AWWA C620-07 pdf download.Spray-Applied In-Place Epoxy Lining of Water Pipelines, 3 In. (75 mm) and Larger
4.3.1 Cutting the existing pipe. The existing pipe shall be cut to provide access for the cleaning and lining operations. Generally, a short section is removed from the pipe, usually with the removal of valve or fitting, to allow entry of equipment. If one side of the pipeline has to be capped and repressurized during the cleaning and lining operations, the constructor shall block, brace, tie back, or otherwise ensure that the pressurized pipeline remains in service.
4.3.2 Cleaning the pipe sections. The interior surfaces of the pipe to be lined shall be cleaned by methods approved by the purchaser to remove corrosion products; chemicals or other deposits; loose and deteriorated remains of old coating materials; and oil, grease, and accumulations of water, dirt, and debris. If flushing water is used for cleaning, the constructor shall collect and dispose of the water after consulting with the purchaser and in accordance with the regulating organization. Generally, cleaning debris is deposited into a sump in the access pit. However, depending on the quantity of scale being removed, a sediment tanker may be required. Disposal of effluent and solids shall be made in accordance with regulatory disposal requirements.
4.3.3 Drying the pipe interior. The constructor shall ensure that residual water and debris are removed from the pipe prior to lining. Water and debris may be removed by pulling rubber disk squeegees through the pipe, but they are normally removed by swabbing. Oversized foam swabs can be driven through the main using filtered compressed air. The filters must be capable of removing the compressor oil and must be checked and cleaned regularly. The number of swab passes required depends on the condition of the main, but swabbing must continue until the swabs emerge clean and dry. The constructor shall observe manufacturer recommendations on dehumidifying the pipe, if any. The presence of substantial amounts of debris or water suggests inadequate cleaning or leaking valves. These faults should be investigated and remedied before epoxy lining begins.AWWA C620-07 pdf download.