The Fea Simulation And Fitness-for-service Assessment Of Hydrogen Induced Blister Of The Equipment Operated Under Hydrogen Sulfide Enviroment

In this thesis, the equipment which contain hydrogen blister operated under hydrogen sulfide environment is mainly researched. The FEA software ABAQUS/Standard will be used to model the equipment which contain hydrogen blister. The method of fitness-for-service is used to assess the cylinder specimen which contains multiple hydrogen blisters so that reduce the unnecessary shut down of refinery.In order to research the diffusion process of hydrogen atom in the base metal during the initial stage of the hydrogen blister, the transient analysis will be used to simulate the diffusion of hydrogen atom in the base metal which contains inclusion. Some three dimensional models of the cylinder which contain ellipse hydrogen blister crack are established to analysis the stress intensity factor of the blister crack with different blister size and internal pressure under the condition of elastic material, the trend of crack propagation may be assessed. Through hydrogen charging of the sample material, the material which contains damage under actual service condition can be obtained. The tensile test of the material is conducted to obtain the true stress and true strain data of material. The J integral and other characters of blister crack which is contained in the base metal are analyzed.The transient analysis of the hydrogen diffusion shows that whether the inclusion exists or not and its position play a very important role in the development of the hydrogen blister. The hydrogen concentration of inclusion area is higher than that of base metal. The tensile stress will promote the hydrogen diffusion but the pressure stress will hinder the hydrogen diffusion. The results of three dimensional models show that the stress intensity factor and J integral of ellipse hydrogen blister crack are gradually increased with the path which from semi-major axis counterclockwise to semi-minor axis. Under the same condition except the size, the greater the size of blister crack, the easier to propagation. Under the same plump height of blister, the J integral is almost very close no matter whether the size of blister is same or not, the trend of blister crack propagation is almost the same with each other.