Abstract
New type of repairing technology for branch connection defects on gas pipelines has been designed recently. Repairing technique is based on manufacturing of split sleeve and welding of its parts together and to the repaired pipes by manual metal arc welding technology. Appropriate testing has to be performed to ensure practical and permanent use of such kind of sleeve in commercial area. Destructive testing was performed to confirm quality of the welds on the prototype sleeve repair. Macrostructural and hardness evaluation showed inhomogeneity present in some welds. According to that, microstructure observations, spectral analysis and mechanical tests were performed on the base metal of the sleeve. It has been showed that even when some problems may be present, repairing technique by split sleeve can be still suitable for permanent repairs of the defects of the branch connections.
Highlights
Quality of weld joints is very important factor to ensure safety and long term lifetime of the gas transport pipelines
Welding quality control is important and every new type of weld joint has to be analyzed by non-destructive evaluation and it should be tested by destructive testing methods
Macrostructural analysis and hardness evaluation of the weld joints of split sleeve for branch connection repairs was performed on four characteristic welds
Summary
Quality of weld joints is very important factor to ensure safety and long term lifetime of the gas transport pipelines. Welding quality control is important and every new type of weld joint has to be analyzed by non-destructive evaluation and it should be tested by destructive testing methods. Numerous kinds of repair techniques are available including the cut out and replace of the pipeline, construction of the bypass along the damaged area, grinding, weld deposition, metallic or composite sleeves [2]. Complicated construction together with different manufacturing processes of sleeve parts might cause weld joint problems and precise weld examination is necessary. Non-destructive examination of weld joints has been proposed by ultrasonic technique TOFD [5] but destructive testing of such welds has not been proposed yet
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