| 摘要 |
The aim of the invention is to provide an alternative to the circular cross-section. To this end, two partial cover sheets (4, 5) are bent into their required final position in such a way that they overlap each other with edge areas (12 to 15) extending in the longitudinal direction of the monolith (2) and tightened around the monolith (2), an expanding mat (3) being provided between said monolith and said sheets, before the edge areas (12 to 15) are welded together. |
