The operations for shaping boiler plates are as follows:

(1) Planing plate edges.

(2) Rolling plates to cylindrical form.

(3) Flanging.

(4) Drilling holes for rivets, stay bolts, tubes, etc.

These operations prepare the plates for assembling, although a few rivet holes are drilled immediately after the plates are marked, for the purpose of handling them. These holes are drilled slightly smaller than the finished size and their worn edges are reamed out when ready for riveting.

Fig. 222.