Fastening system for fastening a through pipe to a hearth wall, the pipe opening into a box

A fastening system for fastening a through pipe and a box to a hearth wall of a hearth, the hearth wall including an outside metal screen, an inside layer of refractory material which defines an inside face, an orifice, the box including a wall provided with a further orifice and being disposed proximate to the inside face, the through pipe passing through the hearth wall via the orifice and through the further orifice and opening into the box which is subjected to a pressure and to a temperature that are different from those of the hearth, said fastening system comprising:

• external pipe-securing means for securing the through pipe to the outside metal screen;
• an internal metal guide tube fitted over the through pipe and having one end interposed between the orifice and the through pipe, and another end being externally threaded;
• a rigid washer fixedly secured externally to said internal metal guide tube and disposed so as to abut against the inside face of the inside layer of refractory material, the wall of the box being mounted against said rigid washer, and the further orifice in the wall of the box being larger than a cross-section of said internal metal guide tube;
• a sealing device fitted over said internal metal guide tube and disposed against the wall of the box;
• and
• a threaded nut screwed onto the threaded end of said internal metal guide tube so as to clamp said sealing device against the wall of the box, thereby sandwiching the wall of the box between said rigid washer and said sealing device.