UK
Summary
A 50.8-mm (2-inch) transformer cooling line in a nuclear plant had ruptured, and there was no way to isolate the line, which was leaking 3.75 liters (1 gallon) of transformer oil every hour. With the unit’s two other transformers offline for maintenance, it was critical to address the leaking line quickly without interrupting operations. CSNRI experts repaired the leak using ThermoWrap® MT, a custom engineered repair system that uses a fiberglass, composite-reinforced coating. The quick response and expertise of the repair team allowed the leak to be sealed without incident, restoring the line to safety without incurring a shutdown.
Pipe Details
- 8-mm (2-inch) diameter cooling oil line leak in a nuclear plant
- A pinhole leak at a flange resulted in oil loss at a rate of 3.75 liters (1 gallon) per hour
- 2 CSNRI technicians completed the ThermoWrap™ MT installation in 1.5 days
- No interruption to operations
- No negative environmental consequences
Benefits
- 8-mm (2-inch) diameter cooling oil line leak in a nuclear plant
- A pinhole leak at a flange resulted in oil loss at a rate of 3.75 liters (1 gallon) per hour
- 2 CSNRI technicians completed the ThermoWrap MT installation in 1.5 days
- No interruption to operations
- No negative environmental consequences
Safety is vital in nuclear power plant operations, so when a pinhole leak was detected in a 50.8-mm (2-inch) diameter cooling oil line serving one of three transformers, the owners immediately initiated efforts to contain the leak and restore the line to safe operation.
The ruptured line was under 2 bar (29.01psi) pressure and operating at a temperature of 120°C (248°F). Oil was leaking from just above the slip on a flange at a rate of approximately 3.75 liters (1 gallon) per hour. Because the other two transformers in the plant had been taken offline for maintenance, it was critical to address the line damage for the one in-service transformer as soon as possible. The was no way to isolate the line, so the owner needed a repair solution that could be performed with the cooling oil line in service to allow the facility to remain up and running while the damage was being addressed.
Having contracted CSNRI for repair work in the past, the owner reached out for support, explaining the emergency conditions and the requirements for the repair. CSNRI experts assessed the situation and concluded that the leak could be repaired using ThermoWrap™ MT.
ThermoWrap™ MT is a custom engineered repair system that uses a fiberglass, composite-reinforced coating to repair corroded and damaged piping conveying product at elevated temperatures. It is commonly used on chemical processing lines, flare lines, blowdown lines, and steam piping and because of its flexible properties is easily applied to girth welds, elbows, tees and other complex geometries. The ability to contend with complex geometries was important in this installation because the leak was located at a flange.
With the proper repair designed, a team of 2 CSNRI technicians was dispatched to the site the next day. The relevant paperwork for the repair, including COSHH assessments, a risk assessment method statement, and quality control requirements were all in hand when the team arrived.
Before any work began on the leaking line, the repair team held a detailed pre-job brief to ensure everyone understood the risks associated with this sensitive job. The repair plans had to take into account the fact that the work would be carried out beneath a tank holding 35°C (95°F) oil. The CSNRI team developed contingency arrangements for the repair in the event that it was more complicated than expected.
Once all the safety precautions were put in place, the repair got underway.
The CSNRI team began the repair by preparing the pipe surface for the composite system installation. Once the pipe surface was ready, they used a two-part epoxy to improve the geometry of the line at the flange, then applied ThermoWrap™ MT to stop the leak and restore the strength of the pipe. The entire project was completed in 1.5 days.
By calling in the CSNRI experts, the nuclear plant owner was able to repair the oil cooling line and restore the plant to safety without disrupting operations.
The client credited the team with having the expertise and experience to carry out a “top-class repair” of the leaking system and praised the professionalism and responsiveness of the team. “The task was completed in a safe, timely manner,” the client said. “I have no complaints at all about the quality of this repair and the service provided by CSNRI. I will use them again on site and I’m more than happy to recommend them to others.”
