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Considering reinforcement pad and the cylindrical shell as an integral model and a contact model, stress analysis for opening-reinforcement structures of a cylindrical shell is performed by elastic and elastoplastic FEM. By comparison of two sub-models and two material constitutive relations (elastic and elastoplastic), the stress distribution of cylindrical shell intersections by the contact model is similar to that by the integral model, but there are some differences of the stress at contact surfaces of the shell and the reinforcement pad between by the contact model and by the integral model. In general, the stress analysis of the integral model for pad reinforcement can approximately represent that of the contact model. Finite element analyses for different nozzle diameters and different oblique angles in nozzle and cylinder shell intersections are carried out. The stress distribution and the maximum stress are affected by oblique angle. But the difference of the maximum stress intensity among different diameters is small.Copyright © 2007 by ASME

The residual stresses of mismatch butt welds of a cylinder were measured by the blind-hole method before and after a vibratory residual stress relief treatment. The results show that this treatment could greatly reduce the maximal butt weld residual stress of dissimilar steel from 540MPa to 119MPa. The concentrated distributions of the first and the second principal residual stresses became gentle after the vibratory residual stress relief treatment.Copyright © 2007 by ASME

Finite element method is applied to calculate the stress distribution and the maximum stress location of the tubesheets, tubes and other parts of a tubular heat exchanger in a petrochemical plant. Comparison between FE results and TEMA results is discussed. The temperature and stress distribution of tubesheets and other important parts can be accurately calculated by FE method, also the safety margin of the parts in the heat exchanger can be clearly given by FE method. For multi-pass heat exchanger, FE method is more useful. By analyzing FE results, it is easily to know whether the stresses in exchangers are over the allowable value. Therefore, FE method is a good measure to aid heat exchanger design when standard of TEMA is used.

Tube pulling apart loads of tube-and-shell heat exchangers are very complicated, because these loads are affected by many factors, such as, tube to tubesheet joint structure, pressure, and temperatures. The tubes may break or be fouled during the service, which will result in change of tube metal temperatures and affect pulling loads. Some tubes may be pulled out from the tubesheet because of too much high tube pulling apart loads and the heat exchanger cannot be operated normally. Depending on the different flow passes of the fluid and the temperature change in the service, the tube pulling loads for several cases with different temperature distribution are calculated and analyzed for a heat exchanger using finite element (FE) method. The results show that the pulling loads of different tubes are different obviously. The pulling loads of the heat exchanger are assessed with ASME Code. The maximum pulling load is over the allowable force. FE method is a good technique to assess the distribution of the pulling loads and the location of the maximum pulling load. So it is useful and important to use FE method for forecasting the break and leak of the tubes.Copyright © 2005 by ASME

The safety analysis and test research are done to inspect the safety of 300MW control rod drive machine (CRDM) pressured shell structure in a systematic way. The test result agrees accords with FEA result. In actual operating mode (300 °C) inner-pressure fatigue simulative test, the axial and hoop pre-cracks are made, and the fatigue crack growth is observed. The load-bearing capability and deformation are tested in shell-burst test. Based on test research, this paper analyses theoretical load-bearing capability and safety margin in accordance with ASME CODE Sec. III design is calculated. Elastic-plastic fracture mechanics theory and GEGB.R6 method is used to analyze structure safety. The test results show pressure shell’s safety allowance is large enough.Copyright © 2005 by ASME