3rd Class Power Engineering (3B1) Practice Exam

The technique used in shell and drum fabrication primarily involves rolling plates to form a complete cylinder. This approach is essential in the manufacturing of cylindrical components like shells for pressure vessels and drums. The rolling process allows metal sheets to be shaped smoothly into a cylindrical profile, which is crucial for applications requiring structural integrity under pressure, such as in boilers or storage tanks.

Once the plates are rolled into a cylinder, they are typically welded along the seam to complete the fabrication process. This method ensures uniformity and strength in the finished product, making it ideal for the high-pressure environments these components often operate within. The design also facilitates efficient handling and transportation given the geometric characteristics of the cylinder.

Other methods listed, such as welding flat panels or stacking solid pieces, do not effectively create the continuous shape required for the shell, while pouring liquid metal into molds is more associated with casting processes than with fabrication techniques necessary for cylindrical components.