ATV-DVWK-M_275E-Pipelines for the Area or Technical Installation of Wastewater Treatment Plants

8/10/2019 ATV-DVWK-M_275E-Pipelines for the Area or Technical Installation of Wastewater Treatment Plants

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GERMANATV-DVWK RULES AND STANDARDS

ADVISORY LEAFLET

ATV-DVWK-M 275E

Pipelines for the Field

of the Technical Equipping

of Wastewater Treatment Plants

May 2001


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ADVISORY LEAFLETATV-DVWK-M 275E

Pipelines for the Fieldof the Technical Equipping

of Wastewater Treatment Plants

May 2001ISBN 978-3-937758-73-2

GERMANATV-DVWK RULES AND STANDARDS

Publisher/Marketing:

Deutsche Vereinigung fr Wasserwirtschaft, Abwasser und Abfall e.V.

German Association for Water, Wastewater and Waste

Theodor-Heuss-Allee 17 53773 Hennef Germany

Tel.: +49 2242 872-333 Fax: +49 2242 872-100

E-Mail: [email protected] Internet: www.dwa.de


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The German Association for Water, Wastewater and Waste, DWA (former ATV-DVWK), is the spokesman

in Germany for all universal questions on water and is involved intensely with the development of reliable

and sustainable water management. As politically and economically independent organisation it operates

specifically in the areas of water management, wastewater, waste and soil protection.

In Europe the DWA is the association in this field with the greatest number of members and, due to its spe-

cialist competence it holds a special position with regard to standardisation, professional training and infor-

mation of the public. The ca. 14,000 members represent the experts and executive personnel from munici-

palities, universities, engineer offices, authorities and businesses.

The emphasis of its activities is on the elaboration and updating of a common set of technical rules andstandards and with collaboration with the creation of technical standard specifications at the national and

international levels. To this belong not only the technical-scientific subjects but also economical and legal

demands of environmental protection and protection of bodies of waters.

Imprint

Publisher and marketing:

DWA German Association for

Water, Wastewater and Waste

Theodor-Heuss-Allee 17

D-53773 Hennef, Germany

Tel.:

Fax:

E-Mail:

Internet:

+49 2242 872-333

+49 2242 872-100

[email protected]

www.dwa.de

Translation:

Richard Brown, Wachtberg

Printing (English version):

DWA

ISBN-13:978-3-937758-73-2

The translation was sponsored by the

German Federal Environmental Foundation (DBU)

Printed on 100 % Recycling paper.

DWA Deutsche Vereinigung fr Wasserwirtschaft, Abwasser und Abfall e.V., Hennef 2006

(DWA German Association of Water, Wastewater and Waste)

All rights, in particular those of translation into other languages, are reserved. No part of this Advisory Leaflet may be reproduced in

any form byphotocopy, microfilm or any other process or transferred into a language usable in machines, in particular data proc-ssing machines, without the written approval of the publisher.


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Foreword

Pipelines form a crucial point in the technical equipment of wastewater treatment plants. They serve for theconveyance of the media which is to be treated and utilised (liquids with and without solid matter component,gases). Pipelines are to be found in all areas of the technical equipment of wastewater treatment plants.

Pipelines can be subjected to widely differing stresses (static and dynamic), corrosion (caused by the me-dium and/or the environment), abrasion, erosion, temperature (heat, cold) etc. The selection of the pipematerial and the dimensioning of the pipelines with regard to diameter and wall thickness demand a highdegree of specialist knowledge above all with regard to the type of stress, the material characteristic values,the possibilities for processing and not the least the comprehensive standard specifications and regulationsassociated with this field.

With this Advisory Leaflet planners, those inviting tenders and those responsible for decisions are to beprovided with assistance in achieving professional and economic solutions.

In many cases proven solutions can be recommended, in other cases reference has to be made to techni-cal documents and regulations in order to develop proper standards for invitation to tender and for the im-

plementation in terotechnology.

Authors

This Advisory Leaflet has been elaborated by the ATV-DVWK Working Group KA-11.2 Mechanical engi-neering within the ATV-DVWK Specialist Committee KA-11 Technical equipping and construction ofwastewater treatment plants.

Members of the Working Group are:

Dipl.-Ing. John Becker, Worpswede

Dipl.-Ing. Wolf-Dieter Blackert, TaunussteinDr.-Ing. Rdiger Hohmann, Essen (Chairman)

Dipl.-Ing. Erwin Klauwer, Essen (Chairman up to 9/2000)

Dr.-Ing. Hans-Herrmann Niehoff, Gladbeck

Dipl.-Ing. Joachim Maow, Rohrbach

Dipl.-Ing. Christian Schnatmann, Essen


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Contents

Foreword.................................................................................................................................................. 3

Authors .................................................................................................................................................. 3

User Notes ............................................................................................................................................... 6

1 Area of Application ................................................................................................................ 6

2 Abbreviations Used................................................................................................................ 6

3 Stressing of the Pipelines by the Media .............................................................................. 7

4 Selection of Material .............................................................................................................. 8

4.1 Pipelines Made from Mild or Low Carbon Steel....................................................................... 8

4.1.1 General..................................................................................................................................... 8

4.1.2 Processing of Pipelines Made from Mild or Low Carbon Steel................................................ 8

4.2 Pipelines Made from Stainless Steel........................................................................................ 9

4.2.1 General..................................................................................................................................... 9

4.2.2 Corrosion Resistance of Pipelines Made from Stainless Steel................................................ 9

4.2.3 Processing of Pipelines Made from Stainless Steel................................................................. 10

4.3 Pipelines Made from Non-ferrous Metals................................................................................. 10

4.4 Pipelines Made from Plastic..................................................................................................... 11

4.4.1 General..................................................................................................................................... 11

4.4.2 Processing of Pipelines Made from Plastic.............................................................................. 12

5 Dimensioning of Pipelines .................................................................................................... 12

5.1 Flow Rates and Minimum Nominal Diameters......................................................................... 13

5.2 Pressure Losses with the Transport of Viscous Liquids .......................................................... 13

5.3 Selection of Pipelines............................................................................................................... 14

5.3.1 Pipelines Made from Steel and Stainless Steel ....................................................................... 14

5.3.2 Pipelines Made from Plastic..................................................................................................... 14

6 Laying of Pipelines ................................................................................................................. 15

6.1 Expansion and Settling Compensation .................................................................................... 15

6.2 Connection of Pipelines............................................................................................................ 16

6.2.1 Permanent Connections of Pipelines made from Metallic Materials........................................ 16

6.2.1.1 Welding and Brazing ................................................................................................................ 16

6.2.1.2 Press Fittings............................................................................................................................ 17

6.2.2 Permanent Connections Plastic ............................................................................................... 17

6.2.2 Separable Connections............................................................................................................ 17

6.2.3.1 Flange Connections for Steel Pipelines................................................................................... 17

6.2.3.2 Flange Connections for Plastic Pipelines................................................................................. 18

6.2.3.3 Pipe Couplings ......................................................................................................................... 18

6.2.3.4 Bolts, Nuts, Washers................................................................................................................ 18

6.2.3.5 Seals......................................................................................................................................... 18

6.3 Fittings...................................................................................................................................... 19

6.4 Pipe Supports and Fixtures...................................................................................................... 19

6.5 Emptying, Ventilation and Cleaning ......................................................................................... 20

6.6 Wall Leadthroughs ................................................................................................................... 20

6.7 Lubrication Lines ...................................................................................................................... 21


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7 Other Matters ........................................................................................................................... 21

7.2 Insulation................................................................................................................................... 21

7.1.1 Execution of Hot Protective Insulation...................................................................................... 21

7.1.2 Execution of Cold Protective Insulation .................................................................................... 22

7.1.3 Insulation to Prevent Condensation Water ............................................................................... 22

7.1.4 Frost Protective Insulation ........................................................................................................ 227.1.5 Insulation for Pipes Made from Stainless Steel ........................................................................ 22

7.1.6 Insulation Thicknesses.............................................................................................................. 22

7.1.7 Insulation Cladding.................................................................................................................... 22

7.2 Equipotential Bonding............................................................................................................... 22

7.3 Measurements .......................................................................................................................... 23

7.4 Marking ..................................................................................................................................... 23

7.5 Tests.......................................................................................................................................... 24

Bibliography............................................................................................................................................. 25

Appendix .................................................................................................................................................. 26

Appendix A: Tables ................................................................................................................................... 26

Appendix B: Normative References .......................................................................................................... 35


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DVS German Welding Society

EG (Directive) European Community

EPDM Ethylene-propylene diene monomer(Ethylene-propylene-terpolymer)

ISO International StandardisationOrganisation

KRV German Plastics Association

LAWA German Federal State WorkingGroup Water

NBR Acrylnitrile-butadiene rubber

NPSH(-value)

Net positive suction head,a measure for the minimum suc-tion head of a centrifugal pump(American source)

PTFE Polytetrafluoroethylene

RAL(-colour register)

German Institute for QualityAssurance and Marking

TRB Technical Rules for PressureVessels

TRR Technical Rules for Pipelines

UVV German Accident PreventionRegulation

VAwS German Ordinance on Facilities forthe Handling Water Hazardous andon Specialist Operations

VbF German Ordinance on CombustibleLiquids

VDE Association of German ElectricalEngineers

VdTV German Federation of TechnicalSurveyance Associations

VOB German Contract Proceduresfor Construction Works

WHG German Water ResourcesManagement Law

3 Stressing of thePipelines by theMedia

The media in the pipelines dealt with here are es-

sentially wastewater and its sludge, process anddrinking water, water in heating circuits, air, com-bustible gases as well as chemical additives forprecipitation and flocculation. The temperatures ofthe surroundings or of the medium do not in gen-eral place any special requirements on metallicpipe materials. With the employment of plasticstheir permitted limiting temperature is, however, tobe observed (e. g. with pipelines for pressure ven-tilation systems). The pipeline pressures apartfrom a few exceptions, for example with waterhammer, transport of sludge, explosion or detona-

tion endangered pipeline sections lie below 6 barand place no increased demands on stability orwall thickness. The pressure level to be selectedresults from the maximum operating pressurewhich occur taking into account all particular oper-ating conditions. With pipelines endangered bywater hammer a pressure surge calculation is tobe carried out in cases of doubt.

Taking into account the service life the followingare to be named as the most important selectioncriteria for the pipe materials, steel and plastic,most frequently employed in wastewater treatmentplants:

the resistance to corrosion and

the resistance to wear against abrasive contentsubstances.

Table 1 (Appendix) gives an overview on mediaand pipe materials in wastewater treatment plantsand the recommended proven combinations.(Note: in this Table pure oxygen is not listed asmedium as, due to increased tendency to oxidationand possible fire hazard in connection with oils,

greases, seal materials etc., the selection of mate-rials should be assessed by specialist firms.)


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4 Selection of Material

With the selection of pipeline materials, from thepoint of view of operations, the media and the in-fluences on the environment are decisive. Accord-ing to economic aspects the costs for delivery, lay-

ing, operation, maintenance and for other operatingfactors (converted to annual costs) have a consid-erable influence.

4.1 Pipelines Made from Mildor Low Carbon Steel

4.1.1 General

For numerous cases of application mild steel iswell-suited as pipe material due to its high stability,easy joining and laying techniques and due to its

favourable price. For reasons of corrosion suchpipes can be galvanised and/or coated with ce-ment mortar or plastic (for this see ATV AdvisoryLeaflet M 263 (not yet available in English)) or bejacketed. Steel pipes are produced either withoutseams through rolling or mechanically from platesor strip welded with a longitudinal seam or, withlarger diameters, welded in spiral form. The qualityof welding seams of mechanically welded pipes isvery high so that, as a rule, they satisfy the de-mands placed on them. The reduction of the mate-rial properties is laid down in the relevant deliverystandard specifications (e.g. DIN 1626 and DIN1628). Due to their significantly higher price seam-less pipes only are used in exceptional cases only(see Table 2, Appendix). Spiral welded pies canbe economic from DN 500 upwards.

Due to the new European standardisation, in ac-cordance with EN 10027-1 the abbreviations forsteels are formed according to their employmentand the mechanical or physical properties. Forwastewater treatment plants inter alia the followingmain symbols are of interest:

S = steels for general structural steel work

P = steels for the construction of pressurevessels

L = steels for the construction of pipelines

E = engineering steels

These main symbols have appended the minimumyield strength in N/mm2.

The previously employed steel designations St37.0 or RSt 37.2 are thus L 235 and S 235JRG2.Unfortunately this new classification system hasnot been taken over uniformly for all steels and in

individual cases are, for example, to be ascer-tained from the manufacturers.

Material quality L 235 (previously: St 37.0) is normalin accordance with EN 10027-1 for welded pipes.As today steel plates of the same continuous highquality are produced, the previous normal qualityspecification, for example for fully killed cast steelwith verified suitability for welding, is unnecessary.

Mild or low carbon steels with specially verifiedproperties are necessary only for high strength re-quirements or for creep resistant pipelines.

In the following Sections (4.2 ff) the selection crite-ria are given which make the employment ofstainless steel qualities or plastics as pipe materialappear as advisable or necessary.

4.1.2 Processing of Pipelines Madefrom Mild or Low Carbon Steel

EN 25817 (previously DIN 8563-3) applies for theassessment of the welding seam quality. Forslightly stressed pipelines, with which in cases ofdamage or leakage no hazards due to the mediumoccur, the lowest Assessment Group (D) can besufficient as limit for irregularities in the weldingseams. For higher requirements, for example withpipelines laid underground and with dynamicstresses as well as for the internal seam surface(towards the medium) at least Assessment GroupC is to be called for. The required welding seamquality is to be laid down.

For pipelines in the area of application of theDVGW as well as of the Pressure Vessel Ordi-nance the regulations applicable there are to beobserved.

For the technical welding processing only qualifiedwelders may be used for manual and partly me-chanical welding processes who can produce avalid welding test certificate in accordance with EN287-1 for the required welding process. The firmcarrying out the work should meet the technicalwelding quality requirements in accordance with

EN 729-1 to EN 729-4.

The following quality assurance measures arerecommended and are to be laid down in the re-quest for tenders:

welding inspection,

documentation of the welding tasks carried outby each welder,

testing of welding seams (test method, possiblewelding specialist, size of random samples,

documentation of the tests etc.).


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4.2 Pipelines Made fromStainless Steel

4.2.1 General

Stainless steels are employed if particularly corro-

sive stresses are present for which other materialsare longer equal to the situation or if there are spe-

cial advantages according to other assessment

criteria, for example if a pipeline made from

stainless steel is more economic than one made

from normal steel with corrosion protection. The

corrosion resistance of stainless steels with their

high alloy components of chromium and nickel is,

however, only guaranteed if the selection of mate-

rial to meet the application and the processing to

match the material has been observed.

Stainless steels are in particular to be recom-mended if

increased corrosion resistance against aggres-

sive substances, in particular against the con-

tent substances of wastewater,

resistance with higher temperatures

(no oxidation),

high resistance against corrosion erosion in

flowing media,

low wear and through this low pollution of the

medium (product cleanliness) is promoted.

Typical areas of employment and cases of applica-

tion are, for example:

digester gas pipes,

exhaust pipes,

air pipes in activated sludge and grit chamber

facilities, particularly in the underwater area,

pipelines for chemicals.

Further cases of application can be taken from Ta-

ble 1(Appendix).

Straight bead welded circular pipes in accordancewith DIN 17455 are sufficient as pipelines made

from stainless steel the weld factor 0.8 is, as a

rule, sufficient from hot or cold rolled strip, in

each case non-heat-treated (D1/K1), matt pickled

and rendered passive full bath, with tolerances

D2/T3 for the external diameter and the wall thick-

ness in accordance with DIN EN ISO 1127 as well

as tolerances F2/S1 according to ISO 5252 (see

Table 2in the Appendix).

4.2.2 Corrosion Resistance of PipelinesMade from Stainless Steel

The corrosion resistance of stainless steels de-pends on a thin, invisible surface layer which formsspontaneously through the reaction between the

chromium in the alloy and the oxygen from the sur-roundings. This chromium oxide layer, the so-called passive layer, prevents corrosive attacks onthe metal lying below. Mechanical damage or otherimpairment of the passive layer is only harmless ifa spontaneous repassivation can form. Stainlesssteels are thus resistant against surface corrosionin oxygen-rich environments.

Nevertheless stainless steels can also be impairedin their durability and resistance through corrosion.The following types of corrosion are frequently to

be observed: pitting corrosion (pitting),

crevice corrosion,

stress corrosion cracking,

corrosion fatigue,

stress and corrosion fatigue.

Pitting and crevice corrosion are caused mainly by

high chloride concentrations in the medium. The

resistance against pitting and crevice corrosion

grows with increasing alloying component. In addi-

tion to the chromium content, above all the molyb-

denum content and, with the higher alloyed steels,

also the nitrogen content have an influence on the

resistance. The effect of these alloying components

is expressed simplified in the working sum

= % Cr + 3.3 % Mo + 16 % N. The resistance to

corrosion increases with increasing working sum.

Under ideal conditions (inter alia no stagnant flow

conditions) as well as with ambient temperatures,

the following guidance values for the stability ap-

ply: stainless steels with the material number

1.4301 (X5 CrNi 18-10) and similar (Working sum

18) in (non-sensitised) delivery condition up to ca.

100 mg/l chloride, the material 1.4571 (X6 CrNiMoTi17-12-2 with the working sum 25) and similar up to

800 mg/l chloride are seen as stable. With normal

hot water temperatures (e.g. 60 C 80 C) lower

values are to be set. With higher chloride ion con-

tents more corrosion resistant qualities such as, for

example 1.4439 (X2 CrNiMoN 17-13-5 with the

working sum 35) must be employed.

In narrow gaps such as, for example, of flange gas-

kets or press fittings, due to a lack of flushing effect

(stagnant flow conditions) there are concentrations

of chloride ions, so that there pitting and crevicecorrosion can occur to an increased degree.


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Note:With a later heating up to temperatures betweenca. 425 C to 870 C, for example wit welding inthe area of the heat affected zone, a so-calledsensitisation takes place through structural trans-formation, i.e. corrosion can already occur with

lower chloride concentrations.

4.2.3 Processing of Pipelines Madefrom Stainless Steel

For the technical welding processing of high alloyCr-Ni steels only certified welders can be em-ployed for manual and semi-mechanical weldingprocesses, who can produce a valid welding testcertificate in accordance with EN 287-1 for the re-quired welding process, semi-finished products(plate or in this case for pipes), the type of seam,material group (here W11), welding position andseam design. Attention is drawn to 4.1.2 with re-gard to quality assurance measures.

The highest resistance to corrosion is providedwith a clean, smooth and metallically polished sur-face. Cracks, scratches and crevices are weakpoints and encourage the creation of crevice cor-rosion. Therefore, to maintain the resistance tocorrosion, the annealing colours, scaling and slagresidues must be removed as they, as imperfec-tions in the passive layer, lead to corrosion dam-age at the welding seams. Equally metallic abra-

sion, in particular that of normal steel, has to beeliminated, which occurs on the surface of the ma-terial with the processing by tools. Resistance tocorrosion is equally reduced through adhesive de-posits of all types, for example from metallic oxidesand metallic hydrated oxides (extraneous rust).

In general, with the handling of stainless steels thefollowing requirements apply:

with the storage and processing of stainlesssteels spatial separation from normal steel andunalloyed steels (otherwise formation of extra-neous rust, initial easily removable rust).

avoidance of any contact with unalloyed or lowalloy steels (bearing and tensioning elements,means for fastening, brushes etc.).

In the case that these requirements cannot be metreliably, not only the welding seams but also thecomplete workpiece is to be pickled and, if re-quired rendered passive after processing.

As a rule only welding processes using protectivegas, such as, for example, the wolfram-inert gas(WIG welding, Code No. 141 in accordance with

EN 24063) or metal-active gas welding (MAGwelding, Code No. 135), are employed.

The employment of electric arc manual welding(E-Hand welding, Code No. 111) is to be agreed inindividual cases with the customer.

The statements under Sect. 4.1.2. apply for theassessment of the quality of welding seams.

With pipelines carrying digester gas the Assess-ment Group C should be specified.

Ignition points next to welding seams and weldspatter are to be avoided and must be eliminatedthrough grinding and polishing. Only those abra-sives which are approved for high alloy Cr-Ni steelsare to be employed.

Through suitable forming processes (i.e. rinsing ofthe weld on the inside of the pipe using specialinert gas mixtures, no forming pastes) and forming

installations it must be ensured that, in particular inthe area of the root no inadmissible annealing col-ours appear. (Note: on welding seams which areproduced on site, even with the best possible weld-ing seam preparation and using sufficient quanti-ties of forming gases there are, nevertheless,straw yellow annealing colours; therefore weldedjoints should as far as possible be carried out un-der factory conditions).

With the occurrence of inadmissible annealing col-ours (e.g. blue or even brown) it is necessary forthe seams to be post-treated until free of annealing

colours. Grinding using suitable abrasives, picklingor shot blasting with micro-glass beads is recom-mended. With pickling using pickling paste the rins-ing water is to be disposed of correctly.

4.3 Pipelines Made fromNon-ferrous Metals

For water pipelines, inter alia seamless copperpipes in accordance with EN 1057 are employed(material Cu-DHP in accordance with EN 12449,previously SF-Cu). For pipes according to the stan-

dard specifications there are internationally stan-dardised pipe connections and fittings. These pipescan also be used for lubrication lines (see Sect.6.7). Copper and copper alloys (e.g. brass or redbrass) have only limited resistance against hydro-gen sulphide and ammoniac, above all in wet media(e.g. digester gas). The resistance as a rule reducesfurther with increasing copper content. For exampleblack copper sulphide is formed with the presenceof hydrogen sulphide. With the presence of the trig-gering constraints, in addition to the corrosion strip-ping an uncontrolled failure of the components (e.g.

fittings) is caused. Therefore, for digester gas, non-ferrous metal designs are to be used.


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For pipelines in technical ventilation facilities thealuminium alloy AlMg 3 is suitable (see also Ta-ble 1, Appendix).

4.4 Pipelines Made from Plastic

4.4.1 General

For numerous application cases there are avail-able pipelines made from plastic due to the follow-ing advantage:

small weight,

very good resistance to chemicals,

low maintenance costs,

easy shaping and economic working properties.

These advantages are opposed by disadvantages

which are to be taken into account with the respec-tive application case, for example:

as a rule low mechanical resistance,

low dimensional stability and resistance to theeffects of heat,

susceptibility to ageing due to the effects of light(UV radiation) and heat,

to a high degree combustible (under certain cir-cumstances toxic combustion products),

limited possibility of recovery,

tendency to shrink and creep,

danger of static electricity charging, large thermal coefficient of elongation.

Plastics are divided into thermoplastics, duroplasticsand elastoplastics. Essentially plastic in accordancewith Table 1are employed as pipeline materials.

Table 1: Plastics for pipelines

Thermoplastic plastics: Abbreviation

Polyvinyl chloride,unplasticised

PVC-U

Polyvinyl chloride, chlorinated PVC-CPolyethylene PEPolypropylene PPPolybutene PBPolyvinylidene fluoride PVDFPolyamide PADuroplastic plastics:

Unsaturated polyester resin,glass-fibre reinforced

UP-GF

Phenacrylate resin, glass-fibrereinforced

PHA-GF

Epoxy resin, glass fibre rein-forced EP-GF

The choice of materials and the pressure level ofthe pipeline components are of decisive signifi-cance for operating safety and achievement of aplanned minimum service life. The following applyas relevant influencing factors: the operating pres-sure, the operating temperature, the medium to be

transported and different to metallic materials also the duration of the loading. In particular to beobserved is, due to the lower stability also the wa-ter hammer behaviour of plastic pipes, above allwith regard to possible underpressure conditions.

With the selection of plastics fundamentally theemployment of secondary plastics should also beinvestigated.

The suitable material dependent on pressure andtemperature can be taken from Fig. 1. In this the

influence of temperature on the material stability isclearly identifiable. Reductions in stability are al-ready to be taken into account from 25 C 30 C.For example, for the material PVC-U, in generaldesignated as PVC, the limits of the employment ca-pability are achieved already at 60 C and with PVC-Cat 90C.

Fig. 1: Application limiting values for pipes

made from thermoplastic materials [1]

(25 years service life with safety factor

included)

Included in all cases are the normal material safetyfactors. Deviating requirements due to shorter orlonger service lives, deviating operating tempera-tures and special media conditions require an indi-vidual calculation.

For pipes, fittings and accoutrements made fromplastic the pressure levels for an operating tem-perature of 20 C applies. In accordance with ISO4065 the pipes are divided into series wherebypipes of the same serial number are approved forthe same loading capability, which comparatively is

the case with the designation according to thenominal pressure levels. The series is marked by


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the letter S (see Table 4, Appendix). With plasticpipes the external diameter de

1)is given. Particularattention is to be paid with the calculation of flowrates and pressure surges that, with larger wallthicknesses as a result of high stability require-ments, significantly smaller internal diameters re-

sult. Large wall thicknesses also signify a jump innominal diameter with the changeover to metallicpipelines if the internal diameter is to remain moreor less the same (e.g. transition steel wall pipe toPE earth pipe).

4.4.2 Processing of PipelinesMade from Plastic

The Standard DVS 2210-1 is to be applied for thefabrication of pipelines made from thermoplasticplastics. The Standard DVS 2201-1 applies for the

assessment of the quality of the welding seam con-nections made from thermoplastic plastics. Assess-ment Group I should be specified for undergroundpipelines as these pipelines can no longer be moni-tored at a later date. For surface pipelines Assess-ment Group II can be agreed as sufficient. Only forlightly loaded pipelines, with which in the case ofdamage or leakage, no hazards from the mediumoccur, Assessment Group III can also be agreed.

The required quality of welding seams is to be laiddown.

Only qualified welders who can produce a validwelding certificate in accordance DVS 2212-1 forthe required welding process may be employed forthe technical welding processing for manual andsemi-mechanical welding processes.

A certificate of qualification in accordance withVdTV MB K 001 or in accordance with DVS2221-1 is to be produced for the execution of ad-hesive joints.

The KRV Standard A 9.8.4 is to be used for the

fabrication of pipelines made from glass reinforcedplastics (GRP)2).

For pipelines within the area of application of theDVGW as well as the (German) Pressure VesselOrdinance if required in deviation to the abovegiven statements the there applicable regulationsare to be observed.

1) Translator`s note: de, the index used reflects the Englishtranslation of the German index da

2) Translator`s note: GRP is equivalent to GFK in theGerman version

The following quality assurance measures are rec-ommended and are to be laid down in the requestfor tenders:

supervision of the laying tasks (e.g. supervisionof welding),

documentation of the work of the respectiveperformer (e.g. welding tasks, bonding tasks),

testing of welding seams, bonding etc. (testmethod, possible experts, size of random sam-ples, documentation of the tests etc.).

5 Dimensioning ofPipelines

A first preliminary dimensioning of the pipeline cantake place in accordance with the specifiedrecommended values for normal rates and mini-mum nominal diameters. The selection of the de-sired flow rate is limited through technical flow lim-iting data (e.g. danger of blockage, deposits, vibra-tions, development of noise, erosion etc.).

The first dimensioning in particular with longerpressure lines should follow a determination ofthe economical diameter including material vari-ants. Here it applies that the annual costs (capitaland operating costs are to be compared with each

other and are to be optimised. The methods to beapplied here as well as proposals for service livesto be applied are, for example, described in [2].

As one has to assume an ageing of the materialwith plastic pipelines the service life must be speci-fied for the determination of the creep strength.With this, in addition to the pressure and tempera-ture, the desired service life also has a certain,however, only small influence on the dimensioningand selection of material.

The operating costs are essentially determined bythe electrical work to be used for the transport. Thisresults from the flow quantity, the delivery head hy-draulic losses in the pipe plus the geodetic heightdifference, the pump efficiency, the annual operat-ing hours and the price for electricity.


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5.1 Flow Rates and MinimumNominal Diameters

For the transport of water and wastewater with lowsolid matter contents the economical flow rates ofTable 2can serve as reference values [3].

Table 2: Economic flow rates

DN 25 40 65 100 150 200 300 500

V [m/s] 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.9

Q [m3/h] 2.5 7 21 56 140 270 660 2050

In suction pipelines the flow rate is to be so se-lected, taking into account the pump characteristic(NPSH value), that cavitation can be avoided withcertainty.

With raw wastewater and in particular water-sandmixtures minimum flow rates 2 m/s are to besought in vertical pressure pipelines, in order toavoid deposits and demixing.

To avoid blockages the following minimum nominaldiameters are laid down in accordance with Table 3for the conveyance of certain media in wastewatertreatment plants in accordance with DIN 19569 13)(for this compare also EN 12255-1):

Table 3: Minimum nominal diameters

Medium Minimum nomi-

nal diameter

Water-sand mixture, sus-pended solids, activatedsludge

DN 80

Raw sludge DN 100 1)

Thickened digested sludge,thickened raw sludge

DN 100 1)

Thermally conditioned sludge DN 651)

With upstream fine screens, comminution or screen facilitiesand with short delivery stretches smaller minimum nominaldiameter can be selected.

Conveyance of gases:In areas in which the pressure losses are coveredfrom the system pressure, flow rates of 3.0 m/s to5.0 m/s are to be recommended for digester gas.

Ventilating ducts should have a maximum velocityof 8 m/s.

3) Authors afternote: In the meantime DIN 19569 has beenwithdrawn and replaced by EN 12255-1

The design velocity in air pipes for activated sludgeplants and similar is to be limited with full blowerperformance to 15 m/s, with very short pipe lengths(e.g. directly after the compressor) to 25 m/s.

Note:

With the determination of the flow rates the valuesin compressedcondition are to be applied.

5.2 Pressure Losses with theTransport of Viscous Liquids

The methods for the determination of pressurelosses with the transportation of water are also tobe applied for wastewater, sludge liquor and simi-lar with solid matter contents up to ca 2 %. Withhigher shares of solid matter there are significantdifferences with regard to hydraulic conditions. The

parameters for the description of the pressurelosses are essentially dependent on the type ofsludge and on the dry solids content. But also theshare of organic substances of the solid mass andthe treatment process can influence the transporta-tion conditions.

The fundamental difference therefore is due to thefact that sludge with a high share of solid matterdoes not follow Newtons laws. With this the ratio ofthe so-called shear rate to the shear strain exercisedis not constant as the dynamic viscosity is depend-ent on the shear forces operating on the sludge.

The complex conditions demand that each individ-ual case of a transportation of sludge over greaterdistances is examined carefully, in particular ifthickened excess sludge is to be transported. Tothis belongs a viscometric determination of the flowcurve of the original sludge (so far as it exists),which describes the relationship between shearrate and sear strain.

The changes of the pressure losses dependent ondry solids content of a mechanically thickened

sludge are shown as an example in Fig. 2. Addi-tional literature is contained in [4, 5].


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Fig. 2: Pressure losses of sludge in

pipelines [6]

5.3 Selection of Pipelines

The wall thicknesses of pipelines are to be suffi-ciently dimensioned taking into account corrosionand abrasion which occurs and with high pres-sures according to the maximum pressure of themedium. With the transportation of heavily abrasivesubstances (e.g. sand-water mixtures, primarysludge etc.) possibly larger wall thicknesses are tobe selected as wear reserve.

Due to the required resistance the employment of

plastic is necessary as pipeline material with chemi-cals such as, for example, FeCl3as precipitant.

With unavoidable laying of underground pipelinesfor water-hazardous liquids double pipe systems areto be employed (see 19 WHG). With this the coun-try-specific regulations are to be taken into account.

To reduce pressure losses and to avoid deposits fit-tings are to be so selected that hydraulically favour-able conditions result. The radius of curvature ofpipe bends should not be less than 1.5 d.

5.3.1 Pipelines Made from Steeland Stainless Steel

With the selection of the diameter of steel pipelinesas far as possible fall back on Series 1 in accor-dance with ISO 4200; this also corresponds withSeries 1 in DIN 2458 for welded steel pipes as wellas in EN ISO 1127 for welded pipes made fromaustenitic stainless steel.

As wall thickness for these pipes the following suf-fice in the normal case (compare also Table 2,Appendix):

Preferred Wall Thickness Series D according toISO 4200 for steel pipes,

Preferred Wall Thickness Series A according toISO 4200 for pipes made from stainless steel(see also DIN 19569-5 and DIN 19569-6)4). De-

pending on the individual case, in particular withlarger pipeline cross-sections, larger wall thick-nesses are recommended.

For pipes with a diameter greater than DN 1000wall thicknesses are to be laid down in the invita-tion to tender.

For smaller nominal diameters (e.g. up to DN 40)the employment of threaded pipes can be eco-nomical for water, hot water, air etc. In these casesthreaded pipes according to DIN 2440 or to DIN2441 are to be used.

5.3.2 Pipelines Made from Plastic

First the suitable pipe material is chosen accordingto the chemical resistance to the medium. Alongwith this the resistance to UV is also to be consid-ered. (Therefore, with outside facilities and endan-gered areas PE should be used in preference tothe more favourably priced PVC). Following this,via the employment conditions taking into accounta medium-related safety factor, the so-calleddiameter/wall thickness ratio (SDR) and thus sub-

sequently the wall thickness and the external di-ameter are laid down. For practical implementa-tion, E DIN 8074:19975)can, for example, be calledupon for pipes made from polyethylene (PE). First,depending on the temperature, years of operationand permitted operating pressure from Tables 5 - 13,the SDR values (or pipe series S) for various mate-rials (PE 63, PE 80, PE 100) and safety factors areto be determined. For the determination of the pipedimensions (external diameter de, wall thickness s)one can fall back on Table 2 of the same draftstandard specification.

As medium-related safety factors the following val-ues are to be applied:

(Clean) water 1.25Chemicals 1.6Gases and water-hazardous substances 2.0

With the determination of the wall thickness the fol-lowing maximum pressure loading should be as-

4) Author`s afternote: In the meantime DIN 19569 has beenwithdrawn and replaced by EN 12255-1

5 ) Author`s afternote: In the meantime DIN 8047 has beenpublished; Date of issue: August 1999


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In particular with heating pipes and air pipes foractivated sludge plants, the lateral change due tothe high temperature of the medium is to be takeninto account.

With soft material compensators one differentiates

between single-layer rubber compensators andmulti-layer fabric compensators. The rubber com-pensators as a rule have the advantage of greaterimpermeability. The disadvantage is, however,their limited service life (observe manufacturersdetails). The material and, in particular, the sealface are dependent on the medium and other con-straints such as, for example, compressive stress,operating temperature, resistance to UV or con-densate produced and are therefore to be deter-mined before construction. Below in Table 4 arethe normal areas of employment of soft materialcompensators in wastewater treatment plants.

The compensators should be realised with a flangeconnection.

Support rings in soft material compensators areonly required when, for example, an unacceptableunder pressure for the compensators can occur inthe suction line of pumps.

Metal compensators, usually realised with an ex-pansion bellows, made from several layers ofmetal bands, are employed with special demandson sealing and temperature. In pipelines fordigester gas metal compensators are always to beinstalled.

Compensators are to be designed with lateral lim-iters, in case the exceeding of the permitted lateralchange is possible.

For settling compensation, for example between astructure threatened by settling and an under-

ground pipeline, on many occasions compensatorsare not sufficient. For this articulated pipe joints orsimilar pipe fittings are to be employed.

6.2 Connection of Pipelines

With the connection of single pipes one differenti-ates between permanent and non-permanentconnections.

6.2.1 Permanent Connections ofPipelines Made from Metallic

Materials

6.2.1.1 Welding and Brazing

Welding is the most frequent method of connectingpipes permanently (for this see Sects. 4.1.2 and4.2.3). Due to this economic connection technol-ogy, the brazing of pipelines today is still used onlywith copper pipes in the area of heating.

Table 4: Areas of application of materials for soft material compensators

Wastewater/process wa-

ter:

EPDM Ethylene-propylene diane monomer (terpolymer),not suitable for oils and media containing grease

CR: Chloroprene rubber (Brand-name for example Neopren)Application for process water and wastewater if laying of thepipeline takes place within the building (limited UV resistance)

Gas/mineral oil/digestergas:

NBR: Acrylonitrile-butadiene rubber (Brand-name for example Perbu-nan-N. With digester gas the resistance is dependent on theconcentration of gas content substances, in particular of H2S

Chemicals: CSM: Chlorosulphonated polyethylene (Brand-name for example Hy-palon)

FPM: Fluorinated rubber (Brand-name for example Viton)

PTFE: Polytetrafluoroethylene (Brand-name for example Teflon)

Drinking water: IIR: Butyl rubber

NR: Natural rubber

Hot water: EPDM: Ethylene-propylene diane monomer (terpolymer), rubber mix-

ture matched for application areas up to ca. +130 C.


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6.2.1.2 Press Fittings

Pipelines made from stainless steel up to a nominaldiameter of DN 100 can be joined to each otherpermanently using pressed sleeves. This connec-tion technique is very interesting economically due

to the small amount of time with assembly. Theslight undercutting of the preferred wall thicknessSeries A in accordance with ISO 4200 is, as a rule,justifiable. Attention is drawn to the manufacturersinstructions with regard to application.

6.2.2 Permanent Connections ofPipelines Made from Plastic

Pipeline components made from plastic can beconnected together permanently using gluing,welding or laminating. In particular with these

work steps trained and qualified personnel withappropriate technical equipment are be employed(welding test and similar, see Sect. 4.4.2).

Connections to PVC pipes are mainly glued.(PVC pipes normally to be found in building in-stallations have bell joints).

Pipe connections made from PE, PP and PVDFare welded (for this see also DVS 2207-1),whereby essentially the following welding meth-ods are used:

heated tool sleeve welding,

heated tool butt welding,

(butt welding with heat reflectors),

heated spiral welding.

Laminating is employed for connections of pipeli-nes made from GRP

8)with each other as well as

with other materials.

6.2.2 Separable Connections

Separable connections for pipelines made from

metallic materials and plastic can be providedusing threaded joints, flanges, pipe couplings andclamping joints. For plastic pipelines clamp cou-plings and bell joints can be used.

With smaller diameters threaded joints in place offlange couplings are normal.

Attention is drawn to DVS 2210-1 for the designof separable connections for plastic pipelinesand to KRV A 9.8.4 for thermoplastics and forGFP pipelines.

8) Translator`s note: GRP is equivalent to GFK in the Ger-man version

6.2.3.1 Flange Connections forSteel Pipelines

The flange is the most frequently employed con-

nection technique for joining pipelines non-

permanently.

Welding neck flanges (DIN 26309)

to DIN 26339)

),

lapped or slip-on flanges (DIN 26419)

and DIN

26429)

) as well as plain face flanges for brazing or

welding (DIN 25739)

and DIN 25769)

) are laid

down in DIN Standard Specifications.

Within the area of application of this Advisory

Leaflet pressure level PN 10 as a rule is suffi-

cient. With large nominal diameters (> DN 1000)

as far as possible, PN 6 is used.

Basic standard specification for flanges is DIN2501-1, in which the connection dimensions are

laid down. Requests for tender must contain the

note Flange connection dimensions in accor-

dance with DIN 2501-1 together with the nominal

pressure level (e.g. PN 10), in order to define the

interfaces clearly. For nominal diameters up to

DN 1000 and nominal pressures up to 10 bar

flanges with connecting dimensions PN 10 are to

be used for standardisation. Flanges for fittings

are to be described analogously.

The previously frequently used welding neck

flanges are, particularly with stainless steel pipe-

lines, being more and more being supplanted by

lapped pipe ends or welding neck collar. The

material of the lapped flanges is to be matched to

the corrosive stress of the external medium.

Coated lapped flanges should not be employed:

in underwater areas,

underground,

in corrosive atmospheres.

The smooth flange represents a simple form of

flange connection and can be seen as being ofequal value to connections with welding neck

flange connections. It, however, has the disad-

vantage that the welded seams cannot be x-

rayed. If the realisation of flange connections us-

ing smooth flanges is to be excluded then this is

to be included in the request for tenders.

The flange leaf thicknesses given in the individual

DIN Standard Specification are basically to be

observed, a verification of the flange connection

9) Author`s afternote: In the meantime these standard speci-fications have been withdrawn and replaced by EN 1092-1


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is then as a rule not required. If flanges with re-

duced leaf thickness are to be employed a verifi-

cation of the connection in accordance with DIN

V 250510)

or EN 1591 is to be produced by the

contractor.

6.2.3.2 Flange Connections forPlastic Pipelines

Welding neck flanges and loose flanges are laid

down in sets of rules and standards.

Flange connections are to be realised in the

pressure stage of the continuing pipeline or the

subsequent fittings.

The material of loose flanges is to be matched to

the corrosive stress by the external medium.

Coated loose flanges should not be employed:

in underwater areas,

underground,

in corrosive atmospheres.

6.2.3.3 Pipe Couplings

Through the employment of pipe couplings the

assembly time in comparison with flange connec-

tions can be shortened and repair work more sim-

ply carried out. Pipe couplings are suitable for thecospecific connection of thin- and thick-walled

pipes made from metal or plastic as well as for

the connection of pipes made from different ma-

terials. With transition from steel to plastic and

with more or less the same internal diameters, a

connection using pipe couplings is not possible

due to the in general different external diameters

(only ca. 1 mm divergence allowed!).The material

1.4301 is common for pipe couplings; special ma-

terials are available. The installation torques are

given on the couplings.

The realisation of the pipe coupling is to bematched to the required operating pressure. For

the transfer of axial forces tensile resistant con-

nections are, depending on manufacturer, avail-

able up to nominal diameter DN 600, flexible and

thrust-free connections up to nominal diameter

DN 2000. The selection of material for the base

structure as well as for the fastening/locking de-

vice is dependent on the surrounding conditions

only and not on the medium as these compo-

nents do not come into contact with the medium.

10) Authors afternote: This DIN standard specification hasbeen withdrawn and replaced by EN 1591-1

If required, the necessary steel band inserts are

to be matched to the medium. This applies also

for the material of the sealing collars. As normal

sealing materials the following are, for example,

employed: for wastewater EPDM and for gases

and hydrocarbons NBR. With digester gas with

H2S-contents > 5 mg/m3 the guidance value forthe gas properties in accordance with the ap-

proval by the DVGW is exceeded. (See Area of

Application of the DVGW Standard 260 Part 1).

Therefore, above this guidance value, due to the

lack of stability of the sealing material NBR, cur-

rently the employment of pipe couplings is not to

be recommended or is to be released in individ-

ual cases by the manufacturer.

6.2.3.4 Bolts, Nuts, Washers

Materials for bolts, nuts and washers are to beplanned according to the pipeline materials as

well as the surrounding conditions. In the un-

derwater area one selects them from stainless

steels of the quality A2 or A4 in accordance with

EN ISO 3506-1 to EN ISO 3506-3, in rooms

with small corrosion stress from hot or electro-

galvanised steel and in outside and wet room

atmospheres from stainless steel (A2) or in hot

galvanised qualities. Due to the tendency to

seize, in particular with machine cut screw

threads, and to counter rusting in, the applica-

tion of thread lubricants is recommended. Vibra-

tions can lead to the loosening of non-positively

screwed connections. The tightening of the

screwed connection using the correct preload-

ing force is therefore important. The securing of

screwed connections with suitable adhesive is

effective.

6.2.3.5 Seals

As seal material synthetic rubbers, for water and

sludge EPDM and for gas NBR have proved

themselves due to there previous, long-term em-

ployment under the same or similarly conditionedoperating conditions. Furthermore, seals made

from asbestos-free fibrous material slabs (AFP)

are used which have replaced the seals known

under the abbreviation IT.

The selection of the sealing material is dependent

on the medium and other constraints such as, for

example, compression stresses, operating tem-

perature or resistance to UV, and therefore is to

be laid down before realisation. Below is listed a

selection of sealing materials with abbreviations:


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EPDM: Ethylene-propylene diene monomer(terpolymer)

NBR: Acrylnitrile-butadiene rubber(brand name e.g. Perbunan-N)

AFP: Asbestos-free fibrous material slabs(successor of the so-called IT seals)

PTFE: Polytetrafluoroethylene(brand name e.g. Teflon)

CSM: Chlorosulphonated polyethylene(brand name e.g. Hypalon)

Seals made from metal are to be preferred forhigh compression stress; seals made from graph-ite for individual cases with requirements for fireprotection.

The thickness of seals made from AFP, due tothe lower compressive creep stability, are deter-mined with only 2/3 of the normal seal thicknessof the IT seals. With seals made from PTFE theflow of this material is to be taken into accountand therefore the seal thickness is to be selectedas small as possible.

Compared with EPDM, as a rule NBR has ahigher gas imperviousness against hydrocarbons.The resistance to digester gas of the NBR mix-tures to be used for sealing materials is, as a ruleproven due to the available operating experience.The hydrogen sulphide normally contained in di-

gester gas and the weak acids resulting from thesolution of hydrogen sulphide in the condensate,dependent on the concentrations can, under cer-tain circumstances lead to a decomposition of theseals. Seals made from AFP, for example usingcarbon fibres, are considered as resistant againstmethane and hydrogen sulphide.

Sealing materials with low water absorption suchas, for example, NBR are preferred for the em-ployment of stainless steels.

Normally with larger diameters or higher pressureseals with fabric or steel inserts or made fromAFP are installed due to the high stiffness.

With flange connections on PE pipes it is recom-mended that profile flange seals are used andthat the bolts are tightened using a torque wrenchin accordance with manufacturers details.

6.3 Fittings

Fittings take on important functions in processand operating technology, for example shutting,opening, regulating, aerating and ventilating etc.The following are differentiated:

valves with straight-lined movement of thesealing component parallel to the local direc-tion of flow,

slide valves with straight-lined movement ofthe sealing component vertically to the flowdirection,

stopcocks and butterfly valves with rotating orslewing movement of the sealing component.

The type of fitting is to be determined dependingon the application purpose (closure, regulation,

type of medium, volume flow, pressure and tem-perature etc.). With the selection of the fittings thepressure ratings are to be chosen according tothe respective application case. A summary forthe selection of suitable fittings for the respectivemedia is given by Table 8in the Appendix.

The connecting flange of the fitting is to be de-scribed analogous to Sect. 6.2.3.1. In addition,the required closure pressure, against which thefitting must close securely, is to be stated in theinvitation to tender documents.

The dead weight and the operating forces of theinstalled fittings may not load the pipelines unac-ceptably, this applies in particular for plastic pipe-lines.

With the planning of the pipelines attention is tobe paid to easy operation and dismantling of thefitting. Normally, all hand operated fittings abovean operating height of 1.80 m are to beequipped with chain wheel and chain, spindleextension or similar.

6.4 Pipe Supports and Fixtures

Permitted spans L of filled and unfilled steel pipesin the range of diameters from DN 25 to DN 500and a flowing medium with the density of water(1,000 kg/m3) can be extracted from Table 9.1(Appendix).

With plastic pipelines, due to the low strengthvalues, the significantly differing modulus of elas-ticity and the effects of temperature which are notto be ignored, there are smaller separations be-

tween supports.


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Permitted spans for thermoplastic plastic pipesfilled with water can be taken from Table 9.2(Appendix); those made from duroplastic plasticsfrom Table 9.3(Appendix).

In the main pipe clips in accordance with DIN

3567 and round steel stirrups in accordance withDIN 3567 are employed.

The supports are, for example, produced aswelded construction, galvanized and in accor-dance with Table 10(Appendix). They are to bedivided into sliding and fixed bearings. Designand assembly must ensure an arrangement con-forming in alignment and angle, free of deforma-tion and tension. The freedom of movement ofthe pipeline must be ensured taking into accountthe variation of the media and ambient tempera-

tures. The working surfaces of the sliding bear-ings are to be so designed that edge pressure isexcluded. Fixed bearings are to be so developedthat forces and moments can be taken up in threeaxes and be fed into the structure.

Pipe racks are also used as standardised attach-ment system as an alternative to the normalwelded structures. An advantage of these systemsas a rule lies in the simplified verification of thestatic dimensioning and the significantly lowerweight.

6.5 Emptying, Ventilation andCleaning

The following information is to be taken into ac-count with the planning and laying of pipelines forthe emptying, ventilation and cleaning of pipe-lines:

high points are to be avoided or fitted with ven-tilation devices (interruption of delivery throughgas bubbles at the high points),

low points are to be avoided and, with the

danger of deposits, precautions are to betaken for the flushing of the system,

minimum nominal diameters of emptying facili-ties are to be observed (danger of blockages);the following have proved themselves:

DN 20 for condensate and other liquidswithout solid matter

DN 50 for viscous pumping media e.g.sludge,

drainage pipelines are to be laid to pump pits,floor drains etc.,

pipelines which, due to the medium to bepumped (e.g. thickened sludge), tend particu-larly to blockages, are to be fitted with flushingconnections, cleaning ports, connections forcleaning brushes or similar.

For pipeline systems in the field of gas the follow-ing are to be observed:

as far as possible no rise in the direction offlow as condensate is produced. In the casethat this cannot be avoided an appropriate di-mensioning must be carried out.

low points are to be provided with condensateinterceptors for drainage.

6.6 Wall Leadthroughs

Often walls and ceilings have to be penetrated inthe course of the laying of pipelines. The so-called wall leadthroughs are to be designed inaccordance with the generally recognised rules oftechnology. The following criteria are, in particu-lar, to be observed:

sealing against gas with neighbouring explo-sive areas,

fire protection,

corrosions protection (with aggressive atmos-pheres),

sealing against water under pressure, time of implementation (during construction

work or later).

Wall leadthroughs can be realised as chases forsubsequent casting or as fairleads with subse-quent sealing by means of annular seals.

If annular seals are used in core bore holes par-ticular value is to be placed on the execution ofthe boring. Scoring due to blunt tools can usuallyno longer be compensated by the seals. Boringsmust be carried out perpendicular in order that no

unbalanced forces act on the seal, otherwise thesealing ability and service life of the annular sealis influenced negatively. The weight of the pipe-line may not be taken up by the annular seal. Anadditional sheathing pipe is, as a rule, not re-quired.

Annular seals are to be avoided if wall or ceilingpenetrations are no longer accessible or accessi-ble only with difficulty following assembly as afurther tightening with leakages is no longer pos-sible. With penetration of digesters one should, ingeneral, avoid annular seals. The leadthrough isto be designed as installation pipe with wall


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flange or as equivalent solution. The wall or ceil-ing leadthrough is to be considered structurally asfixed restraint and is to be dimensioned as fixedbearing. Axial or angular changes which occurare taken up by the pipelines leading outside orby pipe installation components such as, for ex-

ample, compensators. If wall flanges are usedwith PE pipelines the flange should be reinforcedwith an additional steel ring in order to improvesealing.

The provisions of DVGW Standard G 600 for walland ceiling leadthroughs of pipelines carry gasare to be applied analogously. (It can be as-sumed that with reinforced concrete the dangersdue to gas conducting layers as, for example,occur with brickwork, do not exist.)

In accordance with DIN 1988-7 in general no cor-

rosion protection is required with surface or bur-ied laying. Before the plastering-in of galvanisedsteel pipes, protective bandages or protectivefoils are to be employed as corrosion protection.With stainless steel pipelines chloride-free mortarand, in case of need (e.g. with winter buildingmeasures), a building supervisory approved con-crete additive (control of the chloride content) isto be employed.

Provisions resulting from fire protection are to beobserved. The constructor of the pipeline is there-fore to be given which walls and ceilings, from theaspect of fire protection, are to be classified asfirewalls and/or complex dividing wall. In accor-dance with the recommendations of the GermanAssociation of Property Insurers (VdS 2234)openings in firewalls are not permitted. If they arenecessary for operating reasons they must be fireresistant protected. Pipelines may not produceany inadmissible forces on the wall. The followingdesigns have, inter alia, proved themselves:

in firewall level movable pipelines with bush-ings made from non-combustible material, with

which the remaining intermediate space isstuffed with non-combustible material of build-ing material class A 1 with a melting pointabove 1000 C, e. g. rock wool,

in firewall level fixed pipes, with which the in-termediate space between pipeline and wall isto be completely filled using mortar or fire pro-tection mortar, and a compensator is to be lo-cated before and after the firewall.

Leading pipelines made from combustible mate-rial through firewalls is basically to be avoided. Ifthis is not possible then they are to be compart-mentalised using [German) Fire Resistance Class

R 90 systems with general construction supervi-sory approval (e.g. R 90 bulkheads).

6.7 Lubrication Lines

Unalloyed steel or copper (see Chap. 4.3) is rec-

ommended for the production of lubrication linesin dry spaces, in the open and in wet spacesstainless steel with Material No. 1.4301 or1.4571. Lubrication lines made from Polyamid,e.g. PA 12 in accordance with DIN 73378, arealso possible. The pipelines are to be so laid thatthey cannot be mechanically damaged. All lubri-cation points should be easily accessible. Wherethis is not possible then they are to be broughttogether at easily accessible positions. The indi-vidual lubrication points and lines are to bemarked.

7 Other Matters

7.1 Insulation

With pipe insulation one differentiates betweeninsulation as heat and cold protection and insula-tion as corrosion protection or as sound proofing.Here only the area of heat and cold insulation isto be considered.

Pipelines in which cold or warm media aretransported are to be provided with pipe insula-tion for the reduction of the cold or heat losses,taking into account economic efficiency, operat-ing safety and protective quality. For this, asinsulation materials, there are available fibre orpowder formed insulation matter, plastic foamsand natural organic matter.

7.1.1 Execution of Hot ProtectiveInsulation

As a rule, for heat protective insulation, mineralsubstances made from rock wool are employedas insulation material. This material can be em-ployed in the form of

mineral fibre mats for the insulation of pipe-lines, containers and devices,

mineral fibre shells for the insulation of pipe-lines,

short floccy fibres for stuffing insulation.


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7.1.2 Execution of Cold ProtectiveInsulation

As a rule, foam materials are employed for therather seldom cold protective insulation in waste-water treatment plants.

7.1.3 Insulation to PreventCondensation Water

Moisture precipitation on cold pipelines should beprevented though a sufficient insulation of thepipeline (surface temperature of the insulationgreater than the temperature of the dew point ofthe surrounding atmosphere). Particularly suitablefor such condensation water insulation are insula-tion materials which are resistant to the penetra-tion of moisture (foamed materials), although also

here the employment of mineral fibres is possibleand normal.

In addition to the demands on the mechanicalproperties an especially high demand is to beplaced on the steam-tight design of the insulation.

7.1.4 Frost Protective Insulation

Water pipes in which, over long periods, the waterdoes not flow can freeze up in winter. Cooling canbe delayed through an insulation and thus thedanger of a freezing up can be reduced. In orderfundamentally to prevent freezing up, the pipelinesmust be provided with secondary heating and in-sulation. With the use of mineral fibre productsnormal here special value is also to be placed onthe steam-tight closure of the insulation cladding.

7.1.5 Insulation for Pipes Madefrom Stainless Steel

Insulation materials for heat protective and coldinsulation of stainless steel pipes may not have apercentage by mass of water soluble chloride

ions which exceeds 0.05 % (insulation materialwith AS Quality in accordance with StandardAGI Q 135 are suitable).

7.1.6 Insulation Thicknesses

For the determination of sufficient insulationthickness there are tables available, both for heatand cold protective insulation as well as for con-densation and frost protective insulation, which,depending on the nominal pipe diameters, thetemperatures which occur and other relevant pa-

rameters give information on the required mini-mum insulation thickness.

If required, consideration of economic efficiencyfor insulation thickness (costs) in comparison tothe heat energy saved (benefits) is also to be car-ried out.

Insulation thicknesses of heat protective insula-

tion on heating pipes are to be produced accord-ing to the details of the heating plant ordinance.

7.1.7 Insulation Cladding

All insulation is to be provided with cladding forprotection against external stresses. With this gal-vanised thin sheet, aluminium sheet, stainless steelsheet and, in heating systems also PVC foil with athickness of 0.5 mm 1.0 mm can be employed.

Flanges, valves, other fittings and pipe accesso-ries must be clad for insulation using a cap madeup from two or more parts and made in the formof the fitting to be clad. Removal and replacementof the insulation cap must be possible at all timeswith ease and rapidly.

7.2 Equipotential Bonding

All electrical conducting pipelines, independent ofother electrical protective measures, are to beintegrated into a equipotential bonding system.The equipotential bonding can be carried out on acentral equipotential bonding rail or between

each other.

Suitable terminal lugs are to be planned on pipe-lines, flanges, containers etc. for connection to anequipotential bonding system. If non-conductingfittings or adapters are installed into the pipelinesystem these integrated items must be bridgedusing suitable lines. The electrically non-conducting properties of plastic pipes are to benoted in explosion endangered areas and witheasily combustible pumping media. Here there isthe possibility of employing special conductingraw materials (e.g. PE 80 el.).

Equipotential bonding of pipeline systems is to beintegrated into the overall system equipotentialbonding. Depending on the structure of the protec-tive measure and taking into account the validVDE regulations for this, the foundation earth con-nection, null or earth conductor, earthling conduct-ers for antenna and telephone systems as well asearth conducters or lightning protection must beintegrated into the system. The linkages and con-nections to the equipotential bonding lines are tobe correctly and permanently carried out by theinstaller of the electrical system in accordance withthe valid provisions and regulations.


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7.3 Measurements

With invitations to tender (ITTs), which concern

the VOB [German Conditions Concerning Con-

tracts], in addition to DIN 18299: 199611)

, Section

5, DIN 18381: 19989)

, Section 5, also applies with

regard to measurements and settlement. In thiscase, with measurements, mouldings and fittings

and are overmeasured.

7.4 Marking

It is recommended to mark pipelines within sys-

tems in accordance with the medium which flows

through them using coloured emphasis or

through labelling.

If, with the media, one is concerned with hazard-

ous substances within the meaning of the [Ger-man] Chemical Law, there can be an obligation

for marking in accordance with the [German]

Hazardous Substance Ordinance. In accordance

with 23 (Packaging and Marking) there have to

be markings at sufficient frequency on visibly laid

pipelines and clearly visible close to potentially

hazardous points such as gate valves and con-

nection points.

Attention is drawn to the Chemical Law and Haz-

ardous Substance Ordinance with regard to the

media as examples are given digester gas,acids, caustic solutions and details of marking.

Where no regulations for marking exists, DIN

2403 should be applied. (Marking in accordance

with DIN is laid down as generally applicable,

special media of wastewater treatment are not

given there.)

In accordance with DIN 2403 pipelines can be

marked according to the substance which flows

through them using signs, adhesive labels, col-

oured rings or through coloured cladding. Signs

have the advantage that, in addition to the sub-stance flowing through, they can also hold impor-

tant details (e.g. direction of flow, markings corre-

sponding to flow diagram, serial number for main-

tenance). Labelling, which is obtainable on the

market as ready-made article, should be written

simply, easily and permanently readable as well

as being secure and simple to attach.

11) Authors afternote: DIN 18299, DIN 18381: New edition,date of issue: October 2006

For the coloured marking of pipelines it is rec-

ommended that coloured rings or adhesive labels

if required with additional naming of the me-

dium are provided but not, however, to choose

a continuous coat of paint as many pipe materials

for the avoidance of corrosion must not be addi-

tionally coated.

A proposal for the selection of colour for the

marking of the media, based on DIN 2403 is con-

tained in Table 5.

It is proposed that:

1. fundamentally, marking is in accordance with

the above given colour groups.

2. rings and/or adhesive labels or similar are to

be selected in the basic colours and are to be

provided additionally with written details anddirection arrows.

3. all water (e.g. wastewater, process water,

sludge liquor 2 % dry solid matter (DS)) are

to be assigned to Group 1. Heating water is

also to be listed under Group 1. Here, if

necessary, DIN 2404 is to be observed.

4. all sludge > 2 % DS is to be assigned to

Group 9.

5. all other substances (e.g. flocculation aids or

flocculants, inert gases etc.) are to beassigned to obvious groups (e.g. FeCl3, FeCl2

Group 6, milk of lime Group 7, nitrogen

Group 5 etc.).


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Table 5: Classification of colours to the flowing substances in accordance with DIN 2403

Substance flowing Group Colour name Nearest colour sample

in the RAL colour

register

RAL 840 HR

Water 1 Green RAL 6018Steam 2 Red RAL 3000Air 3 Grey RAL 7001Combustible gases 4 Yellow

oryellow

with additional colourred

RAL 1021

RAL 3000

Non-combustible gases 5 Yellowwith additional colour

black

RAL 1021

RAL 9005Acids 6 Orange RAL 2003

Alkaline solutions 7 Violet RAL 4002Combustible liquids 8 Brown

orbrown

with additional colourred

RAL 8001

RAL 3000Non-combustible liquids 9 Brown

with additional colourblack

RAL 8001

RAL 9005Oxygen 0 Blue RAL 5015

7.5 Tests

Pipelines for an overpressure of more than0.5 EG bar as a rule fall under the EC DirectivePressure equipment.

In accordance with the basic concept of the EGDirective Pressure equipment the direct respon-sibility of the manufacturer is emphasised, i.e. thespecialist no longer establishes the correctnessof the pressure equipment, for example the pipe-line, but rather the manufacturer. The manufac-

turer declares the conformity with the EuropeanStandards and, if required, affixing the CE marks

Until common basic European standards areavailable, for example for pipelines, nationalstandards and technical specifications, for exam-ple DruckbehV with [German] Technical Rules forPressure Vessels (TRB) and [German] TechnicalRules for Pipelines (TRR) are to be enlisted.

Depending on the hazard potential (pressure, vol-ume, dangerousness of the liquid) there are differ-ent categories for the assessment of conformity to

be carried out by the manufacturer specified in theEG Directive Pressure Equipment.

For the lowest category of conformity evaluation,i.e. application cases which come under Article 3,Para. 3, equipment and pipelines must be de-signed and produced in agreement with goodengineering practice applicable in one of theMember Countries. This means that the nationalstandards and provisions in these cases can beused unlimited, but then, however, must withoutfail be specified in the invitation to tender.

(Note a large part of the pipelines in wastewatertreatment plants fall under the category in accor-

dance with Article 3, Para. 3.)

Below the controlled region of 0.5 bar nationalregulations apply and acceptance and test criteriafor the individual case are to be laid down, interalia, in accordance with

the [German] Pressure Vessel Ordinance(DruckbehV),

the [German] Ordinance on Combustibleliquids (VbF),

the [German] Ordinance on Facilities for the

handling of Water Hazardous Substances(VAwS),


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the Standards of the German Technical andScientific Association for Gas and Water(DVGW),

the applicable Accident Prevention Regula-tions ([German] UVV),

the [German] Steam Boiler Ordinance(DampfkV),

the respective building regulations etc.

Pipelines which are operated within the frame-work of the public water and/or gas supply withan overpressure of at the most 16 bar, are to beallocated to the area of application of the DVGW.Under this fall the pipelines of the works network,fed from the public network of the supply com-pany, with the connection up to and including theconsumer facilities, e.g. the gas burners.

Furthermore, it is to be recommended, in the ex-amination of the pipeline, to also include a checkthat the laying is correct with regards to planningand material. In the first instance this concernsthe possibility of the unhindered absorbingchanges is length, the functionally correct instal-lation of device for changes of length as well asthe arrangement of pipe mountings.

If fittings with actuators or also measurement,control and monitoring devices are installed thecorrect and planned function of the equipment isalso to be examined.

Bibliography

[1] DVS 2210 Part 1: 1987Deutscher Verband fr Schweitechnik undverwandte Verfahren e. V., Deutscher Verlagfr Schweitechnik GmbH, Dsseldorf

[German Association for Welding Technolo-gy and Related Processes]

[2] LAWA: Leitlinien zur Durchfhrung von Kos-tenvergleichsrechnungenLnderarbeitsgemeinschaft Wasser, 1998[German Federal State Working Group Wa-ter (LAWA): [Guidelines for the carrying outof cost comparison calculations]

[3] Wagner, W.: RohrleitungstechnikVogelverlag und Druck KG, Wrzburg 1993[Pipeline technology]

[4] Proff, E.; Lohmann, H. J.: Rheologische Cha-rakterisierung flssiger KlrschlmmeKorrespondenz Abwasser (44), No. 9, 1997[Rhealogical characterisation of liquid sewa-ge sludge]

[5] Proff, E.; Lohmann, H. J.: SchlammfrderungKorrespondenz Abwasser (44), No. 10, 1997[Conveyance of sludge]

[6] Klauwer, E. u. a.: Druckverluste bei Frde-rung von Klrschlmmen in Rohrleitungen.

Untersuchungen des Ruhrverbandes,unverffentlicht[Pressure losses with the conveyance ofsewage sludge pipelines. Investigations ofthe Ruhr Association, unpublished]


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Appendix

Appendix A: Tables

A1 Table 1: Media and pipe materials in wastewater treatment plants

A2 Table 2: Dimensions of steel and stainless steel pipelines

A3 Table 4: Pipe wall thicknesses for plastic pipes

A4 Table 8: Media in wastewater treatment plants and fittings employable for these

A5 Table 9.1: Permitted supporting spans steel pipes

A6 Table 9.2: Permitted supporting spans thermoplastic plastic pipes

A7 Table 9.3: Permitted supporting spans duraplastic plastic pipes

A8 Table 10: Design of supports and securing material


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A2 Table 2: Dimensions of pipelines made from steel and stainless steel

12) Authors afternote: DIN 2440 has been withdrawn and replaced by EN 10255

Steel pipes Stainless steel pipes

Nominaldiameter

DN

Threaded pipemedium gauge

DIN 244012)

Steel pipe,welded Welded or seamless

68

1015

20

1/81/43/81/23/4

10.2 x 2.0013.5 x 2.3517.2 x 2.3521.3 x 2.6526.9 x 2.65

13.5 x 1.617.2 x 1.621.3 x 1.826.9 x 1.8

10.2 x 1.613.5 x 1.617.2 x 1.621.3 x 1.626.9 x 1.6

253240506580

11 1/41 1/22

2 1/23

33.7 x 3.2542.4 x 3.2548.3 x 3.2560.3 x 3.6576.1 x 3.6588.9 x 4.05

33.7 x 2.042.4 x 2.348.3 x 2.3

60.3 x 2.376.1 x 2.6

88.9 x 2.9

33.7 x 1.642.4 x 1.648.3 x 1.660.3 x 1.6

76.1 x 1.688.9 x 2.0

100125150

200

250

4 114.3 x 4.50 114.3 x 3.2139.7 x 3.6168.3 x 4.0219.1 x 4.5273.0 x 5.0

114.3 x 2.0139.7 x 2.0168.3 x 2.0219.1 x 2.0273.0 x 2.0

300350400450500

323.9 x 5.6

355.6 x 5.6406.4 x 6.3457.0 x 6.3508.0 x 6.3

323.9 x 2.6

355.6 x 2.6

406.4 x 2.6457.0 x 3.2508.0 x 3.2

600

700

8009001,000

610.0 x 6.3711.0 x 7.1813.0 x 8.0914.0 x 10

1,016.0 x 10

610.0 x 3.2711.0 x 4.0813.0 x 4.0914.0 x 4.0

1,016.0 x 4.0

Notes:

The external diameters are classified in accordance with ISO 4200 Series 1.

With wall thicknesses for the steel pipes one is concerned with the Preferred Wall

Thickness

Series D from ISO 4200.

With wall thicknesses for the stainless steel p

Documents

ATV-DVWK-M_275E-Pipelines for the Area or Technical Installation of Wastewater Treatment Plants