10.  Assembling tubes on tube sheets

10.1  Joining by rolling alone

Figure 6 describes this type of fastening, which must ensure both mechanical strength and tightness. According to current European regulations (Pressure Equipment Directive – DESP 97/23CE), this type of assembly, described as "permanent", must be the subject of an operating mode qualification.

The operation consists in plastically deforming the tube, either by :

• mechanical chucking (action of rollers on a tapered shank) ;

• hydraulic expansion ;

• explosive charge (for very specific cases).

The outer edge of the tube...