When and why Expansion is necessary in Tube to tube-sheet joints?

1. When & why expansion is necessary? Expansion is necessary in all cases because the tube hole in the tube sheet is slightly highe...

1. When & why expansion is necessary?

Expansion is necessary in all cases because the tube hole in the tube sheet is slightly higher than the tube OD. So if we do not expand it will cause crevice and ultimately tends to leakage.

For the strength of the tube to tube sheet joint weld, contact expansion is necessary as explained above.

2. Difference between contact(light) & heavy expansion and what its range?

For Heavy expansion, normally grooves shall be provided in the tube sheet as per TEMA RB-7.24. Tubes will be expanded in such a way that it will flow in these grooves. In Heavy expansion normally 5% thinning of tube thickness occurs.

3. what are the applications to expand the tube?

Tubes are expanded using standard roller expander or sometimes using a hydraulic expander.