During Heat Exchanger maintenance, if inside the tube bundle a defect occurs (thus allowing internal leaks) or a tube joint with tubesheet doesn’t work properly, it becomes necessary to close the tube inlets with conical plugs in order to isolate the tube.
STP for tube bundles
Safe heat exchanger tubes maintenance
This solution is applied both for spindled tubes and spindled&welded ones.
The problem and the solution
Most common exclusion method of tube bundles is to close the tube inlets by wedging inside it a conical plug. Furthermore some others, make also a welding on plug, tube bundle and tubesheet.
Using conical plugs wedged and/or welded in the heat exchanger tubes can create multiple risks, including:
- Mandrelled or welded tube domino effects, close to excluded ones
- Spontaneous wedged plug disassembly, during plant operation
- Due to blows on the plug, this causes damages to the hole on the tube sheet, jeopardizing the subsequent maintenance restoration.
- Working on damaged tube bundle exclusion could be very dangerous.
- During tube bundles cleaning and pressure tests, a wedged expansion plug could become a bullet.
To solve these problems we have patented  the STP threaded plug.
Features of the STP threaded plug
- Threads of the plug let it to be fixed into the tube, avoiding it to become a bullet in case of any pressure inside the tube.
- Easy to be dismantled and safe, also in case of pressure inside the tube.
- No plug welding necessary anymore.
- Due to no damaging domino effects, only specific tubes will be repaired, then avoiding the reduction of heat exchange surfaces.
- Avoiding the tubesheet’s holes damage, then no further repairs will be needed.