Product Applications – Splice Welding System
Gullco KAT Travel Carriages: Case Study of Automated Splice Welding System for Ohio Steel Fabricator
Product Applications File – Splice Welding System
For this 12-year old Cleveland Ohio fabricator of steel-annealing furnace equipment, improving welding productivity is essential for survival in a competitive market. A large part of its business is fabrication of large furnace vessels called inner coves, these weldments require the firm to splice several sheets of plates into one, then roll-form the spliced work piece into a cylindrical cover. Splice welding by proved much too time consuming, and the company has relied on Kat travel carriages since 1987 to automate the long, straight splice welds. The company recently purchased another Gullco carriage for an upgrade to the inner-cover-fabrication area of the shop.
The inner covers, of stainless-steel sheet 11 gage (0.12 inch) to 3/16 inch thick, measure 48 to 132 inches o.d., 60 to 192 inches tall. Covers contain the atmosphere in the annealing furnace. Most are of Type 309 stainless. An alternative material, popular in Europe and gaining acceptance in the United States, is Rolled Alloys RA253MA. An ASTM A250 stainless (11 Ni, 21 Cr, 65 Fe), it exhibits superior strength and oxidation resistance to Type 309. Gullco visited the company during an order for 96 inner covers for a major steel mill in the Detroit area.
In the inner-cover area of the shop, Dever has prepared a section of the floor specifically for splice welding of steel plate in the concrete foundation, then welded steel rails to the steel flooring, 48 by 20 feet in area. For guiding the Gullco Kat travel carriages, two 120 inch long section of tack mounts on a wheeled gantry. The gantry rides the steel rails, and raises and lowers manually using hydraulic jacks at both ends. Before upgrading this area of the shop, an operator used a crane to move the travel carriage gantry to each weld joint. The steel flooring provides a level work surface and acts as a heat sink during welding.
Each of the 76-inch-i.d. vessels for the Detroit-area mill is rolled of a 240 inch long steel blank, of five 48 inch wide panels, 12 feet long, splice welded together. Weld joints are zero gap butts. An operator lays the sheets, 3/16 inch thick, on the floor and tack welds them to each other, and then positions the gantry over the first weld joint. He takes the GMAW torch off the carriage and uses it to weld run-on and run-off tabs to both joint ends. He also fills in fit up gaps wider than 3/16 inch. Each splice weld takes one pass on each side, ensuring full penetration. The carriage makes the four welds on the top side, and then a crane flips the assembly for welding the back side of the four joints. During welding, the operator observes the arc, adjusting cross slides to keep the arc on the joint. He adjusts torch position vertically and horizontally. The 12 foot long weld takes 6 minutes. With both sides of all four joints welded, the assembled sheet feeds through a 5/8 by 16 foot capacity roll former; finished welding to close the cylinder is manual.