Allied Pipefreezing Services Ltd attended site and surveyed the site and discussed options with the client. Our linestopping option was decided upon as the best course of action in this scenario, as this would allow local isolation of the existing branches to allow the installation of new inline valves whilst still allowing the rest of the site to continue with production. Ultrasonic testing of the existing branches was carried out to ensure the pipework was thick enough in the first instance but also to confirm there were no internal issues with the pipework that might cause issues with the upcoming works. Following a satisfactory test confirming the pipe was safe to be welded to, a single bespoke 4” on 4” linestop fitting was welded to each of the 3 branches along with a couple of purge points on each line to allow the lines to be purged safely. These 3 new linestop fittings and purge points were tested to 2 bar to ensure the welds were sound. Following a successful pressure test confirming no leaks the linestop fittings and purge points were drilled and the linestop paddles installed. A let-by test was carried out to ensure the paddles were in place and holding back the main supply, the branches were purged. A section of pipe was cut out of each branch and new flanges welded in place. New in-line butterfly valves were installed, and a blank flange bolted to each one. Tasks Involved: Ultrasonic Thickness Test,Welding, Pressure Test, Hot Tapping/Under pressured drilling, Linestopping, Indirect Purge & Gas safe Purge Certificate.
