TRAINING MODULES - IRC · 2014-03-07 · Training modules for waterworks personnel in developing countries Module 3.6 Page 6 1.3 ' Use of sight rails Sight rails are needed to prepare

TRAINING MODULESFOR

WATERWORKS PERSONNEL

Special Skills3.6

Pipe-laying procedures and testing of water mains

.0. 8(33 o!

Training modules for waterworks personnelin developing countries

Foreword

Even the greatest optimists are no longer sure that the goals of the UN "International DrinkingWater Supply and Sanitation Decade", set in 1977 in Mar del Plata, can be achieved by 1990.High population growth in theThird World combined with stagnating financial and personnelresources have led to modifications to the strategies in cooperation with developing coun-tries. A reorientation process has commenced which can be characterized by the followingcatchwords:- use of appropriate, simple and - if possible - low-cost technologies,- lowering of excessively high water-supply and disposal standards,- priority to optimal operation and maintenance, rather than new investments,- emphasis on institution-building and human resources development.Our training modules are an effort to translate the last two strategies into practice. Experiencehas shown that a standardized training system for waterworks personnel in developingcountries does not meet our partners' varying individual needs. But to prepare specificdocuments for each new project or compile them anew from existing materials on hand can-not be justified from the economic viewpoint. We have therefore opted for a flexible system oftraining modules which can be combined to suit the situation and needs of the target groupin each case, and thus put existing personnel in a position to optimally maintain and operatethe plant.The modules will primarily be used as guidelines and basic training aids by GTZ staff andGTZ consultants in institution-building and operation and maintenance projects. In themedium term, however, they could be used by local instructors, trainers, plant managersand operating personnel in their daily work, as check lists and working instructions.45 modules are presently available, each covering subject-specific knowledge and skillsrequired in individual areas of waterworks operations, preventive maintenance and repair.Different combinations of modules will be required for classroom work, exercises, and prac-tical application, to suit in each case the type of project, size of plant and the previous qualifi-cations and practical experience of potential users.Practical day-to-day use will of course generate hints on how to supplement or modify thetexts. In other words: this edition is by no means a finalized version. We hope to receive yourcritical comments on the modules so that they can be optimized over the course of time.Our grateful thanks are due to

Prof. Dr.-lng. H.P. HaugandIng.-Grad. H. Hack

for their committed coordination work and also to the following co-authorsfor preparing the modules:

Dipl.-lng. Beyene Wolde GabrielIng.-Grad. K. H. EngelIng.-Grad. H. HackIng.-Grad. H. MauserDipl.-lng. H. R. JolowiczK. Ph. Muller-OswaldIng.-Grad. B. RollmannDipl.-lng. K. SchnabelDr. W. Schneider

It is my sincere wish that these training modules will be put to successful use and will thussupport world-wide efforts in improving water supply and raising living standards.

Dr. Ing. Klaus ErbelHead of DivisionHydraulic Engineering,Water Resources DevelopmentEschborn, May 1987

s^ Training modules for waterworks personnelin developing countries

•Module

3.6

Page

Title: Pipe-laying procedures an testing of water mains

Table of contens:

_!_.____Simple surveying and setting-out work

1.1 Setting-out of straight lines and angles1.1.1 Setting out of a straight line1.1.2 Setting out of a right angle1.1.3 On- site determination of the angle of a bend

1.2 Levelling1.2.1 Stepping down1.2.2 Spirit Levelling

1.3 Use of sight rails

2_.____Transport and storage of pipes

3_.____Preparation of trench floor and backfilling of the trench

£.____Tools, accessories and other equipments used in pipe laying

4.1 Tools for cutting and re-working of pipes4.2 Special devices and tools for jointing

socket pressure pipes and fittings

5.____Pipe jointing

5.1 General points5.2 Tyton socket <5.3 Flange joint5.4 Screwed socket joint5.5 Jointing of plastic pipes5.5.1 Socket - and - spigot joints5.5.2 Adhesive sockets5.5.3 Welded and screwed joints5,6 Jointing of asbestos cement pipes

Page

2223

445

10

10

13

14

14141.5161717171718

J&

6.

6.16.2

6.36.46.4.16.4.26.5

7.

8.

8.18.28.2.18.2.28.3

Training modules for waterworks personnel Moc

in developing countries

Concrete thrust blocks for pressure pipes ,

General pointsCalculation of the resultant shearstress at elbows *Concrete thrust blocks for horizontal elbowsConcrete supports for vertical elbowsResultant force directed towards the airResultant force directed towards the groundConcrete supports for pipe ends

Pressure Testing

Laying of cummunication pipes to private or publicdraw - off points

General requirementsConnection of communication pipes to the mainDescription of tapping procedureInstallation of water metersPublic taps

Jule Page

19

19

192022222324

24

27

2728

293131


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_!_._____Simple surveying and setting-out work

1.1 Setting out of.straight lines and angles

1.1.1 Setting out of a straight line

Ranging rods are planted vertically at the beginning andend of the required straight line, and other range poleslined in at intermediate points between them by sightingfrom one end. The observer should stand roughly 2 to 3 metresbehind the first range pole to achieve a better sight.

For precise setting-out work a theodolite or level withhorizontal circle is used. The telescope is set up verticallyabove one extremity of the line and the required straightline set out by adjusting a given horizontal angle and sight-ing along the bases of the ranging rods.

1.1.2 Setting out of a right angle

A right angle can be plotted by setting out the sides ofa triangle in the ratio 3:4:5.

In practice, this involvesmeasuring out the lengths ofthe two adjacent sides (inthe example 3.00 and 4.00 m).and moving the positions ofthese sides about until the•lenght of the hypotenuse isexactly 5.00 m. The trianglecan be made larger or smallerby multiplying or dividing

h

the lengths of the sides bythe same figure, i.e. theratio remains the same.

N

N

\\

A-.QQ

In the example shown by dotted lines, the lengths of thesides of the triangle have been multiplied by 2:(3.00 m x 2 = 6.00 m, 4.00 m x 2 = 8.00 m, 5.00 m x 2 = 10.00 m)

Revised:

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1.1.3 On-site determination of the angle of a bendWhere the location route of a pipe changes direction, theangle of the bend can be determined on site, using specialtables.For this purpose, the alignment of the approaching pipeaxis is continued beyond the bend and the alignment of1 thediverging pipe axis sighted in. Then, from the point ofdivergence, an arc with a radius of 10.00 m is marked out,to cut both the fixed and the diverging pipe axis, andthe two points of intersection are joined by a straightline. The length, of this'line is used to find the angleof the bend from table 1. .In the example shown in fig. 2, the length of the connectingline is 6.01 m and the angle of the bend 35°.Fig. 3 shows an instance where an elbow giving an angleof 30° is installed and the remainder of the required angleachieved, by bending two^socket joints through .2 1/2° each.

sm

0.0000.1750.3500.5500.7000,8751.0451.2201.3951.5701.7451.9202.0902.2652.4402,6102.7852.9553.1303.300 .3.4753,6453.8153.9904 SO

Y°

. 0123456789011

" 12131415161718192021222324

sm

4.3304.500 ,4,6704.8405.0105,1755.3455.51S5.6805.8506,0106.1806.3506.5106,6806.8407.0007,1707.5307.4907.6507.8107.9808.1358.295

Y"

2526,2728293031323334353637383940.414243444546474849

Sm8.4508.6108.7708.9259.0809.2409.3909.5459.7009.85010.00010.15010.30010.45010.60010,75010.89011,04011,18011.33011,47011,61011.76011.90012.040

Y°

505152535455565758596061626364 .65666768697071727374

sm

12.18912.31012,45012.58512.72012.86012,99013.12013.25013.38013.51013,64013.77013.89014.020.14.140

V

75767778798081828384858687888990

Table 1 - On-site determination of the angle of a bend

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Fig. 2 Measuring the angle of a bend Range poles

Fig. 3 Constructing a pipe bend

1.2 Levelling1.2.1 Stepping down

This is the simplest method of levelling and it is necessaryon steep slopes. An offset staff orlevelling rod is adjusted with the aidof a spirit level so that it is exactlyhorizontal, and the perpendicular dis-tance from the ground measured alonga plumb line.

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5

1.2.2 Spirit levelling

This is the most commonly used method of leveling. Thetechnique is used to ascertain the varying levels of theground along a pipe route, longitudinal and cross sections,depths of foundations, elevations of buildings, etc.

Fig. 4 Spirit levelling

Basic principles of the technique

The line of sight of the levelling instrument (telescope)is adjusted with the aid of a spirit level until it isexactly horizontal , and the height h, between the line ofsight and the upper edge of a known fixed point is readoff the levelling staff. The height of the collimation line'ZH is then . .ZH = FPj/m.s.l + h1 100.000 + 2.252 = 102.252 (back sight)

After this, the levelling staff is set up on the point W, ,the level of which is sought, and the height h« betweenthe horizontal line of sight and the point of elevation isread off the levelling staff.The level of 1 is then given byW = ZH - h = 102.252 - 1.212 = 101.040 (foresight)

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1.3 ' Use of sight rails

Sight rails are needed to prepare a trench floor with therequired fall of gradient.

Sight rails are set up at all changes of gradient and at bends,the bends lie out of sight of each other, intermediate sightrails are set up.

At least 2 fixed sight rails and 1 boning rod (traveller)are needed.

The upper edge of the two fixed sight rails is related tothe planned level of the trench floor at each position.The difference in level between the top edge of the sightrail and the planned bottom of the trench is the same foreach fixed sight rail. This is selected (as a round number)in such a way that the top edge of the sight rail is roughlyat eye level. The height of the boning rod corresponds tothe difference in level between the fixed sight rails and thetrench floor at each position.

The sighting procedure is begun by setting up the boningrod at an arbitrary position in the trench between the twosight rails. The trench is at the correct level if, whensighting along the trench, the upper edges of the sight railsan.d of the. boning rod are seen to be in alignment,.

Example

Position 1: planned trench floor level 124.35 m above m.s.l.level of ground 125.80 m above m.s.l.

Position 2: planned trench floor level 124.85 m above m.s.l.level of ground 126.10 m above m.s.l.

Calculation of length of boning rod:

= mean ground level + eye level - mean trench floor level= 125.85 + 1.50 m - 124.60 m = 2.75 m, rounded off 2.50 m

Height of sight rail at position 1:124.35 m + 2.50 m = 126.85 m above m.s.l.Height of sight rail at position 2:124.85 m + 2.50 m = 127.35 m above m.s.l.

If

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S»VCXHT KA.IL

Fig. 5 Boning in a trench

2. Transport and storage of pipes

Pipes for water supply systems are normally transportedby lorry, and unloaded either directly where they are tobe used, along the route of the pipeline, or first storedfor an intermediate period. Smaller pipes can be unloadedby hand; larger pipes need a crane or excavator. If nomachines are available, a temporary structure must be erected,- e.g. a ramp constructed out of planks or square-sawn timbers.

When unloading, transporting or storing pipes, attentionmust be paid to the following points:

To prevent any damage to the external insulating layer,no sharp-edged devices or tools may. be used when unloadingthe pipes.

Revised:

(olfpZ Training modules for waterworks personnel Module Page>-T^ in developing countries 3.6 8

All pipe lengths must be stored in such a way that theirinternal surfaces cannot be contaminated by earth, dirt, mudor dirty water.

When storing the pipes, care must be taken to securethem against rolling, slipping or vibration.

Seals, rubber rings and plastics pipes must be covered to .prevent direct exposure to sun! ight.

If pipes are stacked, a level, adequately strong (depend-ing on the height of the pile) supporting surface shouldfirst be made out of planks or square-sawn timbers.

When stacking large-diameter pipes, it is advisable toprovide intermediate stages made of square timbers and tosecure each layer separately with wedges. The supportingtimbers should be approx. 1 m away from the end of thepipes. The storage area should be chosen in such a waythat the pipes do not come into

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Preparation of the trench floor and backfilling ofthe trench

right

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Fig. 7 Preparation of trench floor

The reliable function-ing and efficiency ofpipe systems dependvery largely on the correct,competently performedlaying of the pipes.Pipes must be laid sothat they slope steadily,with rising and fallinggradients.Socket holes mustbe provided forthe joints. Point andlinear loads must notoccur. Trench .floors notproviding adequate sup-port must be stabiliziedwith broken stone, coarsegravel or layers oflean-mixed concrete.These stabilizing layersshould be covered withfine sand or suitablelocal material to preventdamage to the insulatinglayer on the pipe.

Fig. 7 Laying of pipes

When the pipes have been laid thrust blocks must be con-structed to support bends, branches and fittings at pipe ends.Before the pressure test, the pipes must be weighted withearth bridges to prevent changes of position and, if thereis ground water in the trench, to counter upthrust.

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Following the pressure test, the socket holes and trenchesshould be carefully filled in with earth or otfier suitablefilling material. Care must be taken to use only stone-freematerial, especially when covering plastics or asbestoscement pipes. Aggressive peat or heavy clay soils shouldnot be used.

Trenches under roads or other areas used by traffic shouldbe back-filled and compacted in layers.

4____Tools, accessories and other equipment used in pipelaying

4.1 Tools for cutting and re-working pipes

In addition to standard small tools such as hammers, spanners,pliers, emery paper and wire brushes, use is made in pipelaying of other, special tools and accessories, which arespecifically adapted to the material and the internal diameterof the pipes. Some of these tools and appliances are des-cribed below.

Metal bow saws with insertedsaw blade can be used for alltypes of material and smallerdiameters.

Fig. 8 Metal bow sawPlastics pipe cutters are suit-able for cutting polyethylenepipes up to DN 2"

Fig. 9 Plastics pipe cutterHandsaws can be used to cutPVC pipes up to DN 200.

Fig. 10 Handsaw

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Fig. 11 Electric angular-typedisc grinder . . -

Electric angular-type discgrinder .

This appliance is suitable forall materials and diameters.It should be noted, however,that cutting asbestos cement pipeswith this tool produces a finedust which is detrimental tohealth; appropriate precautionsshould therefore be taken. Toprevent accidents, under wet con-ditions a cutting grinder drivenpneumatically or by a petrolengine should be used.

Four-wheel pipe cutters areavailable in various sizes andare especially suitable forsteel or cast iron up to DN 250.The cutting wheels are exchange-able and should be matched tothe pipe material. • "

Fig. 12 Four-wheel p.ipecutter

Fig. 13 Pipe cutter

The pipe cutter is suitable forall pipe materials and for dia-meters up to 400 mm. The deviceis simple to use, not dependenton any energy supply and can beused where space is limited. Thetool is adjusted to differentpipe diameter'by means of guideattachments. The cutters areground on both sides and can bere-ground several times.

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Motor-driven pipe saws are usedfor large-diameter pipes. Thepipe saw is fixed to the pipewith an adjustable, spring-mountedstirrup chain and guide rollers.When power feed is switched on,the saw automatically travelsround the pipe. Saws providedwith pneumatic motors can alsobe used under water.

Fig. 14 Pipe saw

After cutting, the cut pipe ends must be prepared for jointing.The cut ends of steel, cast-iron and plastics pipes areskimmed and chamfered using a file suited to the material.The^ cut errds of'asbestos cement-pipes must be re-workedto recover the bore for jointing.

The turning device for re-covering the bore of asbetoscement pipes is fixed in thepipe with the aid of a clampingattachment adjusted to the pipe'sinternal diameter. The turningtool can generally be set to acutting depth of at most 1.5 mm.If necessary, the pipe must beturned several times until therequired external diameteris achieved.

Fig. 15 Turning device

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4.2 Special devices and tools for jointing socket pressurepipes and fittings.

When fitting pipes using alever, the spigot end is pushedinto the socket of the pipelength in front of it. A thickpiece of square-cut wood shouldbe placed between the socketand the lever.-Suitable up to DN 150-

Fig.. 16. Fitting with alever

Fig. 17 Fitting device

When a fitting device is used,a clamping ring is placed overthe spigot end of the pipe anda cable with bracket fixed tothe socket. Then the fork isplaced over the clamp pin, thecables connected up and thespigot end pushed in.-Suitable up to DN 400-

A hoist or windlass is usedfor. larger-diameter pipes. Oneend of the windlass is attachedto a cable fastened to the spigotand the other to a cable attachedto the socket, and the pipelengths are pushed in together.

Fig. 18 Windlass

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14Pipe jointing

5.1 General points

Fig.. 19 Cleaning thesocket

The most common types of joints in pipe laying are socket .and flange joints, with rubber seals. Depending on thepressure stage, type of pipe material and pipe diameter,screwed or adhesive joints and compression screwed jointsare also used. Some of the methods commonly used to jointpipes are described below. When carrying out the work, theinsructions and recommendations of the manufacturer shouldalways be followed. ' •

5.2 Tyton socket

The inside of the socket mustbe thoroughly cleanded, payingparticular attention to removingany remains of paint or dirtfrom the retaining groove andthe seat of the seal. The spigotend should be well cleaned upto the mark showing the depthof insertion in the socket.The sealing surface inside thesocket is coated with the lubri-cant provided by the pipe manu-facturer.The sealing ring is cleaned

and held in such a way thatit takes on the form of a heart.The sealing ring is placed inthe socket so that the outerhard-rubber rim engages in theretaining groove inside thesocket. Then the complete ring ispressed smoothly into placeround the socket. The inner hard-rubber rim of the ring must

Fig. 21 and 22 Insertion of thesealing ring

Fig. 20 Applicationof lubricant

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Fig. 23 Correct seatingof the sealing ring

-••-. I.-. •

not project over the spigot.A thin layer of lubricant isapplied to the sealing ring. Thespigot is coated with lubricant,especially at the bevelled edge,and then pushed up to the mark.into the socket. After the jointis completed, the seat of the .sealing ring should-be inspectedround the complete circumfer-ence of the pipe, using a feeler.

Fig-. 24 Exanrinaticm of seatof sealing1 ring

5.3 Flange joint

A flange joint consists of two.-flanges, a sealing ring anda number of hexagon-head screws.The position'of the screw holes,whatever the material, is suchthat they are arranged symmetric-ally to the two main axes, with- ,out being in these axes, andthat their overall number isdivisible by 4 in all pipe dia-meters.

Fig. 25 Flange joints ,

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Flanges having the *same nominal diameter and the same nominalpressure can be joined regardless of their design and thematerial of which they are made. Corrosion-proof screwsshould be used as far as possible; otherwise a protectivebandage should be wrapped round the flanges.

Before screwing them together, the sealing strips of theflanges should be thoroughly cleaned.

The screws should be thightened in crosswise order, i.e.each screw followed by its opposite, so that compressionis as even possible; finally all screws are fully tightened.

5.4 Screwed socket joint

The screwed socket joint con-sists of a socket, a rubbersealing ring and a threaded ring.The inside of the socket and theoutside of the ring have a castthread. Screwing in the ringcompresses the rubber ring andc:3als the joint.

Procedure:

The sealing and threaded surfacesshould be cleaned particularlythoroughly. The depth of in-sertion in the socket is markedon the spigot end. The threadedring, slide ring and sealingring are pushed in that orderdown the spigot, beyond themark.

The spigot is thoroughly coatedwith the lubricant suppliedby the manufacturer, then placed

Fig. 26 Screwed socket

joint

Fig. 27 Cleaning ofthreaded socket

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in the socket and^the insertiondepth checked. The sealing ringis pressed into its seat andthe slide ring pushed up. Thethreaded ring is screwed inand tightened with a hammeror ram.

Fig. 28. Tightening of ascrewed socket joint

5.5 Jointing of plastics pipes

5.5 Socket-and-spigot joints

Plastics pipes laid underground usually have socket-and-spigotjoints sealed with rubber rings. The procedure is similar"to that described under 5.2 for Tyton sockets.

5.5.2 Adhesive sockets

The proceudre with adhesive sockets is as follows:

The spigot is pushed into the socket and the depth of inser-tion marked.,.Care should be taken to push the spigot, .rightup to the end of the socket. The surfaces which are to bestuck together must be dry, free of dirt and treated witha special cleaner recommended or supplied by the pipe manu-facturer. Where pipes are highly discoloured, these surfacesshould be roughened with emery paper before jointing.

Jointing by this method should not be carried.out at tem-peratures below 5°C. The adhesive is applied with a brushto the inside of the socket and to the spigot, and the spigotinserted wi'hout delay into the socket, up to the mark.

No correction can be made after insertion. Any excess adhesivemust be removed immediately.

5.5.3 Welded and screwed joints

One of the methods of jointing which produces a permanentjoint is welding. Two types of welded joints are describedbelow:

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Fig. 29 Welded joint

One type of welded joint usedfor polyethylene pipes is theelectrically welded socket.Here, heating wires with contactsockets are let into the endsurfaces of the sockets. Thecoil is heated up by an automaticdevice via these contacts. Theheat reaching the material pro-duces a tight joint betweenspigot and socket.

The second commonly used method is butt welding. In this, thepipes are heated by a heating element to approx. 200°C;the heating element is removed and the pipe ends joinedunder pressure of 1 to 2 bars. The disadvantage of thismethod is the welding bead which it produces in the interiorof the pipe.

Screwed joints are separable joints which are mainly usedfor small-diameter polyethylene pipes.

5.6 Jointing of asbestos cement pipes

Various different types of joints are offered by the manu-facturs of asbestos cement pipes. One commonly used typeis the "Gibault" coupling. This is a stuffing-box joint;

it is sealed through the com-pression of rubber "0" rings byscrews which are tightenedbetween an intermediate sleevering and two outer loose flanges."Gibault" couplings can be bent

• -

at an angle, accommodate rela-Fig. 30 "Gibault" coup- tively large tolerances of externalling diameter and can be re-sealed.

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.6_.____Concrete thrust blocks for pressure pipes

6.1 General points " .

Numerous forces act on pipes and their joints.

Pipes are under stress from trie internal pressure - i.e.test or operating pressure. In the operation of a pipe system,sudden increases of pressure may occur, - e.g". pressure surges("water hammer") .caused by closing a stop valve too quickly.Negative pressure may occur when a pipe is being drained.

Where pipes are laid underground, other external forcesalso act on them; e.g. during back-filling of the trenchand compacting of the material,- followed by the pressureof the earth covering and possibly by traffic movements, etc.

In the case of pipes with joints which transmit longitudinalfarce - i.e. welded and flange joints - the shear forces aretransmitted to the entire pipe run. Pipes with jointswhich do not transmit longitudinal force - i.e. Tyton,screwed and socket-and-spigot joints - either cannot transmitforces acting along the longitudinal axis, or only to a verylimited extent.

In this case, unbraced bends, tees and fittings at pipe endsare forced away by the internal pressure in the pipes. ; .

The forces resulting from the internal pressure in the pipemust be resisted by thrust blocks or anchorage.

Generally speaking, the forces should be transmitted to the sideof the trench; if this is not possible, the concrete thrust blocksmust be dimensioned in.such a way that the shear stress -is absorbed through the friction between concrete and .earth-alone.

6.2 Calculation of the resultant shear stress at elbows

The resultant shear stress R is calculated by the formula:

R = 2P X sin OL~T

p = p "Ir x d24-

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where

P = shear stress parallel to pipe axis (N)R = resultant shear stress (N)d = outer diameter of pipe

•p = test pressure

Table 2 below gives the resultant shear stresses R for theusual test pressures from 15 to 21 bars, also for the usualangles and diameters up to ON 500.

Table 2 Resultant shear stresses R in KN1 KN (kilonewton) = 0,1 t

11°22°30°45°

Dia. 100Test press,15 21

3.26.48.512.6

4.59.011.917.6


6.713.317.626.0

9.318.624.736.5


17.334.546.068.0

24.348.564.095.0

Dia. 300Test press.15 21

24.549.065.096.0

34.568.091.0134.0

Dia 400Test press.15 21

42.585.0112.0166.0

60.0119.0157.0232.0

Dia 500Test press.15 . 21

67.0130.0173.0255.0

94.0182.0242.0357.0

6.3 Concrete thrust blocks for horizontal elbows

The calculations below are based on the following assumeddata:.

the side of the trench is to be used to absorb the shear'stress and the thrust block is to be concreted against the trenchside;

the distribution angle of the shear stress is 90°;

the permissible stress applied to the trench side isCfc = 10 N/cm2

( 0? for sand or clay soils);

the permissible compressive stress on the concrete,d = 200 N/cm2

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Theoretical shape of the concrete thrust block:B = width of contact of thrust blockand elbow,

i i 4 N* 4------•-—-^- I 1_ ..«»-;

R0.707d

H = tickness of concrete thrust blockcalculated using the formula:

Jj = (2 H + B) (2 H + 0.707d)OB

Examples:

si—•• i.y~;

The following examples of thrust blocks in varying sizes are shownfor the resultant shear stresses "R" given in table 2:

Example I

DN 80 - 150R = 10 KN (1 t)

Example II

DN 100 - 250R = 10 KN - 20 KN

Example III

DN 150 - 400R = 36 KN - 52 KN

Example IV

DN 200 - 400R = 52 KN - 72 KN

Example V

DN 250 - 500R = 72 KN - 120 KN

r

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Example VI

DN 300 - 500R = 120 KN

It is not permissible to fill any gap that might resultbetween trench side and concrete with trench-filling materialafter construction of the thrust block. The thrust block must befirmly connected to the undisturbed ground. Depending onthe type of fitting, adequate space should be allowed for re-packingor re-tightening the joint.

6.4 Concrete supports for vertical elbows

6.4.1 Resultant force directed towards the .air

In the case of vertical elbows, the shear stress must beb

absorbed by the weight of concrete. The figures given inthe table below and the following examples are given fordry pipe trenches. If the support is in water, the resultingupthrust must be taken into account.

b/1% 1 Co.nc.rete. thPus.t blocks in m3 for test .pressures, between15 and 21 bars

la

11°22°30°45°

Di 100.15 2.1

0.150.290.390.57

0.200.410.540.80

Dia. 150.15 21

0.300.600.801.19

0.420.851.121.66

Dia. 250. 15 .21

0.791.572.083.08

1.102.202.914.31

Dia. 30015 21 ..

1.122.222.954.35

1.513.114.126.10

Dia.•15.

1.933.855.107.54

40021

2.755.387.1410.56

Dia. 500: 15 21.

3.045.917.8511.60

4.258.2810.9916.24

Examples:

Example I

up to DN 150up to 0.65 m3 of concrete

Revised:


Module3 > 6

Page23

IT*Example II

DN 150 - 3000.65 to 1.30 m3

of concrete

Example III

DN 150 - 4001.30 to 2.60 m3

of concrete

Example IV .

DN 200 - 5002.60 to 5.20 m3

of concrete

6.4.2 Resultant force directed towards the ground

The shear stress directed towards the grond is absorbedby the undisturbed trench floor. The amount of the resultantshear stress can be found in Table 2.

Examples

Example IDN 8 0 - 1 5 0R = up to 30 KN (t)

Example II

DN 150 - 250R = 30 - 90 KN

H—a»m

Sctmilt

;<*J—on-

H~.O.»O

Revised:

(vfrZ Training modules for waterworks personnel Module Page^Jr~^ in developing countries 3 6 24

Example III

DN 200 - 300R = 90 - 120 KN

Example IV

DN 250 « 400R = 120 - 160 KN

Example V

DN 300 - 500R = 160 - 220 KN

% ,"- aco-r-^ LjF~

• •" 'H— 1,00—%

n^ C *Sr<^— ——— ——————— —— ———— ;

^5=-

XJ/ i - r r~ — — - — —"-.ojom ^Ipg^lj*''' ' "•*""" <

*~- 130 —— |

6.5 Concrete supports for pipe ends*

Table 4 Dimensions of thrust block at 15 bars test pressure

DN B x B

' 100 10 x 10150 15 x 1520(J 20 x 20250 25 x 25300 30 x 30400 40 x 40500 50 x 50

(figures in cm)

7 Pressure

C x 'C D min '

1 140 -x 40 10 k <n i '60 x 60 15 [ 170- x 70 25 j

*-» A90 x 90 32

110 x 110 40140 x 140 50 .1 __ c __ ,170 x 170 60 -"1- .- ———— -,

° ^3

Ttesting > \>B

d-d

; i ;

^^~ uo^^^

(.1

— wo —

h

A -A. A pressure test is a test carried out over a certain limited

period of time with a test pressure 1.5 times the nominalpressure of the pipe.

Revised:


Module

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25

Longer pipes are divided into lengths of approx. 500 m fortesting. . ,.

Testing procedure: ' • ' ,

Before being filled with water, the pipe length must beadequately .supported and 'anchored not only at the ends of•fhe test run, but also at all elbows.and tees... ..

Pressure tests should not be carried out against closedvalves." The pipe should be closed off with the aid of blankflanges or.plugs. ' • .

The supports an anchors mustbe dimensioned so as to resistthe relevant test pressure.

PBESSUB.E. PUMP Attention should be paid tothe permissible earth pressure(see heading 6 for examples).If the p.ipe is laid in a trench,the pipe bridges should be adequatelystressed and the joints kept free.The water .used for the pressuretest should be as clean as pos-sible. The pipe should be filled

Fig. 31 End construction slowly enough to allow all thefor pressure test air to escape.

Fig. 32 Air release from pipe run

Revised:


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WATER CO»J-suhFO«

Fig. 33 Pressure pump tank

-The amounts of water required toproduce the pressure are read off atthe pressure pump tank.

For the test, calibrated pressuregauges should be installed, whereverpossible at the lowest point of thepipe run. An autographic recorderplus an additional monitoring mano-meter are recommended.

The duration of the test depends on the diameter and im-portance of the main. It should last long enough to allowall defects to be discovered.

In the case of cast-iron and steel pipes without cementmortar lining, also PVC pipes, the test pressure must remainconstant, at temperatures as even as possible, for a periodof several hours.

In the case of asbestos cement or cement-mortar lined pipes,the inner walls of the pipe absorb water.

Standard figures for the water absorption of asbestos cementpipes in 1/m2 of internal surface at a pressure of 10 bars:

During the

3rd half hour0.015

1st half hour 2nd half hour0.03 0.02

4th half hour0.0125

As a safety measure, no work may be carried out on the mainsduring the pressure test. If there is leakage during thetest period, the pipe must be drained slowly and, afterthe defective section has been located and the fault remedied,re-filled and tested again.

Flushing and disinfection

Before new pipes are taken into service, these must bethoroughly cleaned, flushed and disinfected.

Suggestions on methods to follow here are given in Module 3.7

Revised:

J^ Training modules for waterworks personnelin developing countries

Module

3.6

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27

8.1

Laying of communication pipes to private or publicdraw-off points

General requirements

ACTlOtO

Communication pipes are the connecting link betweenthe water mains and the individual draw-off points; theymust be laid with the same care as the mains themselves.

When possible, communication pipes, should be run in a straightline uphill to the draw-off points'and should be covered withearth as a precaution against frost or other damage. ,

If the mains run empty, due to lack of water or repairwork, there is a risk of contaminated water being sucked

back into the drinkingwater supply system from .the draw-off point (fig.34).To avoid the risk of con-taminating of entiremain, with the healthrisk this involves, non-returnvalves preventing backsiphonage and air reliefvalves must be installedin the communicationpipe (fig. 35).The non-return valesshould be. installed before thefirst draw-off point, mostconveniently following thewater meter.The air valve should belocated at the high

Fig. 34

Fig. 35

point of the mains systemafter the back-shiphonagepreventing device.

Revised:

J^ Training modules for waterworks personnelin developing countries

Module

3.6

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28

Water meters are installed to measure the quantity of waterconsumed by individual consumers and to calculate the appropriatecharges. They also discourage unnecessary wastage of water throughdripping or running taps.

Where water is supplied without a meter, spring-loaded,self-closing valves sjiould be installed.

8.2 Connection of communication pipes to the main

Communication pipes are generally connected to the mainby means of tapping clamps or tapping bridges. Due to theirnarrow bracket, tapping clamps are only suitbale for cast-iron pipes. In the case of plastics or asbestos cement pipes,tapping bridges should be used, since the pressure on thepipe-will then be less due to the greater width of the bridge.

Water mains may'be tapped either under pressure or withoutpressure. When a main is tapped under negative pressure,a stop valve is necessary in addition to the tapping clamp.The following examples have been chosen for descriptionfrom the many varieties of tapping devices and valves onthe market.

Fig. 36 Tapping clamp forcast-iron and steel pipes

Fig. 37 Tapping bridge for PVCand asbestos cement pipes

Fig. 38 Tapping clampwith flange

Fig. 39 Valve Fig. 40 Valve tappingclamp

Revised:


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Page29

Fig. 41 Screw-on column-typetapping device

Fig. 42 Tapping operation

8.2.1 Description of the tapping procedure

The tapping device is srewed onto the pipe clamp or bridgeby means of a nipple and a drill, chosen to correspond to thematerial of the pipe and the required drilling diameter. Byturning the spindle, a hole is cut through the side of, the pipe.After the hole has been drilled, the device is removed and thecommunication pipe connected up by means of the tapping clamp.If the clamp has a flange instead of a thread, a tapping devicewith flange instead of thread is als.o used.

If the pipe is to be tapped under pressure, a valve as shownin fig. 39 or a valve tapping clamp as in fig. 40 is installedin addition to the tapping clamp. The procedure is thenas follows:

The top section of the valve is removed and the tap-• ping device screwed on.

*

An auxiliary valve with flushing outlet is connectedat the side.

Revised:


Module

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Page30

Tapping is carried out and the drill withdrawn to itsstarting position.

The flushing outlet on the auxiliary valve is openedand the borings of (flushed out) during the drilling process.

The shutoff piston of the flushing pipe is screwedinto the prepared valve seating and packed.

The tapping device is removed and the top sectionreplaced.

The shutoff piston is withdrawn. »

The tapping valve is closed and the auxiliary valvewith flushing outlet removed.

Communication pipes and water meters

Polyethylene pipes have proved particularly suitable ascommunication pipes. These are supplied in rolls of upto 100 m, depending on diameter.

The brass screwed pipe joint shown below has proved reliableand easy to install.

Fig. 43 Brass screwed joint forpolyethylene pipes

Installation directions:

1. Cut off the polyethylene pipe at right angles,2. Push the coupling nut and clamping sleeve over the pipe,3. Tap the supporting sleeve right in,4. Push the pipe up to the limit into the fitting,5. Tighten the coupling nut with a pipe wrench.

Revised:


Module3.6

Page31

Installation of water meters

Water meters must be protected from frost or other damage.They should be installed in such a way that they can beeasily read and exchanged without an unreasonable amountof work.

Fig. 44. shows a typical meter installation, with intakevalve, water meter .and non-return valve. Exchanging themeter is facilitated by insertion of an approx. 2 cm longscrewed fitting. Where pipes pass through walls, they shouldbe wrappe'd in felt tape or provided with protective outertubing.

Fig. 44 Typical water meter installation

8.3 Public taps ;

Fig. 45 shows a public tap, which can be installed in eithera concrete or .stone masonary structure.

A recess is shown in the lower part of the structure; thisshould be left free for the installation of the valves andthe water meter. The recess should be1 closed off and providedwith a steel door and padlock.

Revised:


Module

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32

At—--(r^i

r

nab QD3P

Fig. 45 Public tap

Revised:


Module

3.6

Page

33

Table 1.. On site determination of the angle of a bendFig. 2 Measuring the angle of a bendRange polesFig. 3 Constructing a pipe bendFig. 4 Spirit levellingSight distance Sigth distanceBack sight ForesightFig. 5 Boning in a trenchSight rail Bonding rod Line of sightFig. 6 Stacked pipe lengthsFig. 7 Preparation of trench floorrigth wrong right wrongFig. 8 Metal bow saw .Fig. 9 Plastics pipe cutterFig. 10 HandsawFig. 11 Electric angular-type disc grinderFig. 12 Four-wheel pipe cutterFig. 13 Pipe cutterFig. 14 Pipe sawFig. 15 Turning deviceFig. 16 Fitting with a leverFig. 17 Fitting deviceFig. 18 WindlassFig. 19 Cleaning the socketFig. 20 Application of lubricantFigs.21 and 22 Insertion of the sealing ringFig. 23 Correct seating of the sealing ring right wrongFig. 24 Examination of-seat of sealing ringFig. 25 Flange joints right wrongFig. 26 Screwed socket joint Spacer gaugeFig. 27 Cleaning of threaded socketFig. 28 Tightening of a screwed socket jointFig. 29 Welded joint . -

Revised:


Module

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34

Fig. 30 "Gibault" couplingTable 2 Resultant shear stresses R in KNTable 3 Concrete thrust blocks in m3 for test pressure between 15and 21 barsTable 4 Dimensions of thrust block at 15 bars test pressureFig. 31 End construction for pressure testFrom pressure pumpThrust blockSteel plateScrew jack

Fig. 32 Air release from pipe runFig. 33 Pressur'e pump tankWater consumption for 1 bar

Fig 34Siphonic actionCommunication pipeDrainageMain

Fig. 35

Fig. 36 Tapping clamp for cast-iron and steel pipes

Fig. 37 Tapping bridge for PVC and asbestos cement pipes

Fig. 38 Tapping clamp with flange

Fig. 39 .Valve

Fig. 40 Valve tapping clamp

Fig. 41 Screw-on column-type tapping device

Fig. 42 Tapping operation

Fig. 43 Brass screwed joint for polyethylene pipes

Fig. 44 Typical water meter installation

Fig. 45 Public tap

Revised:

Deutsche Gesellschaftfur Technische Zusammenarbert (GTZ) GmbHDag-Hammarsk/old-Weg 1 + 2 D 6236 Eschborn 1 Tglefon (06196) 79-0 Telex 407SOW go d

The government-owned GTZ operates in the field of TechnicalCooperation. Some 4,500 German experts are working together withpartners from some 100 countries in Africa, Asia and Latin America inprojects covering practically every sector of agriculture, forestry, economicdevelopment social services and institutional and physical infrastructure.- The GTZ is commissioned to do this work by the Government of theFederal 'Republic of Germany and by other national and internationalorganizations.

GTZ activities encompass:

- appraisal, technical planning, control and supervision of technicalcooperation projects commissioned by the Government of the FederalRepublic of Germany or by other authorities

-advisory services to other agencies implementing developmentprojects

- the recruitment, selection, briefing and assignment of expert personneland assuring their welfare and technical backstopping during theirperiod of assignment

- provision of materials and equipment for projects, planning work,selection, purchasing and shipment to the developing countries

- management of all financial obligations to the partnercountry.

The series "Sonderpublikationen der GTZ" includes more than 190publications. A list detailing the subjects covered can be obtained from theGTZ-Unit 02: Press and Public Relations, or from the TZ-Veriagsgesell-schaft mbH, Postfach 36, D 6101 RoSdorf 1, Federal Republic of Germany.

TRAINING MODULESFOR WATERWORKS PERSONNEL

List of training modules:

Basic Knowledge

0.1 Basic and applied arithmetic0.2 Basic concepts of physics0.3 Basic concepts of water chemistry0.4 Basic principles of water transport1.1 The function and technical composition of

a watersupply system1.2 Organisation and administration of

waterworks

Special Knowledge

2.1 Engineering, building and auxiliarymaterials

2.2 Hygienic standards of drinking water2.3a Maintenance and repair of diesel engines

and petrol engines2.3b Maintenance and repair of electric motors2.3c Maintenance and repair of simple driven

systems2.3d Design, functioning, operation, mainte-

nance and repair of power transmissionmechanisms

2.3e Maintenance and repair of pumps2.3f Maintenance and repair of blowers and

compressors2.3g Design, functioning, operation, mainte-

nance and repair of pipe fittings2.3h Design, functioning, operation, mainte-

nance and repair of hoisting gear2.3i Maintenance and repair of electrical motor

controls and protective equipment2.4 Process control and instrumentation2.5 Principal components of water-treatment

systems (definition and description)2.6 Pipe laying procedures and testing of

water mams2.7 General operation of water mam systems2.8 Construction of water supply units2.9 Maintenance ot water supply units

Principles and general procedures2.10 Industrial safety and accident prevention2.11 Simple surveying and technical drawing

Special Skills

3.1 Basic skills m workshop technology3.2 Performance of simple water analysis3.3a Design and working principles of diesel

engines and petrol engines3.3 b Design and working principles of electric

motors3.3 c -3.3d Design and working principle of power

transmission mechanisms3.3e Installation, operation, maintenance and

repair of pumps3.3f Handling, maintenance and repair of

blowers and compressors3.3g Handling, maintenance and repair of

pipe fitt ings3.3h Handling, maintenance and repair of

hoisting gear3.3i Servicing and maintaining electrical

equipment3.4 Servicing and maintaining process

controls and instrumentation3.5 Water-treatment systems: construction

and operation of principal components:Part I - Part II

3.6 Pipe-laying procedures and testing ofwater mams

3.7 Inspection, maintenance and repair ofwater mams

3.8a Construction in concrete and masonry3.8 b Installation of appurtenances3.9 Maintenance of water supply units

Inspection and action guide3.10 -3.11 Simple surveying and drawing work

Deutsche Gesellschaft furTechnische Zusammenarbeit

(GTZ) GmbH

P O. Box 5180Dag-Hammarskjold-Weg 1+ 2

D6236Eschbom/Ts- 1Telephone (06196) 79-0

Telex 407501-0 gtzdFax No (06196)79-1115

TRAINING MODULES - IRC · 2014-03-07 · Training modules for waterworks personnel in developing countries Module 3.6 Page 6 1.3 ' Use of sight rails Sight rails are needed to prepare

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