Indian Welding Journal

Samanvay Shah ¹, Ankit Gandhi ¹, Ritesh Patel ¹, Krunal Rana ², Hemant Panchal ²

Affiliations
1 Larsen & Toubro Limited, Heavy Engineering IC, Hazira Works, Surat – 394510, IN
2 The Maharaja Sayajirao University of Baroda, Vadodara – 390002, IN

Abstract

Tube to tubesheet welds are very important for functioning of any heat exchanger. Generally, corner or fillet type of joint design is used for these welds. However, both type of joint design is undesirable in certain applications since it leaves “crevice” between tube and tubesheet which acts as potential site for initiation of corrosion. Moreover, volumetric examination of weld is also not feasible. Hence, for very critical applications, tubes are welded to tube sheet using “full penetration – butt joint” which eliminates crevice and makes volumetric examination of weld feasible. Welding of this type of joint is termed as “Internal Bore Welding” since welding is made from inside of tube. Mostly, automatic GTAW process is used. L&T is manufacturing a stainless steel heat exchanger wherein tubes were to be butt welded using internal bore welding technique. This heat exchanger consists of more than 4500 tubes of 15.75 mm inside diameter and 1.65 mm thickness to be welded to tubesheet of thickness greater than 150 mm. 100% Visual Examination from outside and inside, dye penetrant testing from outside surface of weld, radiography examination (PQR) and helium leak testing are required for these joints. Special torch is developed to facilitate IBW for such small diameter of tubes. Welding without filler wire addition is done in 5G position to produce weld metal having acceptable visual appearance. This paper describes selection of welding machine, special considerations for IBW, development of welding procedure.

Keywords

Welding, Internal Bore Welding, Tube to Tubesheet Welding, 5G Welding.

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A. K. Vaish ¹, Ritesh Patel ¹, J. Krishnan ¹, B. J. Chauhan ¹, S. D. Kahar ¹, K. M. Bhaisaheb ¹, Ankit Bhojani ²

Affiliations
1 Department of Metallurical and Materials Engineering The M. S. University of Baroda, Vadodara - 390001, IN
2 Department of Metallurical and Materials Engineering The M. S. University of Baroda, Vadodara - 390001, IN

Abstract

Underwater weiding invoives a high degree of technicai compiexity. It is basicaiiy appiied in ship buiiding and maintenance, waterway structures, submarines, subsea pipelines, offshore oii rigs and nuciear reactors etc. High quaiity standards are required for underwater weiding systems and personnei. Undenwater weiding profession is attracting much more than other professions since it is more chaiienging and highiy paid. In view of this fact, an attempt has been made to briefly discuss its mechanism, chalienges, risi<s and recent advancements.

Keywords

Underwater weiding, Mechanism, Challenges, Risks, Advancements

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A. K. Vaish ¹, Ritesh Patel ², B. J. Chauhan ¹, S. D. Kahar ¹, Ankit Bhojani ¹, K. M. Bhaisaheb ¹, Keshva Narayana ²

Affiliations
1 Department of Metallurgical and Materials Engineering, The M.S. University of Baroda, Vadodara- 390001, IN
2 Larsen and Toubro Ltd., Hazira, IN

Abstract

Among different metals steel can be easily welded and welded steel has required strength, good ductility and sufficient resistance to general corrosion media. Since steel welding is being used in all types of fabrication industries, the mechanism of steel welding has been explored for different types of steel along with its multiple applications.

Keywords

Steel Welding, Mechanism, Carbon Content, Alloying Elements, Grain Coarsening, Hardening, Pre-Heating.

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