EXPLOSIVE TUBE PLUGS
High pressure boiler feedwater heater shell and tube exchanger tube failures have a significant negative effect on feedwater heater and power plant availability, reliability, and maintainability. Tube and plug-repair failures often lead to heaters being “valved-out” of service, or result in bringing a unit off line for an unplanned, forced outage. Removing a feedwater heater from service leads to reduced unit thermal efficiency, overloads the other heaters in service as well as the steam turbine. Continuing to operate a feedwater heater with a tube leak will lead to progressive secondary damage and eventually lead to premature failure of the entire feedwater heater.
Permanent Tube Repair
High pressure exchanger reliability can be improved through proactive inspection services, and the use of permanent explosive tube plugs. Technicians are trained in the safe and reliable installation of explosive tube plugs which use a safe and relatively low explosive charge for detonation. Numerous utilities currently use explosive tube plugging as their preferred method of permanently repairing leaking high pressure feedwater tube leaks.
Charged plug creates welded bond
Explosive tube plugs involve a welding process that permanently joins two metal surfaces by using a small amount of explosive by moving one or both of the metal surfaces together at a high collision velocity. The progressive impact of the metal surfaces at high velocity creates a welded bond. At the correct collision angle, a wavy bonded weld is formed at the metal to metal interface. This type of weld is stronger than a typical fusion type weld and even stronger than the base metals used to create the weld. Additionally, unlike fusion tube plug welding, explosive tube plugs do not damage the tube or tubesheet.
Advantages of explosive tube plugs:
- The shock of the detonation dissipates rapidly and does not affect the surrounding tubes and tubesheet ligaments.
- Explosive plugs can be inserted and detonated where tube ends are not accessible by conventional methods.
- Explosive tube plugs can within stand pressures up to 10,000 PSI.
- The material of construction is compatible with all tube and tubesheet materials.
- Wide dimensional variances are tolerated including “out of round” tube or tubesheet holes.