The study of the characteristics of changes in the mechanical properties of the fillet weld region of a reservoir during cyclic loading using Small Punch Test specimens

Abstract

The study investigated the fillet weld region of vertical steel reservoirs using the Small Punch Test(SPT) method. The main focus was on determining material characteristic parameters such as fracture,elongation, and creep, as well as finding optimal method parameters. The analysis aimed to enhancethe safety of using vertical steel reservoirs in hydrocarbon extraction, transportation, and processing,as accidents involving these reservoirs can have severe consequences. The research revealed that theSmall Punch Test method is effective, and further investigations should be conducted not only on thefillet weld zones but also on the base material, including the heat-affected zones. It was recommendedto surface treat the specimens to remove wire marks, as polished surfaces with lower roughness valuesshowed higher correlation with mechanical characteristics compared to rough unpolished specimens.The study concluded that testing specimens smaller than 1 mm is not accurate, and specimens largerthan 1 mm should be chosen, considering the deformation capacity of the equipment. Additionally,the possibility of increasing the diameter of specimens without compromising their stability shouldbe explored to improve the accuracy of diagnostic testing. However, finding the optimal balancebetween specimen size and testing accuracy requires further calculations. The cutting of specimensfor SPT testing should be performed using methods that do not introduce internal stresses, such aselectroerosion methods followed by grinding the cutting plane. This is crucial to avoid erroneousresults caused by the deformation of the edge layer. In summary, this research provides valuablerecommendations for using the Small Punch Test method to investigate vertical steel reservoirs andenhance their safety.