1. Scope

This practice describes the full-length monitoring and recording of the temperatures occurring on the interior host pipe surface, during the installation and the entire curing process of a CIPP liner. Smaller diameter pipes (less than 60-inch) only require the monitoring of the invert surface, while larger diameter pipes (60-inch and greater) and extra thick liners (large diameter with thickness over 40mm) present the opportunity and in some cases the need to monitor both the invert and the crown area of the liner-host pipe interface. The Cured-In-Place Pipe (CIPP) is a reconstruction process that is used in a variety of gravity and pressure applications such as sanitary sewers, force main sewers, storm sewers, potable water lines, process piping, electrical conduits, and ventilation systems. The real time monitoring of the curing process temperatures verifies that the curing process meeting the Resin Manufacturers requirements, providing optimal results.

Keywords

Curing Monitoring System; CMS; Fiber-optic Distributed Temperature Sensing; DTS; Cool-Down; Post-Cure

Rationale

The Cured-In-Place lining process utilizes a thermoset resin system. It is essential that the polymerization process has been initiated and that the temperature of the hardening resin remains elevated sufficiently throughout the curing process, known as the post-cure (finishing of the polymerization process of the resin). Post-cure time influences the integrity and corrosion resistance properties of the liner. Furthermore, the liner temperature must be reduced along its entire length to a temperature at which it will be dimensionally stable after the release of the required internal processing pressure; this is known as the cool-down process. Traditional methods have monitored temperature at the host conduit ends and other access points (intermediate manholes). Traditional methods are unable to capture unknown site conditions during the curing process. Monitoring the entire length of the liner captures a more complete understanding of temperatures reached throughout the cure process and allows installers to adjust post-cure time as needed. The ability to monitor and interpret the temperature data in real time and to adjust the post-cure accordingly, results in a reduction to the potential for defects along the installation. Sags (bellies) in the vertical alignment of the host pipe, cold groundwater movement, larger diameters where the heat differential between the invert and the crown of the pipe can become significant, steam vapor collapsing into condensate, and many other processing challenges can be monitored by knowing the temperature along the invert of the liner-host pipe interface. Additionally, in large diameter (60-inch and greater) installation or where liner thickness exceeds 40mm, monitoring of the crown of the pipe should also be considered. This will address the potential for significant difference between temperatures in the crown and the invert of the host while also providing an alternative signal path should one of the cables become compromised.

The title and scope are in draft form and are under development within this ASTM Committee.