

m/sd 5. 1905 3.6

53 . 86

10

53 . 862 2

=

=u Q=

m/su Q=d

2. 5557 4.4

53 . 8610

53 . 862 2

=

=


24/8424

Reynolds ident ifi ed t hese categori es by calculat ing a

dimension less group of three fl ow paramet ers, later given

the name Reynolds number , which is defi ned by:-

Where Re Reynolds number

u Flow velocity (m/s)

d Pipe int ernal diameter (m)

v Kinematic viscosity (m/s), see table 5.2 below

The friction factor (f) can also be determined graphically

using t he Moody diagram (Chart 5.1) shown at the end of

this chapter.

DArcy presented the follow ing relationship t o determine t he

Head loss ( ) due to fr ictional resistance to the fl ow

in p ipelines: -

Where f Coeffi cient of fr iction

L Length of pipe (m)

g Acceleration due to gravity (9.81m/s)


d Pipe int ernal diameter (m)

Usually hydraul ic loss is evaluated in metres per 100m length

(i.e.L = 100) so the above formula can be simplifi ed to: -

5.4 Pressure losses due to obstructionsin pipeline systems

Obstruction losses are due t o t he presence of valves and fi tt ings

in p ipeline systems. These losses are grouped int o one lot

and the associated hydraulic loss ( ) is calculat ed as the

sum of all loss coeffi cients mul tiplied by the velocity head of the

approaching fl uid: -

Where g Acceleration due to gravity (9.81m/s)


ki

The sum o f k-values fo r fi tt ings and valves for

the pipe system, see tables 5.5 and 5.6

Reynolds concluded that if Re is less than 2000 the fl ow is

clearly laminar and w henRe is over 4000 the fl ow is clearly

turbulent. How ever when Re is between 2000 and 4000 the

fl ow is tr ansient and the fl ow prediction i s not reliable.

5.3 Pressure losses due to frictionin pipelines

The coeffi cient o f fr iction w hich is an indication of the

resistance the pipe surf ace off ers to the fl ow is dependent on

the value of the Reynolds number and t he roughness of the

pipe int ernal surface. Plasti cs have a unique advantage over

metal pi pes in t hat they are considered perfectly smooth

when new and do not suff er from t he build up of rust or

coagulation; thus their original internal dimension is

retained. The friction factor f or plastic pipes is given in table 5.4


Table 5.2 Kinematic viscosity of water

Temperature Kinematic viscosity (m/s x 10-6)

0 1.752

5 1.501

10 1.300

15 1.137

20 1.004

25 0.893

30 0.800

35 0.722

40 0.656

45 0.600

50 0.551

Table 5.3 Reynolds flow regimes

Regime Reynolds number (Re ) Characteristics

Laminar 4000 Very mixed flow

Table 5.4 Friction coefficients

Regime Reynolds number (Re) Coefficient of friction (f)

Laminar 4000 0.079Re -0.25

g

u

d

f LHf

2

42 =

f u 2

d

02 .4 Hf =

Hf

( )g

u

2

2

= HO ik

HO

Table 5.5 Obstruction loss coefficient for fittings

Obstruction k

Pipe entry 0.5

Pipe exit 1.0

90 elbow 0.40

45 elbow 0.30

90 bend 0.60

45 bend 0.40

Tee straight through 0.80

Tee branch 90 0.95

Sudden enlargement diameter ratio

1:2 0.15

1:3 0.19

1:4 0.241:5 0.30

Sudden contraction diameter ratio

5:1 0.40

4:1 0.37

3:1 0.33

2:1 0.30


25/8425

Table 5.6 Obstruction loss coefficient for valves

Valve 25% Open 50% Open 75% Open 100% Open

Ball 10.53 5.54 1.25 0.28

Diaphragm 1.94 1.59 1.39 1.25

Butterfly 3.74 0.42 0.14 0.10

Non-return 6.37 3.5 2.1 1.0

5.5 Pump rating

5.5.1 Hydraul ic losses in pipeline systems

The pum p in a fl uid pipeli ne system has to: -

Overcome frict ional losses,

Overcome obstruction losses due to valves and fi t t ings,

The total hydrauli c loss (metres) is therefo re given by

Transfer t he fl uid at the requir ed fl ow rat e betw een

tw o stations,

The stat ic-lift is the physical dif ference in elevation betw een

the t wo stat ions in metres.

5.5.2 Pressure losses in pipel ine systems

The relationship between head loss and pressure loss is

given by: -

Where P Pressure lo ss (N/m or Pa)

Densit y of fl uid (kg/m)

g Accelerati on due t o gr avity (9.81m/s)

5.5.3 Energ y loss in pipeli ne system

The af orement ioned hydrauli c losses in a pip eline system

are to be accommodated in t he design process and t hese

losses should be considered when selecting the correctpump size (duty).

The pumps rating (pow er requirement in Wat ts) is given by: -

Where

Q Volumetr ic fl ow rate

Hydraulic effi ciency of pump

(Refer to manufacturers data)

Htotal

Total eff ecti ve head Htotal

=Hstatic-lift

+ Hlosses

(Due to pipe-friction, fi ttings, plus stat ic-lift )

Worked example 5.2A PVCu pipeline system, pumping water, comprises the

foll owin g items: -

Pipe Length 200m

Outside diameter 110mm

Wall thickness 10mm

Fit t ings 2x 90bends k = 0.6

1x pipe ent ry k = 0.5

1x pipe exit k = 1.0

1x but terfl y valve (25% open) k = 3.74

(a) Determin e the t ot al hydraulic and pressure losses of th is

system when the fl ow rate of w ater is 30 l/s if t he

oper ati ng t emperatu re is 10C. (Take th e viscosit y of

wat er from t able 5.2)

(b) Determine t he pump pow er to deliver this fl ow r ate to a

point situated 20m above the source given the pumps

hydrauli c effi ciency is 80%.

Solu t ion

(a)

Total hydraulic losses

Total pressure losses

(b) Total eff ecti ve head

Pump power

Hence fl ow

is tur bulent.

Hlosses =Hf + Ho = 33 + 7.2= 40.2 m

P = g Hlosses = 103 9.81 40.2394 kPa=

Htotal

=Hstatic- lift

+ Hlosses20 + 40.2

60.2 m==

Q g Htotal /10

330 10 -3 9.81 60.2 / 0.822.1 kW

=

=

=


26/8426


5.6 Pressure transients in pipelinesystems (water hammer)

There are times when either by poor design or abrupt

changes in t he fl ow condit ion t he pipeli ne system

undergoes a pressure surge, th is phenomenon know n as

Water Hammer , may be initiated by any of t he follow ing

acti ons in th e pipeli ne system: -

Abru pt valve closure

Pump start up, shut dow n or an abrupt change in speed

Ent rapped gas in the liquid fl ow

There are four important parameters to be considered

at t he design stage so t hat t he effect of water h ammer

is minimised: -

1. The velocity of the pressure wave (m/s)

Where K Bulk modu lus of elast icity f or fl uid (Pa)

Fluid densit y (kg/m3)

E Modulus of elasticity of pipe material (Pa)

d Pipe inside di ameter (mm)

e Pipe wall thickness (mm)

2. Pressure fl uctu atio n consist s of bot h an upper and lower

pressure limit and th ese must be kept w ithin the p ipes

pressure characteri sti cs, such th at the upper limit is wit hin

the pipes maximum operating pressure and the lower

limi t is above the pipes collapsing pressure, in order t o

avoid permanent damage to the pipe system.

The pressure fl uctuation is given by

Where u is the velocity change (m/s).

The pressure fl uctuat ion r esult s in up per and l ow er limi t s of

oper at ion and is defi ned as:-

The maximum pressure:

The m inim um pressure:

3. The eff ecti ve safet y facto r f or f requent surges should be

lower than the materials safety factor.

4. Critical wave period (seconds) given by

WhereL is pipe length (m)

Actuated valves must have closure t imes greater t han

this wave period in order to minimise the eff ect of

water hammer.

Worked example 5.3A PVCu pipeline system, PN6 rated, 300m in lengt h, w ith an

out side diamet er of 50mm and a wall t hickness of

1.8mm wit h an operati onal pr essure of 4.4 bar, has an

actu ated valve wi th a closing t ime of 2 seconds.

Where PVCus Youn gs modu lus (E) is 2.6 GPa and it s

circumf erent ial stress is 29 MPa; and wat ers bulk modu lus

of elasti city (K) is 2.05 GPa and i ts density o f 1000 kg/m .

Determine the water hammer characteristics where the

fl ow rat e is 10m/h and 20m/h.

Solution

PropertyFlow rate (m/h)

10 20

1. Pressure wave velocity

310 m/s 310 m/s

2. Initial wave velocity

1.643 m/s 3.285 m/s

3. Pressure fluctuation

5.09 bar 10.18 bar

3.1 Maximum pressure

9.49 bar 14.58 bar

3.2 Minimum pressure

-0.69 bar -5.78 bar

4. Critical wave period

1.9 second 1.9 second

Collapsing pressure

-2.88 bar -2.88 bar

Maximum allowablenegative pressure

-1.44 bar -1.44 bar

Effective safety factor

2.37 1.54

Statement

Pmin

is within thePe parameter, hence thesystem will withstand thenegative pressure.

Pmax

is less than themaximum permissiblepressure of 15 bar.

Pmin

is outside thePe parameter, hence thepipe will collapse.

Pmax

is less than themaximum permissiblepressure of 15 bar.

u

Note: In cases of negative pressure Chas a value of 2

as in section 3.3. In t his example the water hammer

procedure was followed (4 steps) in addition Pc and Pe

were calculat ed as out lined in sect ion 3.3 and Cmax

as

outlined in section 5.6.

Where is circumferent ial stress (MPa)


27/8427

Reynolds number

Frictionfa

ctor

Relativeroughness

Laminar flow

0.008

0.01

0.00001

0.0001

0.0005

0.001

0.005

0.01

0.02

0.03

0.04

0.05

0.02

0.03

0.04

0.05

0.06

0.07

0.08

103 104 105 106 107 108

Turbulent flow

Transientzone

Chart 5.1 The Moody diagram


28/8428

Storage, handling and installation

6.0 IntroductionOne of th e key part s of a successfu l install ation comes fr om

th e way that plasti c pipes and component s are

stored and handled. This chapter deals with the installation

of plastic pipeline systems and describes the

methods for preserving stru ctur al int egrity and

compensating for thermal expansion.

6.1 Storage and handling

Pipe is often stor ed directly on the gr ound o r support ed in

racks or pallets and the f ollow ing condition s

should be observed: -

Ensure th at t he ground surf ace is level and cleared of

debris to prevent the pipes from becoming bent, scored

and damaged.

Pipes should never be stacked more t han 6 layers high

and in hot climat es th is shoul d be restr icted t o 4 layers.

Large bo re pipes shoul d not be stacked greater than

1 metre high, t hus avoiding ovality due to heat

and pressure.

Pipes of di ff erent diamet ers and wall t hickness shoul d be

stacked separately. If t his is not practical th e larger

diameter and t hicker walled pipes should be sto red at t he

bott om of t he stack.

Pipe racks shoul d be const ructed to pr ovide ful l support

to each pipe layer. Side supports should be at least

100mm wide and be placed at regu lar int ervals of

1.2 metr es along t he pipe length .

Narrow straps to suppo rt t he pipe stack should

be avoided.

Pipes can be stored in pal let ised stacks as lon g as the

pallets and not the pipes support the stack weight andpallet s shoul d be stacked no more than 3 pallet s high fo r

shor t periods only.

Pipes and fi tt ings sto red for an extend ed period of ti me

should be pr otected from direct sunlight t o avoid UV

degradation. Fittings should be stored using a method

that allows air circulat ion such as por ous hessian sacks,

boxes or on shelves.

The whole purpose of correct handling is to avoid damage

to pipes and should encompass loadin g, t ransit and

unloading of the pi pes. The fol lowi ng guid elines should b e

addressed w hen handling p ipes: -

Pipes shoul d be loaded and unloaded manually wi th out

draggi ng t hem over t he ground , as th is causes damage.

However if handling pallets of pipe by forklif t ensure that

th e for ks do not cause damage.

Flatbed vehicles shoul d be used to distr ibut e pipe loads

and th e largest di ameter pi pe shoul d be loaded fi rst w it h

the smaller pipe loaded on top or nested inside to avoid

damage. Do not drop pipes off the vehicle whenoff loading but handle and stack them correctly.

6.2 Installation of plastic pipes

Thermoplasti cs expand and contract t o a far g reater extent

th an metals and t he fo llow ing sketch provides a compari son

between some metals and plastics: -

There are tw o facto rs to consider w hen calculating

expansion o r cont raction i n pipes: -

Environmental temperature (external temperature) at

which the pip e will stabilise prior t o installation .

Fluid temperature (internal temperature) whi ch is the

operational t emperature of the p ipeline system.

The change in length due to thermal expansion or

cont raction i n a pipelin e system i s determined by the

following f ormula: -

Where L Expansion (Le) or contraction (Lc) in mm

T Difference in temperature betw een the

installation and the operating

temperatu res in C (=Toperate- Tinstall)

L Length of pipe when in stalled

Coef fi cient o f expansion

Figure 6.1 Comparison of thermal expansion of

plastics and metals

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Mild steel

Stainless steel

Copper

PVCu

ABS

Polypropylene

Polyethylene


29/8429

Solution

StepOperating temperature (oC)

30 8

Calculate temperature difference

T (=Toperate- Tinstall)= 30 - 10

= +20C

= 8 - 10

= -2C*

Calculate change in length due to expansionand contraction

L = T x L x( = 0.078 for PVCu)

= 20 x 30 x 0.078= 46.8mm

= -2 x 30 x 0.078= -4.68mm*

Select length of flexiblearm or compensator

Take the greater value (change inlength) regardless of whether it is dueto expansion or contraction that canaccommodate the maximum movement.

In this caseL= 46.8mm

For example PVCu will expand 0.078mm per metre for

every 1C raised in mid-wall temperatu re above t he installatio n

temperature.

Please note t hat t he temperatu re diff erence is the di ff erence

between the installation temperature and t he working temperature,

in deg rees Celsius (C).

Table 6.1 Coefficient of linear expansion for thermoplastics ()

Thermoplasticmaterial

Coefficient (10-5m/mC)

Length/temperatureequivalent (mm/mC)

PVCu 7.8 0.078

ABS 10.1 0.101

PP 15.0 0.150

PE 20.0 0.200

* Please note a (-) minus value repr esents th e dif ference in

temperature (it is not a subzero) and hence it causes a contraction

of t he length of t he pipe.

Worked example 6.1Find t he expansion and cont raction on a 4 diamet er PVCu

pipe system installed at 10C, where t he maximum and

minimum operat ing temperatu res are 30C and 8C

respectively and the overall length of the installation is 30m.

Table 6.2 Calculated expansion for 1 metre length pipe

Temperaturedifference (C)

Expansion (mm) CommentPVCu ABS PP

1 0.078 0.101 0.150

2 0.156 0.202 0.300

3 0.234 0.303 0.450 For the temperaturerange not on thechart add the factors

4 0.312 0.404 0.600

5 0.390 0.505 0.750

6 0.468 0.606 0.900

7 0.546 0.707 1.050 i.e.For PVCu @ 37C

8 0.624 0.808 1.200

9 0.702 0.909 1.350 20C = 1.560mm

10 0.780 1.010 1.500 +17C = 1.326mm

11 0.858 1.111 1.650

12 0.936 1.212 1.800 37C = 2.886mm13 1.014 1.313 1.950

14 1.092 1.414 2.100

15 1.170 1.515 2.250

16 1.248 1.616 2.400

17 1.326 1.717 2.550

18 1.404 1.818 2.700

19 1.482 1.919 2.850

20 1.560 2.020 3.000


30/8430


6.3 Flexible arms in pipelineinstallations

Flexible arms or expansion bellow s are used in order t o

avoid the associated stresses generated from a pipes change

in length due to expansion or contraction. Expansion

bellows are not a prime concern of this document and th e

installer is advised t o seek specialist gu idance fro m t he

manuf acturers of such pr oducts. The fl exibilit y of plasti cs

permits expansion or contraction to be compensated for by

means of eith er directional change wit hin a pi pe system

(single fl exible arm) or by t he installati on of expansion l oops

consisti ng o f tw o fl exible arms (double fl exible arm), asshow n in t he follow ing illustr ations: -

6.5 Pre-stressing flexible arms

Somet imes changes of l engt h (L) can on ly be channelled in

one di rection, p ossibly du e to a fl exible secti on h aving t o

operate in a confi ned space. When this occurs the fl exible

arm can be pre-str essed achieving t he followi ng:-

The fl exible arm can be reduced in lengt h

The fl exible arm will straight en under working condit ions

thus relieving a large amount of stress

The installation w ill look bett er when in service

6.4 How to find the flexible arm (a)length

To calculate the lengt h of a fl exible arm () the fol low ing

fo rmul ae can be used: -

Single arm:

Double arm:

Where a Flexible arm lengt h (mm)

D Pipe out side diamet er (mm)

L Expansion o r Cont raction (mm ) for single

arm, for double arm useL/2

Cm Constant fo r mat erial, see table 6.3Figure 6.2 Single arm

Figure 6.3 Double arm (expansion loop)

(Lc) (Le)

a

(Lc)(Le)

ab

Fixed point

Table 6.3 Thermoplastic materia l constant (Cm)

Thermoplastic material Constant

PVCu 33.5

ABS 32.7

PP 30.0

PE 26.0

Solution

Single arm Double arm

a = 970mm a = 686mm

Worked example 6.2

A 40mm ABS pip e (Cm = 32.7) has expanded in lengt h by

22mm, what is the lengt h required f or single and double

fl exible arm arrangement s?


31/8431

Worked example 6.3A 15 metre lengt h of 63mm PVCu pipe (= 0.078 for PVCu)

was install ed at 10C, if th e workin g t emperature is 50C

determine the layout of the non pre-stressed and

pre-stressed arm arrangements.

Solution

Non pre-stressed Pre-stressed

There will be an expansion of 47mm,therefore the flexible arm length will be 1823mm.

Half of the expansion (23.5mm) is now pre-stressed,therefore the flexible arm length will be 1289mm.

FixedPoint

15m

a = 1823mm

= 47mmL

FixedPoint

15m - 23.5mm

a = 1289mm

= 23.5mm2L

( )a 33.5= 1823mm=63 47


32/8432


Full suppo rt of t he pipeline can be achieved by

running along suitable channel and restr aining it

fro m lateral movement.

Pipelines wh ich are suspended have to be suppo rt ed by

brackets spaced at predet ermined int ervals (see tables

6.4, 6.5 and 6.6).

Limit ing Rings PVCu and ABS: These can be made by

cutting a small length (dissecting 1/3rd of the

circumf erence) of class C o r 10 bar pipe of th e same

outside diameter of the carrier pipe. The remaining

segment can be sprun g open and t hen solvent w elded

into place on t he carrier pipe.

Figure 6.4 Support s, brackets and limit ing rings

6.7 BracketsPipe brackets need to be made with the inside diameter of

the bracket marginally larger t han the pipe out er diameter.

This allows free lineal movement of the pipe and avoids

inhibit ing expansion o r contr act ion. They shoul d also be

smoot h, to avoid damage to t he outer surface of t he pipe.

There are tw o basic types of bracket s, as shown in fi gures

6.5 and 6.6, namely loose brackets and fi xed br acket s.

Tables 6.4 and 6.5 are based on class E pip e (15 bar) or the

PN16 metric rating. For pi pes of a lower rat ing t he spacing

wi ll be closer, derate as fo llow s: -

Class D (12 bar) and PN12 rat ed pipe x 0.75

Class C (9 bar) and PN10 rat ed pip e x 0.62

Figu re 6.5 Loose brackets - axial movement is

required without constraint

A loose bracket

allow s axial

movement.

A sliding bracket

allows movement

along a fl at

supporting surface.

Hanging bracket

allows radial and

axial movement.

Figu re 6.5 Fixed brackets - axial movement

constrained or cont rolled

A bracket oneither side

prevents axial

movement.

A bracket betweentwo pipe sockets or

limiting rings

prevents axial

movement.

A bracket t o controlpipe movement in

one direction .

6.6 Plastic pipe systems supportand bracketing

Plast ic pipe systems requir e regu lar support wh ich can vary

according to pipe material, size and wall dimension o f the

pipe, the weight (density) of the liquid carried and the

temperature of the pi pe wall. There are three t ypes of

mechanism which support or restrain pipe movement:

Restrained within a channel; supported with clips or

brackets at pr edeterm ined int ervals (see tables 6.4, 6.5,

and 6.6) and limiting rings to restrict axial movement.


33/8433

Table 6.4 Bracket spacing for gases and liquids PVCu PN 16 metric pipe and class E (15 bar) imperial pipe

Pipe size Bracket spacing in metres

mm inch 20C 30C 40C 50C 60C

16 3/8

0.80 0.70 0.50 * *

20 0.90 0.80 0.60 * *

25 1.00 0.90 0.70 0.55 0.40

32 1 1.10 0.95 0.75 0.60 0.45

40 1 1.20 1.10 0.90 0.70 0.55

50 1 1.30 1.20 1.00 0.80 0.60

63 2 1.40 1.30 1.10 0.90 0.65

75 2 1.50 1.40 1.20 1.00 0.7090 3 1.60 1.50 1.30 1.20 0.85

110 4 1.90 1.80 1.60 1.30 1.10

125 - 2.10 2.00 1.85 1.60 1.25

140 5 2.20 2.10 1.90 1.65 1.35

160 6 2.30 2.20 2.00 1.75 1.50

225 8 2.60 2.45 2.30 2.00 1.75

250 - 2.80 2.70 2.55 2.20 1.95

280 10 3.20 3.00 2.85 2.50 2.15

315 12 3.60 3.40 3.20 2.80 2.45

Table 6.5 Bracket spacing for gases and liquids - ABS class E pipe (15 bar)


inch 20C 30C 40C 50C 60C

3/8

0.80 0.75 0.65 0.60 0.50

0.90 0.80 0.75 0.65 0.55

1.00 0.95 0.85 0.75 0.70

1 1.10 1.00 0.95 0.80 0.75

1 1.20 1.10 1.00 0.90 0.80

1 1.25 1.20 1.10 0.95 0.85

2 1.40 1.30 1.20 1.00 0.90

2 1.50 1.35 1.25 1.15 1.00

3 1.60 1.45 1.35 1.20 1.05

4 1.80 1.65 1.55 1.35 1.20

5 2.00 1.80 1.70 1.50 1.30

6 2.10 1.90 1.80 1.60 1.40

8 2.30 2.10 1.90 1.70 1.50

* Implies full support requirement.


34/8434


Table 6.6 Bracket spacing for gases and liquids - polypropylene metric 10 bar rated pipe


mm 20C 40C 60C 80C 100C

16 0.74 0.68 0.63 0.54 0.39

20 0.79 0.69 0.64 0.59 0.44

25 0.84 0.82 0.74 0.69 0.49

32 0.99 0.94 0.84 0.74 0.54

40 1.05 1.03 0.94 0.84 0.59

50 1.20 1.14 1.04 0.89 0.69

63 1.38 1.29 1.18 1.04 0.79

75 1.53 1.43 1.28 1.13 0.8490 1.63 1.53 1.43 1.23 0.93

110 1.84 1.73 1.58 1.38 1.04

6.8 The Z dimension

The fo llowi ng steps should b e undertaken in p reparation f or

a pipeline installation: -

Prepar e a basic sket ch of t he pipel ine system,

including fi tt ings.

Ent er the dimensions of t he pipes and fi tt ings and the

cent re to cent re measurement of each secti on eit her by

measuring on site or from the engineers drawings.

Calculate the cut length of each piece of pipe betw een

fi tt ings to enable correct o verall assembled leng th of

section as follows: -

L = M - Z1

- Z2

Where L Cut length of pipe

M Centre to centre length betw een fi tt ings

Z1

- Z2

Linear Dimensions of fi tti ngs

As an example, the install atio n not es fo r a PVCu pip e wou ld

appear as fo llow s: -

M cent re to cent re = 1200mm

Less Z1

fl ange = 4mm

Less Z2

bend = 80mm

- 84mm

L cut lengt h pipe = 1116mm

L

M

Z2

Z1

Figure 6.7 - Z dimension


35/8435

Chart 6.1 Length of flexible arm: general guide for PVCu & ABS

3000

1000

Change in length (mm)

Lengthofflexiblesection

(mm)

1001 10

12"

100 300

315

10"

280

8"

25022

520

06"

160

5"

140

125

4"

110

3"

9021/2"

752"

6311/2"50

11/4"

401"

32

3/4"251/2"203/8"16


36/8436

Methods of jointing

7.0 IntroductionThis chapter deals wit h t he fou r key methods of jo ining

plastic pipes and t he selection of a joint ing m ethod is

dependent on t he pipe mat erial and it s characteristi cs.

Table 7.1 is a guide t o the selecti on of t he type of join t

which can be used fo r t he particular pipe material.

= Suit able = Not suitable

Table 7.1 Thermoplastic jointing methods

MethodPVCu

Thermoplastic material

ABS PP and PE

Solvent cement

Solvent cement is formulated to chemically solvate the surfaces of pipes and fittings, so that when they are pushed together the softened surfaces intermix and cure into a

hard, strong and leak-free joint.

Materials welded this way must be alike, i.e. PVCu to PVCu and ABS to ABS. Not PVCu to ABS or vice versa.

Mechanical

This method uses threads and flanges to connect the different parts of pipeline systems.

Fusion

Fusion jointing involves heating the two components to be joined, so that the fusion/melt temperature on each surface is reached simultaneously. The two melted surfaces

are then brought together at a pressure designed to produce a homogenous joint when cooled. The resulting joint will have an equivalent strength and pressure rating as the

original pipe. Contact Polypipe for further details.

Compression

Compression jointing consists of compressing a rubber ring between the inner wall of the fitting and the outer wall of the pipe to be jointed. Compression joints can be used

to connect different types of pipe, both plastic and metal. As long as the correct fitting is selected, taking into account the outside diameters of the different types of pipe

work, then a satisfactory joint can be made. Note: Compression joints are designed primarily for use on water pipelines.

Contact Polypipe for further details.


37/8437

Table 7.2 PVCu and ABS solvent jointing procedure

Procedure Equipment

Important information: Always use Personal Protective Equipment - gloves

and eye protection

Always carry out work in a well ventilated area

Always refer to Material Safety Data Sheets

Dispose of waste responsibly

Failure to follow the jointing procedure may invalidate

any warranties given

1. Cut the pipe at right angles to its axis

and to the required length.

Deburr the cut end of the pipe with a

sharp knife or scraper.

Pipe cutter

SawScraper or knife

2. Chamfer the leading edge of the pipe at

approximately 15 to 30. This will prevent the

solvent cement being wiped from both the pipe

and fitting when mated together and will also

help to build up a ring of solvent around the

chamfer, thus ensuring a proper seal.

Pipe Size

38 (16mm)

- 1 (20 - 50mm)

2 - 8 (63 - 225mm)

Chamfer Size (mm)

2

3 - 4

5 - 6

Chamfering tool

Fine disc angle

grinder, file or

abrasive paper

80 - 100 grit

3. Mark the pipe back from the chamfered

end to a length equal to the socket

depth plus 5mm.

This mark will act as a visual indicator

to show that the pipe is fully inserted

into the socket.

Marker pen

4. Roughen the pipe surface (up to the

indicator mark) and the inside of the

socket with abrasive cloth or paper.

Do not roughen the pipe and fitting to the

extent that the clearance between them

is noticeably increased.

Abrasive

paper/cloth

80 - 100 grit

5. Clean the inner surface of the socket and the

surface of the pipe up to the mark using a lint

free cloth or absorbent paper dampened with

Effast solvent cleaner.

Lint free cloth or

absorbent paper

Effast solvent cleaner


38/8438

Methods of jointing

Table 7.2 PVCu and ABS solvent jointing procedure - continued

Procedure Equipment

6. Select the correct solvent cement, PVCu to PVCu,

ABS to ABS. (failure to use the recommended solvent

cement may invalidate any warranties given)

Apply the cement straight from the tin and ensure all

relevant surfaces are covered.

Read the instructions on the tin.

Avoid using excessive amounts of

solvent cement.

Effast PVCu cement

Effast ABS cement

Brush (half the diameter

of the socket)

Joints are normally made in temperatures between 5 - 25C and in dry conditions, damp or wet conditions can adversely effect the solvent jointing procedure. The maximum

time before the cement is too dry for jointing is approximately 3 minutes. In hot weather this time is reduced. The joint must be made whilst the cement is still wet.

At temperatures below 5C the curing time will be considerably increased.

7. Push fittings/pipe together without twisting andensure that they are aligned and fully engaged (the

indicator mark should be in line with the edge of

the socket) then hold the assembly for a short time

as specified.

Pipe Size

38 - 2 (16mm - 63mm)

2 - 4 (75 - 119mm)

5 - 8 (140 - 225mm)

10 - 12 (250 - 315mm)

Holding Time

(minutes)

1

2

When the joint is made, an O-ring of cement is formed between the pipe chamfer and the internal socket wall. This ring helps to ensure seal integrity. A bead of cement will

show around the external junction of the pipe and fitting, this should be wiped off leaving the outer part of the joint clean. Do not disturb for at least 10 - 15 minutes to

ensure that the weld integrity is maintained. After this period, the assembly can be carefully handled, prepared for further jointing or left for the recommended curing

time which is:

Up to 8 (225mm) ambient temperature constantly above 5C After 8 hours The joint will have cured enough to withstand the working pressure.

After 24 hours The pipe system can be fully pressure tested.

The number of operators:

For joints of up to 2 (75mm) 1 person is required, from 3 (90mm) up to 6 (160mm) 2 persons are needed, for 8 (225mm) and above 3 people are required.Pipe work should be ventilated during the joining and curing processes. Never seal a pipe system which has been newly jointed as the trapped vapours can cause damage.

Positive ventilation with a small air blower is recommended to purge systems with multiple joints.

Table 7.3 Recommended joints per litre of Effast cement

Pipe size Thermoplastic material

inch mm PVCu ABS

3/8

- 1 16 - 32 300 400

1 - 2 40 - 63 120 175

2 - 3 75 - 90 50 70

4 110 30 45

5 140 20 30

6 160 15 25

8 200 - 225 8 15

10 250 - 280 3 4

12 315 3 4


39/8439

7.1 Important point s Heavy equipment should be support ed independently

fr om t he pi peline. i.e. valves, str ainers, etc.

Pipe clips shoul d be made to allow linear expansion of

the pipeline and if l ined the lining should be of a

material compatible w ith t he pipeline.

Mast ics, int umescent mastics, adhesive tapes and labels

should not be used (as many degrade plastics), unless

manuf acturers provide document s of adhesive or

mastic compatibility.

Insulat ion must be considered very careful ly, as a numberof foam rubber in sulation products and t heir adhesives

may not be compatible with plastic pipes.

Adhesives should on ly be used to bon d t he foam edges

tog ether and should never be used to bond t he

insulation to the pip eline. Refer t o manuf actur ers for

compatibility data. For example, compatible insulations

are fi bre wools (Rockwool), polystyrene, etc.

Trace heating tapes: Dont u se tapes covered wit h

plasticized PVC as this can react with thermoplastic pipes.

Tapes wi th sheaths made from w oven wi re, polyester or

silicone r ubber are acceptabl e.

Oils: A number of synthetic oils are not suit able for use

with plastic pipelines. Oils such as esters, organic

phosphates and polyalkylene g lycols should be avoided.

Health and safet y: Solvent cement and cleaning fl uid

give off vapours that are dangerous to health. During

jointing the w ork place must b e well ventilated.

7.2 Solvent joint ing , " Do Nots"

Make joint s in rain or wet condit ions.

Use dirt y brushes or cleaning rags.

Use the same brushes wi th dif f erent solvent cement s.

Dilut e or thin solvent cements wi th cleaner.

Leave solvent cement t ins open as th e cont ents wi ll

evaporate and the cement performance will be reduced.

Use near naked ligh ts or smoke whi lst join ti ng as solvents

are high ly fl ammable.

Make join ts in a confi ned space as solvents emit

hazardous vapours.

7.3 Mechanical jointing procedure - threadedfi t t ings - plast ic to plast ic

An extensive range of th readed fi tt ings are available, mostl y

parallel threaded but some t apered. Thread compatibi lity is

an essenti al aspect of join ti ng. For jo int ing such part s fo llow

these steps: -

1. Select compatib le thread i.e. Parallel t o Parallel, never

Parallel t o t aper or vice versa.

2. Use PTFE tape to seal t he jo in t . If sealant pastes are used

they must be compatible with the plastic components.

3. Hand tight en and if n ecessary tighten f urt her to a

maximum of turn using a str ap wr ench.

PVCu class 7 and ABS class T pipes, sizes 38 up to 2 are

manufactur ed wit h a thick wall t o enable threads to be cut.

7.3.1 Flanges - plastic to p last ic/metal

Flanges are suit able for j oini ng metals or rubbers to p lasti cs.

Joint ing such part s fo llow th ese steps: -

1. Ensure fl anges are paral lel, close to each other and al low

a gap for the gasket.

2. Insert gasket, ensure th at t he bolt h oles are align ed.

3. Use fl at w ashers betw een bolt h ead, the nut and

the fl ange.

4. Tight en bolt s accord ing t o t he sequence fi gure 7.3

and table 7.4.

Rubber Gasket

Flange

Plastic Female Adaptor

Metal Union Nut

Gasket

Metal Adaptor

Figure 7.1 Flange joint

7.3.2 Composit e unions - metal t o pl ast ics union j oin t

Figu re 7.2 Composit e

NOTE: If metal th read

is used in conjunction

wit h a plastic thr ead

then the temperature

should not vary by

more than 5C.


40/8440

Methods of jointing

1

2

34

5

6 7

8

Table 7.4 Flange bolting torques (approximate)

Pipe sizeInch 1 1 1 2 2 3 4 - 5 6 - 8 10 12

mm 20 25 32 40 50 63 75 90 110 125 140 160 200 225 280 315

TorqueNM 8 9 10 18 24 32 36 40 44 48 50 62 74 76 76 76

Ft/Pdl 6 7 8 13 18 23 26 29 32 35 37 46 54 56 56 56

Figure 7.3 - Flange bo lt t igh tening sequence


41/8441

Pipe and fi ttings dimensions

DIN 8077/8078 PP-H (metric) pipe dimensions

Diameter (mm) Wall thickness (mm)

Outside diameter Mean outside diameter 6 bar 10 bar

Minimum Maximum Min Max Min Max

16 16 16.3 - - 2.0 2.4

20 20 20.3 1.8 2.2 2.5 3.0

25 25 25.3 1.8 2.2 2.7 3.2

32 32 32.3 2.0 2.4 3.0 3.5

40 40 40.4 2.3 2.8 3.7 4.3

50 50 50.5 2.9 3.4 4.6 5.3

63 63 63.6 3.6 4.2 5.8 6.6

75 75 75.7 4.3 5.0 6.9 7.8

90 90 90.9 5.1 5.9 8.2 9.3

110 110 111.0 6.3 7.2 10.0 11.2

EN1452 part 2 PVCu (metric) pipe dimensions

Outside diameter (mm)Average wall thickness (mm)

6 bar 10 bar 16 bar

16 - - -

20 - - 1.5

25 - - 1.9

32 - 1.6 2.4

40 1.5 1.9 3.0

50 1.6 2.4 3.7

63 2.0 3.0 4.7

75 2.3 3.6 5.6

90 2.8 4.3 6.7

110 3.2 4.2 6.6

125 3.7 4.8 7.4

140 4.1 5.4 8.3

160 4.7 6.2 9.5

180 5.3 6.9 10.7

200 5.9 7.7 11.9

225 6.6 8.6 13.4

250 7.3 8.6 14.8

280 8.2 10.7 16.6

315 9.2 12.1 18.7

Safet y facto r c = 2.5

Safet y facto r c = 2


42/8442

Pipe and fi ttings dimensions

DIN 8061 PVCu (metric) pipe dimensions DIN 8063 PVCu (metric) fitting dimensions

Diameter (mm) Average wall thickness (mm) Diameter (mm)

Outsidediameter

Mean outside diameter6 bar 10 bar 16 bar Nominal size

Mean socket internal diameterat midpoint of socket depth

Minimum Maximum Minimum Maximum

16 16 16.2 - - 1.2 16 16.1 16.3

20 20 20.2 - - 1.5 20 20.1 20.3

25 25 25.2 - 1.5 1.9 25 25.1 25.3

32 32 32.2 - 1.8 2.4 30 32.1 32.3

40 40 40.2 1.8 1.9 3.0 40 40.1 40.3

50 50 50.2 1.8 2.4 3.7 50 50.1 50.3

63 63 63.2 1.9 3.0 4.7 63 63.1 63.3

75 75 75.3 2.2 3.6 5.6 75 75.1 75.3

90 90 90.3 2.7 4.3 6.7 90 90.1 90.3

110 110 110.3 3.2 5.3 8.2 110 110.1 110.4

125 125 125.3 3.7 6.0 9.3 125 125.1 125.4

140 140 140.4 4.1 6.7 10.4 140 140.2 140.5

160 160 160.4 4.7 7.7 11.9 160 160.2 160.5

180 180 180.4 5.3 8.6 13.4 180 180.3 180.6

200 200 200.4 5.9 9.6 14.9 200 200.3 200.8

225 225 225.5 6.6 10.8 16.7 225 - -

250 250 250.5 7.3 11.9 18.6 250 - -

280 280 280.6 8.2 13.4 20.8 280 - -

315 315 315.6 9.2 15.0 23.4 315 - -

BS 3505 PVCu (imperial) pip

Effast Tech Manual

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