An 8” GSW pump motor had failed and needed replacement. When plant maintenance attempted to change the pump motor, it was discovered that the isolation valve had also gone bad. The client needed RJStacey to isolate the bad 8” valve and pump without shutting down the 14” common header it was connected to. The GSW system was operating at 115psi and ambient temperature. The work time frame was urgent as downstream processes were being starved of GSW.
RJ Stacey inspected the job site and determined it a perfect candidate for a pipe freeze. The factors that led to this decision were verifiable no flow through the 8” pipe, only mild turbulence, and the orientation of the short run of vertical pipe. A pipe freeze allowed for an economical, and expedient isolation as we would not be waiting on delivery and installation of any linestopping fittings. We decided to use our Co2 Freeze system based on the job conditions, and the fact that the work area was not easily accessible. Co2 bottles are much smaller and lighter than Nitrogen Dewars making them ideal for transport in this environment.
RJ Stacey technicians achieved a safe and reliable freeze isolation in about 6 hours. We also eliminated all the time and expense of purchasing and installing mechanical linestop fittings. The plant pipefitters changed out the valve and pump in safety. The entire process only took one workday, with no welding or hot work permits required.