Combination of Grinding and Wet Welding to Repair Localized Cracking in T-Welded Connections

Abstract:

This paper presents experimental research work on the combination of grinding and wet welding techniques to repair T-welded connections employed in the construction of offshore structures. A longitudinal rectangular grinding profile was performed at the weld toe of T-welded connections for localized cracking material removal. Two different grinding depths of 6 mm and 10 mm were performed in the welded connections to eliminate two different level of damage depth. Subsequent wet welding was applied in the grinded region to repair the grinded material. The wet welding was performed in a hyperbaric chamber simulating three different water depths: 50 m, 70 m and 100 m (shallow water). Once the combined repair techniques were performed, further experimental work was done to characterize the mechanical behavior of the repaired structures. The mechanical characterization was done with tensile, Charpy tests and Vickers Hardness tests. The region of interest from the structures was the weld toes the grinded-wet welding repair of the T-welded connections. Subsequent scanning electron microscopy (SEM) was also performed to examine the developed microstructures in the T-welded connection. The results showed that the combination of the repair techniques can restore the mechanical properties of the damaged structures. This was demonstrated by the measurement of the ultimate tensile strength, which were similar to those measured with no repair applied techniques. But the Charpy energy values were quite lower to those previously measured. This behavior was attributed to the level of porosity formed by the high level of gases created during the welding process for the simulated water depths, which were more severe at the higher water depth resulting in pore formation

• Periodical: Materials Science Forum (Volume 793)
• Pages: 51-58
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.793.51
• Online since: May 2014
• Authors: Gerardo Terán Méndez*, Rubén Cuamatzi-Meléndez, Apolinar Albiter Hernández
• Keywords: Grinding, Microstructure, SEM, T-Welded Connection, Wet Welding

References

[1] Pemex Exploración y Producción –Instituto Mexicano del Petróleo, Criterio Transitorio para la evaluación y el Diseño de Plataformas Marinas Fijas en la Sonda de Campeche (1997).

DOI: 10.22201/fi.25940732e.2017.18n1.001

[2] MMS Project 578, Assessment of fixed offshore platform performance in hurricanes Katrina and Rita - Final Report2 (2007).

[3] G. Terán, A. Albiter, R. Cuamatzi-Meléndez, Stress concentration factors of a T-welded connection with various grinding profiles. Eng. Struct. 53 (2013) 1484-1495.

DOI: 10.1016/j.engstruct.2013.06.031

[4] H. Wu, A. Imad, N. Benseddiq, J. T. Pinho de Castro, M. A. Meggiolaro, On the prediction of the residual Fatigue life of Cracked Structured Repaired by the Stop-hole Method. Int. J. Fatigue 32 (2010) 670-677.

DOI: 10.1016/j.ijfatigue.2009.09.011

[5] K. J. Kirkhope, R. Bell, L. Caron, R. I. Basu, K. T. Ma, Weld detail fatigue life improvement techniques Part 1: Review. Mar. Struct. 12 (1999) 447-474.

DOI: 10.1016/s0951-8339(99)00013-1

[6] M. B. Green, Underwater Repairs Using Wet Welding in the North Sea. OTC 4868 (1985) 249-253.

[7] S. Ibarra, D. L. Olson, C. E. Grubbs, Underwater wet welding of higher strength offshore steels. OTC 5889 (1989) 67-75.

DOI: 10.4043/5889-ms

[8] B. J. Wood, W. A. Bruce, W. A. Boyles, Characteristics of an underwater wet repair weld made at 560 ft. OTC 6216 (1990) 151-159.

DOI: 10.4043/6216-ms

[9] S. Ibarra, R. L. Reed, J. K. Smith, P. E. O´Connor, C. E. Grubbs, Underwater Wet-Welding Technique for Repairs of Higher-Carbon-Equivalent Steels. OTC 6214 (1990) 135-142.

DOI: 10.4043/6214-ms

[10] S. Ibarra, R. L. Reed, J. K. Smith, I. Pachniuk, C. E. Grubbs, The structural Repair of a North Sea Platform Using Underwater Wet Welding Techniques. OTC 6652 (1991) 56-66.

DOI: 10.4043/6652-ms

[11] MSL Engineering Ltd, Assessment of Repair Techniques for Ageing or Damaged Structures C357R001 (2004).

[12] MMS Project 642, Assessment of damage and failure mechanisms for offshore structures and pipelines in Gustav and Ike- Final Report 2 (2010).

[13] S. L. De Franco, T. J. Reynolds, F. J. Buescher, P. O´Connor, Offshore platform repaired by wet welding weathers Hurricane Lili. 22ND International Conference on Offshore Mechanics and Arctic Engineering, June 8-13. OMAE2003-37283 (2003).

DOI: 10.1115/omae2003-37283

[14] M. Souza, Y. Bayazitoglu, L. S. Lu, V. Valdés, R. Vazquez, Repairs of hurricane platforms in the bay of Campeche. OTC 8694 (1998) 107-116.

DOI: 10.4043/8694-ms

[15] Ship structure committee SSC-335, Performance of underwater weldments (1999) 1-239.

[16] S. Ibarra, S. Liu S, D. L. Olson, Underwater wet welding of steel. Welding Research Council Bulletin 401 (1995) 1-39.

[17] Metals Handbook, 7th, Vol 6., Welding, brazing and soldering, ASM International (2005) 1010-1016.

[18] F. Perez-Guerrero, The mechanism of porosity formation in underwater steel welds using SMAW process. Ph Thesis. Colorado school of mines (2007).

[19] ASTM E8/8M.13, Standard Test Method for Tension Testing of Metallic Materials (2013).

[20] ASTM E23-12, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials (2012).

[21] E.C. Pessoa, Estudo da variação da porosidade ao longo do cordão em soldas subaquática molhadas. PH Thesis. Federal University of Minas Gerais (2007).

[22] F. Perez-Guerrero, S. Liu, C. Smith, E. Rodriguez, Effect of Nickel on Toughness of Underwater Wet Welds. 22ND International Conference on Offshore Mechanics and Arctic Engineering, 8-13. OMAE2003-37261 (2003).

DOI: 10.1115/omae2003-37261