I used to work at place that did chromium carbide overlay on pipe for oil sands slurry. They were always busy and 90% of their work was just for Syncrude. There are several other companies doing overlay as well but the place I worked had the only elbow welder in N. America (probably the world) that could weld the inside circumference while rolling the elbow at the same time. It was closely guarded and kept under sheets whenever visitors toured the plant. All employee's had to sign confidentiality agreements. Apparently cost $750,000 to develop but made more profit than anything else at the parent machine shop. It was pretty impressive and had to be exact to burn 7/64" open arc wire at about 600 amps with about an 1 1/4" weave on 20-24" curved pipe elbows. The pipe elbows had to be flat at all times while welding progressed and each revolution the welding head had to move over to put the next bead beside the deposited bead. The bad part was for the operator. He had to sit for hours and just watch the meters on the welder to make sure the volts and amps stayed within a certain range. One of the most boring jobs imaginable. Have heard of big projects that require 3000 or more welders.
