Investigating the influence of flowing fluid on the resistance of materials to sulfide stress cracking

The study aims to investigate the effect of flowing fluid on the susceptibility of metals and alloys to sulfide stress cracking (SSC) using the fracture mechanics circumferential notched tensile (CNT) specimen. The CNT specimen has never been used in the presence of flowing fluid. A novel testing flow loop was invented for performing the experimental work. The new testing rig can be used for determining the stress intensity factor (KI), threshold stress intensity factor (KIssc), and crack growth rate in flowing fluid for different materials in different corrosive environments at different temperatures. The testing flow loop has been registered as a patent in recognition of its novelty and practical applications in several industries. The experimental conditions were testing the resistance of heat treated P110 steel to SSC in deaerated stagnant and flowing solution containing 0.01 M Na2S2O3 (as a source for H2S) and 3.5 w% NaCl at room temperature. The experimental results show the heat treated P110 steel was susceptible to SSC in stagnant solution, while it was not susceptible in flowing fluid.