Fabrication of Process Vessel

Flat plates are formed into cylindrical structure by using a rolling machine as shown in Fig.(2). 


Rolling machine consists of three rotating rolls. By adjusting the distance between the top and bottom rolls, the plates are formed into a required curvature. The curved segments are joint together by welding in the longitudinal direction, to from a cylindrical course. More number of such courses may be formed and welded circumferentially to form the vessel of required height or length. Refer to Fig.(3).


Instead of circumferential welding, the cylindrical courses may also be joined together by bolt-nut connection using flanges. Refer to Fig.(4). The flanges are welded around the end of the cylindrical courses and connected together with by bolt and nuts. To provide leak-proof joint, gasket is to be placed between two mating flanges.


  • Rivetted Joints: The older form of joining two pieces of metals is rivetted joint. Refer to Fig.(5). A riveted joint is easily conceived between two plates overlapping at edges, making holes through thickness of both, passing the stem of rivet through holes and creating the head at the end of the stem on the other side. A number of rivets may pass through the row of holes, which are uniformly distributed along the edges of the plate. Such joints have been used in structures, boilers and ships. In comparison with welded joints, efficiency of rivetted joints are lesser. Rivetted joints are prone to leakage. Rivetted joints are still used in places which require allowance for lateral movements.

    Before welding techniques and bolted joints were developed, metal framed buildings and structures such as the Eiffel Tower were generally held together by riveting. Also automobile chassis were riveted. Riveting is still widely used in applications where light weight and high strength are critical, such as in an aircraft. Many sheet-metal alloys are preferably not welded as deformation and modification of material properties can occur.

  • Welded Joints: Refer to Fig.(6) for various types of welded joints.