The support ring and trunnion support the converter body and transmit tilting torque. The support ring has a rectangular box-like cross-section with vertical ribs welded in the center to increase rigidity. Water cooling reduces thermal stress within the ring. It can be welded from high-quality Q345 steel plates or cast steel. For ease of manufacturing, processing, and transportation, the support rings for large converters can be manufactured in sections and then assembled into a single unit.

Another type of support ring has a semicircular, open-ended structure, known as a horseshoe-shaped support ring. This type of support ring allows the converter body to be removed as a whole and rebuilt at a later location, enabling a single-blow operation.

The trunnion is made of 40Cr alloy steel forging to ensure sufficient strength and rigidity. The trunnion will elongate and warp due to heating. Therefore, to accommodate the trunnion’s elongation, the bearing on one side is axially movable, and its bearing support is a hinged connection structure. The bearing on the drive-side trunnion is usually axially fixed, while the bearing on the other side is axially movable. The trunnion can also be water-cooled.