Analysis of Cracking Causes and Experimental Evaluation of Welds on Spherical Tanks of a Light Hydrocarbon Plant in Western China

LI Yajun; WU Chao; PAN Hong; AN Chao; FANG Yan; XIONG Xinmin

doi:10.7643/ issn.1672-9242.2025.11.016

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Equipment Environmental Engineering ›› 2025, Vol. 22 ›› Issue (11) : 151-159. DOI: 10.7643/ issn.1672-9242.2025.11.016

Analysis of Cracking Causes and Experimental Evaluation of Welds on Spherical Tanks of a Light Hydrocarbon Plant in Western China

LI Yajun^1,2,3,4, WU Chao^1,2,3,4, PAN Hong^5,*, AN Chao^1,2,3,4, FANG Yan^1,2,3,4, XIONG Xinmin^1,2,3,4

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Abstract

The work aims to clarify the specific causes of weld cracking in spherical tanks at a light hydrocarbon plant in western China, as well as the influence mechanism of welding process and environmental factors on the crack resistance of welds, and to provide support for the optimization of welding processes and construction control of similar spherical tanks. With a failed Q345R steel spherical tank as the research object, the damage status of the failed samples and the differences in residual stress magnitude and performance of simulated welded samples under different cooling rates were determined through non-destructive testing and physical and chemical inspection. The results showed that 122 cracks were found in the inner weld of the spherical tank, with the longest reaching 30 mm. The residual stresses of the simulated welded samples No. 1 and No. 2 were 168 MPa and 248 MPa respectively; their impact energies at ‒20 ℃ were 110 J and 93 J respectively, and the hardness values of their heat-affected zones (HAZ) were 276HV0.5 and 301HV0.5 respectively. The martensite content in the HAZ of simulated weld sample No. 1 was lower than that of sample No. 2, which was the fundamental reason for the differences in residual stress and performance between the two samples. Neither sample cracked in the stress corrosion cracking (SCC) test with low H₂S content. Therefore, the weld cracks in this spherical tank are cold cracks caused by the formation of hard and brittle martensite structure due to excessively fast cooling rate under the action of high residual stress, rather than stress corrosion cracking induced by low H₂S content.

Key words

spherical tank / weld cracking / cold crack / residual stress / martensitic structure / welding process

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LI Yajun, WU Chao, PAN Hong, AN Chao, FANG Yan, XIONG Xinmin. Analysis of Cracking Causes and Experimental Evaluation of Welds on Spherical Tanks of a Light Hydrocarbon Plant in Western China[J]. Equipment Environmental Engineering. 2025, 22(11): 151-159 https://doi.org/10.7643/ issn.1672-9242.2025.11.016

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