• 한국안전학회지
• /
• 제11권4호
• /
• pp.115-121
• /
• 1996

This paper describes an analysis of the stress intensity factor (SIF) of the presented cracks in LNG piping. The stress analysis used the Finite Element Method. The stress Intensity factor calculated Raju & Newmann equation and ASME Section XI method. The cracks in the flanges are found to be influenced by temperature, but the cracks of the piping are found not to be influenced by temperature. If the cracks shape in the flanges and the cracks shape of the piping are same each other, the cracks in the flange will be dangerous more than the cracks of the piping.

• 대한조선학회지
• /
• 제52권2호
• /
• pp.19-24
• /
• 2015

A reliable assessment and analysis of the condition of high pressure and temperature steam pipelines requires defining stress state, which will take into consideration not just the impact of internal pressure and temperature but all applied loads. For that, usage of modeling and numerical methods for calculation and analysis of stress state is essential. The main aim of piping stress analysis is to check the design of piping layout, which will allow simple, efficient and economical piping supports and provide flexibility to the piping system for loads and stresses. The piping stress analysis is carried out using CAESER II software. By using this software we can evaluate stresses, stress ratios, flange condition, support loads, element forces and displacements at each node and points. In this paper, only the maximum and minimum displacement results are tabulated, which is also shown in detail by an example of main steam pipelines of UST Main Engine System [1].

• 한국압력기기공학회 논문집
• /
• 제14권1호
• /
• pp.32-37
• /
• 2018

When designing high temperature piping system, creep phenomena must be considered. Since ASME code does not provide detailed methods of design by rule (DBR) for high temperature piping, Finite element analysis should be performed. However, In the case of piping system with frequent design changes, creep analysis of the entire piping system for every change is ineffective and practically impossible. Therefore, based on elastic and elastic-plastic analysis, which takes a relatively short time, the creep stress is predicted by using elastic follow-up factor method provided in R5 code and plastic-creep analogy presented by Hoff. The predicted creep stress for a virtual piping system was compared with the creep analysis result and the two results showed similar stress relaxation tendency in time.

• 동력기계공학회지
• /
• 제13권6호
• /
• pp.35-42
• /
• 2009

The piping systems in the steam-driven power engines lie under the cyclic condition of thermal expansion and contraction by superheated steam. These phenomena might cause some severe damages on the pipes and the accessory devices. To avoid these damages, the calculation of the proper strength and the consideration of the reduced resultant forces on the materials are needed. In the present study, numerical investigations on the effects of the thermal deformation of the industrial piping system were performed with comparison of the design data. Commercial software, ABAQUS with the thermal-fluidic loadings based on the design conditions was used for the thermal stress analysis of the piping system. From the analysis of the initially-designed pipe supporters, the rearrangement was suggested to improve the piping design.

• 한국안전학회지
• /
• 제28권3호
• /
• pp.44-50
• /
• 2013

Process gas piping is one of the most basic components frequently used in the refinery and petrochemical plants. Many kinds of by-product gas have been used as fuel in the process plants. In some plants, natural gas is additionally introduced and mixed with the byproduct gas for upgrading the fuel. In this case, safety or design margin of the changed piping system of the plant should be re-evaluated based on a proper design code such as ASME or API codes since internal pressure, temperature and gas compositions are different from the original plant design conditions. In this study, series of piping stress analysis were conducted for a process piping used for transporting the mixed gas of the by-product gas and the natural gas from a mixing drum to a knock-out drum in a refinery plant. The analysed piping section had been actually installed in a domestic industry and needed safety audit since the design condition was changed. Pipe locations of the maximum system stress and displacement were determined, which can be candidate inspection and safety monitoring points during the upcoming operation period. For studying the effects of outside air temperature to safety the additional stress analysis were conducted for various temperatures in $0{\sim}30^{\circ}C$. Effects of the friction coefficient between the pipe and support were also investigated showing a proper choice if the friction coefficient is important. The maximum system stresses were occurred mainly at elbow, tee and support locations, which shows the thermal load contributes considerably to the system stress rather than the internal pressure or the gravity loads.

• 플랜트 저널
• /
• 제8권2호
• /
• pp.52-58
• /
• 2012

Pipe means the connection of the tube in order to transfer fluid from one device to another device. The piping stress analysis is to analyze the structural stability considering the location and the features of piping support after completing the piping design, The allowable stresses comply with the requirements of the relevant standards by examining whether the support of the function and location of pipe or re-operation is confirmed. Allowable stresses are to make sure that the maximum stress should not exceed the allowable stress presented in the ASME B31.1 POWER PIPING code. ASME B31.1 POWER PIPING code ensures a smooth stress analysis can be performed during the initial pipe stress analysis as provided in the case of straight pipe to the horizontal distance between the supports. However, because there is no criteria set in the case of curved pipe, the optimum pipe supporting points were studied in this paper. As mentioned about the curved pipe, loads applied to the support of the position of 17% and 83% of the position relative to the elbow part have results similar to the load acting on the support of straight pipe.

• Nuclear Engineering and Technology
• /
• 제51권2호
• /
• pp.561-572
• /
• 2019

In the design criterion for the nuclear power plant piping system, the limit state of the piping against an earthquake is assumed to be plastic collapse. The failure of a common piping system, however, means the leakage caused by the cracks. Therefore, for the seismic fragility analysis of a nuclear power plant, a method capable of quantitatively expressing the failure of an actual piping system is required. In this study, it was conducted to propose a quantitative failure criterion for piping system, which is required for the seismic fragility analysis of nuclear power plants against critical accidents. The in-plane cyclic loading test was conducted to propose a quantitative failure criterion for steel pipe elbows in the nuclear power plant piping system. Nonlinear analysis was conducted using a finite element model, and the results were compared with the test results to verify the effectiveness of the finite element model. The collapse load point derived from the experiment and analysis results and the damage index based on the stress-strain relationship were defined as failure criteria, and seismic fragility analysis was conducted for the piping system of the BNL (Brookhaven National Laboratory) - NRC (Nuclear Regulatory Commission) benchmark model.

• 한국압력기기공학회 논문집
• /
• 제6권1호
• /
• pp.43-49
• /
• 2010

The piping failure probability of the reactor coolant system in Kori unit 1 was evaluated considering stress corrosion cracking. The P-PIE program (Probabilistic Piping Integrity Evaluation Program) developed in this study was used in the analysis. The effect of some variables such as oxygen concentration during start up and steady state operation, and operating temperature, which are related with stress corrosion cracking, on the piping failure probabilities was investigated. The effects of leak detection capability, the size of big leak, piping loops, and reactor types on the piping failure probability were also investigated. The results show that (1) LOCA (loss of coolant accident) probability of Kori unit 1 is extremely low, (2) leak probability is sensitive to oxygen concentration during steady state operation and operating temperature, while not sensitive to the oxygen concentration during start up, and (3) the piping thickness and operating temperature play important roles in the leak probabilities of the cold leg in 4 reactor types having same inner diameter.

• 한국기계가공학회지
• /
• 제13권1호
• /
• pp.23-29
• /
• 2014

The purpose of this paper is to assess the structural integrity of piping penetrations for nuclear power plants. A piping qualification analysis describes loads due to deadweight, pressure difference acts normal to the plate, thermal transients, and earthquakes, among other events, on piping penetrations that have been modeled as an anchor. Amodel was analyzed using a commercial finite element program. Apiping penetration analysis model was constructed with an assembly of pipe, head fittings and sleeves. Normally, the design load, thus obtained, will consist of three moments and three forces, referred to a Cartesian coordinate system. When comparing the stress analysis results from each required cutting position, the general membrane stress intensities and local membrane plus bending stress intensities during a structural evaluation cannot exceed the allowable amount of stress for the design loads. Therefore, the piping penetration design satisfies the code requirements.

• 한국압력기기공학회 논문집
• /
• 제18권1호
• /
• pp.1-10
• /
• 2022

Currently, there is no technical standard and regulation for seismic analysis of non-nuclear safety piping. Accordingly, ASME Sec.III ND, a standards applied to safety class 3 piping, is applied. However, the technical standard applied for other than seismic analysis is ASME B31, which leads to controversy. In this study, the feasibility of applying ASME B31E was confirmed by reviewing rulescomparing technical standards, and evaluating piping allowable stress margins. The evaluation revealed that applying ASME B31.1 as a technical standard is too conservative compared to ASME Sec.III ND. On the other hand, ASME B31E (issued at the request of the industry) clearly presents the technical standards for seismic analysis of ASME B31 piping, and shows a similar level of conservatism compared to ASME Sec.III ND. It is expected to reduce the controversy over technical standards for seismic analysis of non-nuclear safety piping by applying ASME B31E.