Justification for Reducing In-Service Weld Inspection Delay Times for Liquid Pipelines

2018 ◽  
Author(s):  
Matt Boring ◽  
Mike Bongiovi ◽  
David Warman ◽  
Harold Kleeman
Keyword(s):  
Hydrogen Concentration ◽  
Delay Time ◽  
Time Dependent ◽  
Accelerated Cooling ◽  
Hydrogen Cracking ◽  
Inspection Method ◽  
Time To Peak ◽  
Preventative Measures ◽  
Increased Risk ◽  
Delay Times

Welds that are made onto an operating pipeline cool at an accelerated rate as a result of the flowing pipeline contents cooling the weld region. The accelerated cooling rates increase the probability of forming a crack-susceptible microstructure in the heat-affected zone (HAZ) of in-service welds. The increased risk of forming such microstructures makes in-service welds more susceptible to hydrogen cracking compared to welds that do not experience accelerated cooling. It is understood within the pipeline industry that hydrogen cracking is a time-dependent failure mechanism. Due to the time-dependent nature and susceptibility of in-service welds to hydrogen cracking, it is common to delay the final inspection of in-service welds. The intent of the delayed inspection is to allow hydrogen cracks, if they were going to occur, to form so that the inspection method could detect them and the cracks could repaired. Many industry codes provide a single inspection delay time. By providing a single inspection delay time it is implied that the inspection delay time should be applied for all situations independent of the welding conditions or any other preventative measures the company may employee. There are many aspects that should be addressed when determining what should be considered an appropriate inspection delay time and these aspects can vary the inspection delay time considerably. Such factors include the cooling characteristics of the operating pipeline, the welding procedure that is being followed, the chemical composition of the material being welded and if any preventative measures such as post-weld heating are applied. The objective of this work was to provide an engineering justification for realistic minimum inspection delay times for different in-service welding scenarios. The minimum inspection delay time that was determined was based on modelling results from a previously developed two-dimensional hydrogen diffusion model that predicts the time to peak hydrogen concentration at any location within a weld HAZ. The time to peak hydrogen concentration was considered equal to the minimum inspection delay time since the model uses the assumption that if a weld was to crack the cracking would occur prior to or at the time of peak hydrogen concentration. Several factors were varied during the computer model runs to determine the effect they had on the time to peak hydrogen concentration. These factors included different welding procedures, different material thicknesses and different post-weld heating temperatures. The post-weld heating temperatures were varied between 40 F (4 C) and 300 F (149 C). The results of the analysis did provide justification for reducing the inspection delay time to 30 minutes or less depending on the post-weld heating temperature and pipeline wall thickness. This reduction in inspection delay time has the potential to significantly increase productivity and reduce associated costs without increasing the associated risk to pipeline integrity or public safety.

An Alternative Approach to Time Delay Prior to Inspection for Hydrogen Cracking

2018 ◽  
Author(s):  
William A. Bruce ◽  
Jared Proegler ◽  
Brad Etheridge ◽  
Steve Rapp ◽  
Russell Scoles
Keyword(s):  
Time Delay ◽  
Delay Time ◽  
Good Practice ◽  
Welding Process ◽  
Time Dependent ◽  
Hydrogen Cracking ◽  
Slow Cooling ◽  
Alternative Approach ◽  
Delay Times ◽  
Hydrogen Assisted Cracking

Hydrogen-assisted cracking in welds, which is also referred to as ‘hydrogen cracking’ or ‘delayed cracking,’ often requires time to occur. The reason for this is that time is required for the hydrogen to diffuse to areas with crack susceptible microstructures. Prior to inspection for hydrogen cracking, general good practice indicates that a sufficient delay time should be allowed to elapse — to allow any cracks that are going to form to do so and for the cracks to grow to a detectable size. What is a ‘sufficient’ delay time? Why does a delay time tend to be required for some applications (e.g., installation of a hot tap branch connection) and not for others (e.g., construction of an offshore pipeline from a lay barge)? This paper will address these and other related questions and present the results of recent experimental work on this subject. When determining appropriate delay times prior to inspection, it is important to consider not only the time-dependent nature of hydrogen cracking, but also the expected susceptibility of the weld to cracking. From a time-dependent nature standpoint, longer delay times decrease the chance that cracking can occur after inspection has been completed. From a probability standpoint, if measures can be taken to assure that the probability of cracking is extremely low, then determining an appropriate delay time becomes a moot point. In other words, if the weld is never going to crack, it does not matter when you inspect it. The probability of cracking can be minimized by using more conservative welding procedures (i.e., by designing out the risk of hydrogen cracking during procedure qualification). For example, if hydrogen levels are closely controlled by using low-hydrogen electrodes or a low-hydrogen welding process, or if the hydrogen in a weld made using cellulosic-coated electrodes is allowed to diffuse away after welding by careful application of preheating and slow cooling, or the use of post-weld preheat maintenance (i.e., post-heating), the probability of cracking is significantly reduced, and immediate inspection may be justified. This alternative approach to time delay prior to inspection for hydrogen cracking, which can allow for immediate inspection, will be presented.

Pipeline In-Service Fillet Weld Inspection Delay Time

2006 ◽  
Author(s):  
A. Dinovitzer ◽  
Vlado Semiga ◽  
L. N. Pusseogda ◽  
Scott Ironside
Keyword(s):  
Delay Time ◽  
Hydrogen Diffusion ◽  
Time Estimate ◽  
Hydrogen Diffusivity ◽  
Hydrogen Cracking ◽  
Time To Peak ◽  
Novel Approach ◽  
Environmental Material ◽  
Delay Times ◽  
Weld Inspection

Traditionally, in-service welding procedures have been developed to minimize the risk of hydrogen cracking by considering the weldment cooling rate and chemistry to control the susceptibility of the resulting microstructure. To further ensure that weld hydrogen cracks do not enter service, weldment inspection is completed. The BMT Hydrogen Diffusion and Cracking Model has been used to develop a means of conservatively estimating the delay time for hydrogen cracking in multi-pass welds. The hydrogen cracking delay time estimate is developed based upon the Time To Peak Hydrogen (TTPH) concept that is evaluated numerically considering the hydrogen diffusivity in the weldment. CSA Z662 indicates that the pipeline operator should delay weld inspection until the risk of cracking is over. This requirement includes a suggested delay time of 48 hours after weld deposition. The BMT Hydrogen Diffusion Model and TTPH concept were used to define conservative inspection delay times for pipeline repair sleeve end circumferential fillet welds deposited in-service. This paper describes the investigation results and the effect of variations in welding, environmental, material and pipeline characteristics on the recommended inspection delay time. These delay times are compared to those recommended by CSA Z662 to illustrate this novel approach to establishing weldment inspection delay times.

Abstract 47: Atrial Fibrillation is Associated With Increased Risk of Incident Venous Thromboembolism: The Atherosclerosis Risk in Communities Study

Circulation ◽  
2017 ◽  
Vol 135 (suppl_1) ◽  
Author(s):  
Pamela L Lutsey ◽  
Faye L Norby ◽  
Alvaro Alonso ◽  
Mary Cushman ◽  
Lin Y Chen ◽  
...  
Keyword(s):  
Risk Factors ◽  
Atrial Fibrillation ◽  
Venous Thromboembolism ◽  
Incidence Rate ◽  
Case Reports ◽  
Time Dependent ◽  
Atherosclerosis Risk In Communities ◽  
Increased Risk ◽  
Atherosclerosis Risk ◽  
Shared Risk

Background: It is well-established that atrial fibrillation (AF) is associated with thrombus formation in the left atrium, which can lead to ischemic stroke. Case reports, autopsies, and transesophageal echo data have indicated that clot formation also occurs in the right atrium (i.e. right-side intracardiac thrombosis) of AF patients, which could lead to pulmonary embolism (PE). However, it is unclear whether this occurrence is common. Objective: Test the hypotheses that individuals with incident AF are at elevated risk of developing venous thromboembolism (VTE), and that the association will be stronger for those presenting with PE alone versus PE and deep vein thrombosis (DVT) or DVT alone. Methods: A total of 15,205 Atherosclerosis Risk in Communities (ARIC) study participants, aged 45-64 years, were followed from baseline (1987-1989) to 2011 for incidence of AF and VTE (median follow-up 19.8 years). Incident AF and VTE events were identified via active surveillance and defined by relevant hospital discharge ICD codes. VTE events were validated by medical record review. Multivariable-adjusted Cox proportional hazards regression models were used, with AF modeled as a time-dependent covariate. We also evaluated separately risk of PE without evidence of DVT, DVT without PE, and events presenting with both PE and DVT. Results: At baseline participants were on average 54 years old, 55% female and 26% black. In the absence of AF there were 678 VTE events, for an incidence rate of 2.6 per 1000 person-years. After an AF diagnosis there were 77 events, with an incidence rate of 7.1 per 1000 person-years. In multivariable-adjusted models, having AF (versus no AF) was associated with a greater risk of incident VTE; the HR (95% CI) was 2.10 (1.65-2.68) after adjustment for demographics, 1.82 (1.42-2.32) additionally accounting for numerous AF and VTE risk factors, and 1.97 (1.53-2.53) after further adjusting for time-dependent anticoagulant use. When we restricted to PE events without evidence of DVT there were 188 events in total, of which 19 occurred following a diagnosis of AF. The HR for AF (versus no AF) was 1.53 (0.92-2.56) in fully adjusted models. For DVT alone there were 384 events in total, of which 48 occurred after AF diagnosis; the HR for AF was 2.43 (1.77-3.33). Among the 116 events presenting with both DVT and PE, 10 occurred after AF diagnosis, and the HR for AF was 1.36 (0.67-2.75). Conclusions: Diagnosis with AF was associated with a nearly 2-fold increased risk of incident VTE. The association was not stronger when isolated to those with PE without DVT, suggesting that higher risk of VTE among AF patients may be due to either the coagulation abnormalities that accompany AF, or shared risk factors that were not fully accounted for in this analysis.

scholarly journals Estimation of Delay Times in Coupling Between Autonomic Regulatory Loops of Human Heart Rate and Blood Flow Using Phase Dynamics Analysis

2017 ◽  
Vol 9 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Vladimir S Khorev ◽  
Anatoly S Karavaev ◽  
Elena E Lapsheva ◽  
Tatyana A Galushko ◽  
Mikhail D Prokhorov ◽  
...  
Keyword(s):  
Heart Rate ◽  
Delay Time ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Phase Dynamics ◽  
Oscillatory Systems ◽  
Low Frequency Oscillations ◽  
Delay Times ◽  
The Difference ◽  
Regulatory Loop

Objective: We assessed the delay times in the interaction between the autonomic regulatory loop of Heart Rate Variability (HRV) and autonomic regulatory loop of photoplethysmographic waveform variability (PPGV), showing low-frequency oscillations. Material and Methods: In eight healthy subjects aged 25–30 years (3 male, 5 female), we studied at rest (in a supine position) the simultaneously recorded two-hour signals of RR intervals (RRIs) chain and finger photoplethysmogram (PPG). To extract the low-frequency components of RRIs and PPG signal, associated with the low-frequency oscillations in HRV and PPGV with a frequency of about 0.1 Hz, we filtered RRIs and PPG with a bandpass 0.05-0.15 Hz filter. We used a method for the detection of coupling between oscillatory systems, based on the construction of predictive models of instantaneous phase dynamics, for the estimation of delay times in the interaction between the studied regulatory loops. Results: Averaged value of delay time in coupling from the regulatory loop of HRV to the loop of PPGV was 0.9±0.4 seconds (mean ± standard error of the means) and averaged value of delay time in coupling from PPGV to HRV was 4.1±1.1 seconds. Conclusion: Analysis of two-hour experimental time series of healthy subjects revealed the presence of delay times in the interaction between regulatory loops of HRV and PPGV. Estimated delay time in coupling regulatory loops from HRV to PPGV was about one second or even less, while the delay time in coupling from PPGV to HRV was about several seconds. The difference in delay times is explained by the fact that PPGV to HRV response is mediated through the autonomic nervous system (baroreflex), while the HRV to PPGV response is mediated mechanically via cardiac output.

scholarly journals Mortality Risk and The Progression of The Electronic Frailty Index and Hospital Frailty Risk Score Over Time

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Joe Hollinghurst ◽  
Alan Watkins
Keyword(s):  
Risk Score ◽  
Frailty Index ◽  
Time Frame ◽  
Time Dependent ◽  
Cox Models ◽  
Hazard Ratios ◽  
Increased Risk ◽  
The Matrix ◽  
Time Dependent Covariates ◽  
Over Time

IntroductionThe electronic Frailty Index (eFI) and the Hospital Frailty Risk Score (HFRS) have been developed in primary and secondary care respectively. Objectives and ApproachOur objective was to investigate how frailty progresses over time, and to include the progression of frailty in a survival analysis.To do this, we performed a retrospective cohort study using linked data from the Secure Anonymised Information Linkage Databank, comprising 445,771 people aged 65-95 living in Wales (United Kingdom) on 1st January 2010. We calculated frailty, using both the eFI and HFRS, for individuals at quarterly intervals for 8 years with a total of 11,702,242 observations. ResultsWe created a transition matrix for frailty states determined by the eFI (states: fit, mild, moderate, severe) and HFRS (states: no score, low, intermediate, high), with death as an absorbing state. The matrix revealed that frailty progressed over time, but that on a quarterly basis it was most likely that an individual remained in the same state. We calculated Hazard Ratios (HRs) using time dependent Cox models for mortality, with adjustments for age, gender and deprivation. Independent eFI and HFRS models showed increased risk of mortality as frailty severity increased. A combined eFI and HFRS revealed the highest risk was primarily determined by the HFRS and revealed further subgroups of individuals at increased risk of an adverse outcome. For example, the HRs (95% Confidence Interval) for individuals with an eFI as fit, mild, moderate and severe with a high HFRS were 18.11 [17.25,19.02], 20.58 [19.93,21.24], 21.45 [20.85,22.07] and 23.04 [22.34,23.76] respectively with eFI fit and no HFRS score as the reference category. ConclusionFrailty was found to vary over time, with progression likely in the 8-year time-frame analysed. We refined HR estimates of the eFI and HFRS for mortality by including time dependent covariates.

scholarly journals Fatal, Fulminant and Invasive Non-Typeable Haemophilus influenzae Infection in a Preterm Infant: A Re-Emerging Cause of Neonatal Sepsis

2020 ◽  
Vol 5 (1) ◽  
pp. 30 ◽  
Author(s):  
Sudipta Roy Chowdhury ◽  
Srabani Bharadwaj ◽  
Suresh Chandran
Keyword(s):  
Haemophilus Influenzae ◽  
Preterm Infant ◽  
Neonatal Sepsis ◽  
Group B Streptococcus ◽  
Invasive Disease ◽  
Preventative Measures ◽  
Increased Risk ◽  
Extremely Preterm ◽  
Serotype B ◽  
Group B

Early-onset neonatal sepsis (EOS) is a major cause of neonatal death and long-term neurodevelopmental disabilities among survivors. The common pathogens causing EOS are group B streptococcus (GBS) and Escherichia coli. Haemophilus influenzae (H. influenzae) is a Gram-negative coccobacillus that can cause severe invasive disease and can be divided into either typeable or non-typeable strains. H. influenzae serotype b (Hib) is the most virulent and the major cause of bacterial meningitis in young children prior to routine immunization against Hib. Hib infection rates have dramatically reduced since then. However, a number of studies have reported an increasing incidence of non-typeable H. influenzae (NTHi) sepsis in neonates worldwide and concluded that pregnant women may have an increased risk to invasive NTHi disease with poor pregnancy outcomes. We present a case of fulminant neonatal sepsis caused by NTHi in an extremely preterm infant and discuss potential preventative measures to reduce its re-emergence.

scholarly journals The Game of Developers and Planners: Ecosystem Services as a (Hidden) Regulation through Planning Delay Times

2020 ◽  
Vol 12 (15) ◽  
pp. 5940
Author(s):  
Dani Broitman
Keyword(s):  
Ecosystem Services ◽  
Social Welfare ◽  
Delay Time ◽  
Open Space ◽  
Simple Game ◽  
Land Development ◽  
Theoretic Model ◽  
Land Use Regulation ◽  
Main Hypothesis ◽  
Delay Times

Planning delay time is a ubiquitous but under-researched land use regulation method. The aim of this study is to link planning delay time with the loss of urban locally provided ecosystem services (ULPES) caused by land development. Our main hypothesis is that the planning delay is an informal tool that ensures social welfare in a given urban area increases even if land is developed and the ULPES associated with the undeveloped land are lost. Whereas the developer’s objective is to maximize his profits, the planner’s target is to achieve the greatest social welfare, as calculated by considering public interest based on the value of open space and the developer’s expected profits. Our results show that, when the ULPES provided by an undeveloped parcel are sufficiently high, planning delay times can be used to prevent the execution of low quality initiatives and to only permit projects that improve general welfare and justify the potential ULPES loss. Planning delay times are interpreted as the expression of continuous negotiation between the interests of the public and those of real-estate developers, regarding the value of ULPES. The implication of the study is that ULPES values are introduced using a simple game-theoretic model allowing interaction between developers and planning authorities. The main significance is an alternative explanation for planning delay times as a consequence of ongoing negotiations between developers and urban planners that represent the general public in the city.

What a Difference a Drink Makes: Determining Associations Between Alcohol-Use Patterns and Condom Utilization Among Adolescents

2020 ◽  
Vol 56 (1) ◽  
pp. 34-37
Author(s):  
Stephen Scroggins ◽  
Enbal Shacham
Keyword(s):  
Alcohol Consumption ◽  
Alcohol Use ◽  
Risk Behavior ◽  
Consumption Patterns ◽  
Youth Risk Behavior Survey ◽  
Use Patterns ◽  
Preventative Measures ◽  
Increased Risk ◽  
Significant Difference ◽  
Survey Results

Abstract This study aimed to identify differences in condom use among adolescents by alcohol consumption patterns using the 2017 Youth Risk Behavior Survey. Results suggest significant increased risk of condomless sex among binge drinking youth. Surprisingly, no significant difference in condom utilization was identified between non-drinkers and only moderate drinkers. Findings highlight the need to tailor STI preventative measures accordingly.

Anomaly Criteria for General Visual Inspection of Subsea Flexible Pipes

2020 ◽  
Author(s):  
Damir Tadjiev
Keyword(s):  
Visual Inspection ◽  
Service Failure ◽  
Lessons Learned ◽  
Inspection Method ◽  
Deep Waters ◽  
Flexible Pipes ◽  
Increased Risk ◽  
Competent Person ◽  
Routine Basis ◽  
Areas Of Concern

Abstract For flexible pipes in subsea applications, General Visual Inspection (GVI) by Remotely Operated Vehicles (ROV) remains the most common inspection method that is used on a routine basis. It enables verification of pipe configuration or layout and also helps to identify any areas of concern indicative of an increased risk of in-service failure. The success of ROV GVI chiefly relies on the anomaly criteria used, these help inspectors to identify any areas of concern, which can then be assessed by a competent person to ensure any threat to the integrity of an inspected component is identified and addressed. Currently there are no commonly accepted anomaly criteria for ROV GVI of flexible pipes. As a result there is no consistent approach between different operators and experience shows that the inspection approach and anomaly criteria are often adopted from what has traditionally been used for rigid pipes. Since flexible pipes have different design and associated failure threats and mechanisms to rigid pipe, use of this approach may result in under or over inspection of flexible pipes. This paper presents a set of anomaly criteria for ROV GVI of flexible pipes. The criteria were developed using the experience and lessons learned from a population of approximately 350 flexible pipes from two different manufactures operating in deep waters of the UKCS for over a period of 20 years. The criteria cover dynamic flexible risers and associated ancillary equipment, seabed flexible flowlines and jumpers. The applicability of the proposed anomaly criteria to other systems, the benefits of having commonly accepted anomaly criteria, the anomaly detection capability of ROV GVI and the reporting of anomalies are also discussed.

scholarly journals Advancements and challenges in generating accurate animal models of gestational diabetes mellitus

2013 ◽  
Vol 305 (11) ◽  
pp. E1327-E1338 ◽  
Author(s):  
Raymond C. Pasek ◽  
Maureen Gannon
Keyword(s):  
Diabetes Mellitus ◽  
Animal Models ◽  
Gestational Diabetes ◽  
Gestational Diabetes Mellitus ◽  
Well Being ◽  
Perinatal Complications ◽  
Preventative Measures ◽  
Increased Risk ◽  
Surgical Manipulation

The maintenance of glucose homeostasis during pregnancy is critical to the health and well-being of both the mother and the developing fetus. Strikingly, approximately 7% of human pregnancies are characterized by insufficient insulin production or signaling, resulting in gestational diabetes mellitus (GDM). In addition to the acute health concerns of hyperglycemia, women diagnosed with GDM during pregnancy have an increased incidence of complications during pregnancy as well as an increased risk of developing type 2 diabetes (T2D) later in life. Furthermore, children born to mothers diagnosed with GDM have increased incidence of perinatal complications, including hypoglycemia, respiratory distress syndrome, and macrosomia, as well as an increased risk of being obese or developing T2D as adults. No single environmental or genetic factor is solely responsible for the disease; instead, a variety of risk factors, including weight, ethnicity, genetics, and family history, contribute to the likelihood of developing GDM, making the generation of animal models that fully recapitulate the disease difficult. Here, we discuss and critique the various animal models that have been generated to better understand the etiology of diabetes during pregnancy and its physiological impacts on both the mother and the fetus. Strategies utilized are diverse in nature and include the use of surgical manipulation, pharmacological treatment, nutritional manipulation, and genetic approaches in a variety of animal models. Continued development of animal models of GDM is essential for understanding the consequences of this disease as well as providing insights into potential treatments and preventative measures.

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