Old Dominion Fabricators custom manufactures a range of products, including shell and tube heat exchangers, pressure vessels, towers, columns, feedwater heaters, reactors, condensers, evaporators, desuperheaters, and storage hoppers-bins. They offer duplicates of previously supplied units and provide mechanical and thermal design services through B-JAC International, using advanced software for optimized designs. Standards include ASME, TEMA, AD Merkblatter - DIN, CODAP, and others.
Key Components and Construction
- Shell Assembly: Constructed from steel pipe or rolled plate metal, the shell ensures economic efficiency and durability. Shell roundness is critical to minimize baffle spacing and optimize performance, achieved through mandrel expansion or double rolling. Impingement plates distribute fluid evenly, preventing erosion, vibration, and cavitation.
- Tubes: Heat exchangers use tubing made from low carbon steel, copper, stainless steel, and more, with diameters from 0.625 to 1.5 inches. Tubes can be seamless or welded, with enhancements like fins to improve heat transfer rates. Finned tubes are ideal for lower heat transfer coefficient shell-side fluids. U-tube designs handle significant thermal differences but are harder to clean and maintain.
- Bonnets and End Channels: Bonnets regulate fluid flow in the tube-side circuit and are fabricated or cast. Mounted against the tube sheet with bolts and gaskets, they may include pass ribs for consistent fluid velocity and pressure drop. Materials include iron, steel, bronze, Hastelloy, nickel-plated, or stainless steel.
- Baffles: Baffles guide tubes during assembly, prevent vibration, and direct shell-side fluids to increase heat transfer. They must fit tightly within the shell to prevent fluid bypass. Stamped, punched, or machined, baffles are precisely manufactured for easy assembly and maintenance. In liquid applications, baffles occupy 20-30% of the shell diameter; in gas applications, 40-45%. They are evenly spaced to reduce pressure drop and ensure even fluid velocity.
