Have an Answer?
JOSE MANUEL MARTINEZ
I learned a lot about welding processes during my mechanical engineering career in the commercial nuclear power generation industry. My career started in 1968 with a company that was the market leader in providing nuclear steam supply systems in the world for the generation of electricity . These included the nuclear primary components such as pressure vessels, reactor internals, steam generators, pressurizers, coolant circulating pumps, etc. At the time all the raw materials and product manufacturing were done in the USA. One common thing about all these components was that they all needed large cylindrical components that required 100% weld penetration girth joints to very strict volumetric Radiographic and UT inspections per the ASME B&PV Code, Sections III and VIII. The diameter of these cylinders were 10+ feet, with cross sectional thicknesses of 4 to 10 inches. The vessel cylindrical lengths ranged from 20 to 40 feet. Welding these cylinders together was definitely a manufacturing challenge.
Most of the welding was automated though some was manually done. The welders were trained and qualified to the applicable specifications and maintained qualified by actual welding work hours or by retesting. Some of the welding processes employed on the vessels were narrow groove welding, hot-wire-tungsten inert gas welding and submerged arc welding. The cladding processes included plasma cladding and strip cladding of stainless steel and Inconel on plates, cylinders and vessel heads weighting up to 150 tons.
The welders earned some of the highest wages per hour in the manufacturing facility because of the high quality level requirements that the final weld joints had to meet and the high cost investment of these components as the manufacturing assembly steps progressed. If an unacceptable indication was detected by X-Ray or UT inspections, the entire cylinder weld cross section where the defect was located had to be manually removed, re-welded and re-inspected, introducing days/weeks of schedule delays plus high rework cost. Welders that specialized in some of the more difficult welding processes and with a good record of reliability (high welds acceptance record) were always on high demand and enjoyed the highest pay grades in their class.
Now, one thing that the student needs to recognize is that most of this type of pressure vessel, nuclear grade vessels, shipyard vessel products manufacturing have been absent in the USA for many years and most of it was gradually outsourced to other countries. Today, the good welder profession opportunities continue to be where large components fabrication activities are that require welding processes meeting high quality standards. These may be ships, navy submarines, aircrafts, wind power turbines, pressure boilers, large oil pipelines fabrication, etc.