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Production • Processing • Handling


inadequate weld penetration in a section of the weld seam. Another common problem is porosity in the weld. Porosity can be scattered, cluster, or hollow-bead, but all types are defects and must be repaired. Tere are a lot of causes for porosity, which occurs when gas bubbles get trapped in the weld bead as it solidifies. During outdoor projects such as pipelines, windy conditions can cause the shield gas to be blown away while the welding is taking place, resulting in high porosity. While repairing weld defects adds time and cost to a project, the consequences of not repairing them would be far more severe. In fact, inadequate penetration and high porosity in welds, along with other issues, are actually the suspected cause of a September 2010 pipeline explosion in San Bruno, California. Federal investigators say they found dozens of substandard welds on the pipe; welds that could have been easily repaired with plasma. Another advantage of using plasma is the


increased visibility of the repair area. When making a repair, the goal is to remove the weld bead without touching the pipe section. “Tis is where plasma really pays off for the welder doing the job,” says Glaze. “Te welder can


see very precisely what he is doing.” A wrong move while gouging or grinding can require the removal of a complete section of pipe at a cost of $60 000 or more.


Pipeline construction Pipeline construction is a highly technical and regulated industry. Companies like Associated, which has been building pipelines for more than 50 years, have to meet stringent quality demands. In addition, Associated specializes in working in difficult terrain. Te company prides itself on its innovative approach and willingness to use new technology to meet these challenges. “New technology makes the industry much more efficient and works to eliminate hazards, such as those associated with the use of old hand grinders,” states Sonny Weems, Superintendent of Associated Pipe Line Contractors.


Although gouging was the first application Associated found for plasma, they are finding other uses for the cutting method. One such use is for the actual cutting of pipe. Te crew has discovered that using another Hypertherm product, the slightly larger Powermax65, with a mechanized torch and


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Fig. 2. In addition to gouging out metal, Ruby workers used plasma to cut new sections of pipe prior to the tie-in process. Because the Hypertherm Powermax system used on the line came with several different torches, workers were able to use the same system for both handheld gouging and mechanized pipe cutting.


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