Award Bid - 2024 Sewer and Manhole Rehabilitation Proj No. 122-019 - Visu-Sewer, LLC

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SUGGESTED CURING FOR RESIN USED IN PIPE REHABILITATION A properly designed, fabricated, and installed cured-in-place pipe made with an isopthalic polyester resin or a vinyl ester resin should give satisfactory service in gravity flow sewer systems. VARIABLE CURE STRATEGY: The temperature and times for curing liners are varied as a function of liner thickness. The purpose is to optimize the water temperature so the resin is cured completely without generating too much heat during the polymerization process. If the resin is allowed to exotherm above 270ºF the styrene in the resin will vaporize, producing a liner having increased porosity. This phenomena is sometimes referred to as "styrene boil" because styrene monomer boils at 270ºF. When a liner experiences styrene boil, the properties of the final product may be reduced and/or the liner may have increased porosity. Curing at lower temperatures over longer periods of time produce the highest quality and most consistent cures that can be obtained. THERMOCOUPLE PLACEMENT: It is recommended that thermocouples be placed at both ends of the tube at the top and bottom (i.e. 12 and 6 o'clock positions) of the tube between the liner and the host pipe. Where the tube goes through an intermediate manhole, thermocouple wires should be placed at the top and bottom of the tube between the tube and the host pipe. Additional thermocouples within the layers of the tube are also an option that can be helpful. The purpose of placing thermocouples is to have an indication of how the tube may be curing, as well as a thermal history of the cure at various places on the tube. Thermocouples are also necessary for trouble shooting in case problems occur with the boiler or circulation hoses. Where chart recorders are not being used as a permanent record of the thermal history, hand held thermal recorders should be read and the data recorded with the time every fifteen minutes. In addition to the thermocouples, a sharpened tube should be used to pierce the downstream end of the liner. Attach a heater hose to the end of the tube so that it can be brought up and out of the manhole or piping access. This tube can then be used to bleed water out of the lining tube and the water temperature at the downstream end can be measured. The water temperature at the water heating truck should also be measured at the suction side as well as the output. These water temperatures must also be recorded along with the thermocouples that have been placed between the liner and the existing pipe.