As a provider of customized metal fabricating, Bassett Mechanical was recently contracted by Ellicott Dredges to fabricate a 90,000-pound mining dredge.
According to the company, Ellicott approached Bassett and was looking for a metal fabrication contractor that could build a large stainless steel mining dredge. Due to the material specifications, Ellicott didn’t want to make this type of dredge in-house, so they reached out to a qualified, experienced contractor.
The project was a 90,000-pound, 18-foot-wide by 52-foot-long and 9-foot-tall 316L stainless steel dredge barge hull. The dredge was to be fully welded, passivated, and watertight.
“It was clear from our initial meetings that Bassett had the expertise in working with stainless steel and the reputation for quality. Through plant visits, they demonstrated capacity, capability, and strong organization,” said Duncan McTaggart , Director of Applications Engineering, Ellicott Dredges.
During the project, Bassett overcame two challenges: passivation of the stainless steel in a confined space and flipping the dredge.
Passivation is a widely used metal finishing process to prevent corrosion. In stainless steel, the passivation process uses nitric acid or citric acid to remove free iron from the surface.
The other challenge was flipping the dredge – twice – which required a lot of prep and communication. At the time of the first flip, the dredge weighed 50,000 pounds. To flip it, because of its weight, Bassett crew used three overhead cranes simultaneously. The company continued with the weld sequence and then repeated the process to flip it back.
After five months of construction and once the dredge passed the final inspection, the vessel was loaded on a special-sized truck with extensive rigging and two cranes.