Failures Related to Welding

This article describes some of the welding discontinuities and flaws characterized by nondestructive examinations. It focuses on nondestructive inspection methods used in the welding industry. The sources of weld discontinuities and defects as they relate to service failures or rejection in new construction inspection are also discussed. The article discusses the types of base metal cracks and metallurgical weld cracking. The article discusses the processes involved in the analysis of in-service weld failures. It briefly reviews the general types of process-related discontinuities of arc welds. Mechanical and environmental failure origins related to other types of welding processes are also described. The article explains the cause and effects of process-related discontinuities including weld porosity, inclusions, incomplete fusion, and incomplete penetration. Different fitness-for-service assessment methodologies for calculating allowable or critical flaw sizes are also discussed.

Effect of Feed Intake on Water Consumption in Horses: Relevance to Maintenance Fluid Therapy

Maintenance fluid therapy is challenging in horses that cannot drink or are denied feed and water because of concerns about gastrointestinal tract function and patency. Intravenous fluid delivery to meet water needs based on current recommendations for maintenance requirements were obtained in fed horses and therefore might not apply to horses that are not being fed. This is a critical flaw because of the interdependence between intestinal tract water and extracellular water to support digestion while preserving water balance, a concept explained by the enterosystemic cycle. Because horses drink less when they are not eating and hence have lower water needs than fed horses, maintenance water requirements need to be adjusted accordingly. This article reviews this topic and identifies benefits of adjusting maintenance fluid therapy to meet lower demands from gastrointestinal function, such as reduced volumes, lower cost, avoidance of overhydration.

In Line Inspection in Lieu of Hydrotesting for Low Frequency ERW Pipelines: Developments and Experiences in 12 - and - 22 Inches Pipelines

Pipeline operators use different approaches, often in combination, to ensure the safe operation of an asset. Historically, hydrostatic testing is the most accepted methodology for assessing critical flaws in a pipeline system, achieved by stressing the pipeline above the standard operating limits. By design, a release during this test removes a critical flaw from the system. There are significant drawbacks to this type of assessment. Such drawbacks include high costs of implementation, feature growth, previously blunt defects sharpening and system downtime. Driven by the operator (Marathon Pipe Line) to investigate alternative approaches, a consortium of (4) parties formed to develop and validate an alternative and enhanced solution. The research and execution of the project was structured in (4) phases. • Phase I — Determine which crack morphologies are challenging to ILI technology in terms of detection and depth determination and test initial improvements to ILI technology. This included loop testing improved crack detection ILI robots and destructive assessment with pipe samples to identify gaps in ILI technology and analysis techniques. • Phase II — Assess vendor improved ILI technology on the operating pipelines using advanced in the ditch non-destructive evaluation (NDE) methods and destructive testing of pipe samples from the pipelines. Identify the additional improvements if necessary. • Phase III — Implement specific improvements to ILI technology that are completed based on Phase I and II results. Validate the new ILI platform on the specific pipeline. • Phase IV — Determination whether the new ILI platform can provide equivalent pipe seam system reliability to hydrostatic testing. A probabilistic approach will be used that would account for the expected statistical distribution of pipe properties, fatigue crack growth rates, position along the pipeline, and flaw sizes. This paper is a summary of the research and work for this ILI In Lieu of a Hydrostatic Testing initiative.

Systematic Reviews and Meta-Analysis in Spine Surgery—How Good Are They in Methodological Quality? A Systematic Review

Study Design: Systematic review. Objectives: To assess the methodological quality of systematic reviews and meta-analyses in spine surgery over the past 2 decades. Materials and Methods: We conducted independent and in duplicate systematic review of the published systematic reviews and meta-analyses between 2000 and 2019 from PubMed Central and Cochrane Database pertaining to spine surgery involving surgical intervention. We searched bibliographies to identify additional relevant studies. Methodological quality was evaluated with AMSTAR score and graded with AMSTAR 2 criteria. Results: A total of 96 reviews met the eligibility criteria, with mean AMSTAR score of 7.51 (SD = 1.98). Based on AMSTAR 2 criteria, 13.5% (n = 13) and 18.7% (n = 18) of the studies had high and moderate level of confidence of results, respectively, without any critical flaws. A total of 29.1% (n = 28) of the studies had at least 1 critical flaw and 38.5% (n = 37) of the studies had more than 1 critical flaw, so that their results have low and critically low confidence, respectively. Failure to analyze the conflict of interest of authors of primary studies included in review and lack of list of excluded studies with justification were the most common critical flaw. Regression analysis demonstrated that studies with funding and studies published in recent years were significantly associated with higher methodological quality. Conclusion: Despite improvement in methodological quality of systematic reviews and meta-analyses in spine surgery in current decade, a substantial proportion continue to show critical flaws. With increasing number of review articles in spine surgery, stringent measures must be taken to adhere to methodological quality by following PRISMA and AMSTAR guidelines to attain higher standards of evidence in published literature.

Corrosion-Fatigue Evaluation of Uncoated Weathering Steel Bridges

Uncoated weathering steel (UWS) bridges have been extensively used to reduce the lifecycle cost since they are maintenance-free and eco-friendly. However, the fatigue issue becomes significant in UWS bridges due to the intended corrosion process utilized to form the corrodent-proof rust layer instead of the coating process. In this paper, an innovative model is proposed to simulate the corrosion-fatigue (C-F) process in UWS bridges. Generally, the C-F process could be considered as two relatively independent stages in a time series, including the pitting process of flaw-initiation and the fatigue crack propagation of the critical pitting flaw. In the proposed C-F model, Faraday’s law has been employed at the critical flaw-initiation stage to describe the pitting process, in which the pitting current is applied to reflect the pitting rate in different corrosive environments. At the crack propagation stage, the influence of pitting corrosion is so small that it can be safely ignored. In simulating the crack propagation stage, the advanced NASGRO equation proposed by the NASA is employed instead of the classic Paris’ law, in which a modified fatigue limit is adopted. The fatigue limit is then used to determine the critical size of pitting flaws, above which the fatigue effect joins as a parallel driving force in crack propagation. The model is then validated through the experimental data from published articles at the initiation stage as well as the whole C-F process. Two types of structural steel, i.e., HPS 70W and 14MnNbq steel, have been selected to carry out a case study. The result shows that the C-F life can be notably prolonged in the HPS 70W due to the enhancement in fatigue strength and corrosion resistance. Besides, a sensitivity analysis has been made on the crucial parameters, including the stress range, stress ratio, corrosive environment and average daily truck traffic (ADTT). The result has revealed the different influence of the above parameters on the initiation life and propagation life.

Judge Blocks Oil and Gas Leases on Public Land, Citing Climate Change

The ruling pointed out a “critical flaw” in fossil fuel leasing.

Fitness-for-Service Assessment of Passenger Railcars and Trucks

An important consideration when operating a fleet of passenger rail consists is the remaining service life of both the car structure and the trucks. Agencies may choose to undertake studies like this when considering a fleet wide capital improvement program, ranging from minor aesthetic upgrades to major system replacements and interior reconfigurations. With this in mind, the owner needs to determine the remaining fatigue life of the individual cars and trucks within the fleet. This paper describes the fitness-for-service (FFS) assessment performed on railcars and trucks and an example of the method applied in practice. To establish the current condition of the fleet, an initial structural and service history review was undertaken. In addition, nondestructive examinations (NDE) of a sample of cars and trucks were performed to investigate any regions that have experienced damage due to the years of service. After the baseline condition of the cars and trucks was determined, finite element analyses (FEA) were performed on both the cars and the trucks to assist in locating the potential fatigue critical regions. Strain gages and accelerometers were then installed on both the cars and trucks for field testing. Multiple runs of in-service testing were performed and a typical revenue service fatigue life of both the cars and trucks was calculated based on an S-N approach. Based on the calculated fatigue life and the current accumulated consist mileage, the remaining car and truck service lives were determined. For regions with known flaws more detailed fracture mechanics based crack growth analyses were developed to determine critical flaw sizes and their propagation times to critical from the known initial flaw sizes. Results of the FFS assessment provide information on the susceptible areas within the car structure and trucks. Depending on those results, decisions can be made on the required inspections, repairs, or decommissioning necessary to operate the fleet in the short term, while also providing valuable insight into long term fleet planning.