| The equipment has been crucial in the production process of the modern petroleum and chemical industry. To increase the economic efficiency, it is necessary to enhance the efficiency of the equipment and to prolong the running period. To ensure the safety of the production, it is necessary to ensure the reliability of the equipments. Today, the process installation in the petrochemical and power industry etc. is developing to high temperature, high pressure and large scale. In order to increase installation efficiency, higher demands to the safe reliability of the equipment must be put forward.During the glycol production, lots of cracks appeared near the girth weldment between cylinder and head in several glycol evaporators, which directly affected the production safety. In the present paper, based on the understanding of remanufacture technology of petrochemical equipment, study on failure reasons of the glycol evaporators, material selection, simulation of the welding residual stress during the remanufacturing and safety evaluation after remanufacturing are done. Some major works and conclusions are as follows:(1) Failure reasons of the glycol stainless steel evaporators are analyzed in terms of the metallographic examination, fractography and chemical compositions of material and corroded grain boundaries. The results show that the failure of the glycol evaporators is caused by intergranular stress corrosion crack (IGSCC). The detailed reasons are that the serviced stainless steel is sensitized, larger residual stress is caused at the welded joint and Cl~ and SCu2" co-exist.(2) As far as the redesign of the glycol stainless steel evaporators is considered, IGSCC resistance of the three kinds of stainless steel material is investigated. The experiment results show that the IGSCC resistance of lCrl8Ni9Ti is poor, 316L and SAF2205 are excellent with the increasing of the sensitization effects. Based on the synthetical consideration of corrosion resistance, design and manufacture, it is the best choice to use 316L for remanufacturing of the glycol evaporators.(3) Numerical simulation is applied to analyze the welding residual stress for different welding methods and the distribution of residual stress is obtained for whole attachment and local attachment. The simulation results show that the residual stress parallel to weldment is maximum on the HAZ of the cylinder due to attachment for MAW or TIG, which is coincide with the direction of stress corrosion cracking. On the other hand, welding residual stress caused by using TIG methods was smaller than that caused by using MAW, which implies thatTIG welding can reduce the welding residual stress effectively when remanufacture of the glycol stainless steel evaporators are carried out and will be beneficial to prevent the stress corrosion cracking. The simulation results of welding residual stress for different welding methods have some instructive effect on selecting the suitable welding method when repairing.(4) Strength and safety of T532 glycol evaporator after remanufacturing are evaluated. If crack depth and length are less than 6.0mm and 3000.0mm respectively, the fracture failure does not arise in the evaporator. The change in crack depth is one of the important factors determined structure being safe or not. Finite element stress analysis shows that larger stress appears on the welded zone of the reinforcement plate and head after the attachment, but the primary and the secondary stress near fillet between the reinforcement plate and the cylinder met the strength demands when the crack depth is less than 6mm, which means that the attachment can reinforce the structures with defects and the equipment with small cracks can meet the design requirement after the attachment.
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