García González José, Hernández-Ortega Juan José, Jiménez-Ballesta Ana-Eva, Pedreño Rosendo Zamora
Mecánicas Bolea S.A., 30353 Cartagena, Spain.
Departamento de Ingeniería de Materiales y Fabricación, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain.
Materials (Basel). 2021 Dec 30;15(1):261. doi: 10.3390/ma15010261.
The rear wall of the header box serves as a tubesheet in heat exchangers of double plate header box. Tube-to-tubesheet welding must be performed using orbital Gas Tungsten Arc Welding (GTAW) with a head extension, which is passed through the corresponding hole in the front wall (plugsheet) of the header box, where the welding machine is supported. In this project, the effect of parallelism deviations between the plugsheet and the tubesheet of carbon steel header box is analyzed to evaluate its influence on the quality of the tube-to-tubesheet welding. Welded tube (SA-210 Gr. A1) to tubesheet (SA-516 Gr. 70) coupons are manufactured simulating the parallelism deviations previously analyzed in two double plate header boxes of air-cooled heat exchangers using two different preheating temperatures. Macrographic analysis is performed in order to evaluate the weld penetration (minimum leak path) and length of the weld leg in tube-to-tubesheet joints. The results obtained show important variations in those parameters when the parallelism deviations are equal to or greater than -1 mm over the theoretical distance as well as when the distance approaches +1 mm or more. Finally, the incorporation of dimensional controls prior to the welding process is discussed and the implementation of improvements in orbital GTAW equipment is recommended as an optimal solution for this kind of heat exchangers.
集管箱的后壁在双板集管箱式热交换器中用作管板。管与管板的焊接必须采用带有焊枪延长杆的轨道钨极气体保护电弧焊（GTAW）进行，焊枪延长杆穿过集管箱前壁（盲板）上的相应孔，焊接机支撑在该孔处。在本项目中，分析了碳钢集管箱盲板与管板之间平行度偏差的影响，以评估其对管与管板焊接质量的影响。模拟在两个空冷式热交换器的双板集管箱中先前分析的平行度偏差，使用两种不同的预热温度制造焊接管（SA-210 Gr. A1）与管板（SA-516 Gr. 70）的试样。进行宏观金相分析，以评估管与管板接头处的焊缝熔深（最小泄漏路径）和焊缝焊脚长度。所得结果表明，当平行度偏差在理论距离上等于或大于 -1 mm以及距离接近 +1 mm或更大时，这些参数会有显著变化。最后，讨论了在焊接过程之前纳入尺寸控制的问题，并建议对轨道GTAW设备进行改进，作为这类热交换器的最佳解决方案。
