ICE PLUGS HELP IN PIPELINE RETROFIT

Large ice plugs have been used to isolate a section of pipeline so that a valve could be retrofitted onto a previously laid 24-in., gas-import line near Theddlethorp, U.K. ARCO British Ltd. chose the approach because it saved both time and manpower. The plugs were created by Hydra-Tight On Site Services using liquid nitrogen to freeze the pipeline on either side of the section of pipe to be removed. Each plug was 28 in. long and 24 in. wide. The 44-mile pipeline had been filled with

April 26, 1993

Large ice plugs have been used to isolate a section of pipeline so that a valve could be retrofitted onto a previously laid 24-in., gas-import line near Theddlethorp, U.K.

ARCO British Ltd. chose the approach because it saved both time and manpower.

The plugs were created by Hydra-Tight On Site Services using liquid nitrogen to freeze the pipeline on either side of the section of pipe to be removed. Each plug was 28 in. long and 24 in. wide. The 44-mile pipeline had been filled with approximately 3 million gal of chemically treated sea water for hydrostatic testing,

The pair of ice plugs held for 4 days during the operation to modify the pipeline.