Combined Gas Tungsten Arc Welding and Shielded Metal Arc Welding Processes for Joining Tube to Tubesheet in Shell and Tube Heat Exchangers

Abstract

Flawless tube and tubesheet joints are necessary for shell and tube heat exchanger with high leakproof ability and durability. The consequence of mixing of transfer fluids due to the defective welded or expanded tube-to-tubesheet joint results in complete malfunctioning of the heat exchange process. In this case, there is a high demand for quality assessment of the fabricated tube-to-tubesheet joints (TTS) based on the international standards. Additionally, the literature on assessing the mechanical and metallurgical characteristics of tube-to-tubesheet joints using any one welding technique is available; however, articles dealing with the use of multiple welding techniques are scanty. In the current work, the quality assessment of strength welded and light expanded (3%) tube-to-tubesheet joints followed by light expansion was performed whereas for welding, combined gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) as root pass and cap pass were adopted in the fabrication stage. Quality and sound tube-to-tubesheet joints were produced using welding and tube expansion process. Linear and circular indications representing the cracks were absent on the developer in the liquid penetration test. The minimum leak path (MLP) was greater than the two-third of tube wall thickness. The results strongly qualify the use of combined gas tungsten inert gas and shielded metal arc welding process for manufacturing of tube-to-tubesheet joints. The methodology and results in the current article are beneficial for researchers and industrialists working close to shell and tube heat exchangers and boilers.