Brittle Fracture Assessments on Offshore Piping Systems

2013 ◽  
Author(s):  
Kannan Subramanian ◽  
Jorge Penso ◽  
Graham McVinnie ◽  
Greg Garic
Keyword(s):  
Low Temperature ◽  
Brittle Fracture ◽  
Stress Analysis ◽  
Pressure Vessels ◽  
Piping System ◽  
Piping Systems ◽  
Assessment Approach ◽  
Section Viii ◽  
System Information ◽  
Safe Operating

Offshore piping systems may be subject to low temperatures due to operation related scenarios and are cause for brittle fracture concern. The analyses included in this work consider probable events leading to low temperature conditions such as auto-refrigeration. In such circumstances, brittle fracture assessments of piping are typically carried out using API 579-1/ASME FFS-1, latest referred as API 579, procedures. The assessment of piping systems are in many cases very involved, requiring extended piping system information followed by stress analysis and MAT calculations depending on the material type, thickness of the piping analyzed, and stress levels. In addition, the component-by-component assessment approach recommended in API 579 leads to tedious calculations. In this paper, approaches used for static and dynamic low temperature scenarios are presented. Static cases involve constant pressures and temperatures. Dynamic cases involve varying pressures and temperatures as the low temperature events unfold (e.g., blowdown of a valve or a vessel). Dynamic cases warrant the requirement of a safe operating envelope or MAT curve similar to those developed for pressure vessels. Case studies involving the influence of the extent of the system analyzed and the restraint conditions on the results are also presented. In addition, the importance of separately assessing the rated components such as flanges and valves away from the stress analysis is discussed. Based on the assessments carried out, a discussion on the toughness rules defined in ASME Section VIII Divisions 1, 2, and the original piping code of construction is provided.

Brittle Fracture Assessments on Piping Systems: MSOT Curves

2019 ◽  
Author(s):  
Ishita Chakraborty ◽  
Kannan Subramanian ◽  
Jorge Penso
Keyword(s):  
Brittle Fracture ◽  
Case Studies ◽  
Pressure Vessel ◽  
Iterative Process ◽  
Pressure Vessels ◽  
Temperature Changes ◽  
End Conditions ◽  
Piping Systems ◽  
Plant Personnel ◽  
Safe Operating

Abstract Brittle fracture assessments (BFAs) of pressure vessels based on API 579-1/ASME FFS-1, Section 3 procedures are frequently easier and more straightforward to implement in comparison to the BFAs on piping systems. Specifically, the development of the MSOT curves. This is due to the complexities involved in the piping systems due to the branch piping interactions, end conditions of piping systems such as nozzle flexibilities at the pressure vessel connections, temperature changes in the length of piping especially when the piping is significantly long as seen in flare header piping systems. MSOT curves that are alternatively used for MAT curves provide a better picture to the plant personnel in understanding the safe operating envelope. Development of MSOT curves is an iterative process and therefore involves significant number of piping stress analyses during their development. In this paper, an approach to develop the MSOT curves is discussed with two case studies that are of relevance to olefin plants.

Influence of Local Wall Thinning and Support Stiffness in Piping Systems on Safety Assessments for Dynamic Loading

2014 ◽  
Author(s):  
Klaus Kerkhof ◽  
Fabian Dwenger ◽  
Gereon Hinz ◽  
Siegfried Schmauder
Keyword(s):  
Stress Analysis ◽  
Response Spectrum ◽  
System Response ◽  
Piping System ◽  
Load Bearing ◽  
Wall Thinning ◽  
Safety Margins ◽  
Piping Systems ◽  
Bearing Behavior ◽  
Local Wall Thinning

The load bearing behavior of piping systems depends considerably on support distances and stiffness as well as cross section characteristics. Stiffness of supports can often be defined only with difficulty by applying simplified procedures or guidelines based on assumptions. Load cases can be estimated quite well, but the safety assessment of a piping system can only be as reliable as the system model can realistically describe the present support stiffness or imperfections e.g. local wall thinning. As a consequence, the prediction of the system response may be poor. It is likely that calculated frequencies differ from natural frequencies determined experimentally. These frequency shifts lead to unrealistic predictions of stress analysis. Examples for overestimations and underestimations of stress analysis are given regarding the load case earthquake, depending on whether the frequency shift runs into or out of the plateau of the applied floor response spectrum. The influence of local wall thinning on modal characteristics is investigated. Conservative estimations of the influence on the load bearing behavior regarding severe local wall thinning are given. For fatigue checks the linear response of an experimental piping system is calculated and safety margins are demonstrated by comparing calculated with experimental results.

Overview of Revisions to the ASME Boiler and Pressure Vessel Code Section VIII Division 3 for the 2015 Edition and Near Future

2015 ◽  
Author(s):  
Daniel Peters ◽  
Adam P. Maslowski
Keyword(s):  
High Pressure ◽  
Stress Analysis ◽  
Pressure Vessel ◽  
Elastic Stress ◽  
Pressure Vessels ◽  
Chemical Safety ◽  
Linear Elastic ◽  
Section Viii ◽  
American Society ◽  
Near Future

This paper is to give an overview of the major revisions pending in the upcoming 2015 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII Division 3, Alternative Rules for Construction of High Pressure Vessels, and potential changes being considered by the Subgroup on High Pressure Vessels (SG-HPV) for future editions. This will include an overview of significant actions which will be included in the upcoming edition. This includes action relative to test locations in large and complex forgings, in response to a report from the U.S. Chemical Safety and Hazard Investigation Board (CSB) report of a failed vessel in Illinois. This will also include discussion of a long term issue recently completed on certification of rupture disk devices. Also included will be a discussion of a slight shift in philosophy which has resulted in the linear-elastic stress analysis section being moved to a Non-Mandatory Appendix and discussion of potential future of linear-elastic stress analysis in high pressure vessel design.

Elastic-Plastic Analysis of Thick-Walled Toroidal Pressure Vessels

2008 ◽  
Author(s):  
R. Adibi-Asl
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Toroidal Shell ◽  
Piping System ◽  
Straight Pipe ◽  
Element Analysis ◽  
Process Industries ◽  
Piping Systems

Piping systems in process industries and nuclear power plants include straight pipe runs and various fittings such as elbows, miter bends etc. Elbows and bends in piping systems provide additional flexibility to the piping system along with performing the primary function of changing the direction of fluid flow. Distinctive geometry of these toroidal shell components result in a structural behavior different from straight pipe. Hence, it would be useful to predict the behavior of these components with acceptable accuracy for design purposes. Analytical expressions are derived for stresses set up during loading and unloading in a toroidal shell subjected to internal pressure. Residual stresses in the component are also evaluated. The proposed solutions are then compared with three-dimensional finite element analysis at different locations including intrados, extrados and flanks.

Development for Manufacture of Refining Reactors Made of 9Cr-1Mo-V Steel

2017 ◽  
Author(s):  
Tomoaki Nakanishi ◽  
Susumu Terada ◽  
Masato Yamada ◽  
Tadashi Ikeuchi ◽  
Ikuo Maeda ◽  
...  
Keyword(s):  
Base Metal ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Piping Systems ◽  
Section Viii ◽  
Overlay Welding ◽  
Shell Ring ◽  
Fatigue Evaluation ◽  
Welding Consumables ◽  
Division 2

9Cr-1Mo-V steel, which was developed for application as a steam generator for fast breed reactors in the 1970s, has a higher strength at high temperatures and has been used for equipment and piping systems in the fossil power industries. ASME, Section VIII, Division 2 [1] gives 9Cr-1Mo-V steel a maximum design temperature of 649°C and an operating temperature of 500°C. And it has higher allowable stresses at 450°C or over, compared to 2¼Cr-1Mo-V steel. Therefore, if this material can be used, more economical pressure vessels operating at 454–500°C can be designed and manufactured. In our previous study for base metal, a large forged shell ring of 9Cr-1Mo-V steel was manufactured and for base metal welding, cracking susceptibilities and weldability were investigated. For overlay, welding consumables with high resistance to sigma phase embrittlement were developed [2]. In this study, highly efficient welding consumables for tandem SAW designed for circumferential welding of heavy wall shells were developed and welding using the full-scaled shell ring was demonstrated, and then the mechanical properties of the weld metal were evaluated. Results indicated that, regardless of the weld thickness, a minimum of 8 hours postweld heat treatment (PWHT) at 745°C was required to meet hardness and toughness requirements for conventional reactors. The strength of the materials can comply with the Code requirements after 3 cycles of PWHT considering the PWHT in fabrication and after weld repair. Furthermore, the following new Code Cases and Code revision were proposed and approved in order that pressure vessels can be designed in accordance with ASME, Section VIII, Division 2. • New Code Case for Fatigue Evaluation • New Code Case to apply SA-336-F91 in ASME Section VIII, Division 2 • Revision of Table 5A to add SA-336-F91 As a result, it has become possible to design and manufacture refining reactors to operate at 454–500°C.

Computer Piping Analysis, ASME B31.3 Appendix S: Example S3 — Moment Reversal

2007 ◽  
Author(s):  
Don R. Edwards
Keyword(s):  
Stress Analysis ◽  
Petroleum Refinery ◽  
Axial Stress ◽  
Piping System ◽  
Stress Range ◽  
Analysis Software ◽  
Process Piping ◽  
Piping Systems ◽  
Operating Stress ◽  
The Impact

The American Standards Association (ASA) B31.3-1959 Petroleum Refinery Piping Code [1] grew out of an ASA document that addressed all manner of fluid conveying piping systems. ASA B31.3 was created long before widespread engineering use of computer “mainframes” or even before the inception of piping stress analysis software. From its inception until recent times, the B31.3 Process Piping Code [2] (hereafter referred to as the “Code”) has remained ambiguous in several areas. This paper describes some of these subtle concepts that are included in the Code 2006 Edition for Appendix S Example S3. This paper discusses: • the effect of moment reversal in determining the largest Displacement Stress Range, • the impact of the average axial stress caused by displacement strains on the Example S3 piping system and the augmenting of the Code Eq. (17) thereto, • a brief comparison of Example S3 results to that of the operating stress range evaluated in accordance with the 2006 Code Appendix P Alternative Requirements.

Minimum Stress Design of Nozzles in Pressure Vessel Heads

1988 ◽  
Vol 110 (4) ◽  
pp. 460-463
Author(s):  
Y.-J. Chao
Keyword(s):  
Pressure Vessel ◽  
Pressure Vessels ◽  
Design Stage ◽  
Piping System ◽  
Spherical Vessel ◽  
Early Design ◽  
Early Design Stage ◽  
Replacement Method ◽  
Piping Systems ◽  
External Loads

In the early design stage of pressure vessels the configuration of the piping systems is not yet established; hence forces transmitted by the piping systems to the nozzles in the pressure vessels cannot be determined. This often leads to the design of nozzles in pressure vessels guided by consideration of pressure loadings such as the area-replacement method. However, it is true that in many cases the stresses due to external loads can be more critical than those due to the internal pressure. Therefore, engineers often redesign the piping system several times by adding more pipe bends or special restraints for a hot piping system to reduce the reactions at a previously designed nozzle so that the resulting stresses at the nozzle are within the acceptable limit. This paper introduces a rational mechanism whereby the stresses due to the unforeseen external loads can be minimized in the early design stage of the nozzle. An appropriate analysis is discussed which is based on the classical thin shell theory. Analyses using this method allow one to obtain the minimum stresses at a nozzle in a pressure vessel head or a spherical vessel for moment and thrust loadings.

Flexibility Analysis of Piping Systems With Discontinuities in Displacement

2016 ◽  
Author(s):  
Birendra N. Choudhury
Keyword(s):  
Thermal Expansion ◽  
Ambient Temperature ◽  
Stress Analysis ◽  
Elastic Deformation ◽  
The Other ◽  
Piping System ◽  
Current Stress ◽  
Flexibility Analysis ◽  
Other Hand ◽  
Piping Systems

The class of piping flexibility analysis problems discussed in this paper arises when a new piping system at ambient temperature is connected to a piping system that is in operation. At the time of tie-in, the new piping has no thermal expansion and no elastic deformation. Therefore, displacement at the tie-points in the new piping system is zero. On the other hand, the operating piping systems would have undergone some displacements at this point before the tie-in. So there is a discontinuity in displacement at the tie point. This paper discusses how the equations for piping flexibility analysis can be modified to accurately obtain the redundant restraint forces for such cases and their use with current stress analysis programs for some piping configurations.

Shortcut Method for "L" and "Z" Pipe Bend Sizing

2021 ◽  
Author(s):  
Nikola Jacimovic ◽  
Milos Ivosevic
Keyword(s):  
Stress Analysis ◽  
Engineering Practice ◽  
Piping System ◽  
Pipe Bend ◽  
Rule Of Thumb ◽  
Early Stages ◽  
Present Procedure ◽  
Piping Systems ◽  
Shortcut Method ◽  
Material Requirements

Abstract In the engineering practice it may often prove necessary to provide quick and relatively accurate estimates of piping routing and material requirements in very early stages of a project. In these cases there is typically no time to perform detailed pipe stress analysis in order to obtain accurate routing which allows for sufficient piping system flexibility and the designer is constrained to the use of rule of thumb approach and good engineering judgment. This approach, although often used, may prove challenging in many situations, one of which is establishing sufficient pipe loop dimensions. Method proposed by the authors in [1] provides a procedure for quick estimation of U loops while the present procedure aims to provide additional procedures for estimation of L and Z bends, thus completing the circle of shortcut methods for quick estimation of expansion requirements of piping systems.

scholarly journals Stress and stability analysis of steel piping systems in the petroleum industry

2020 ◽  
Author(s):  
◽  
Justin Pillay
Keyword(s):  
Stress Analysis ◽  
Failure Modes ◽  
Petroleum Industry ◽  
Piping System ◽  
Increased Risk ◽  
Piping Systems ◽  
The Many ◽  
The Impact ◽  
Dimensional Specification ◽  
Petroleum Plant

This study aims to reach a level of proficiency on the available technical theories to assess steel pressure piping systems and the identification of potential risks of failure. The research focuses mainly on piping systems in the petroleum industry. The importance of this study is based on the risk reduction of petroleum plant downtime and the harming of life as a result of piping failures. The apparent need for piping systems stress analysis was a result of the many failures that occurred at Indy Oil’s petroleum plant. The recent acquisition of the petroleum plant under the GUD Holdings group brought along minimum engineering experience with regards to piping systems. GUD’s inhouse engineering teams executed the many plant expansion and upgrade projects. A common industry perception is that piping systems are basic and do not require much attention. These misconceptions are a result of many piping failures in the industry. The failures that occurred called for a thorough investigation of all equipment setups and piping installations at Indy Oil. Specific failure identifications at the petroleum plant were done. The research and analysis of piping systems stress analysis were performed to aid in understanding the cause of these failures. Fluid dynamics, as a major contributor to stress and strain state in pipes, is the object of much attention. The dimensional specification and layout optimization of a piping system is highly dependent on the internal piping pressure. Studies, developments, and prediction analysis on the impact of sustained and thermal loads are reviewed to understand the numerical and analytical techniques available which enables the analysis of various piping systems. A risk- informed approach is applied that incorporates various design criteria, as well as, failure contributors in piping systems. At first, each component and failure mode is determined separately. Thereafter, the instances of simultaneous loading and increased risk of failure in piping systems have been determined. The available literature is used to source necessary data, as well as, compare the obtained results with those available in the literature. Government statutory requirements are used as a basis in the design process. Material specifications and engineering quality is controlled by these governing standards. The application of this study is done by the design and analysis of a piping system for Indy Oil’s Tank Farm. Piping systems failures as a result of improper design raised importance for a thorough stress analysis at the Petrochemical site. The calculations of stress-strain contributions are done using theoretical methods, as well as, computer software programs. The piping system is analysed on various conditions according to the process requirements of the Plant. Various load cases were developed to account for simultaneous loadings. The expected result of the system is for stress contributions to not exceed the maximum allowable stresses. CAESAR II software is selected as the most suitable for the analysis. The simulation is done on each pipe element and demonstrates a three-dimensional analysis. The results of the study were used to determine the failure modes of previously installed piping systems and to create a design guide for all future piping systems projects.

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