Fatigue Life and Reliability Consideration During Field Repair of Coke Drum and Piping

2017 ◽  
Author(s):  
Tej Chadda ◽  
Umakanthan Anand
Keyword(s):  
Fatigue Life ◽  
Case Studies ◽  
Fatigue Cracks ◽  
High Stress ◽  
Cost Effective ◽  
Thermal Operation ◽  
Delayed Coking ◽  
First Case ◽  
Crack Repair

Aging coke drums and their connected overhead piping in delayed coking units experience fatigue cracks which most commonly occur at the skirt junction and high stress pipe welds. This paper presents 2-case studies of this new cost-effective repair methodology with fatigue resistant design upgrade. The first case study applies to coke drum weld build-up solid skirt crack repair and the second for overhead vapor line weld crack repair. This paper presents new field repair methodology which could also improve long term fatigue resistance. It also suggests optimizing the thermal operation & thermal gradients of coke drums for further reliability improvement. Based on FEA, successful field execution and our experience, these case studies demonstrate a long term improvement in reliability and fatigue life of the order of 2.5 to 3 or higher especially if combined with thermal operation optimization.

scholarly journals Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Iryna Danyliuk ◽  
Lyubomyr Poberezhnyi ◽  
Taras Pyrig ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Quantitative Analysis ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Fatigue Cracks ◽  
Preliminary Deformation ◽  
Term Operation ◽  
Steel Pipes

AbstractThe study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

E-Governance

2011 ◽  
pp. 1-27
Author(s):  
Srinivas Bhogle
Keyword(s):  
Web Services ◽  
Case Studies ◽  
Computer Networks ◽  
Cost Effective ◽  
Communication Technologies ◽  
Illustrative Case ◽  
Digital Information ◽  
Human Race ◽  
Long Term Prognosis

E-governance uses Internet and communication technologies to automate governance in innovative ways, so that it becomes more efficient, more cost-effective, and empowers the human race even more. E-governance exercises are being attempted for more than a decade now, but have so far achieved only mixed success. The long-term prognosis for e-governance, however, remains extremely positive. The emergence of Web-services technologies, the continually proliferating computer networks, and the irreversible migration towards digital information strongly confirm the view that e-governance is here to stay. The eventual success of any e-governance project is intimately linked to the methodology used, and to that complex mesh between men, machines, and mindsets. We explain the “what,” “why,” and “how” of e-governance. We also talk of e-governance concerns, and discuss a few illustrative case studies.

scholarly journals Cost-Effective High-Performance Concrete: Experimental Analysis on Shrinkage

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2730
Author(s):  
Barbara Kucharczyková ◽  
Dalibor Kocáb ◽  
Petr Daněk ◽  
Ivailo Terzijski
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Setting Time ◽  
Mechanical Strain ◽  
Cost Effective ◽  
Strain Gauges ◽  
Early Age ◽  
Dry Air ◽  
First Case

This paper focuses on the experimental determination of the shrinkage process in Self-Compacting High-Performance Concrete (SCC HPC) exposed to dry air and autogenous conditions. Special molds with dimensions of 100 mm × 60 mm × 1000 mm and 50 mm × 50 mm × 300 mm equipped with one movable head are used for the measurement. The main aim of this study is to compare the shrinkage curves of SCC HPC, which were obtained by using different measurement devices and for specimens of different sizes. In addition, two different times t0 are considered for the data evaluation to investigate the influence of this factor on the absolute value of shrinkage. In the first case, t0 is the time of the start of measurement, in the second case, t0 is the setting time. The early-shrinkage (48 h) is continuously measured using inductive sensors leant against the movable head and with strain gauges embedded inside the test specimen. To monitor the long term shrinkage, the specimens are equipped with special markers, embedded into the specimens’ upper surface or ends. These markers serve as measurement bases for the measurement using mechanical strain gauges. The test specimens are demolded after 48 h and the long term shrinkage is monitored using the embedded strain gauges (inside the specimens) and mechanical strain gauges that are placed, in regular intervals, onto the markers embedded into the specimens’ surface or ends. The results show that both types of measurement equipment give a similar result in the case of early age measurement, especially for the specimens cured under autogenous conditions. However, the early age and especially long term measurement are influenced by the position of the measurement sensors, particularly in the case of specimens cured under dry air conditions. It was proven that the time t0 have a fundamental influence on the final values of the shrinkage of investigated SCC HPC and have a significant impact on the conclusions on the size effect.

Fatigue of Cold Expanded Open Hole Coupons with Pre-Existing Cracks

2014 ◽  
Vol 891-892 ◽  
pp. 69-74 ◽  
Author(s):  
Pud S. Baburamani ◽  
Rob Ogden ◽  
Qian Chu Liu ◽  
P. Khan Sharp
Keyword(s):  
Fatigue Life ◽  
Load Transfer ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
Cost Effective ◽  
Fatigue Loading ◽  
Experimental Program ◽  
Cold Expansion ◽  
Open Hole ◽  
Life Improvement

Fastener holes have a high stress concentration at the edge of the hole and are primary sources of fatigue crack initiation, resulting in widespread fatigue damage leading to fatigue failures in airframe structures. The split-sleeve cold expansion (SsCx) technology is a simple and cost-effective way to improve the fatigue resistance of fastener holes by the introduction of compressive residual stresses around the holes. An investigation was carried out by DSTO to quantify the effectiveness of this technology, in terms of fatigue life improvement factors on a typical airframe aluminium alloy. Open hole (zero load transfer) coupons were tested to failure in non-cold expanded and cold expanded conditions. Coupons were also pre-cracked to specified crack lengths at the open hole, and cold expanded or left non-cold expanded, and tested to failure. This paper will present the results of the initial phases of the experimental program, involving constant amplitude fatigue loading of open hole coupons with and without cracks. The fatigue life improvement achieved by the use of hole cold expansion technology will be presented.

scholarly journals FATIGUE LIFE ANALYSIS OF RAIL-WELDS USING LINEAR ELASTIC FRACTURE MECHANICS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mequanent M. Alamnie ◽  
Yalelet Endalemaw
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Cracks ◽  
High Stress ◽  
Fatigue Cracking ◽  
Linear Elastic Fracture Mechanics ◽  
Frequency Interval ◽  
Element Analysis ◽  
Linear Elastic ◽  
Elastic Fracture

The initiation and growth of fatigue cracking is mainly due to high stress concentration, heterogeneity and poor quality of weld. The detection and rectification of such weld defects are major concerns of rail network managers to reduce potential risk of rail breaks and derailments. To estimate the fatigue life of welded joints and to analyze the progress of fatigue cracks, a fracture mechanics-based analysis and fatigue models were developed using Finite Element Analysis. The initial flaw is obtained from a sample weld using ultrasonic flaw detecting machine test. Linear Elastic Fracture Mechanics (LEFM) approach based on the Paris law was applied to determine critical crack size and the number of cycles to failure using FRANC3D software. The inspection interval of rail welds before fracture (failure) was suggested based on reliability and life cycle analysis that correspond with minimum overall cost and frequency interval. It is recommended that fracture-based models in combination with reliability analyses can be a sustainable infrastructure decision-making algorithm.

Estimation of Probability of Fatigue Failure on Tubular Joints

2021 ◽  
Author(s):  
N. Lokesh ◽  
S. Nallayarasu ◽  
S. Karunanithi
Keyword(s):  
Fatigue Life ◽  
Failure Mode ◽  
Fatigue Failure ◽  
Limit State ◽  
Probabilistic Approach ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
State Function ◽  
Reliability Method

Abstract Fatigue is generally considered the most critical failure mode in mechanical and structural systems. Due to high-stress concentrations, welded joints represent the most common fatigue crack initiation in steel structures susceptible to fatigue. In India, especially in western offshore, there are about 300 platforms, and 50% of them have reached their design life but still operating due to existing oil and gas reserves. Fatigue prediction in offshore structures is an extremely complicated process involving many factors such as complicated geometry, material, loading, and environment. These uncertainties are modelled as random variables. The assessment of failure probabilities takes a basis to formulate a limit state function for the relevant failure mode and deterioration mechanisms. The fatigue failure assessment based on a simplified probabilistic approach using the application of reliability-based procedures such as the First Order Reliability Method (FORM) is a useful tool. In the simplified fatigue assessment method, the two-parameter Weibull distribution is used to model the long-term distribution of fatigue stresses. Reliability of tubular joint using known fatigue life is an important factor in decision making for life extension of aged platforms. The methodology adopted in this study uses the linear damage accumulation model of Palmgren-Miner, double slope S-N curve, and one-to-one transformation of the probability density functions of long-term stress range and uncertainties to obtain the probability of fatigue failure as a function of the service life from known fatigue life.

E-Governance

2011 ◽  
pp. 67-88 ◽  
Author(s):  
Srinivas Bhogle
Keyword(s):  
Web Services ◽  
Case Studies ◽  
Computer Networks ◽  
Cost Effective ◽  
Communication Technologies ◽  
Illustrative Case ◽  
Digital Information ◽  
Human Race ◽  
Long Term Prognosis

E-governance uses Internet and communication technologies to automate governance in innovative ways, so that it becomes more efficient, more cost-effective, and empowers the human race even more. E-governance exercises are being attempted for more than a decade now, but have so far achieved only mixed success. The long-term prognosis for e-governance, however, remains extremely positive. The emergence of Web-services technologies, the continually proliferating computer networks, and the irreversible migration towards digital information strongly confirm the view that e-governance is here to stay. The eventual success of any e-governance project is intimately linked to the methodology used, and to that complex mesh between men, machines, and mindsets. We explain the “what,” “why,” and “how” of e-governance. We also talk of e-governance concerns, and discuss a few illustrative case studies.

Principles for integrated island management in the tropical Pacific

2014 ◽  
Vol 20 (2) ◽  
pp. 193 ◽  
Author(s):  
Stacy D Jupiter ◽  
Aaron P Jenkins ◽  
Warren J Lee Long ◽  
Sean L Maxwell ◽  
Tim J B Carruthers ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Case Studies ◽  
Pacific Islands ◽  
Management Practice ◽  
Cost Effective ◽  
Well Being ◽  
New Approach ◽  
The Pacific ◽  
National Systems

We propose a new approach for island-wide planning and implementation of ecosystem management in the Pacific, recognizing a lack of replicability, sustainability and cost-effectiveness in other approaches. ʻIntegrated island managementʼ (IIM) operates through coordinated networks of institutions and communities focused on sustainable and adaptive management of natural resources. IIM enables simultaneous and cost-effective achievement of ecosystem-based management, climate change adaptation and disaster risk reduction while conserving biodiversity, maintaining ecosystem services and securing human health and well-being. We present ten guiding principles for IIM, and then use these to evaluate 36 case studies from the Pacific islands. Most case studies were pilot or demonstration projects with little evidence of planning to ensure long-term financial and human capacity needs were sustained, beyond the life of the projects, or could be replicated at significant scales. Management outcomes in the Pacific will be enhanced by: (1) building on foundations of customary management practice and social networks; (2) working holistically across relevant ecological and governance scales, through coordinated but decentralized and nested institutions; (3) empowering local communities to participate in integrated planning and implementation; and (4) embedding IIM practice into national systems for long-term sustainability and replication. These also ultimately depend on the context and externalities, beyond the control of practitioners. Cost-effectiveness and appropriateness are also critical for successful IIM in the Pacific islands but ultimately there is little alternative for effective biodiversity conservation.

scholarly journals HCF Failure Modes and Mechanisms of Dissimilar Welds of Martensite/Austenite Metals at Elevated Temperature

2019 ◽  
Vol 269 ◽  
pp. 03004
Author(s):  
Chendong Shao ◽  
Haichao Cui ◽  
Fenggui Lu ◽  
Zhuguo Li
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Fatigue Cracks ◽  
High Stress ◽  
Crack Origin ◽  
Dissimilar Welds ◽  
Micro Cracks ◽  
High Stress Level

In this paper, the high cycle fatigue (HCF) behavior and failure mechanism of welded joint for martensite/austenite dissimilar metals were systematically investigated at elevated temperature. The HCF tests were performed at different elevated temperatures of 550, 600 and 630°C with stress ratio of -1. Most tested specimens failed in the heat affected zone (HAZ) of martensite metal, while minor failure occurred on the weld metal (WM) with comparatively more scattered fatigue life. Fatigue crack in the WM initiated from welding defects like porosities and non-metallic inclusions. For failures in the 10Cr-HAZ, fatigue cracks nucleated from the interior matrix of HAZ, which possessed lower hardness. The initiation of cracks was divided into facet type crack origin (FTCO) and rough type crack origin (RTCO). FTCO was observed for specimens tested at high stress amplitude with fatigue life below 107 cycles. Micro-cracks were observed at prior austenite grain boundaries (PAGBs) at high stress level. Micro-cracks preferred to form at martensite lath boundaries and coalesced into macro-crack leading to the formation of RTCO under the condition of lower stress.

E-Governance

2010 ◽  
pp. 40-62
Author(s):  
Srinivas Bhogle
Keyword(s):  
Web Services ◽  
Case Studies ◽  
Computer Networks ◽  
Cost Effective ◽  
Communication Technologies ◽  
Illustrative Case ◽  
Digital Information ◽  
Human Race ◽  
Long Term Prognosis

E-governance uses Internet and communication technologies to automate governance in innovative ways, so that it becomes more efficient, more cost-effective, and empowers the human race even more. E-governance exercises are being attempted for more than a decade now, but have so far achieved only mixed success. The long-term prognosis for e-governance, however, remains extremely positive. The emergence of Web-services technologies, the continually proliferating computer networks, and the irreversible migration towards digital information strongly confirm the view that e-governance is here to stay. The eventual success of any e-governance project is intimately linked to the methodology used, and to that complex mesh between men, machines, and mindsets. We explain the “what,” “why,” and “how” of e-governance. We also talk of e-governance concerns, and discuss a few illustrative case studies.

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