The powerful new steam dredge 'Bill Bauer,' now on location at its first job in Pascagoula, Miss., has set an industry standard by using 100,000-psi yield strength steel in critical structures.
Recently constructed by Bauer Dredging Co., the dredge is the 14th in the company fleet. Besides being the company's largest, it is the first with steam power. It is 316 feet long, including the ladder, and has a beam of 50 feet.
Two working components of the dredge are unusual. The suction ladder and the spuds are made of Armco Steel's SSS 100, a quenched and tempered alloy steel with minimum yield strength of 100,000 psi and tensile strength ranging from 115,000 to 135,000. SSS 100 is about three times stronger than the steel normally used for such construction.
Strength and reliability were two of the prime requirements for the ladder and spuds. The SSS 100 steel plate not only provided the extra strength, it actually reduced the weight of ladder and spuds as compared to conventional steel construction.
Total weight of the 86-foot-long suction ladder and the cutter head is 350 tons. The head is powered by two 1,000-hp electric motors through a 17-inch-diameter drive shaft. The ladder, made of twin box sections, was fabricated of 1 3/4-inch-thick SSS 100 plate by the Wyatt Division, U.S. Industries, Inc., Port Houston Shipyard.
Internal baffles in the twin-box structure are 3/4-inch SSS 100 plates. Sections of the structural boxes are 96 inches tall and 32 inches wide.
The 42-inch-diameter spuds are 96 feet long and weigh 40 tons each. Fabricating the cylindrical spuds of SSS 100 gives them strength and resistance to bending and flexing.
Welding was a critical step in fabrication because of the stresses and strains in the ladder and spuds. Tacking and manual fillet welding was done with E 8018 electrodes. Submerged arc—used for butt and fillet welds — used Armco's W-15 welding wire with a neutral flux. The wire contains nickel, chromium and molybdenum. The welded joints have a strength level slightly lower than the SSS 100 steel, but have exceptional ductility.
The 'working end' of the dredge Bill Bauer shows the suction ladder after installation. The ladder, weighing 350 tons, including the suction head, is made of Armco SSS 100 steel plate, with yield strength of 100,000 psi.