Maximizing Material Temperature Capability in Pressure Equipment Design: A Case Study of ISGEC Hitachi Zosen Limited

ISGEC Hitachi Zosen Limited is a market-leading manufacturer of complex pressure vessels and heat exchanger equipment. The company serves customers all over the world, providing solutions for a variety of industry segments in which it is a manufacturing leader. ISGEC Hitachi Zosen Limited also assists in reducing the scale-up risks from lab to plant, demonstrating its commitment to innovation and customer satisfaction. The company's focus on utilizing the maximum temperature capability of materials for the design of structural components in the oil and gas sector underscores its dedication to cost-effective and efficient design solutions.

ISGEC Hitachi Zosen Limited, a leading manufacturer of complex pressure vessels and heat exchanger equipment, was faced with the challenge of utilizing the maximum temperature capability of materials for the design of structural components in the oil and gas sector. The current ASME code (Section VIII, Division 2) limits the generation of fatigue curves up to a maximum of 371 °C. However, manufacturers wanted to use ASME Code Case 2605, a special rule for fatigue evaluation of 2.25Cr-1Mo-0.25V steels at temperatures greater than 371 °C and less than 454 °C. The challenge was to carry out full inelastic analysis, such as ratcheting elastic shakedown analysis, using the actual time-dependent thermal and mechanical loading histograms. The existing methods of treating plasticity and creep as two independent phenomena in stress and strain calculations using spreadsheet-like applications were subject to human error and could lead to unrealistic damage parameters.

ISGEC Hitachi Zosen engineers, with the help of ANSYS technical team members, used the user programmable feature (UPF) in ANSYS MAPDL to implement a Code Case 2605 creep model. This model was designed to analyze creep at the higher temperatures specified in Code Case 2605. By combining user creep with standard plasticity material models already available in ANSYS solutions, they were able to calculate the overall creep strain and creep damage under cyclic loading conditions at temperatures up to 454 °C. This solution not only increased the accuracy of the calculations but also accelerated the calculation process. The implementation of the creep subroutine for the calculation of creep damage and creep strains for chrome-moly steels eliminated the chances of human error common in manual spreadsheet calculations.

• The implementation of the creep subroutine in ANSYS MAPDL led to significant operational improvements for ISGEC Hitachi Zosen Limited. The company was able to optimize the weight of their equipment by maximizing the material capacity at high temperatures, ensuring that any creep damage was within the acceptable code limit. This not only improved the efficiency of their designs but also enhanced their cost-effectiveness. The time required for calculation and post-processing of creep strain and creep damage results was drastically reduced, leading to faster turnaround times for projects. Furthermore, the elimination of human error common in manual spreadsheet calculations led to more accurate results, reducing the risk of over-estimating creep damage and improving the overall reliability of their products.

• Optimized the equipment weight by maximizing the material capacity at high temperatures, ensuring that any creep damage was within the acceptable code limit
• Drastically reduced the time required for calculation and post-processing of creep strain and creep damage results
• Eliminated chances of human error common in manual spreadsheet calculations, which often over-estimate creep damage