Joint integrity success at nuclear plant
A 24-inch valve at a nuclear power plant was rendered totally leak free for the first time in seven years, following the application of a technology driven approach to achieving joint integrity.
Engineers at the plant called in James Walker after attending a presentation on assuring joint integrity using RotaBolt® tension control systems. Their problem was a giant steam valve that always leaked on start up.
Test pressure for the valve is 130bar, with start-up at 160bar under increasing temperature. Working pressure is 60bar at 260°C. In order to achieve a perfect seal, James Walker recommended the use of 20 off 3-inch OD by 580mm long RotaBolt 2 studs, and a complete redesign of the valve's flange joint.
The new joint design incorporated a Metaflex® CW/IR spiral wound gasket, plus a silver plated C-ring and a modified housing arrangement. All design modifications were checked and approved for the plant operator by an external consultancy. The upgraded steam valve was then installed during the plant's main shutdown.
On start-up the steam valve was completely leak free, and it has remained leak free ever since — thanks to a totally integrated approach to assuring bolt integrity.