Pipe Laying Metode

8/10/2019 Pipe Laying Metode

1/27

PIPELINE INSTALLATION


2/27

Table of Contents

UNOPS SDOC ToC - I

CHAPTER 4 PIPELINE INSTALLATION

TABLE OF CONTENTS

Page Nr.

CHAPTER4 PIPELINEINSTALLATION 1

SECTION4.1- PIPELAYING 1

4.1.1 General Requirements......................................................... ...................................................... 14.1.2 Installation of Pipe and Fittings...................................................... ........................................... 24.1.2.1 Installation of Ductile Iron (DI) Pipe and Fittings......................................................... ........... 24.1.2.2 Installation of Steel Pipe (SP) and Fittings............................................ ................................. 54.1.2.3 Installation of PE Pipe and Fittings............................................................................... ........... 64.1.2.4 Installation of Un-plasticized Polyvinyl Chloride (uPVC) Pipe and Fittings...................... 114.1.2.5 Installation of Galvanized Steel (GS) Pipe and Fittings...................................................... 13

4.1.2.6

Installation of Reinforced Concrete (RC) Pipe and Fittings................................................ 13

4.1.3 Exposed Piping............................................................................................................... .......... 14

4.1.4 Canal or River Crossing and Culvert Crossings.............................................. .................... 15

4.1.5 PIPELINE MARKER TAPE.................................................................................................... 15

SECTION-4.2 CONNECTIONSTOEXISTINGMAINS ........................................................... 16

4.2.1 General...................................................................................................................................... 164.2.2 Execution.................................................................................................... ............................... 174.2.3 Testing............................................................... ................................................................ ......... 17

SECTION-4.3 INSTALLATIONOFVALVES&MARKERPOSTS .......................................... 17

4.3.1 General...................................................................................................................................... 174.3.2 Materials.................................................................................................................................... 184.3.3 Location of Installation.................................................................................................... ......... 18

4.3.4

Execution.................................................................................................... ............................... 18

4.3.5

Installation of Marker Posts............................................................ ......................................... 19

SECTION4.4- TESTING&DISINFECTION ............................................................................ 19

4.4.1 General...................................................................................................................................... 194.4.2 Colouring Tests for Welding........................................................... ......................................... 194.4.3 Field Hydrostatic Pressure Test......................................................................... .................... 204.4.4 Field Leakage Test............................................................... .................................................... 204.4.5 Disinfection............................................................................................................ .................... 214.4.6 Connection of Pipes and Fittings.................................................. ......................................... 23

SECTION-4.5 PIPEJACKINGFORRAILWAYCROSSING ................................................... 23

4.5.1 Scope of Work............................................................ ............................................................... 233.5.2 General Requirements............................................................... .................................................... 234.5.3 Driving Pipe................................................................................................ ............................... 24

4.5.4

Driving and Arrival Shaft...................................................... .................................................... 24

4.5.5 Cutting Edges............................................................. ............................................................... 243.5.6 In-Pit-Based Jacks................................................................................................................... 244.5.7 Installation of Casing Pipe.............................................................. ......................................... 244.5.8 Submittal of Shop Drawings and Reports............................................................................. 25


3/27

General Technical Specification

UNOPS SDOC C 4 - 1

CHAPTER 4 PIPELINE INSTALLATION

SECTION 4.1 - PIPE LAYING

4.1.1 General Requirements

The Contractor shall provide all labour, materials, equipment and incidentals required to install, test, clean

and disinfect all new water pipelines.

All pipes shall be laid to lines and grades as shown on the Drawings and to comply with BS 8010 Section

2 pipe lines on lands: Design, Construction and Installation. The type of bedding and minimum clear

cover to the pipes shall be as shown on the Standard Drawing or else where in the Contract Document

but not limited to what is shown therein. Pipes, fittings and valves that are supplied either by the

Contractor or Employer (Transmission Mains only) shall be used in this work. Loading, transporting and

handling shall be done very carefully as described in conformance with the recommendations of the

manufacturer.

Pipe end covers and other transit protections provided by the pipe supplier shall be retained in place

except for taking over inspections until the pipes are finally inspected shortly before they are laid in

trench. All pipes, fittings and accessories shall be examined and no piece, which is found to be defective,

shall be installed. When pipes, fittings, etc. are strung adjacent to the pipe trench prior to laying they shall

be supported clear of the ground on suitable approved prop up to prevent damage to their external

coating. Excavation, bedding and backfilling shall be done as specified in Part I - Section 2.3 Trench

Excavation and in this section, all to the satisfaction of the Engineer.

The open ends of the installed pipes shall be plugged with a watertight cap or by other approved means

after the Contractor has finished the installation works on each working day until he is ready for

continuation of pipe laying subsequently. The Engineer reserves the right to order the Contractor to

remove any pipe length or lengths that has not been plugged as required for cleaning the inside of the

pipes before reuse. Material to be used for plugging shall be approved type that shall adequately protect

the pipe from damage, and prevent dirt, debris and water from entering the pipe. The Contractor shall

prevent trench water, mud, sand or sewage from entering the pipe during installation.

The type of joint required for each pipe material shall be in accordance with provision in this Specification.

All rubber joint rings and gaskets must be stored in a cool damp location in black polythene bags and

shall not be distributed to the trench side until just prior to its assembly thereof. Rubber gaskets shall be

well lubricated prior to fitting. Particular care shall be taken during joining the pipes and all pipefittingsshall be checked for defects and thoroughly cleaned before joining.

Any field cutting of the pipe shall be done only with the approval of the Engineer. The Contractor shall

submit to the Engineer for prior approval details of his cutting method along with types and sizes of pipes

to be cut. Any damage to the coating and/or lining shall be immediately repaired. Where cut pipe has

been installed without complying with the above requirements and prior approval of the Engineer and the

work is found not to conform to the specifications, the Engineer has the right to order the Contractor to

remove that pipe length for rectification. All expenses involved in this process shall be borne by the

Contractor.

Each pipe and fitting shall be laid true to alignment, curve and gradient in accordance with the drawing or

as directed by the Engineer. The minimum cover and the minimum gradient shall unless otherwise stated


4/27


UNOPS SDOC C 4 - 2

not be less than one metre and 1:400 respectively. The pipes shall be laid to even gradients and sight

rails shall be provided for this purpose at intervals not exceeding 50 metres and at changes of direction

and grade. Pipes and fittings suppose to be exposed at culvert or bridge crossings and in manholes or

chambers shall be painted in accordance with requirement of the Engineer.

The following applicable standards are referred to various pipe materials:

ISO 4482 Asbestos-Cement Coating Guide for laying

AWWA C203 Coal-Tar Protective Coating and Lining for Steel Water Pipeline

Enamel and Tape-Hot-Applied

AWWA C206 Field Welding of Steel Water Pipe Joints

AWWA C210 Coal-Tar Epoxy Coating System for the Interior and Exterior of Steel

Water Pipe

AWWA C600 Standard Specifications for the Installation of Gray and Ductile Cast-Iron

Water Mains and Appurtenances

AWWA C603 Standard Specification for the Installation of Asbestos-Cement Pressure

Pipe

AWWA Manual M11 Steel Pipe Design and Installation

4.1.2 Installation of Pipe and Fittings

4.1.2.1 Installation of Ductile Iron (DI) Pipe and Fittings

All pipes shall be carefully inspected for defects before installation. No pipe or a fitting that

shows defects excluded by the specification shall be used. Any injury to protective coating of the

pipe or fittings shall carefully be repaired before installation at no extra cost to the Employer.

The Contractor shall after excavating the trench and preparing the bed for laying the pipes,

furnish all necessary facilities for properly lowering and placing the section of the pipe in trench

without damage and shall properly install the pipe subsequently. The section of the pipe shall be

fitted together correctly and laid true to line and grade in accordance with the benchmark

established by the Contractor. The full length of the barrel of the pipe except the socket (bell) or

flange shall have a uniform bearing upon the bed of the trench. Suitable excavation shall be

made to receive the socket (bell) or flange, which shall not bear on the sub-grade.

The pipe shall be lowered into trench using cranes as far as possible and no pipe shall be rolled

into place for lowering into the trench except over suitable timber planking free from roughness

likely to damage any coatings. If the prepared bed is damaged for any reason, the pipe shall be

raised and the bed made good before pipe laying is continued. The open end of the pipeline

shall be securely closed with a tight fitting plug or cover whenever the work interrupted for any

reason. The interior of each pipe after being laid shall be thoroughly cleaned. Any pipe that is

not in true alignment both vertical and horizontal or experience any undue settlement after

laying shall be taken up and re-laid correctly by the Contractor at his own expenses when so

ordered by the Engineer.

Any underground water encountered in the pipe trench shall be pumped out regularly and the

water level be kept below the sockets when joining. In no case shall pipes and/or fittings be

jointed before being lowered into its final destination in the trench. Any damage occurs to the


5/27


UNOPS SDOC C 4 - 3

pipes through failure of the Contractor to comply with these conditions shall be made good at

the Contractors expenses.

The Contractor shall take necessary care to install the pipes with polyethylene sleeves or tape

wrap in locations where instructed, strictly in accordance with the specifications of the

manufacturer and using the recommended material, tools and equipment and methods that arerecommended. The sleeves or tap wrap fails to provide the protection to the pipe as intended

due to improper material, tools or methods used by the Contractor in the opinion of the

Engineer, then he shall replace the sleeves or tape wrap in the affected area as directed by the

Engineer at no extra cost to the Employer.

(i) Concrete Protection of Pipe

The pipe shall be encased in concrete in accordance with the details shown on the drawings or

instructed by the Engineer. Such concrete shall not be placed until the joints at each end of the

pipe have been completed. Each pipe to be encased shall be supported on at least two purpose

made pre-cast concrete blocks of same grade of encasement concrete which shall be left in

place and the full width and depth of concrete encasement shall be placed and carefully tamped

beneath the pipe followed at once by the addition of the encasing concrete.

(ii) Push-in Joints and Restrained (Self Anchored) Joints

Installation of pipes shall be in accordance with the recommendations of the pipe manufacturer.

Sockets and spigots shall be thoroughly cleaned prior to making the joint. Only lubricant

recommended by the manufacturer shall be used and it shall be non-toxic. The completed joint

shall have a uniform contract by the gasket between the outer surface of the spigot and the

rubber ring seat of the socket.

(iii) Flanged Joints

Joints shall be made up square with even pressure upon the gasket and shall be properly

watertight. Gaskets shall fit the inside dimension of the pipe accurately so that no surface

material projects out into the flow area. The completed joint shall be perfectly aligned. Flanged

joints shall be coated including all bolts and nuts with Denso paste and primer, Denso mastic,

Denso tape and PVC or polyethylene outer wrapping.

(iv) Slip-on Coupling, Collars and Flange Adapters

Coupling, collars and flange adapters, which are as specified shall be used where shown on the

drawings and as approved by the Engineer. Installation shall be accordance with the

manufacturers recommendations. Gasket seats and gaskets shall be thoroughly cleaned before

assembly. The completed joint shall have uniform contract by the gasket between the outer

surface of the spigot and the gasket seat at the socket. Coupling and flange adapters shall be

coated including all bolts and nuts with Denso paste and primer, Denso mastic, Denso tape and

PVC or polyethylene outer wrapping.

(v) Deflection of Pipeline


6/27


UNOPS SDOC C 4 - 4

Minor deviation of direction in pipeline both vertically and horizontally shall be achieved through

deflections at the joints. Such deflections shall not exceed the values given below or as

stipulated by the pipe manufacturer.

Nominal Diameter Maximum Allowable Deflection (degree)

(mm) Push-on Joint Mechanical Joint

80 to 200 5.0 5.0

250 to 350 4.0 4.0

400 to 600 3.0 2.5

700 to 900 2.5 2.0

1000 to 1200 2.0 1.5

1400 and above 2.0 1.2

Joints with deflection shall be installed in accordance with the manufacturers instruction.

(vi) Cutting of Pipes

Pipe shall be cut using power driven abrasive wheel cutting machine. Acetylene torch and chisel

methods will not be permitted in any circumstances. Cut spigot ends shall be beveled to the

same dimensions as the normal spigot ended pipe. The edges of the cutter shall be given two

coats of approved paint and the internal coating shall be repaired if damaged.The Contractor

shall ensure that the diameter at the point of cutting will match the pipe to which it is to be

jointed.

(vii) Welding

The Contractor without the approval of the Engineer shall not undertake site-welding work on

ductile iron pipe and fittings. Welding work shall be undertaken in accordance with the

manufacturers recommendations when approved by the Engineer.

(viii) Protection of Joints

All buried flange joints, and any un-coated mechanical coupling shall be protected by wrapping

with Denso Paste, Densyl Mastic, Densyl Tape and PVC Outerwrap manufactured by

Winn and Coales Limited, Denso House, Chapel Road, London, S.E.27 or similar approved

materials. The joints shall be thoroughly cleaned to remove all loose rust and extraneous matter

and thoroughly coated with Denso Paste over the whole of the joint. A liberal amount of paste

should be left around all bolt heads, narrow cavities, etc.

Densyl Mastic shall then be applied to cover all bolt heads and nuts to form a triangular fillet

against flanges and to fill all gaps and abrupt changes in contour to provide an even contour for

wrapping. Densyl Tape shall be applied circumferentially, care being taken to smooth and

eliminate any air pockets and to form the tape well into all angles and changes in contour. The

tape shall be applied with an overlap of at least 25 mm and extend at least 50 mm on either side

of the joint.


7/27


UNOPS SDOC C 4 - 5

Finally an outer wrapping of PVC Outerwrap shall be applied with minimum lap of 25 mm to

completely cover the Densyl Tape. Contractor may use any equivalent joint protection

materials exclusively with the approval of the Engineer.

4.1.2.2 Installation of Steel Pipe (SP) and Fittings

All pipes and fittings to be used in this work shall be in accordance with Section 4.3.2 Pipe

Material.

All pipes and fittings shall be handled and installed in accordance with the applicable section of

AWWA Manual M11 and the requirements described herein.

The exposed steel pipes and fittings shall be painted with two coats of synthetic red lead primer

and one coat of aluminum paint at crossings over canals and ditches. The underground steel

pipe shall be tied around with synthetic asbestos cloth. Steel sleeve pipe shall be painted with

two coats of coal-tar epoxy.

The ends of the pipe shall have wooden stiffeners installed inside of the pipe at quarter points

and at both ends of the pipe. This blocking shall remain inside the pipe until the pipe has been

ready for installation. When field cutting or mitering of the pipe is required, the acceptable

cutting machine leaving a smooth cut at right angles to the axis of the pipe or deflection angle

shall do the cutting. Cut ends of the pipe shall be beveled with a special tool made for this

purpose and the beveled end shall be exactly the same as the plain end of the pipe as

manufactured at the factory.

Steel pipe with plain ends shall be joined together with a flexible coupling as specified, or where

shown on the drawings. The Contractor shall make excavation of sufficient width and depth toprovide the suitable room for joining the pipes and fittings. The bedding at the joint shall be

installed and compacted after the joining has been completed. Where fittings such as bends,

tees and blanks are used, all fittings shall be joined with single butt-welded joints unless

otherwise shown on the drawings.

Any damage inflicted to the exterior coating and interior lining shall be repaired in accordance

with the manufacturers recommendations. In the opinion of the Engineer, the damage is not

properly repaired by the field method, the Engineer reserves the right to order the Contractor to

use the method of repairing that is the same as the manufacturers procedure. The expenses of

repairs shall be borne by the Contractor.

Welded joints shall be butt and weld and in full conformance with AWWA C206. Welders in

charge shall have the qualification stipulated in JIS Z3801 or equivalent. The Contractor shall

submit the qualification of the proposed welders for the steel pipe jointing for the approval of the

Engineer. The Engineer may request the Contractor to conduct special test welding session to

verify the capability of the welders. The Contractor shall, when requested by the Engineer make

the necessary arrangement for such testing for joint welding at his own cost.

Subsequent to satisfactory completion of all field welded joints and approved by the Engineer,

the joints shall be provided with the protective coating and lining as specified below.

(i) Coal Tar Enamel Coating (Underground Buried pipe)


8/27


UNOPS SDOC C 4 - 6

All field welded joints in the underground buried pipeline shall be field-coated with coal tar

enamel and bonded with double asbestos felt wrap in accordance with BS534 or Appendix A

Section A1.2 of AWWA203. The coating system shall be equivalent to the shop-applied coating

of the pipe section and shall be applied across and around the outside of the joints. The joints

protective coating shall overlap the main body of the shop coating on each side of the field jointto form a continuous coating free from defects. The overlapping length shall be at least 200 mm

on each side of the joint.

(ii) Epoxy Painting (Above-ground Exposed Pipe)

All field-welded joints in the aboveground level exposed pipeline shall be field coated with at

least two (2) coats of epoxy resin paint. The first and second coats shall be of minimum coating

thickness not less than 40 and 30 microns, respectively. The Engineer from the samples

submitted by the Contractor shall determine the colour of epoxy paint. The method of field

painting shall conform to the paint manufacturers instruction and recommendations. Unless

otherwise permitted by the Engineer, shop coating and field-painting materials shall be from the

same manufacturer.

(iii) Cement Mortar Lining

All field-welded joints shall receive field applied protective cement mortar lining in accordance

with AWWA C602. The lining system shall be equivalent to the shop applied lining and shall be

applied across the inside of the joints.

Bolts and nuts for mechanical joints, flanged joints and blank flanges shall be given a coat of

bituminous paint after the jointing has been completed.

4.1.2.3 Installation of PE Pipe and Fittings

(i) General

All PE pipes and fittings shall be inspected carefully for any possible defects prior to installation

and any pipe shows defects shall not be used for the works. The PE pipes shall be jointed by

employing any one of the methods namely electro-fusion or butt-fusion. In general, pipes for this

project shall be jointed with butt fusion method of welding.

(ii) Transportation and Storage

Polyethylene is a resilient, lightweight and easy to handle material. Adequate care shall be

taken to prevent scuffing or gouging of the surface. The PE pipes shall be transported and

stored carefully in order to avoid external mechanical damage. Large quantities of straight pipe

tubes are transported in unit piles. Vehicles for transporting bulk loads shall be provided with a

clean flat bed free from nails or other projection that may cause damage to pipes. Extra care

shall be taken to prevent excessive bowing and tumbling of pipes as well as stacking near sharp

edges. Smaller diameter coiled pipes shall be placed either horizontally or vertically during

transportation provided that the highway regulations are not violated. Pipes shall not be allowed

to rest on the integral socket and the fittings shall not be loaded in a way that could distort the

ends. Precautions shall be taken when stacking pipes and fittings near heat sources including


9/27


UNOPS SDOC C 4 - 7

exhaust system to prevent damage. Contamination with materials such as grease, diesel oil,

lubricants, hydraulic oils, gasoline, solvents, other aggressive chemicals etc. shall be avoided.

Large quantities of straight pipe tubes are transported in unit piles. Loading and off-loading of

pipes shall preferably be performed with the aid of non metallic wide band slings or ropes and

load spreading beams of length not less than a quarter of that of the pipe or bundle pack shallbe employed for pipes of over 6m length. Hooks, metal chains or slings are usually not

permitted for this purpose but in any case shall not be allowed to have direct material contact

with the pipes. Any damage to pipes and pipe ends during lifting shall be avoided particularly for

those pipes with couplers. Forklift trucks may handle bundled packs of standard 6m length pipes

by properly placing the forks and lifting in order to take care of the flexible nature of the pipes.

Bundled packs of greater than 6m in length shall be managed either by a side loader with a

minimum of four supporting forks or by a crane using a spreader beam and suitable slings. The

flexible nature of the pipes permit certain degree of bending at the middle during lifting and thus

the lifting points shall always be well spread and evenly spaced.

Pipes and fittings shall be meticulously inspected at the time of delivery for any defects. Any

defective material identified during delivery shall be set aside and promptly notified to the supply

source either for repairs or replacement. Pipe with incise in excess of 10% of wall thickness

shall be clearly marked as damaged and discarded. The pipes shall be stacked on a sufficiently

firm and flat ground to support the weight of the pipes and movement of necessary lifting

equipment. Height of stacking shall be kept to a minimum but in any case not more than 3m or 3

bundle height which ever is less and adequate space allowed in the storage area for lifting

machinery to maneuver freely without causing accidental damage. Materials of different polymer

manufacture shall be clearly identified and kept separately. Polyethylene fittings shall be stored

under a roof cover preferably on racks with manufacturers wrapping on or kept intact with

cartoons until lifting is required for use.

The individual pipes, fittings or bundles shall not be dragged or dropped from the delivery

vehicles. Protective packaging such as buttons, shirk-wrap, pallets, strapping, etc. shall be

intact until individual items are required for use. Pipes and fittings shall be kept well away from

sharp objects such as flints. Special care shall be exercised when handling slippery prone pipes

in wet conditions. Pipe lengths stored individually shall be stacked in a pyramid like shape of not

more than one meter high with the bottom layer fully restrained by wedges. The bottom layer of

pipes shall be laid on timber battens placed at one-meter centre where possible. Pipe end caps

shall be left in place to prevent the ingress of dirt, vermin etc.

Black coloured PE pipes may be stored under the open air without any restriction up to a periodof 12 months and utilization after longer periods of storage shall be subject to material quality

tests. Blue polyethylene pipes shall preferably be stored under cover and protected from direct

sunlight beating until required for use. Pipes stored outside and exposed to direct sunlight shall

be covered with opaque protective sheeting material such as black polyethylene sheeting that

contained pigment to provide an excellent protection against degradation due to UV radiation.

Fittings that are to be joined by electro-fusion welding shall be stored under cover in dry

conditions preferably on racks or kept in their respective boxes intact with plastic packaging until

ready for use. Materials subject to butt-fusion and spigot end fittings may be stored outdoors

provided that they are sufficiently protected against damage and prolonged direct sunlight

beating.

(iii) Excavation


10/27


UNOPS SDOC C 4 - 8

The Contractor shall initially carry out a recognizance survey along the proposed pipeline route

with the assistance of the representatives from relevant authorities to identify the existing utility

service lines within the right of way. Some of the existing utility service lines identified in the

pipeline route have been indicated in the tender drawings but its accuracy cannot be assured

and the Contractor shall be fully responsible for the establishment of the true situation. TheContractor immediately with the consent of the authority concerned shall rectify any damage

inflicted to the existing services without any additional cost to the contract.

The width and the depth of the trench shall be in compliance with the relevant drawings

provided by the Employer. The width of excavation normally governed by the diameter of the

pipe shall be kept to a minimum and limited to its outer thickness plus 250mm. The minimum

depth of cover shall be 900mm between the crown of the pipe and the finished ground

elevation. Excavators with narrow buckets are best suited to conventional trenching method in

most instances. The trench width may be further reduced in areas where several lengths of

pipes could be fused together by butt-welding to form continuous strings and hence the need for

trench jointing is virtually eliminated. A minimum of three-pipe length to be installed shall beexcavated prior to laying. In the event of installing more than one row of pipeline in the same

trench, adequate working space shall be allowed between the pipelines to facilitate construction

as well as subsequent operation and maintenance.

(iv) Installation of Pipes

All PE pipes and fittings shall be inspected carefully for any possible defects prior to installation

and any pipe shows defects shall not be used for the works. The installation of PE pipes is

relatively easier due to its lightness and flexibility coupled with durability and entirely secured

jointing methods. It is absolutely essential to ensure that the PE pipes are laid on a bed of

granular materials to provide even and continuous support along the whole length of pipe. Aminimum of 100 mm thick bed of granular material free from large stone from trench excavation,

gravel, and broken stone graded between 5mm to 10mm, coarse sand, sand and gravel mix are

all acceptable as bedding material. Polythene pipes may be laid directly on the trimmed bottom

of the trench in some instances where the soil is uniform, fine grained, relatively soft and free

from large stones and flints but subject to approval of the Engineer. The type of bedding

material and its thickness is usually specified in the tender drawings. Caution tapes (warning

tapes) shall be installed in the pipe trench 500 mm above the crest of the pipe for all diameters

of PE pipes.

Butt fusion method of welding shall generally be employed for the jointing of PE pipes under this

contract. Butt fusion method of welding shall only be used for jointing similar grades and SDR of

PE pipes.

(v) Backfilling

The high flexibility of polyethylene material permits certain degree of deformation under load

without any damage. However, it is important that the actual deformation is minimized as much

as possible by systematically placing the backfilling material in the trench. The quality of the fill

material up to a height of 100mm above the pipe crown shall be in compliance with WIS 4-08-

02. Initial backfilling including side fill shall be carried out carefully with sufficient compaction

but without employing any heavy compaction equipment up to a height of 250mm above the

crown of the pipe. Backfilling above this level shall proceed in layers of 250mm of maximumthickness till the final ground elevation using heavy mechanical equipment. Temporary


11/27


UNOPS SDOC C 4 - 9

reinstatement of road surface belonging to relevant road authority on completion of pipe laying

shall be executed in compliance with their respective specifications or as otherwise instructed

by the Engineer.

Backfilling of the completed section of the pipeline shall be commenced as soon as possible in

order to prevent damage to pipes from external objects falling in to the trench. It is a goodpractice to install marker tape at about 300mm above the pipe crown to protect the pipe from

future interference by others. The pipeline shall be protected by placing a 150mm thick

reinforced concrete bridging slab above the pipe in areas where minimum cover cannot be

maintained particularly on heavy traffic flowing highways. A minimum thickness of 150mm

sandwiched cushion of granular material shall be placed between the pipe crown and concrete

bridging slab.

The Contractor shall adjust the moisture content of the refill material either by drying out or by

adding water to assist the compaction of the materials where necessary. The backfill shall have

a uniform moisture content equal to or a little above the optimum moisture content recorded in

the Compaction Test during compaction. Backfill shall be compacted to a dry density value ofnot less than 95% of the Laboratory Modified Proctor Density when tested in accordance with

these specifications. The Contractor shall carry out a minimum of one compaction test each

working day that back filling is taking place. The Contractor is advised to use clean river sand or

other clean granular material approved by the Engineer to obtain the required compaction in the

presence of wet conditions provided, the excavated materials or selected backfill materials

cannot be compacted to the required degree and the compaction work is held up.

(vi) Welding Process and Equipment

Experienced personnel shall supervise the welding process and the method of supervision shall

be agreed with the Engineer in advance. Each welder employed for the work shall be a qualified

person and shall have valid proof of his qualifications in this type of welding. The Contractor

shall submit method data in welding protocols or on data medium and other relevant particulars

to the Engineer for his approval prior to commencement of work.

The Contractor shall demonstrate to the Engineer prior to commencement of installation works

that he has adequate welding plant and equipment to perform the activities on continuous basis

with standby provision.

(vii) Butt Fusion Welding Procedure

Butt-fusion method jointing is a thermo-fusion process that involves the simultaneous heating of

the ends of two components that are to be jointed until a melt state is attained on each contact

surface. The two surfaces are then brought together under controlled pressure for a specific

cooling period and homogeneous fusion is formed upon cooling. The equipment for butt fusion

welding generally shall comprise the following components:

Generator for the supply of power to the heater plate, trimmer and hydraulic pump

Butt-fusion machine fitted with suitable size clamp shells, trimmer, heater plate, hydraulic

pump and timer

Pipe, Pipe support, covers and timer

Welding tent, Base board, Timer, Indelible marker pen, Air temperature thermometer

Cleaning material, lint free cotton cloth or piper towel


12/27


UNOPS SDOC C 4 - 10

External/Internal de-beading tool and Bead gauge

Digital thermometer with surface probe to check heater late

A comprehensive pre-welding check shall be undertaken prior to commencing of welding

operation. This investigation shall include functionality of generator and availability of fuel,

condition of trimming tool and hydraulic pump, cleanliness of heater plate and its sustenance ofcorrect temperature by connecting to power source for at least 20 minutes. The heater plate

shall be thoroughly washed with sufficient quantity of clean water to remove dirt deposits at the

start of each jointing session. Isopropanol or similar solvent shall be used for the removal of

grease and oily film with lint free material. Pipes and fittings to be jointed shall be of equal size,

same SDR and material.

The welding area shall be protected from unfavorable weather condition such as moisture, wind,

intensive UV radiation, temperature, etc. Welding operations shall be performed at any

temperature provided appropriate measures (such as preheating, tent-covering, heating) have

been taken to secure that the pipe wall temperature will be maintained. The joining areas of the

parts to be welded shall not be damaged or contaminated and it shall be cleaned thoroughly

free from dirt, oil, shavings, etc. All joints shall be executed so as to avoid any kind of stresses,

if possible and any stresses that may arise due to temperature differences between laying and

operating conditions shall be minimized.

Large deposits of dirt shall be removed by washing with water but finer dust particles may still

linger on the heater plate. Dummy joint shall be performed at the start of each pipe jointing

session or when the plate temperature has fallen below 130oC or change of pipe diameter in

order to remove fine particles. Two dummy joints shall be made for pipe size of diameter

greater than 180 mm. Dummy joint may be made using pipe cut pieces of the same size, SDR

value and material. This procedure may be discontinued after a full heat cycle and notnecessary to complete the entire joint. The non-stick coating of the heating element shall be

undamaged and it shall be cleaned with fluffless paper before commencing each welding

operation for optimum performance.

The pipe ends to be joined together shall be axially aligned and clamped in the butt fusion

machine in such a manner about 30mm to 50mm of each end is visible and the trimmer shall be

installed between the pipe ends. The misalignment of the joining areas to one another shall not

be more than the permissible degree of 0.1 x wall thickness on the pipe outside. The joining

surface of the clamped shall be machined in a plane parallel way and the maximum permissible

deviations from plane-parallelity at the joining surface are given below in the Table.

Pipe outside diameter

in mm

Deviation

in mm

< 400 0.5

400 1.0

Adequate care shall be taken to prevent movement of the pipes assembly during this process.

The pipes ends shall then be pressed against the trimmer so that to affect the trimmer blades to

cut the pipes ends smoothly. The trimming process shall be terminated by gradually reducing

the pressure in order to ensure even surfaces on both ends of the pipes on completion. Remove

loose shaving from the machine and component ends without touching the prepared surfaces.

The trimming process shall be repeated if the surfaces are not planed. Close the clamps and

check that there is no visible gap between the trimmed faces.


13/27


UNOPS SDOC C 4 - 11

Open and then close the clamps and note the drag pressure needed to move the pipes together

using the hydraulic system. Drag pressure is the minimum gauge pressure required to

overcome the sliding fractional drag on the rams due to the operation of the machine and the

weight of the pipes/fittings being jointed. The trimmer shall then be withdrawn from the machine.

The drag pressure (in bar) must be assessed accurately prior to making each fusion joint andmust be added to the basic ram pressure values shown on the machine and shall be submitted

to the Engineer prior to jointing for his approval. Contractor is not permitted to perform fusion

welding without approval of the Engineer at site. Fully automated welding machines normally

perform this operation routinely.

The heater plate from its protective cover shall be removed and ensure it is sufficiently clean

and up to temperature. Insert the heater plate in the machine between the pipes ends so that

the welding faces of the parts to be jointed shall be aligned under pressure using hydraulic

system onto the heating element and then heated to the welding temperature of 200o to 240oC

under reduced pressure. Maintain this applied pressure until the pipe begins to melt and a

uniform bead of 2.3 mm is formed on each pipe end. Subsequent to initial bead up the pressure

in the hydraulic system shall be released so that pressure gauge registers between zero and the

drag pressure in order to control the bead growth during the heat soak time. Adequate

precaution shall be taken to prevent movement of pipe assembly and continue to sustain

contact with the heater plate. The heater plate shall be removed rapidly on satisfactory

completion of the heating process without touching the melted surfaces and the pipes ends

pressed sufficiently together in accordance with predetermined fusion pressure provided by the

manufacturer of the pipes or from the tables on the welding machine.

The pipe shall be removed from the welding machine when the weld has cooled to the ambient

temperature and the joint shall be undisturbed during the cooling period. The joint shall beexamined for cleanliness, uniformity and verify that the bead width shall within the specified

limits. The external bead and the internal beads if necessary shall be removed using suitable

de-beading tools. The beads and joint shall be numbered and coded using an indelible marker

pen. The beads shall be twisted at several positions and any splits seen at the beads imply

faulty jointing. This faulty joint shall be cut out from the pipeline and the jointing process

repeated until a satisfactory results attained. The strength of the joint at the butt fusion weld

shall at least be equal to that of the designed strength of the pipe.

(viii) Connection of PE to DI Flanges

The joining of PE pipe with ductile iron pipe can be achieved only with mechanical joints using

polyethylene flanged adaptors for main pipe such as SlimFlange, steel flanged converter, stub

ends with steel backing rings drilled to BS 4504 or fittings of the Viking Johnson or WASK type.

It is anticipated that the connection between PE pipe and DI flanged pipe shall be generally

accomplished with one of these joints.

4.1.2.4 Installation of Un-plastic ized Polyvinyl Chlor ide (uPVC) Pipe and Fittings

Careful consideration must be given to the handling and storage of polyvinyl chloride pipe and

fittings. The pipe must be stored out of any direct sunlight. Extreme care shall be taken to

prevent any scarring or nicking of the pipe from bearing on sharp objects. Any pipe that has any

cut or bruise deeper than 10% of the wall thickness of the pipe shall be rejected and not be


14/27


UNOPS SDOC C 4 - 12

used in the work. The section of pipe with such a cut shall be rejected in its entirety. The pipe

shall be stored in such a manner that no directs sunlight beat on the pipe but ventilation is

provided. Covering the pipe with a tarpaulin shall not be allowed and stacking shall not exceed

600 mm in height.

In normal ground, pipe shall be bedded in 150 mm depth of granular material and the samematerial shall be placed either side of the pipe and compacted in 200 mm layers up to the

crown. Same material shall be placed over the pipe and compacted in two layers up to a depth

of 300 mm. In other types of ground, additional bedding types shall be used as shown in

relevant typical drawing. Sleeve pipes as shown on the drawing shall protect the uPVC pipe that

passed under or at the side of culvert.

The joints shall be of the push-in type and both spigot and socket ends of the pipes shall be

carefully cleaned before the rubber ring is set in place. The spigot shall then be covered with an

approved lubricant and the pipe pushed into the socket. Pushing the pipe into the socket shall

be done by barring against the opposite end of the pipe being installed. A wooden block or other

suitable device shall be used to prevent any damage to the socket against which the bar is

being pressed. No blocking will be allowed under the pipe and it shall bear evenly along its

entire length on the bedding material.

Cutting of the pipe shall be kept to a minimum and they shall be cut smoothly and perpendicular

to the axis of the pipe. Cuts shall be made with tools in conformance with the pipe

manufacturers recommendations. Cut ends shall then be tapered and beveled with a special

tool made for that purpose and the beveled end shall be exactly the same as the spigot end of

the pipe as manufactured at the factory.

Solvent weld joints for pipes of diameters 90 mm shall be made strictly in accordance with themanufacturers recommendations and utilize only solvents furnished by the manufacturer. In

addition it will be necessary to snake the pipe so that on offset from true horizontal alignment of

30 centimeters in 30 meters of laying length will be provided. Care shall be taken to ensure that

the temperatures of both sections of pipe being jointed are the same. The Contractor shall use

solvent joints for pipes of diameter less than 90mm with the written approval of the Engineer.

Caution tapes (warning tapes) shall be installed in the pipe trench 500 mm above the crest of

the pipe for uPVC pipes of diameters 110 mm or more.

Concrete thrust and anchor blocks for uPVC pipes shall be provided with a minimum 2mm thick

polythene film or equally suitable material membrane to the satisfaction of the Engineer to

separate the fitting from the concrete. The warning tape shall be of polythene and shall have

performance details applicable to the 100 micron material of Boddingtons underground warning

tapes, or equivalent.

Minimum ultimate tensile strength at break (longitudinal and transverse) shall be

10MN/m2as determined by BS 2782 method 301E.

Minimum Elongation shall be 300% (Longitudinal) and 350% (Transverse)

Shall be resistant to chemical attack from the ground conditions with pH ranging from 3.0

to 9.0.


15/27


UNOPS SDOC C 4 - 13

The width of the tape shall be 100mm and blue in colour with the words printed WATER PIPE

LINE BELOW CAUTION! on upper side of the tape in black letters printed in two rows at an

interval of 1m.

4.1.2.5 Installation of Galvanized Steel (GS) Pipe and Fittings

Installation of pipes, fittings and accessories shall be in conformance with the manufacturers

recommendations or as directed by the Engineer. Gibault or flange joints may be used if

necessary. All threads for screw joints shall be clean, machine cut, and all pipes shall be

reamed before erection. Each length of pipe as erected shall be up-ended and rapped to

dislodge dirt and scale.

Screwed joint shall be made up with good quality thread compound and applied to the male

thread only. After having been set up a joint must not be backed off unless the joint is

completely broken, the threads cleaned, and new compound applied. No close right and left

hand nipples shall be used. All nipples shall be of such length that the correct size of pipe

wrench can be used on them when in place.

At crossing over canals or ditches, the pipe shall be laid in accordance with the details and/or

construction method specified on the drawings or as directed by the Engineer. Pipe laid under

ditches shall be in accordance with the details shown on the drawings or as directed by the

Engineer. Pipe bedding shall be compacted for the entire length of the pipe, good alignment

shall be preserved and fittings may be used where necessary.

4.1.2.6 Installation of Reinforced Concrete (RC) Pipe and Fittings

The pipe shall be stored and handled in such a way to prevent any damage to the ends. Any

pipe with a broken bell or spigot shall not be used in the work. Neoprene gaskets shall be of the

proper circumference and fit tightly on the spigot.

The Engineer shall inspect all concrete pipes delivered to the site and any pieces rejected shall

promptly be removed from the site. Pipes not inspected by the Engineer shall not be

incorporated in the works. The Contractor shall make ample allowance of time to allow such

inspection.

Pipe shall be installed as soon as the excavation is completed to the normal grade of the bottom

of the trench. The Contractor shall immediately place granular material No.2 in the trench and

the pipe shall be firmly bedded in this material to conform accurately to the line and gradeshown. No blocking under pipe will be permitted.

Bedding is indicated on the drawings.

A depression shall be left in the bedding at the joint to prevent contamination of the rubber

gasket immediately before being forced home. Before the pipe is lowered into the trench, the

bell and spigot must be cleaned and free from dirt.

A vegetable lubricant furnished by the pipe manufacturer and harmless to the gasket shall

lubricate the O-Ring gasket and bell. The pipe shall be properly aligned in the trench to avoid

any possibility of contact with the side of the trench and fouling the gasket. As soon as thespigot is centered in the bell of the previously laid pipe, it shall be forced home with jacks or


16/27


UNOPS SDOC C 4 - 14

come-alongs. After the gasket is compressed and before the pipe is brought fully home, each

gasket shall be carefully checked for proper position around the full circumference of the joint.

The jacks or come-alongs shall be anchored sufficiently back along the pipeline so that the

pulling force shall not dislodge the piece already in place. Only a jack or come-along shall be

employed to force home the pipe smoothly and evenly and to hole the pipe while backfilling is in

progress. Under no circumstances shall crowbars alone be used or shall any motor drivenequipment be used.

As soon as the pipe is in place and before the come-along is released, backfill shall be placed

up to the mid diameter for at least one-half the length of the pipe. Not until this backfill is placed

shall the come-along be released. If any motion at joints can be detected, a greater amount of

backfill shall be placed before pressure is released.

All pipes are to be laid in an upstream direction unless otherwise approved by the Engineer for

each specific instance.

4.1.3 Exposed Piping

The Contractor shall furnish and install sleeves or wall casting for all pipes passing through masonry walls

and concrete floors or walls and concrete inserts for hangers and supports as soon as forms are erected

and before concrete is poured. Before setting these items, the Contractor shall check all and figures

which have a direct bearing on his pipe location and he shall be responsible for the proper location of his

pipes during the construction of the structures.

Piping shall be installed to the required lines and grades and as closely as possible to walls, ceilings,

columns and other structural parts so as to occupy the minimum of space and all offsets and fittings

required to accomplish this must be furnished. All dimensioned pipes and fittings shall be installed that nostress or strain is created in the lines and associated equipment due to forcing parts into position.

Changes in direction shall be made using proper fittings. Piping shall run parallel and at right angles to

walls, unless noted otherwise. Temporary bracing and supports shall be provided to adequately support

the pipe during its installation and care shall be taken in placing piping to prevent damage to the

pipelining or pipe coating or to adjacent structures or equipment. All supporting piers and blocking shall

be in place before temporary supports and bracing are removed.

Flanged piping shall have a sufficient number of couplers and adapters to allow convenient removal of

piping. The Contractor shall furnish and place all inserts for the support of piping installed under this

section in masonry and in concrete forms before concrete is placed, unless otherwise permitted. Systems

shall be arranged with low points and drains to be provided with unions or union connections at low pointsto permit draining. Fill connections shall also be provided on closed systems where required. Adequate

air vents shall be provided at high points in all liquid carrying pipes.

All exposed piping shall be rigidly supported by pipe hangers and supports specified hereinafter. All pipes

shall be sound and clean before installation. In case interference develops between piping and

appurtenances, the Engineer will decide which work is to be relocated regardless of which was first

installed. Upon completion of installation and testing, the Contractor shall paint all exposed piping in

accordance with the instructions of the Engineer. Where the pipe passes through wall sleeves, the

sleeves shall be caulked with sealing compounds recommended by the pipe manufacturer and approved

by the Engineer. Sealing compounds shall be applied in accordance with the manufacturers instructions.


17/27


UNOPS SDOC C 4 - 15

4.1.4 Canal or River Crossing and Culvert Crossings

The Contractor shall furnish all labour, equipment and materials and perform all incidental work required

to install canal or river crossings and culvert crossings as shown on the drawings or as specified or as

otherwise directed by the Engineer. The Contractor shall follow the requirements set out in Section 1 of

this Specification for canal or river crossingsusing existing bridges.

(1). General Conditions

The Contractor shall dig test pits near the bridge and/or the bank of the canal prior to installation

of pipe crossing the canal. In the event of underground structures and/or utilities are not in the

same locations as indicated on the Drawings that may cause changes in the pipe routing,

position of form of pipe support structures and other related works, then the Contractor shall

prepare drawings showing detail of the changes and submit them to the Engineer for approval.

The Contractor shall pursue the directions of the Engineer on this matter and any damage

resulting from not carrying out said direction including the costs in changing the method of

construction of the approach pipe laying shall be borne by the Contractor.

Welding of steel pipe shall conform to AWWA C206 and the steel used for pipe supports and

incidental works of canal crossing shall be of structural steel. Concrete thrust blocks and

supports shall be constructed at fittings or bends where indicated on the Drawings or as

directed by the Engineer.

(2). Construction

The Contractor shall submit the proposed method and details of the construction to the

Engineer for his approval. Approval of such details shall not relieve the contractor from theresponsibilities under the Contract. The Contractor shall take extreme care to protect bridges,

surrounding structures and utilities from damage. Vehicular and pedestrian traffic shall be

maintained at all times as well as utility services. Costs or charges resulting from damage

thereto shall be borne by the Contractor.

The Contractor shall provide support to the pipes with proper concrete structures where pipe

trenching is not practical or pipes are to be installed in swampy areas. The installed pipe shall

be levelled as shown on the Drawings and an air valve shall be installed at the highest point of

the pipe or at the end point of the pipe or at the tail water end as shown on the Drawings.

Necessary trench cut off walls and rubble pitching shall be provided for crossing of pipeline

outside of the culvert and under the invert level as shown in the drawing.

4.1.5 Pipel ine Marker Tape

The contractor shall supply and install marker tape for all pipelines to be laid under this contract in

compliance with the provisions in this clause. The polyethylene detectable warning marker tape shall be

resistant to acid and alkaline. The tape shall be blue in colour and clearly marked in black lettering with

CAUTION WATER MAINS BELOW in English with a maximum repeat distance of not more than 1 m.

The width of the marker tape shall be 150mm or the diameter of the pipe, whichever is smaller and shall

consist of all accessories necessary for installation at the chambers, splicing, junctions etc. Methods of

joining and terminating the tape to enable a low resistance connection to be made to the aluminium foil /

wires shall be in accordance with the manufacturers instruction. Electrical connection points shall be


18/27


UNOPS SDOC C 4 - 16

made at each chamber along the pipeline route. The warning tape shall have a minimum strength of 125

kg/cm2in the longitudinal direction and 105 kg/cm

2transversely.

The minimum thickness of the marker tape to be provided for metal pipes such as ductile iron, steel, etc.

shall be 0.5mm composed of 0.4mm thick polyethylene base layer and 0.1mm thick of polyethylene

sealing layer. However, the thickness of the marker tape to be provided for non-metal pipes such aspolyethylene (PE), polyvinyl chloride (uPVC), etc. shall be not less than 0.575 mm composed of

polyethylene sealing layer of 0.1 mm, aluminium foil of 0.075 mm and base layer of polyethylene 0.4 mm.

The additional metal aluminium foil for PE and uPVC pipes marker tapes shall be provided to locate these

pipes from the surface with a metal detector in addition to act as a warning media during excavation

activities by others. The metallic conductor(s) shall be either aluminium foil having a width of not less than

50 mm and a thickness of not less than 0.075 mm or stainless steel wires. The aluminium foil for metallic

conductor shall contain not less than 95% pure aluminium. The aluminium foil / stainless steel wires shall

be totally enclosed within the polyethylene laminate such that the edges of the foil are totally protected

against aggressive soil corrosive action. The aluminium foil / wires shall be easily detectable from the

ground surface with the aid of a buried cable locator.

The marker tape shall be placed in position during backfilling of the completed pipeline trench at a depth

of 300mm above the pipe crown unless specified otherwise in the drawings with the longitudinal

centerlines of the pipeline and marker tape lies on the same vertical alignment. The cost of supplying and

laying of the warning tapes shall be included in the relevant pipe laying item in the bill of quantities.

Notwithstanding the above requirements, warning marker tapes shall not be provided for yard piping

within the treatment plant compound, intake site, storage reservoir sites and booster pumping station

compounds.

SECTION - 4.2 CONNECTIONS TO EXISTING MAINS

4.2.1 General

(1). Scope of Work

The Contractor shall supply all labour, tools and equipment obligatory to connect the new

pipelines to the existing pipes that have been constructed previously in accordance with the

drawings and specifications and as may be directed by the Engineer.

(2). Submittals

The Contractor shall excavate at the point of connection and inspect the existing facilities to

determine the material type and make necessary records. On completion of this data collection,

the hole shall be backfilled and the surface temporarily restored with asphalt pavement. Based

on the field data, the Contractor shall prepare and submit shop drawings showings the method

proposed for making the connection. Field data collected shall be clearly indicated on the shop

drawings.

Generally the connections shall be made under dry unless a wet tap is specified. The Contractor

shall co-ordinate his pipe connection activities and pressure testing with the relevant operational

unit of UWC so that interruption of service to consumers is minimized.


19/27


20/27


UNOPS SDOC C 4 - 18

The Contractor shall prepare and submit a shop drawing for each installation. The shop

drawings shall be based on the schematic arrangement shown on the drawings and include the

dimensions of piping, appurtenances and other equipment to be installed and shall extend to the

limits of the installation shown on the drawings or to the limit of special pipe construction. All

supports, clearances and materials to be installed shall be shown.

4.3.2 Materials

The construction materials such as cement, aggregate, water, admixture, reinforcing steel, concrete, form

work, shall be in accordance with the provision of Chapter 3 Concrete Works.

4.3.3 Location of Installation

(1) Fire Hydrants

The location of the fire hydrants shall be either under the pedestrian walkway or under the

shoulder of the road, but shall not be under the carriageway. The Engineer before installation

shall approve the location.

(2) Valves

The valves shall be located at a distance reasonably away from the road junctions so that the

installation is not adversely affected by future road widening or surfacing by the road

maintenance authorities. The Contractor shall obtain the approval of the Engineer before

installation of any valve.

4.3.4 Execution

(1) Underground Utilities Interference

The Contractor shall excavate test pits where existence of underground utilities are shown on

the drawings or anticipated near the proposed location of the new installation to ensure that they

shall not interfere with the construction of the structure. Proper precautions shall be instituted to

protect the existing underground utilities in order not to disrupt essential services to the general

public.

(2) Manhole Frame and Cover

Manhole frame shall be set with the top conforming to the grade of the pavement or finished

ground surface as indicated on the drawings or as directed by the Engineer. Frames shall be

set in full bed of mortar.

(3) Valve Box

Valve boxes shall be constructed with the top of cover lower by 0.2m from the grade of the

pavement or finished ground surface or as indicated on the drawings or as directed by the

Engineer. The manhole frame and cover shall be raised with its top conforming to the grade of

the pavement or finished ground surface.


21/27


UNOPS SDOC C 4 - 19

4.3.5 Installation of Marker Posts

Marker Posts shall be installed at the locations of all valves and meters of the distribution pipelines,

transmission mains and at the location of fire hydrants. The type, depth, location and diameter of the main

shall be indicated as specified in the relevant drawing for the specified sizes of valves and pipelines. The

Contractor shall obtain the approval of the Engineer regarding the location for installation of marker postsand also obtain the permission from the relevant authorities for their installation.

SECTION 4.4 - TESTING & DISINFECTION

4.4.1 General

(1). Scope of Work

The Contractor shall furnish all labour, equipment, materials and metering device required for

the cleaning, pressure and leakage testing, and the disinfection of the finished pipelines. The

finished pipeline shall include the pipes, fittings, valves, fire hydrants and all other

appurtenances that are constructed under this Contract. The Contractor shall provide the

facilities to convey water from its source as designated by the Engineer to the place where it is

required and shall install the necessary metering device. All cleaning, testing and disinfecting

operations shall be performed in the presence of the Engineer.

The delay in testing and commissioning of a pipeline shall not be permitted due to late delivery

of valves to the site. In such instances, the Contractor shall supply and install spool or make up

pieces so that testing may proceed and the valves shall be installed later in a manner

acceptable to the Engineer.

(2). Standard Specification References

The following standards are referred to in this respect for adherence.

AWWA C600 Standard for Installation of Ductile-Iron Water Mains and their

Appurtenances

AWWA C601 Standard for Disinfecting Water Mains

(3). Submittals

The Contractor shall submit as part of his shop drawings a sketch for each section of pipe to be

tested. The sketch shall show the section schematically in profile and shall contain a sequence

of operation to be followed during the test such as test pressure, observations and closing of air-

valves, blow-offs and other appurtenances; point of water filling and point of monitoring

pressure.

4.4.2 Colour ing Tests for Welding

The colouring test shall be performed at each welding joint covering entire welded circumference and

examined for any defects or incompletion in accordance with JIS Z2343 or equivalent. The Contractor

shall repair any defect or pinhole detected by the colouring test to the satisfaction of the Engineer and the


22/27


UNOPS SDOC C 4 - 20

test shall be repeated to ensure that the repair work has been satisfactorily carried out. The Contractor in

the presence of the Engineer shall carry out all such tests. The faulty welds shall be rectified in

accordance with the instructions of the Engineer at no extra cost to the Employer.

The Contractor shall nominate a qualified chief supervisor for field tests of steel pipes and he shall be fully

responsibility to perform and supervise the field tests of steel pipes. All expenses related to said testingincluding expenses for equipment, tools, materials, labour, reporting, and any other connected works

shall deemed to be included in the rates of payment items for installation of steel pipes.

4.4.3 Field Hydrostatic Pressure Test

Hydrostatic pressure test procedure for the pipeline shall be as specified in Section 4.1 of AWWA C600

that shall be not less than 1.5 times the maximum working pressure. The working pressure shall be of

water column based on the elevation of the lowest point in the pipeline under tests and corrected to the

elevation of the test gauge for all pipe sizes. The pressure tests shall be conducted on the pipelines in

sections after the trench is backfilled except the pipe joints wherever possible, but before restoration of

the road pavement. The selected stretch of the pipeline for testing which is not more than a kilometer

shall be securely anchored by constructing all thrust and anchor blocks before subjected to testing.

The pipelines shall be thoroughly flushed out with water prior to performing pressure testing. The pipeline

shall be prepared for testing by closing all valves and hydrants; placing substantial stops and bulkheads

at openings, opening of air valve assemblies and fitting air release taps at all other high points along the

pipeline. These taps shall later be removed after completion of the testing and disinfection and unless

otherwise specified replaced with permanent plugs.

The pipeline shall be gradually filled with water allowing for all air pockets to be released until the pipe iscompletely filled and attain the required working pressure at which condition it shall be allowed to stand

for 24 hours. The Contractor shall rectify any apparent defects in the pipeline at this stage. The complete

removal of entrapped air in the pipeline shall be verified by the Contractor by adding a measured quantity

of water at the filling point and measure outflow at remote points of pipe being tested. The Contractor

shall install suitable taps for this purpose provided the remote points of pipeline do not contain convenient

points to measure outflow. The hydrostatic pressure of the pipeline shall then be raised to the level of test

pressure and maintained it for two (2) hours duration. Any defective pipe, fittings, joint, valve or hydrant

shall be removed and replaced and the test shall be repeated until to the satisfaction of the Engineer.

In the case of PE pipes, all welding joints shall be completed and cooled down (at least 1 hour after last

welding process) prior to pressure testing. The pressure test shall be performed according to relevant

standards (DIN 4279 or similar) and the imposed maximum test pressure shall be 1.5 x Nominal Pressure

of the pipe. Special care shall be taken during testing since there will be a pressure decay even in a leak

free system due to visco-elastic (creep) response of the flexible nature of the material. The testing

procedure developed by WRc Manual for Polyethylene Pipe Systems for Water Supply shall be

employed for this purpose. No pressure drop shall be allowed at least for 10 minutes during the test

period.

4.4.4 Field Leakage Test

Leakage tests procedure for the pipeline shall be as specified in Section 4.2 AWWA C600 and this test

shall be conducted after the satisfactory completion of hydraulic pressure test. The pipeline shall be


23/27


UNOPS SDOC C 4 - 21

subjected to the same test pressure as stated in the preceding paragraph for a continuous duration of two

(2) hours and the amount of water injected during this period in order to maintain the constant test

pressure shall be taken as the quantity leaked. The allowable pipeline leakage shall be less than 2.3 litres

per mm-pipe diameter per km-length for a period of 24 hours as presented by the formula given below.

Q----------------- * 24 < 2.3

D * L * H

Where:

Q: Amount of leakage in litres

D: Diameter of pipe in millimeters

L: Length of pipeline in kilometers

H: Duration of leakage test in hours

The Contractor shall locate and repair or replace the defective materials or joint to the satisfaction of the

Engineer when any pressure test of laid pipeline revealed a leakage exceeds the specified limit. The test

shall be repeated on the rectified section of the pipeline until extent of leakage falls within the permitted

allowance.

4.4.5 Disinfection

(1). Swabbing

The Contractor shall on the instructions of the Engineer demonstrate that entire length of

pipeline is free from any obstruction on completion of pipe laying and satisfactory pressure

testing in accordance with the relevant Clauses in the Contract. This process shall be performed

by means of passing through the pipelines a polyurethane foam swab of approved grade inaccordance with the procedure setout below.

Impediment free to any portion of the pipelines shall be established in sections between entry

and exit points. The locations of the permanent swabbing points are indicated on the Drawings.

Temporary swabbing points shall be provided in the distribution system by insertion of tees and

valves, which shall be removed on completion and replaced by short lengths of straight pipe.

The swab shall be introduced at the start of the operation through the entry point at the

upstream end of the selected section of the pipeline by means of a tee provided, keeping the

isolating valves on branch mains closed. The isolating valves on either side of the entry point

shall be opened sufficiently to flood the entry tee containing the swab and the sluice valve on

the entry tee shall then be closed. By opening the isolating valves on either side of the entry

point the swab will be free to travel along the pipeline towards the downstream exit point.

The theoretical loss of head between the entry and the exit points located at either end of the

section shall previously have been determined by the Engineer for a flow of water, which shall

cause the swab to travel through the section at a suitable predetermined velocity. This flow and

the corresponding required velocity of the swab shall be controlled by throttling of valves at the

exit point or at hydrants or washouts.

Washouts or hydrants downstream of swabs shall be closely monitored for any rubbish, silt,

debris or other extraneous matter that may be discharged during the passage of the swab along


24/27


UNOPS SDOC C 4 - 22

the pipeline. Demonstration of any section shall be repeated as required by the Engineer until a

satisfactory result has been realized. The Contractor shall provide all transport and labour

required to establish a pipeline that is free from obstructions.

Diameters 300 mm and greater

Visible dirt and debris should have been removed either manually or by the use of cleaning pigs

before testing. The Contractor shall flush out and cleanse the pipelines after the pipelines have

been completed and pressure tested satisfactorily as herein specified. Pipelines shall be

cleansed in sections and this shall be carried out by passing polyurethane foam swabs through

the pipeline. The swabs material shall be to the approval of the Engineer and water for passing

swabs shall be made available by the Employer.

Diameters less than 300 mm

Pipelines shall be cleansed in sections by flushing with potable water provided by the Employer

for a period of time determined by the Engineers representative. Cleansing of any section shallbe repeated as required by the Engineers representative until a satisfactory result has been

realized. The Contractor shall supply all necessary equipment for the cleansing and sterilizing

operations including sufficient swab and swab detectors. Swabs shall be of suitable grade and

dimensions appropriate to the pipelines being cleansed and to the approval of the Engineer.

Swabs shall be passed through pipelines at speeds of between 0.2 and 0.4 metres per second

to obtain the best cleaning result with the minimum number of passes. The Contractor shall be

wholly responsible for repairing of the lining of the pipes, if it is apparent from the debris

collected by the swab that damage to the lining has occurred, to the satisfaction of the

Engineers representative. The cost of the initial sampling analyses and preparing reports on the

bacteriological quality of water shall be borne by the Employer but, in the case of the initial

reports be unsatisfactory the cost of any subsequent sampling analyses and preparing reports

shall be borne by the Contractor. The cost for performing this operation shall be allowed in the

appropriate item in the bill of quantity.

(1). Disinfection

All new pipelines that are intended for conveyance of potable water shall be disinfected with

chlorine and a satisfactory bacteriological analysis of the water certified in accordance with

AWWA C601 shall be submitted to the Engineer before the pipeline being placed into services

or certification of completion by the Engineer whichever occurs earlier.

The amount and concentration of chlorine solution applied shall ensure a minimum dosage of

50 mg per litre introduced into the pipelines as directed by the Engineer. The residual chlorine at

the end of pipeline shall not be less than 25 mg per litre after a contact period of 24 hours. The

system shall then be flushed out with clean water until the residual chlorine is diluted to a value

less than 0.75 mg per litre but not less than 0.25 mg per litre. The point of application of the

chlorination agent is normally at the beginning of the pipeline through a corporation stop

insertion on the top of the laid pipe and the point of withdrawal (normally by blow-off) is at the

opposite end of the line.

In the event of initial treatment failed to achieve the desired results stipulated previously, thechlorination procedure shall be repeated until a satisfactory results are obtained. The Contractor


25/27


UNOPS SDOC C 4 - 23

shall dispose of the water used in the pipeline testing and disinfecting operations without

causing any harm to adjacent property.

4.4.6 Connection of Pipes and Fittings

Prior to commencement of Test on Completion of the entire system, the Contractor shall connect eachother of hydrostatically testified individual sections of pipelines including valves and fittings. The test on

completion shall be arranged in the presence of the Engineers Representative. The minimum duration of

test shall be 48 hours or as decided by the Engineer depending upon the locality.

The transmission systems shall be connected to their inlet and outlet ends and the installed delivery

mechanism such as pumps shall be utilized for testing. All surge protection and safety equipment shall be

functional fully with their desired outputs. Any faults encountered during testing shall be rectified

immediately and repeat the test proceedings.

Distribution system shall be tested for their designated zonal boundaries or their sub zonal boundaries

where appropriate. Systems shall be connected to their intended inlet sources and allowed to carry the

full design discharges by means of end free delivery either through scour-valves or section valves where

appropriate. Any faults encountered during testing shall be rectified immediately and repeat the test

proceedings.

.

Valves, Hydrants, meters and control devices installed in both transmission and distribution systems shall

be demonstrated beyond doubt in operation for their intended purpose and to its design efficiencies and

accuracies. Engineer shall satisfy test on completion in accordance with the manufacturers

recommendations as per his catalogue or shop drawings.

SECTION - 4.5 PIPE JACKING FOR RAILWAY CROSSING

4.5.1 Scope of Work

The Contractor shall furnish labour, materials, equipment and incidentals to install the encasement pipe

by pipe jacking for railway crossing in accordance with the drawings and as specified herein. The work

shall include supply of driving pipe with jointing materials, construction of driving and arrival shafts, pipe

driving and incidentals to complete placing of the encasement pipe under the utilities at the locations as

indicated on the drawings.

3.5.2 General Requirements

Construction method applicable to the pipe driving under this contract shall be open type. Excavation

may be done either by manual or by mechanical methods.

Special measures for pipe driving such as ground treatment and/or use of intermediate jacks are not

indicated on the drawings but may be incorporated in the driving work by the Contractor. The

Contractor's attention is directed to the fact that there will be a large thrusting force required for the pipe

driving operation and that the earth behind the driving shaft must safely withstand the thrusting force

during the operation. The Contractor shall be responsible to there in force the original soil to obtain

sufficient bearing capacity for the jacking force if required, and for this purpose, the Contractor shall carry

out additional subsoil investigation as necessary. All expenses due to this improvement shall be theresponsibility of the Contractor.


26/27


UNOPS SDOC C 4 - 24

Prior to the construction work, the Contractor shall investigate existing subsurface structure and utilities

located in and around the construction site so as not to damage those facilities during all stages of

construction activities. The Contractor shall make a continuous measurement and record of the level of

the existing ground, road surface and railway line at all stages of driving operation.

Any intended change of construction method during driving operations shall require the Engineer's

approval. The Contractor shall liaise with the Railway Authority throughout the pipe jacking work under

the railway lines and comply with all their requirements.

4.5.3 Driving Pipe

Driving pipe (encasement pipe) shall be steel or ductile iron pipe and the pipe material component and

fabrication shall comply with the standard specifications. Wall thickness shall not be less than that shown

on the drawings. Lining and exterior coating will not be required.

4.5.4 Driving and Arrival Shaft

Driving shafts shall be sized so that all equipment needed for the driving operation can be reasonably

accommodated in the shaft, sand filling, jointing of pipe and other works in the shafts can be safely done.

Each driving shaft at the bottom shall be provided with dewatering sumps and pumps to maintain the

shaft dry throughout the driving operation. Each driving shaft shall also be equipped with a crane for

unloading of pipe and driving equipment and for removal of excavated soil.

Arrival shafts shall be sized so that removal of cutting edges and pipe connections in the shafts can be

satisfactorily accomplished. Unless otherwise directed by the Engineer, construction of arrival shafts

shall be delayed until driving operation has been nearly finished.

4.5.5 Cutting Edges

Irrespective of the construction methods to be used by the Contractor, cutting edges shall be designed to

withstand against the required driving force and anticipated earth pressure. Each cutting edge shall be

designed to integrate a reasonable number of jacks of controlling of pipe alignment and grade during

driving operation.

Cutting edges shall have the same outside diameter as that of the steel-encasing cylinder of pipe for

driving.

3.5.6 In-Pit-Based Jacks

The total number of in-pit-based jacks shall be determined on the basis of jack output equal to 70 percent

of the rated jack pressure. The rated pressure of the jack shall not be less than 400-kg/sq.cum and

jacking stroke shall not be less than 500 mm.

4.5.7 Installation of Casing Pipe

The Contractor shall take all necessary steps to ensure that the casing pipe is driven to the proper

alignment and grade. The method of welding for steel pipe casing shall be same as that used for field

welding of steel pipe and fittings. Approved coat of painting equivalent to that of shop applied coating

shall be applied across the joints subsequent to the welded joints have been inspected and approved bythe Engineer. The ductile iron pipe shall be jointed as shown on the drawings.


27/27

Pipe Laying Metode

Documents

Transcript of Pipe Laying Metode