Manual of Mainlaying Practice

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- 35 -epoxy/polyurethane coating. Pipe condition survey may be carried outto identify defects for rectification and improvement works to enhancethe pipe structure before application of the replacement coating. It isalso designated as “RG” in the DMS.(ix)“External Coating Replacement” is defined as a method ofnon-structural rehabilitation that involves removal of the remainingexternal coating from an existing pipeline, preparation of the pipesurface and then manual in-situ spray application of a replacementepoxy coating. Pipe condition survey may be carried out to identifydefects for rectification and improvement works to enhance the pipestructure before application of the replacement coating. It is designatedas “RH” in the DMS.Possible size of the host pipe and characteristics of the lining for variousmethods of rehabilitation are listed below:Type ofrehabilitationClose Fit Lining(Fully-structural)Close Fit Lining(Semi-structural)Cured-in-placePipe(Semi-structural)Possible size of hostpipeDN150 – DN1400Characteristics of liningPE100 pipe (SDR 17 or below)DN600 – DN900 PE100 pipe (SDR above 17,depending on the requiredhole/crack bridging capability)DN150 – DN1400 An outer polyester jacket,internal PE coating and a flexiblepolymer or glass fibre fabriclayer impregnated withthermosetting epoxySliplining DN600 – DN1400 PE100 pipe (SDR 17 or below)with annulus between the liningand the host pipe to be fullygroutedInternal FRPLayer Lining(Semi-structural)External FRPLayer Wrap(Fully Structural/Semi-structural)DN900 – DN1400DN450 – DN1400Layers of overlapping sheets offibre reinforced polymerimpregnated with epoxy(thickness depending on therequired hole/crack bridgingcapability)Layers of overlapping sheets offibre reinforced polymerimpregnated with epoxy
- 36 -The advantages and disadvantages of various methods of rehabilitation aresummarised in Appendix 4.2 for reference.4.4.4 Procedures for Rehabilitation of Water MainsThe procedures for rehabilitation of water mains by various methods havebeen consolidated from the submissions furnished by the contractors of recentR&R contracts, and are for general reference only. Engineers and inspectorsare advised to exercise their own judgments in adopting the most suitablemethod of rehabilitation and evaluating the method statements submitted bycontractors, taking into account of all relevant site specific factors, including,but not limited to, the availability of space and the condition of the existingmain to be rehabilitated.Close Fit LiningStep 1: Preparatory WorkConstruct a launching pit (for insertion of PE close fit lining and towing head)and a receiving pit (for accommodation of winch and associated equipment).Step 2: Pre-lining CCTV Survey, Pipe Cleaning and Local RepairCarry out CCTV survey to assess the condition of the host pipe. Clean thepipe to remove silt, rust, tuberculation, deposits, remains and other foreignmaterials by means of wire brushes, scraper or pressure jetting. Carry outCCTV survey again as necessary to confirm that the host pipe has beencleaned satisfactorily. For mains to be rehabilitated by semi-structural lining,carry out local repair works for the host pipe as necessary.Step 3: Removal of ObstructionsIdentify possible obstructions, such as protruding branch connections,displacement at joints or excessive deformation of the host pipe, and removethe obstructions before commencement of installation of lining.Step 4: Measurement of Dimension of Host PipeUse an appropriate prover of dimensions and/or carry out laser measurementsfor measuring the internal diameter and ovality of the host pipe to confirmsuitability of the proposed lining, and to ensure its free passage along the hostpipe.Step 5: Temporary Deformation of LiningFold the lining into C-shape in factory or in-situ on site by a suitabledeforming device to facilitate the winching of the deformed lining from thelaunching pit to the receiving pit. Alternatively, deform the liningconcentrically (by reducing its diameter) by swaging through a set of static dierollers or an array of compression rollers, to facilitate the insertion to the host
Page 4 and 5: CONTENTSSectionPage No.1 DESIGN 11.
Page 6 and 7: List of Appendices1.1 Guideline for
Page 8 and 9: SECTION 1 - DESIGN1.1 Standard Size
Page 10 and 11: - 3 -installed with fire hydrants,
Page 12 and 13: - 5 -installed at the entry point n
Page 14 and 15: - 7 -provided to facilitate pumping
Page 16 and 17: - 9 -Buried flowmeters should only
Page 18 and 19: - 11 -SECTION 2 - MATERIALS2.1 Spec
Page 20: - 13 -(c) Mechanical joint fittings
Page 23 and 24: - 16 -http://www.emsd.gov.hk/emsd/e
Page 25 and 26: - 18 -Where the works is carried ou
Page 27 and 28: - 20 -3.5 Laying PipesA number of g
Page 30 and 31: - 23 -(iii)For Polyethylene PipesPE
Page 32 and 33: - 25 -The leakage should not exceed
Page 34 and 35: - 27 -(where the pipe-to-soil poten
Page 36 and 37: - 29 -RecordNewly-laid, Diverted,Re
Page 38 and 39: - 31 -4.2 Leak DetectionApart from
Page 40 and 41: - 33 -A semi-structural lining syst
Page 44 and 45: - 37 -pipe by winching.Step 6: Inse
Page 46 and 47: - 39 -Then carry out the hydrostati
Page 48 and 49: - 41 -collar will be in close conta
Page 50 and 51: - 43 -the lining, if needed. Connec
Page 52 and 53: - 45 -External FRP Layer WrapStep 1
Page 54 and 55: - 47 -SlipliningStep 1: Preparatory
Page 56 and 57: Appendix 1.1Sheet 1 of 6JOINT UTIIL
Page 58 and 59: Appendix 1.1Sheet 3 of 6c) As storm
Page 60 and 61: Appendix 1.1Sheet 5 of 6e) When the
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Appendix 3.2M E M OFrom E/C To E/Re
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Appendix 3.3Sheet 2 of 7ItemItem De
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Appendix 3.3Sheet 4 of 7ItemItem De
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Appendix 3.3Sheet 6 of 7(C) Unmappe
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WATER SUPPLIES DEPARTMENTNotificati
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Appendix 4.2Sheet 2 of 2Type ofReha
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Manual of Mainlaying Practice

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