Oxifree UK were asked to provide SSE (Scottish and Southern Energy) a solution to costly SF6 gas release from GIS and SPL type circuit breakers on PowerStation’s and substations in the south of England and Scotland. SF6 is the most potent greenhouse gas, with a warming potential of almost 2400 x that of CO² and as such, any accidental or general release results in heavy fines for the operator, plus has the potential to cause devastating results to the environment.
To stem the unrequired release of SF6 from circuit breaker stacks into the environment, as a short to medium-term repair (ten years) until repair of the corroded concrete pillar support can be scheduled. To provide an environmentally stable and safe means of sealing the porous concrete / aluminium gas charged pillar that has means of coping with Scottish weather.
The first step of the cure / repair / stem was to fully understand the nature of the leaks; it was determined that years of vulnerability to weather and pollutants caused the concrete interface between the jointing flanges and aluminium support to become porous and allow exertion of the contained SF6 through micron-sized holes and as the circuit breaker ‘stacks’ were charged up to 5bar with SF6, any point of weakness would be means of escape.
Oxifree UK adapted a practice known as pipe wrapping, with which it has had many years of success throughout the oil and gas industries, and modified the practice to suit SSE’s requirements by providing gas release stemming and environmental protection.
Oxifree UK has conducted many applications for SSE of the SF6 stemming practise, however, the process for each application is similar: Oxifree personnel arrive at site, at a time and date provided by SSE, ensuring the area is safe, Oxifree personnel use the honed techniques to stem any and all SF6 release from the pillar or flange, then apply a leak detecting dye compound that will alert personnel should a leak be present, then place a coating of Oxifree TM198 atop of the securing structure, to prevent any further degradation of the ‘stack’ and to provide elemental protection to the repair.
The malleability of applied Oxifree also provides a visual aid should any further leaks occur, by forming a highly visible bubble on the coating. Oxifree will contain low pressure release, but the use is purely environmental protection.
Due to the nature of the application area and due to the size of Oxifree application, the polymelt 12 unit is utilised, which only required a 240vac 16amp, household power supply.
For more information, please contact Oxifree.