Ring Segment Life Improvement Through Hook Gap and Stiffness Optimization

2021 ◽  
Author(s):  
Saurabh Gorai ◽  
Ravi Khandelwal ◽  
Debdulal Das ◽  
Fathi Ahmed ◽  
Radulovic Radan
Keyword(s):  
Customer Value ◽  
Systematic Approach ◽  
Transfer Functions ◽  
Stiffness Optimization ◽  
Higher Power ◽  
Current Design ◽  
Ring Segment ◽  
Sensitivity Studies ◽  
Life Improvement ◽  
Temperature And Pressure

Abstract For large gas turbine new make or standard customer value program always aims for higher power and efficiency which calls for an incremental stage loading in terms of higher gas pressure and temperatures distributions for the new upgrade with less ownership costs. To bring down the ownership cost without compromising on the performance or operating hours it becomes important to squeeze and optimize the current design to its maximum limits. This leads to a situation where existing static components fails to meet the MI Strength and Lifing requirements due to change in pressure and temperature. This paper describes the design challenges and the applied mitigations in the design optimizations of aft stage Ring Segment Hooks and Rails to meet requirements for higher loads at higher performance. Several sensitivity studies were carried out and transfer functions were developed to bring down the hook loads and hook stresses for steady state max temperature and pressure conditions. Two strategies were adopted to optimize the hook loads. The first is to find the adequate gap between hook and slot and the other one is to vary the hook stiffness by changing the circumferential length. This paper also presents a systematic approach and check points to decide the optimum gaps and the stiffness of the hooks. For that purpose, a co-relation was developed between hook load and hook to slot gap and the hook circumferential length and hook stiffness.

The great Mexican earthquake of 19 June 1858: Expected ground motions and damage in Mexico City from a similar future event

1996 ◽  
Vol 86 (6) ◽  
pp. 1655-1666 ◽  
Author(s):  
S. K. Singh ◽  
M. Ordaz ◽  
L. E. Pérez-Rocha
Keyword(s):  
Mexico City ◽  
Transfer Functions ◽  
Ground Motions ◽  
Careful Examination ◽  
Great Earthquake ◽  
Normal Faulting ◽  
Cocos Plate ◽  
Current Design ◽  
Peak Horizontal Acceleration ◽  
The City

Abstract The description of the great earthquake of 19 June 1858 is unusual: damage and high intensities were reported both in the state of Michoacan and in Mexico City. Although a coastal epicenter for this earthquake cannot be ruled out, the reports agree better with an intermediate-depth (about 50 km), normal-faulting event in the subducted Cocos plate. A careful examination of the reports of this event and other normal-faulting events below the Mexican altiplano suggests that a likely location is 18.0 °N, 100.8 °W, near the epicenter of the 6 June 1964 (M7.3, H = 55 km) event. This location is 220 km SW of the city. The magnitude of the earthquake is estimated to be about 7.7. We synthesize expected ground motions in CU, a hill-zone site in the city, from an event similar to that of 1858, using records from the 23 May 1994 earthquake (18.0 °N, 100.6 °W, H = 50 km, M5.7) as an empirical Green's function and stress parameter, Δσ, of 50, 160, and 300 bar. The expected peak horizontal acceleration in CU of Δσ = 160 bar is about 30 gals. Similar acceleration was recorded in CU during the 1985, Michoacan earthquake (M8.0). We compute expected ground motions at many sites in Mexico City using empirical transfer functions and random vibration theory and compare these motions and the expected damage in the city with those from the 1985 Michoacan earthquake. Results show that the overall expected damage during the postulated earthquake is ⅔ and 1⅓ of that during the Michoacan earthquake for Δσ = 160 and 300 bar, respectively. A greater percentage of low-rise construction, which constitute about 80% of the total in the city, will be damaged during the postulated earthquake than during the Michoacan earthquake. The expected ground motions for Δσ = 50 bar are smaller at all periods than those from the Michoacan earthquake. As the present building code for Mexico City contemplates coastal earthquakes of magnitude greater than 8.0, the case of Δσ = 50 bar is not of interest in this article. This preliminary study suggests a need for a more careful evaluation of expected ground motion in the Valley of Mexico from the postulated earthquake and its impact on the current design spectra of the city.

scholarly journals Retrieval of temperature and pressure using broadband solar occultation: SOFIE approach and results

2011 ◽  
Vol 4 (5) ◽  
pp. 893-907 ◽  
Author(s):  
B. T. Marshall ◽  
L. E. Deaver ◽  
R. E. Thompson ◽  
L. L. Gordley ◽  
M. J. McHugh ◽  
...  
Keyword(s):  
Measurement Technique ◽  
Atmospheric Temperature ◽  
Co2 Absorption ◽  
Gas Mixing ◽  
Absorption Bands ◽  
Atmospheric Processes ◽  
Mixing Ratios ◽  
Solar Occultation ◽  
Sensitivity Studies ◽  
Temperature And Pressure

Abstract. Measurement of atmospheric temperature as a function of pressure, T(P), is key to understanding many atmospheric processes and a prerequisite for retrieving gas mixing ratios and other parameters from solar occultation measurements. This paper gives a brief overview of the solar occultation measurement technique followed by a detailed discussion of the mechanisms that make the measurement sensitive to temperature. Methods for retrieving T(P) using both broadband transmittance and refraction are discussed. Investigations using measurements of broadband transmittance in two CO2 absorption bands (the 4.3 and 2.7 μm bands) and refractive bending are then presented. These investigations include sensitivity studies, simulated retrieval studies, and examples from SOFIE.

Assessment of VIV Induced Fatigue in Long Free Spanning Pipelines

2003 ◽  
Author(s):  
Kim Mo̸rk ◽  
Olav Fyrileiv ◽  
Muthu Chezhian ◽  
Finn G. Nielsen ◽  
Tore So̸reide
Keyword(s):  
Failure Modes ◽  
Cross Flow ◽  
Computational Procedure ◽  
Design Guidelines ◽  
Model Tests ◽  
The State ◽  
Mode Behavior ◽  
Vortex Induced Vibrations ◽  
Current Design ◽  
Sensitivity Studies

Current design practice for free spanning pipelines is to allow free spans as long as the integrity with respect to potential failure modes are checked and found acceptable. The case study for Ormen Lange (OL) pipelines planned in the deep waters of the Norwegian Sea is associated with a large number of very long free spans, which requires significant intervention work if based on the state-of-practice acceptance criteria. The design philosophy of the state-of-the-art design code DNV-RP-F105 “Free Spanning Pipelines” is applied in combination with the experience gained from dedicated OL model tests. Updated project specific design guidelines with multi-mode behavior, typical for OL long free spans, is taken into account and an updated Cross-Flow (CF) response model has been developed. An approach to select the In-Line (IL) mode excited by CF response is suggested. Methods for combining stresses from multiple active modes have been proposed and tested, for both IL and CF Vortex Induced Vibrations (VIV). Fatigue analysis has also been performed on the stress series measured in the model tests and this has been successfully used to verify and validate the presented computational procedure. Uncertainty in the model test based fatigue estimates has been assessed and sensitivity studies have been carried out. Reasons for deviations and potential problem areas for long free spanning pipelines have been identified.

The IN Vessel Retention Strategy to Mitigate the Severe Accidents for the VVER 1000/320 Type NPPs

2013 ◽  
Author(s):  
Jiri Zdarek
Keyword(s):  
Systematic Approach ◽  
Fukushima Accident ◽  
Experimental Proof ◽  
Retention Strategy ◽  
Severe Accidents ◽  
Final Treatment ◽  
Higher Power ◽  
Defense In Depth

After the Fukushima Accident there is a worldwide strategy to develop the Defense in Depth strategy to mitigate the Severe Accidents. This effort has long tradition for new designs of NPPs. However the existing NPPs are lacking such a systematic approach. For the VVER 440 type NPP family the concept of the IN Vessel Strategy was adopted many years ago for the Loviisa NPP in Finland. However the VVER 1000/320 Units are lacking final treatment with the Severe Accidents. Effort of our research is to prepare the analytical and experimental proof to justify this concept for higher power VVER type NPPs.

Risk Design for Stable ‘Thin-Walled’ Pipelines Subject to Global Buckling and Excessive Bending From Seabed and Pipelay Induced Out-of-Straightness

2008 ◽  
Author(s):  
E. A. Maschner ◽  
N. Y. Wang
Keyword(s):  
External Loading ◽  
Limit States ◽  
Lateral Buckling ◽  
Seabed Topography ◽  
Current Design ◽  
Bending Capacity ◽  
Global Buckling ◽  
Sensitivity Studies ◽  
Structural Risk ◽  
Thin Walled

Relatively thin walled moderate water depth pipelines prone to lateral buckling can have very limited bending capacity in terms of their through-life load, strain and fatigue limit states. For such pipelines effective force mitigation schemes are often impracticable and the use of intermittent rock dump constraint if available, expensive. An alternative option is to design the pipeline to be stable along its length under operational and external loading. However a multitude of uncertainties can impact on such an assessment among them the concrete weight coat properties (stiffness and weight), residual lay tension, field joint SCF, corrosion rate, seabed topography, pipe embedment with associated non-linear pipe soil interactions and the size and frequency of external impacts. This paper reports on a methodology for achieving quantitatively low risk designs meeting regulatory approval through in-place 3D finite element sensitivity studies coupled with structural risk assessments. A current design project utilizing this approach is described along with analytical equations governing excessive seabed and pipelay induced out-of-straightness and lateral buckling initiations. Ultimately this enabled specification of practical limits on pipelay imposed out-of-straightness to safeguard the heavy weight coated pipeline and its field joints during operation.

Representing the Object, Process and Designer in Designing

2012 ◽  
Vol 229-231 ◽  
pp. 1781-1784
Author(s):  
Yue Min Hou ◽  
Lin Hong Ji
Keyword(s):  
Design Process ◽  
Transfer Functions ◽  
Design Framework ◽  
Evaluation Functions ◽  
System A ◽  
Dynamic View ◽  
Current Design ◽  
Design Activities ◽  
Computer Based ◽  
Design Systems

The goal of the presented work is to establish foundation for design systems combining both human intelligence and computing power of computers for real engineering design. The lack of involving designers in current design models impairs the design flexibility of computer-based design systems. This paper investigates design process with a developmental and dynamic view and develops a designer dominating designing (DDD) framework involving the object, process and designer. The design framework consists of six stages, three types of transfer functions, measurement functions, and evaluation functions, and it is represented as a dynamic system. A bio-inspired design framework (six-stages) is used to present the design process into six phase states and three mechanisms. An integrated product engineering model (iPeM) is used to generalize various design activities into transfer functions and measurement functions. Examples are presented to validate the method.

scholarly journals Retrieval of temperature and pressure using broadband solar occultation: SOFIE approach and results

2010 ◽  
Vol 3 (6) ◽  
pp. 5743-5794 ◽  
Author(s):  
B. T. Marshall ◽  
L. E. Deaver ◽  
R. E. Thompson ◽  
L. L. Gordley ◽  
M. J. McHugh ◽  
...  
Keyword(s):  
Measurement Technique ◽  
Atmospheric Temperature ◽  
Co2 Absorption ◽  
Gas Mixing ◽  
Absorption Bands ◽  
Atmospheric Processes ◽  
Mixing Ratios ◽  
Solar Occultation ◽  
Sensitivity Studies ◽  
Temperature And Pressure

Abstract. Measurement of atmospheric temperature as a function of pressure, T(P), is key to understanding many atmospheric processes and a prerequisite for retrieving gas mixing ratios and other parameters from solar occultation measurements. This paper gives a brief overview of the solar occultation measurement technique followed by a detailed discussion of the mechanisms that make the measurement sensitive to temperature. Methods for retrieving T(P) using both broadband transmittance and refraction are discussed. Investigations using measurements of broadband transmittance in two CO2 absorption bands (the 4.3 and 2.7 μm bands) and refractive bending are then presented. These investigations include sensitivity studies, simulated retrieval studies, and examples from SOFIE.

Exceeding Limitations: Ultrasonic Crack Inspections Become Feasible for Liquid Natural Gases

2018 ◽  
Author(s):  
Thomas Hennig ◽  
Rogelio Guajardo ◽  
Ernesto Suarez ◽  
Victor Haro ◽  
Peter Haberl
Keyword(s):  
Crack Detection ◽  
Systematic Approach ◽  
External Boundary ◽  
Tool Development ◽  
Natural Gases ◽  
Standard Solution ◽  
The Common ◽  
Temperature And Pressure ◽  
Sound Density ◽  
Propane Butane

Ultrasonic crack inspection services have become a standard solution for pipeline integrity programs, especially for liquid pipelines. ILI tools provide reliable and accurate data for assessment of axial and circumferential cracking defects to derive educated decisions on the integrity and maintenance of the asset. This technology inspects common media such as crude and light oils, water, diesel, benzene, or similar. Running tools in mediums used for commercial operations does not affect the throughput of the line. Crude and light oils, water, diesel, benzene etc. have relatively constant ultrasonic characteristics with varying pressures and temperatures and are very suitable for ultrasonic inspections, therefore called common media within the context of this paper. If the medium in the pipeline does not fall within the common media, the situation changes. These media are called challenges media. Especially for liquefied natural gases (LNG) or liquefied petroleum gases (LPG) where temperature and pressure have a significant impact on the ultrasonic characteristics of speed of sound, density, and attenuation. LNGs and LPGs typically contain high amounts of propane, butane, and some other higher order alkanes. Due to the high variability of these components to external boundary conditions, inline inspections in these type of pipelines are usually performed by replacing the medium with a more feasible one, e.g. water or diesel. This causes significant impact to productivity and throughput and increases costs and efforts. The authors will present the work performed to overcome and solve this workaround and run an ultrasonic crack inspection tool in LNG. This paper highlights the challenging aspects considered to successfully perform inline inspections in LNGs. We will present a standardized and systematic approach to overcome limitations of the technology in such media. Starting with the challenges and ideas for enhancement of the service, the paper will discuss the design of the experiment, the experiment itself, the results, and present the conclusions that resulted in the tool development and the analysis procedure. Finally, the authors will present the application of the enhanced service in a customer pipeline, including ILI preparation, execution, analysis, and in-the-ditch verifications. The structured and systematic approach allows the inspection company to perform successful and reliable crack detection inspections in LNG lines. This includes axial and circumferential cracking threats.

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

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