In situations where, foremost, the required weld joints must exhibit strength, integrity and corrosion resistance, such as for thick walled components for super critical power plants or nuclear power plants, the application of hot-wire Gas Tungsten Arc Welding (GTAW), specifically GTAW Narrow Gap Welding (GTAW – NG), is finding increased use. The new GTAW-NG, from Polysoude SAS, is generally regarded as a low deposition process whereas higher deposition processes find wider use within the power generation industry. However, GTAW hot wire offers weld properties and joint efficiency in narrow gap applications. A variation of the GTAW process, where the low metal deposition is offset by an extremely narrow groove, GTAW-NG welding becomes suitable for thick walled components, including steam generator tubes, nozzles, casings, rotors and valves. Other GTAW features include: low distortion, low residual stresses, and its capability for cracking-free deposit.
