Experimental Investigation of Tube-to-Tubesheet Welding in Stainless Steel Heat Exchangers

Shell and tube heat exchangers are widely used in various industries for effective heat transfer between fluids. However, these exchangers often encounter challenges such as corrosion and wear, which can greatly affect their performance and lifespan. To address these issues, utilizing stainless steel (SS) made heat exchangers can significantly improve the corrosion and wear resistance of heat exchangers and their components. In this study, welding procedure specifications (WPS) for welding tube-to-tube sheet (TTS) joint mock up is qualified as per ASME IX QW 193 and ASME Section VIII Div. 1 UW-20. Experimental studies were performed on a 50 mm thick SS tube sheet (SA240 Gr TP 316 L) welded with SS tubes that have an outside diameter (OD) 19.05 mm and thickness 1.65 mm (SA 312 Gr TP 316 L). Both the tube and tubesheet materials are SS which is widely used due to their excellent corrosion resistance, strength and versatility. The welding of 10 samples was carried out using a gas tungsten arc welding (GTAW). In order to evaluate the quality of TTS joint, visual testing (VT), penetrant testing (PT) and macro-examination for minimum leak path (MLP) was performed according to welding procedure which can also satisfy the inspection standard. Furthermore, hardness test, ferrite test, and chemical analysis were also conducted to confirm the quality and integrity of the welds. The successful WPS provides a good reference (process parameters) for the welding quality control during the manufacturing SS heat exchangers for corrosion resistance.