American Society Of Mechanical Engineers Code Research Articles

Design and Analysis of a Typical Vertical Pressure Vessel Using ASME Code and FEA Technique

This study aims to address the hazards associated with the design and manufacture of pressure vessels used for storing dangerous liquids, specifically focusing on the increased demand for liquefied petroleum gas (LPG) worldwide. The construction of more LPG facilities necessitates the implementation of safer pressure vessels to mitigate risks such as explosions and leakage. The primary objective of this project is to design a vertical pressure vessel, in accordance with the American Society of Mechanical Engineers (ASME) code, capable of safely storing 10 m3 of pressurised LPG. To ensure the safety of the pressure vessel, the researchers employed Autodesk Inventor Professional 2023 for geometric modelling and utilised Inventor Nastran for finite element analysis (FEA) to investigate displacements, deflections, and von Mises stresses. The vessel is cylindrical in shape and features two elliptical heads, two nozzles, a manway, and four leg supports. The FEA analysis conducted using Autodesk Inventor Nastran enabled the researchers to identify areas where structural modifications were necessary to reduce stress within the vessel. The results revealed an inverse relationship between the displacement and the tank section shell thickness. Additionally, the factor of safety exhibited a linear increase as the shell thickness increased. The researchers carefully considered permissible pressures and determined the required wall thickness to maintain acceptable maximum stresses. The findings indicate that the design of the pressure vessel is safe from failure. Among the components, the manway experiences the highest stresses, followed by the shell, while the heads, nozzles, and leg supports experience lower stresses. The researchers also conducted theoretical calculations for the entire model and ensured that the results fell within acceptable limits, further validating their design approach. The research emphasised the importance of designing pressure vessels in compliance with ASME codes to ensure safety and prevent hazards associated with improper design and manufacturing. The combination of Autodesk Inventor Professional and Inventor Nastran proved to be an effective approach for simulating and evaluating the performance of the pressure vessel. Through the analysis, the researchers found that changes to the pressure vessel structure were necessary to reduce stress. They observed an inverse relationship between displacement and tank section shell thickness, while the factor of safety increased linearly with shell thickness. Stress distribution analysis revealed that the manway and shell experienced the highest stresses, while the heads, nozzles, and leg support exhibited lower stresses. Employing the finite element method, potential stress points within the pressure vessel were identified, enabling necessary modifications to enhance its safety.

A Structural Design Approach Tailored for the Rapid Preliminary Design of Microreactor Components

High-temperature microreactors can play a role in developing reliable, portable energy sources for off-grid remote locations, microgrid concepts, and industrial process heat. Portability and passive safety criteria tend to skew microreactor structural component designs toward complex geometries, high thermal stresses, and design bases with large numbers of startup/shutdown cycles. Current design rules, as typified by Section III of the American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code, are less than optimal for these conditions, particularly for preliminary component designs where developers need to rapidly consider a large number of potential component configurations. This paper presents a design method targeted toward rapid, efficient evaluation of preliminary component designs using modern finite element analysis. The new method retains key connections with the ASME Code rules and design data while streamlining the design approach. This paper presents the design method, several verification examples illustrating the similarities and differences between the new method and the current ASME rules, and the application of the new approach to the evaluation of a test article mimicking key features of a heat pipe–cooled microreactor.

전산 해석을 통한 안전밸브 구조 최적화 연구

The safety valve is an essential device for high-pressure equipment; because high-pressure equipment is used in many fields, the use of safety valves is also increasing. Safety valves are used in various fields such as the petroleum industry, power plants, and nuclear power industries. In the 19th century, many boiler explosion accidents occurred due to improper boiler design or the failure of safety valves used in boilers. These incidents drew the attention of the US government, and the American Society of Mechanical Engineers (ASME) enacted the first ASME code for safety valves in response to government requirements. A safety valve is a device used to protect high-pressure systems and people from accidents, and because of its importance, many related studies have been conducted, and related standards are continuously being updated.<BR> In actual safety valve experiments, it is difficult to observe the characteristics of fluid flow. In this study, the opening process of a safety valve under high pressure was studied using a simulation method. Analysis was conducted using the commercial software COMSOL Multiphysics and the fluid–structure interaction (FSI) technique. The FSI is calculated by reflecting the interaction between a structure and fluid and is a suitable method for analyzing the safety valve operation process. Two shapes that can reduce flow resistance were designed by analyzing the simulation results and the same flow analysis was performed on these shapes. By comparing the proposed shape’s simulation results with those of existing shapes, it was confirmed that the pressure loss was reduced in the improved method, and the flow rate was further increased due to a relatively low pressure loss. This means that the fluid inside the pressure vessel can be discharged faster and the pressure can be lowered faster, so it was determined that the improved shape safety valve showed better performance.

Suitability of fatigue crack growth thresholds at negative stress ratios for ferritic steels and aluminum alloys in flaw evaluation procedures

Fatigue crack growth thresholds for ferritic steels and aluminum alloys in flaw evaluation documents are reviewed. The WRC (Welding Research Council) Bulletin, ASME (American Society of Mechanical Engineers) Code Section VIII, IIW (International Institute of Welding) and BS (British Standards) 7910 give constant fatigue crack growth threshold values at negative stress ratios. However, the definitions of the thresholds at negative stress ratios are different between these flaw evaluation documents. From fatigue crack growth tests and collection of fatigue crack growth threshold data, the thresholds are affected by compressive stresses. It can be said that the thresholds at negative stress ratios are not constant. Therefore, the thresholds given by the WRC Bulletin, ASME Section VIII and IIW are slightly un-conservative. The threshold given by BS 7910 is considerably conservative. A suitable definition of the threshold at negative stress ratios for application in flaw evaluation procedures is proposed as the variable threshold expressed by full range of stress intensity factors.

ASME Boiler and Pressure Vessel Code Roadmap for Compact Heat Exchangers in High Temperature Reactors

Abstract The mission of the U.S. Department of Energy (DOE), Office of Nuclear Energy is to advance nuclear power in order to meet the nation's energy, environmental, and energy security needs. Advanced high temperature reactor systems will require compact heat exchangers (CHXs) for the next generation of nuclear reactors. The DOE is sponsoring research to support the development and deployment of CHXs for use in high temperature advanced reactors. The project is being executed by an Integrated Research Project (IRP) that includes university research institutes, national laboratories, manufacturers, and industry experts. The objective is to enable the use of CHX designs in advanced reactor service. A necessary step for achieving this objective is to ensure that the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 5 has rules for the construction of CHXs for nuclear service. However, construction rules alone are not sufficient to deploy a CHX in an advanced reactor. A strategy for ASME Boiler and Pressure Vessel Code, Section XI, Inservice Inspection (ISI) of a heat exchanger in an operating nuclear reactor will also be required. The purpose of this ASME Code Roadmap is to identify the research gaps impeding the development of suitable construction and ISI rules for CHXs for high temperature reactor service and to provide a framework to utilize the research project results consistent with the expectations and needs of the industry and future owners.

Application of the Advanced Surface Modification Process to the ASME Code Case for Sections III and XI of Nuclear Power Plants

The advanced surface modification process is known as a promising solution to improve the performance of machine components and systems, especially for vehicles, nuclear power plants, biomedical device, etc. There have been several successful applications of water jet peening and underwater laser peening to nuclear components in Japan since 2001 which resulted in inspection and repair cost savings. The prerequisite condition for the application of the advanced surface modification process to nuclear power plants is the approval of the American Society of Mechanical Engineers (ASME) Code Case, so performance criteria and requirements (PCRs) in the ASME Code Case for repair and maintenance of nuclear power components are explained. A challenging project to apply advanced surface modification processes, such as ultrasonic nanocrystal surface modification and air laser peening to new nuclear power plants and new canisters, was created with the goal to develop a technical basis and the PCRs for ASME Section III (New Manufacturing). The results of this work will be an ASME Section III Code Case which is currently in progress. An initial draft of the new Code Case with the intermediate results of this work is introduced. Four kinds of advanced surface modification processes are explained and compared briefly.

Development of Fatigue Crack Growth Thresholds for Austenitic Stainless Steels Exposed to Air Environment for ASME Code Section XI

Fatigue crack growth thresholds ΔKth define stress intensity factor range below which cracks will not grow. The thresholds ΔKth are useful in industries to determine durability lifetime. Although massive fatigue crack growth experiments for stainless steels in air environment had been reported, the thresholds ΔKth are not codified at the American Society of Mechanical Engineers (ASME) Code Section XI, as well as other fitness-for-service (FFS) codes and standards. Based on the investigation of a few FFS codes and review of literature survey of experimental data, the thresholds ΔKth exposed to air environment have been developed for the ASME Code Section XI. A guidance of the thresholds ΔKth for austenitic stainless steels in air at room and high temperatures can be developed as a function of stress ratio R.

Effect of Light Water Reactor Water Environments on the Fatigue Life of Reactor Materials

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) provides rules for the design of Class 1 components of nuclear power plants. However, the Code design curves do not address the effects of light water reactor (LWR) water environments. Existing fatigue strain-versus-life (ε–N) data illustrate significant effects of LWR water environments on the fatigue resistance of pressure vessel and piping steels. Extensive studies have been conducted at Argonne National Laboratory (Argonne) and elsewhere to investigate the effects of LWR environments on the fatigue life. This article summarizes the results of these studies. The existing fatigue ε–N data were evaluated to identify the various material, environmental, and loading conditions that influence the fatigue crack initiation; a methodology for estimating fatigue lives as a function of these parameters was developed. The effects were incorporated into the ASME Code Section III fatigue evaluations in terms of an environmental correction factor, Fen, which is the ratio of fatigue life in air at room temperature to the life in the LWR water environment at reactor operating temperatures. Available fatigue data were used to develop fatigue design curves for carbon and low-alloy steels, austenitic stainless steels (SSs), and nickel–chromium–iron (Ni–Cr–Fe) alloys and their weld metals. A review of the Code Section III fatigue adjustment factors of 2 and 20 is also presented, and the possible conservatism inherent in the choice is evaluated. A brief description of potential effects of neutron irradiation on fatigue crack initiation is presented.

Combination Criterion for Multiple Laminar Flaws in Steel Components

A laminar flaw is a planar subsurface flaw parallel to the rolling direction of the plate, where the applied stress is typically parallel to the rolling direction. The laminar flaw oriented within 10 degree of a plane parallel to the component surface is defined as a laminar flaw, in accordance with the definition of the American Society of Mechanical Engineers (ASME) Boiler &amp; Pressure Vessel (B&amp;PV) Code Section XI. The ASME Code provides combination criterion for multiple laminar flaws. If there are two or more laminations, these laminations are projected to a single plane and, if the separation distance of the projected laminations is less than or equal to 25.4 mm, the laminations shall be combined into a single large laminar flaw in the assessment. The combination criterion was established on the basis of the non-destructive examination capabilities in the 1970’s. However, this methodology did not consider the offset distance of the laminations nor the mechanical interaction between the flaws. Therefore that combination methodology is not suited in case of a large number of laminar flaws. This may occur e.g. in case of hydrogen flaking in steel forging components. Actually, when multiple discrete laminar flaws are close to each other, interaction between the flaws has to be taken into account and these flaws shall be combined to a single laminar flaw for assessment. Stress intensity factor interactions for inclined laminar flaws were analyzed in the frame of hydrogen flaking issue in reactor pressure vessels of Doel 3 and Tihange 2 Belgian nuclear power plants. Based on the mechanical interaction between flaws, new combination criterion was developed and was presented in this paper.

Design and Analysis of Boiler Pressure Vessels based on IBR codes

Pressure vessels components are widely used in the thermal and nuclear power plants for generating steam using the philosophy of heat transfer. In Thermal power plant, Coal is burnt inside the boiler furnace for generating the heat. The amount of heat produced through the combustion of pulverized coal is used in changing the phase transfer (i.e. Water into Super-Heated Steam) in the Pressure Parts Component. Pressure vessels are designed as per the Standards and Codes of the country, where the boiler is to be installed. One of the Standards followed in designing Pressure Parts is ASME (American Society of Mechanical Engineers). The mandatory requirements of ASME code must be satisfied by the manufacturer. In our project case, A Shell/pipe which has been manufactured using ASME code has an issue during the drilling of hole. The Actual Size of the drilled holes must be, as per the drawing, but due to error, the size has been differentiate from approved design calculation (i.e. the diameter size has been exceeded). In order to rectify this error, we have included an additional reinforcement pad to the drilled and modified the design of header in accordance with the code requirements.

Remaining Fatigue Lives of Similar Surface Flaws in Accordance With Combination Rules

When multiple flaws are detected in structural components, the remaining lives of the components are estimated by fatigue flaw growth calculations using combination rules in fitness-for-service (FFS) codes. Many FFS codes provide combination rules for multiple flaws; however, these rules differ significantly among the various codes. Fatigue flaw growths for two similar adjacent surface flaws in a flat plate subjected to a cyclic tensile stress were obtained by numerical calculations using these different combination rules. In addition, fatigue flaw growths taking into account the interaction effect between the two similar flaws were conducted by the extended finite-element method (X-FEM). The calculation results show that the fatigue lives calculated by the X-FEM are close to those obtained by the American Society of Mechanical Engineers (ASME) Code. Finally, it is noted that the combination rule provided by the ASME Code is appropriate for fatigue flaw growth calculations.

A study on the development of creep rupture and temper embrittlement properties in 21/4Cr-1Mo-V steel weld metal

21/4Cr-1Mo-V steel, such as the ASTM A542/A542M type D, which has remarkable anti-hydrogen embrittlement and creep rupture properties, is widely used in main components such as pressure vessels in oil refinery plants. Submerged arc welding (SAW), shielded metal arc welding (SMAW), and gas-shielded tungsten arc welding (GTAW) consumables, equivalent to base metal, are selected for the welding of this steel. As referred to in American Society of Mechanical Engineers (ASME) Section VIII, various properties, such as tensile strength and impact toughness in addition to creep rupture, are required in 21/4Cr-1Mo-V steel weld metal. Especially in creep rupture properties, the lower limit of the design temperature, which is required in main components (mentioned above), was lowered from 470 to 440 °C, based on the revision of the ASME code in 2009. Additionally, temper embrittlement behavior, occurring under high temperature over a long period of time, should be considered as well when dealing with this deposited metal. In this study, we have discussed the validity of precipitates in order to develop the creep rupture and temper embrittlement properties of 21/4Cr-1Mo-V steel weld metal. As a result, it was found that MX in crystal grains improves creep rupture lifetime and that, in the prior γ grain boundaries, it inhibits embrittlement caused by the segration of impurities.

Strain-Rate Sensitivity Analysis for Ni Alloys to Be Used in Very High Temperature Reactors

Both Alloy 617 and Alloy 230 have been considered the most promising structural materials for the Very High Temperature Reactor (VHTR). In this study, mechanical properties of both alloys were examined by performing tensile tests at three different strain rates and at temperatures up to 1000°C. This range covers time-dependent (plasticity) to time-independent (creep) deformations. Strain-rate sensitivity analysis for each alloy was conducted in order to approximate the long-term flow stresses. The strain-rate sensitivities for the 0.2% flow stress were found to be temperature independent (m [approximate] 0) at temperatures ranging from room temperature to 700°C due to dynamic strain aging. At elevated temperatures (800°C to 1000°C), the strain-rate sensitivity significantly increased (m > 0.1). Compared to Alloy 617, Alloy 230 displayed higher strain-rate sensitivities at high temperatures. This leads to lower estimated long-term flow stresses. Results of this analysis were used to evaluate the current American Society of Mechanical Engineers (ASME) allowable design limits for each alloy. The study showed that the allowable design stresses in the ASME Boiler and Pressure Vessel Code for either alloy do not provide adequate long-term degradation estimation. Nevertheless, rupture stresses for Alloy 617, developed in the ASME code case N-47-28, can generally satisfy the safety margins at 800°C and 1000°C estimated in the study following the strain-rate sensitivity analysis. Furthermore, additional material development studies might be required, since the design parameters for rupture stresses are constrained such that the current VHTR conceptual designs cannot satisfy the material limits.

Design-Guideline Strategies for High-Pressure/High-Temperature Equipment

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 23943, ’Design-Guideline Strategies for High-Pressure/High-Temperature Equipment,’ by H. Brian Skeels, Kwok Lun Lee, and Anand Venkatesh, FMC Technologies, prepared for the 2013 Offshore Technology Conference, Houston, 6-9 May. The paper has not been peer reviewed. As the need for oil and gas equipment working in hotter and higher-pressure environments continues to mount, the effort to develop an adequate set of design, material, and validation practices continues to be challenging. More-rigorous stress analysis and design methods that more closely model fast-fracture burst conditions are needed to achieve safe, reliable, and cost-effective equipment designs. Introduction As oilfield equipment is subjected to more-severe and longer periods of cyclic forces (internally from irregular wellbore flowing conditions or externally from metocean conditions), many agree that fatigue life and monitoring for these conditions has to be a part of the design equation. This fact is mentioned in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, recognizing the two failure modes of a pressure vessel: leak before burst or a fast-fracture burst. Many oilfield design guidelines negated a need for fatigue analysis because of the long-standing practice of keeping maximum design loads and stresses well below two-thirds material yield strength, a practice that also keeps cyclic-loading issues well inside the “infinite” region on S/N curves in most cases. Unfortunately, this quasi-static design philosophy grows less accurate as the pressure vessel’s wall thicknesses grow or geometries become more complex when addressing high-pressure/high-temperature (HP/HT) conditions. As a result, many have turned to the ASME Boiler and Pressure Vessel Code for guidance. Divisions 2 and 3 of the ASME Code present alternative design methodologies to be considered as internal pressure and temperature increase. However, the designer, using the code, is still free to select which division to follow for his application. The American Petroleum Institute (API) has long followed a subset of Division 2 of the ASME Code, but it now recognizes many shortcomings as one considers HP/HT conditions. The published technical report only cites the current state of the art and discusses the issues to be tackled. Many observers agree that leaving the issue to so-called “sound engineering judgment” would result in many variations of opinion between operators and manufacturers, likely resulting in inefficiency and repeated tasks. Current efforts address two options: extending current API design practices to higher pressure ratings or establishing a demarcation when different design practices are needed.

A plan for safety and integrity of research reactor components

Safety and integrity of a research reactor that has been operated over 40 years requires frequent and thorough inspection of all the safety-related components of the facility. The need of increasing the safety is the need of improving the reliability of its systems. Diligent and extensive planning of in-service inspection (ISI) of all reactor components has been imposed for satisfying the most stringent safety requirements. The Safeguards Officer's responsibilities of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code ASME Code have been applied. These represent the most extensive and time-consuming part of ISI program, and identify the components subjected to inspection and testing, methods of component classification, inspection and testing techniques, acceptance/rejection criteria, and the responsibilities. The paper focuses on ISI planning requirements for welded systems such as vessels, piping, valve bodies, pump casings, and control rod-housing parts. The weld in integral attachments for piping, pumps, and valves are considered too. These are taken in consideration of safety class (1, 2, 3, etc.), reactor age, and weld type. The parts involve in the frequency of inspection, the examination requirements for each inspection, the examination method are included. Moreover the flaw evaluation, the plan of repair or replacement, and the qualification of nondestructive examination personnel are considered.

Recent Status of ASME Code on Creep Strength Enhanced Ferritic Steels

Abstract Since the introduction to modified 9Cr-1Mo steel (Gr.91) in 1982, new grades of creep strength enhanced ferritic (CSEF) steels including the Gr.91 have been developed and practically used in the power plants worldwide in 1990s to date increasing the steam temperature to improve thermal efficiency for energy conservation and reduction of CO 2 emission. The chemistry and heat treatment conditions for these CSEF steels are highly optimized and the elevated temperature properties such as creep strength are strongly influenced by the heat and strain cycles during the material manufacturing and fabrication. These steels have already been included into the international codes and standards, however a number of failure experiences with these steels throughout the manufacturing, fabrication and services have been reported. The American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code Committee has discussed on the material issues and taken the actions to improve or revise the specification of these steels based on the latest technical information and discussion results. This paper presents the recent status of ASME Code on CSEF steels.

ASME Code Case N-806을 활용한 매설배관 사용적합성 평가 고찰

Fitness-for-Service is a useful technology to determine replacement timing, next inspection timing or in-service when nuclear power plant's buried pipes are damaged. If is possible for buried pipes to be aged by material loss, cracks and occlusion as operating time goes by. Therefore Fitness-for-Service technology for buried pipe is useful for plant industry to perform replacement and repair. Fitness-for-Service for buried pipe is studied in terms of existing code and standard for Fitness-for-Service and a current developing code case. Fitness-for-Service for buried pipe was performed according to Code Case N-806 developed by ASME (American Society of Mechanical Engineers).

Prediction Method for Plastic Collapse of Circumferentially Cracked Pipes Subjected to Combined Bending and Torsion Moments

When a crack is detected in a pipe during in-service inspection, the failure estimation method given in the Codes such as the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section XI or the Japan Society of Mechanical Engineers (JSME) S NA-1-2008 can be applied to assess the integrity of the pipe. In the current edition of the ASME Code Section XI, the failure estimation method is provided for combined bending moment and pressure loads. The provision of evaluating torsion load is not made in the ASME Code Section XI. In this paper, finite element analyses are conducted for stainless steel pipes with a circumferential surface crack subjected to the combined bending and torsion moments, focusing on the entire range of torsion moments, including pure torsion. The effect of the internal pressure on failure behavior is also investigated. Based on the analysis results, a prediction method for plastic collapse under the combined loading conditions of bending and torsion is proposed for the general magnitude of torsion moments.

Collapse of Nuclear Reactor SG Tubes Pressurized From Outside: The Influence of Imperfections

Some innovative nuclear power plant proposals consider for the design tubes of considerable thickness subjected to external pressure (e.g., steam generators tubes). The collapse of thick tubes is expected to be dominated by yielding but, because of the decreasing nature of the postcollapse evolution, interaction with buckling is likely to be significant enough to demand consideration. At the present, few studies have been carried out both experimentally and numerically, as witnessed by the really conservative attitude that codes assume for thick tubes. A numerical investigation has been performed in this context at the Politecnico di Milano, which was originally intended as a support for requesting a relaxation of American Society of Mechanical Engineers (ASME) regulations. Actually, in 2007, ASME code case N-759 was approved, permitting significant thickness saving in the tube design. Nevertheless, the numerical investigation was pursued to assess the influence of different parameters, such as eccentricity, initial stresses, and material hardening, on the collapse of tubes with diameter to thickness ratios D/t&lt;20. Results are thought to be useful under at least two respects: first, providing some understanding on the collapse behavior in a thickness range so far unexplored; second, giving an indication on the assumptions on which computer codes ought to be based when numerical analyses are required.

A Review of the Effects of Coolant Environments on the Fatigue Life of LWR Structural Materials

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code specifies design curves for the fatigue life of structural materials in nuclear power plants. However, the effects of light water reactor (LWR) coolant environments were not explicitly considered in the development of the design curves. The existing fatigue-strain-versus-life (ε-N) data indicate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives in water relative to those in air can be a factor of 15 lower for austenitic stainless steels and a factor of ≈30 lower for carbon and low-alloy steels. This paper reviews the current technical basis for the understanding of the fatigue of piping and pressure vessel steels in LWR environments. The existing fatigue ε-N data have been evaluated to identify the various material, environmental, and loading parameters that influence fatigue crack initiation and to establish the effects of key parameters on the fatigue life of these steels. Statistical models are presented for estimating fatigue life as a function of material, loading, and environmental conditions. An environmental fatigue correction factor for incorporating the effects of LWR environments into ASME Code fatigue evaluations is described. This paper also presents a critical review of the ASME Code fatigue design margins of 2 on stress (or strain) and 20 on life and assesses the possible conservatism in the current choice of design margins.