CHAPTER 10 REPAIR OF PIPE LINE - CPHEEO

1 212It is one of the most important responsibilities of a Water Undertaking to properly maintainthe transmission and distribution mains in order to prevent waste and provide a constantpressurized flow of potable water to the consumers. It is equally important to prevent damageto the public property which could arise for not properly repairing a defective pipe. Properplanning and implementation of remedial measures will avoid leakages and CAUSES OF FAILURE IN PIPELINEFor proper planning for the operation of the REPAIR work it is necessary to assess the probablecauses of failure. Following guidelines outline some of the factors to be duly considered toensure protection of pipes from HANDLING AND STORAGE OF during transport of the piping stacking and to the pipe wall and in pipe during careless unloading and pipes striking against each effect due to unfavorable up of different classes of pipes and their jointing LAYING OF PIPELINE1.

2 Deviation from proper laying . Improper bedding3 . Loss of support of bedding after . Slipping of trench . Sinking of soil after . Poor quality of backfill . Improper compaction of trench backfill and its subsequent . Excessive overburden on piping trenches, not taken care of during the design . Point loads coming on the pipe through the Excessive vibrations due to traffic during the laying of 10 REPAIR OF PIPE JOINTING OF jointing strike on the body of the pipe with any sharp edge, while of jointing material like rubber ring or lead CHARACTERISTICS OF nature of soil causing damage to the external surface of the of climate: frost heave or clay of support or anchorage (horizontal or vertical), both in case of pipes embeddedand those laid above ground of soil due to filled soil, of soil while work of laying pipes or other activities like laying of cablesetc.

3 Is taken in soil moisture or water table EXCESSIVE TEMPERATURE : severe compression, end : pull out or separation of : pipe blockages and INTERNAL test surge, water separation, pipe connections without proper AGGRESSIVE WATERD amage to the internal surface of pipe as well the lining GALVANIC SPECIAL OBSERVATIONS ON FAILURE OF PIPE BARRELC ertain failures connected with the deterioration of the barrels of pipe are given Brittle type fracturesThese may be found in rigid and semi-rigid materials such as cast iron, asbestos cement are characterized by relatively clean, sharp-edged splits or cracks. These may occuras circumferential breaks or longitudinal cracks which may run straight but more oftenirregularly curved along the pipe Ductile type failuresThese occur in polyethylene and ductile iron.

4 These are usually found as relatively short splitsor tears with irregular edges which are often associated with some local swelling around Blow OutsThese are localized failures which only occasionally occur and are usually associated withhigh pressure, pumping surges in weakened brittle PinholesThese may be caused by an impurity or inclusion in the wall of the pipe wall or, more often,by localized chemically or electrically induced corrosion which thins and weakens the pipewall until a small plug is blown out by internal pressure. Pinholes often enlarge quite quicklydue to erosion around the edges of the hole. Pin holes are frequently found within the metallicgroup of Generalised DeteriorationMore generalized deterioration of pipe barrel may be due to a manufacturing defects but isusually the result of some form of chemical attack.

5 The overall effect is reduction in wallstrength depending on the material group. Some of the examples are the graphitization ofiron mains, sulphate attacks on AC and concrete, lime leaching from cement lining by softwaters and solvent attacks on the polymeric group of materials leading to softening ordelamination of composites such as FAILURE AT PIPE JOINTSSome of the points for consideration are given may occur due to originally careless installation practices causing displacementsof the seal and/or eventual separation of the mating cracking of pipe material around the of the sealing Flanged connectionsStress cracking of the flange can occur due to unequally tightened bolts. Such a situation arisesduring ground movement or the forceful activation of a valve or Crushing of pipe endsCracking may occur due to crushing of pipe ends when they touch or bind and are thensubjected to high compressional or bending Lead jointsHardening of lead in association with joint movement may lead to weeping which graduallydevelops into a more serious Sealing rings or gasketsMany mechanical joint designs rely upon the compression of sealing rings or gaskets whichhave varying compositions and different resiliences.

6 The physical breakdown ( ) or change of resilience with time can lead to leaking joints. The loss ofcompression combined with corrosion of pressure rings or collars or the bolts may aggravatethe REPAIR ACTION GENERAL PROCEDUREF ollowing procedure may be followed:1 . Internal . Detection of pipe failure: Inspection of site3 . Notification of interruption in water supply and related . Location and demarcation5 . REPAIR planning6 . REPAIR work: Selection of most appropriate method for . Testing of dry . Restoration9 . Completion10. Hygiene11. Notice of restoration and IMPLEMENTATION OF ACTION Monitoring of Internal MobilizationSome of the important activities relating to the mobilization of the internal activities aresummarized below;(a) Senior Level ManagementNecessary information to the Senior Level Management may be submitted and their interimapproval sought.

7 Details approval can follow in due course of time.(b) Operation and maintenance staff of the running water supply systemThe entire staff must be made fully aware of the likely activities required to be undertakenso as to ensure minimum possible interruption in the system.(c) Alternative arrangementAlternative arrangement for water supply may be planned and duties of staff fixed accordingly.(d) Existing installationsThe operation of the water supply system with regard to Intake, Headworks, Pumpingmachinery, Treatment Plant, Piping system etc. must be co-related with the proposed (e) Mobilization of menNecessary staff may be arranged for the following duties; of section; of section; of section; transport, material, machinery, equipment, tools, pipes, fittings miscellaneous duties.

8 (f) Manpower, material, machinery, transport, lighting, safety measures, communication,pipes with fittings and specials etc. for the repairing details are variable and depend upon various factors as per the local situation. Someof the factors to be considered are;i)The importance, utility and function of the affected pipeline with the piping net may be the only transmission main of the system. It may be one of the two ormany parallel transmission mains. It may be initial portion of the distribution systemserving as the only main to supply water to the rest of the area to be served. It maybe a distribution pipe serving only a part of the )Size and material of the affected are very important factors which determine the magnitude of the REPAIR to )Depth of the pipeline.

9 Deeper pipes require more labour work for )Subsoil water the pipe is laid much below the local water table, additional work will be requiredto dewater the trenches excavated for REPAIR .(v) Other unforeseen on these factors the requirement of manpower, material, machinery, tools,equipments, pipes, specials, fittings etc. is to be worked out. Given below is a list to meet therequirement of a big transmission main which is a life for the water supply system. This maybe considered as a guideline only. Exact requirement may be worked out depending uponthe local powerDesig-Manager Super-Fitters WeldersCraneExcavatorTruckJeepnationviso roperator operator operator operatorNumber11 3 31111 Desig-EmergencyElectricianMechanicHelper Semi-PumpnationVan operatorskilledoperatorNumber111181217 MaterialElectrodes, Gaskets, Rubber insertion, Bolts and nuts, Gland rope, Manila rope, Pig lead, Cottonwaste, Wooden sleepers, PVC hose pipe, Canvas hose, Engine oil, Wire slings, Grease, , Diesel, Kerosene, Fire wood, Cement, Sand, Spun yarn, Hard crete, M seal, Sand (Electric)

10 Dieselgenerator generator generatorpumpsetNumber1122111 MachineryWeldingMudGas CuttingPressureFlexibleHandsetpumpsetGro uting machinegrinderdrillingNumber222111 TransportVehicleTruckJeepEmergency breakdown vanNumber111 ToolsScour rod with lever, motor driven pipe cutter with extra cutters, cutter, sheet cutter,screw jacks, hammers, spades, buckets, baskets, crow bars, hammers, showels, caulking tools(spun caulking, cement caulking, lead caulking), power wrenches 36 in. to 15 in., adjustablespanner 18 in. to 12 in., chain tong 36 in. long, ring spanner set, DE spanner set, screw drivers,cutting plier, knife, nose plier, knife, chisels, lead pan with sport and bucket, Temporaryplatforms, files, bench vice and pipe SpecialsMS gap special, ms barrels, ms split collars (different types available), ms girder, ms set, mobile wireless set, cell phone, lighting, tube light fittings, wire, 3 core cable, insulation tape, main switch, fuse wire,kit kats, welding cable, emergency lights, torch lights, gas EquipmentFirst aid box, helmets, headlight, gum shoes, hand gloves (rubber, leather), gas masks, , water cans, jugs and glasses, tarpaulins, electric heaters, rain coats, food (tea andsnacks, meals) Detection of Pipe Failure1.