Abstract: The apparatus includes a first protection sleeve element having a substantially radially upturned annular end portion, a second protection sleeve element having also a substantially radially upturned end portion and a bellows. The bellows ends at both sides in a neck. A cylinder shaped portion of the first protection sleeve element is surrounded by an envelope part having a cylinder shaped portion and a substantially radially upturned annular end portion. Likewise, a cylinder shaped portion of the second portion sleeve element is surrounded by an envelope part having a cylinder shaped portion and a substantially radially upturned annular end portion. The necks of the bellows are sandwiched between the cylinder shaped portions of the respective envelope parts and the first protection sleeve element and the second protection sleeve element and are welded thereto.

Abstract: The apparatus consists of three single integral sheet metal structures interconnected by weldings. The first structure is the bellows element. The second structure is an integral formed sheet metal part which forms the one flange element and simultaneously the protection sleeve element. The third structure is a further integral formed sheet metal part which forms the other flange element and simultaneously the pipe stub element in which the free end of the protection sleeve element is received. The flange elements are formed in that the sheet metal parts include a first and a second portion, whereby the respective second portions are folded back over the respective first portions and welded thereto.