bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Rolling Parameters on the Low-Temperature Toughness and Microstructure of High-Strength Linepipe Steel
Authors: Stallybrass C. , Völling A. , Meuser H. , Grimpe F. 
Published: November 2016

In recent years, large-diameter pipe producers around the world have witnessed a growing interest to develop gas fields in arctic environments in order to fulfill the energy demand. High-strength linepipe grades are attractive for economic reasons, because they offer the benefit of a reduced wall thickness at a given operating pressure. Excellent low-temperature toughness of the material is essential under these conditions. Modern high-strength heavy plates used in the production of UOE pipes are produced by thermomechanical rolling followed by accelerated cooling (TMCP). The combination of high strength and high toughness of these steels is a result of the bainitic microstructure and is strongly influenced by the processing parameters. For this reason, the relationship between rolling and cooling parameters of heavy plate production, the low-temperature toughness and the microstructure is at the center of attention of the development efforts at Salzgitter Mannesmann Forschung (SZMF) in collaboration Salzgitter Mannesmann Grobblech (SMGB).
It has been shown previously that a variation of the processing parameters has a direct influence on the microstructure and correlates with mechanical properties that are accessible via small-scale tests. Modern characterization methods such as scanning electron microscopy in combination with electron backscatter diffraction have broadened our understanding of the underlying mechanisms and have helped to define processing conditions for the production of heavy plates with optimized low-temperature toughness in small scale tests. Within the present paper, the results of a recent laboratory investigation of the effect of a systematic variation of rolling parameters on the microstructure and low-temperature toughness of as-rolled and pre-strained Charpy specimens are discussed. In these trials, final rolling temperatures above the onset of the ferrite-austenite transformation and cooling stop temperatures above the martensite start temperature were selected. The microstructure of the plates was investigated by scanning electron microscopy and electron backscatter diffraction. In a series of Charpy tests in a specific temperature range, it was found that plate material in the as-rolled condition is not strongly sensitive to variations of the selected processing parameters, whereas pre-straining the Charpy specimens made it possible to assess the potential of individual processing concepts particularly with regard to low-temperature toughness.
In addition to Charpy testing, the toughness was also quantified via instrumented drop-weight tear (DWT) testing. By comparing total energy values from regular pressed-notch DWT-test specimens to J-integral values determined in drop-weight testing of pre-fatigued DWT-test specimens, the impact of variations of specimen type on material tearing resistance is shown.
A Life-Cycle Approach to the Assessment of Pipeline Dents
Authors: Turnquist Michael , Smith Ian 
Published: November 2016

The application of in-line inspection (ILI) to assess pipelines for various anomalies is standard practice in the pipeline industry. When ILI data identifies the presence of anomalies such as denting or ovalization, current convention is to perform either a depth-based or strain-based assessment to assess the severity. Although a strain-based methodology is generally accepted in the pipeline industry, this approach does not address all of the primary damage mechanisms associated with pipeline dents. Assessment based upon either depth or strain alone may not only provide non-conservative results but also fail to properly rank dents in order of their true severity. A life-cycle assessment approach that considers the damage caused by the dent formation, the stress intensification effect of the dent profile, and the severity of future pressure cycling provides an improved understanding of the probability of failure, allowing for more informed integrity management decision making.
Strain-based assessment of dents in pipelines is typically performed by calculating the local curvatures in the dent geometry as measured by ILI. Local strains are then calculated based on these local curvatures. However, this approach does not address that once a dent has been formed, continued pressure cycling at that location is what will ultimately cause a failure. The current strain-based methodology does not account for the severity of the pressure cycling at the dent.
A new and innovative methodology has been developed which takes a life-cycle approach to the assessment of pipeline dents. This approach estimates the remaining life of a dent based on fatigue damage accumulation. Finite element analysis (FEA) is used to calculate various stress concentration factors (SCFs) based on the geometry of the dent. These SCFs are used to calculate an equivalent alternating stress for a unit pressure cycle event. Past representative pressure cycling data is gathered using a rainflow counting approach. The amount of damage accumulated during each pressure cycle is calculated using stress or strain based (S-N) fatigue curves; this allows for a damage rate to be calculated based on past operational history. A remaining life can be estimated based on this damage rate and an estimation of the initial fatigue damage accumulated during formation of the dent. This estimation is made based on previous elastic-plastic FEA of various scenarios which simulate the formation and shakedown of a pipeline dent.
Case studies which explore the use of different assessment methods to analyze dents will be presented. A comparison of different assessment methodologies will illustrate the improved understanding of the probability of failure of dents based upon the life-cycle assessment.
Integrity Management and Life Extension for a CALM Buoy Oil Export Terminal
Authors: Gordon Robert B. , Ruiz-Rico Juan Carlos , Brongers Michiel Peter Hein , Gomez Julian 
Published: November 2016

This paper applies state-of-the-art integrity management and life extension methodologies to address degradation and failure modes specific to CALM buoy export terminals. The main objectives are to (1) classify the components of the export terminal according to their criticality, (2) establish risk-based inspection and maintenance plans to reduce or mitigate risk to acceptable levels and (3) assess remaining life.
The method is applied to a CALM buoy operating off the coast of Colombia. This buoy serves as the oil export terminal for all crude oil transmitted by the Ocensa pipeline, which has a capacity of 560 kBPD or around 60% of total Colombia oil production. The buoy is nearing the end of its design life, and options for life extension have been investigated based on an integrity assessment of the current condition of the equipment. As part of the assessment, detailed plans for future Risk Based Inspections (RBI) and Mitigation, Intervention, and Repair (MIR) have been developed.
Integrity Management of Ground Movement Hazards
Authors: Wang Yong-Yi , West Don , Dewar Douglas , McKenzie-Johnson Alex , Sen Millan 
Published: November 2016

Ground movements, such as landslides and subsidence/settlement, can pose serious threats to pipeline integrity. The consequence of these incidents can be severe. In the absence of systematic integrity management, preventing and predicting incidents related to ground movements can be difficult. A ground movement management program can reduce the potential of those incidents.
Some basic concepts and terms relevant to the management of ground movement hazards are introduced first. A ground movement management program may involve a long segment of a pipeline that may have a threat of failure in unknown locations. Identifying such locations and understanding the potential magnitude of the ground movement is often the starting point of a management program. In other cases, management activities may start after an event is known to have occurred. A sample response process is shown to illustrate key considerations and decision points after the evidence of an event is discovered. Such a process can involve fitness-for-service (FFS) assessment when appropriate information is available. The framework and key elements of FFS assessment are explained, including safety factors on strain capacity. The use of FFS assessment is illustrated through the assessment of tensile failure mode. Assessment models are introduced, including key factors affecting the outcome of an assessment. The unique features of girth welds in vintage pipelines are highlighted because the management of such pipelines is a high priority in North America and perhaps in other parts of the worlds. Common practice and appropriate considerations in a pipeline replacement program in areas of potential ground movement are highlighted. It is advisable to replace pipes with pipes of similar strength and stiffness so the strains can be distributed as broadly as possible. The chemical composition of pipe steels and the mechanical properties of the pipes should be such that the possibility of HAZ softening and weld strength undermatching is minimized. In addition, the benefits and cost of using the workmanship flaw acceptance criteria of API 1104 or equivalent standards in making repair and cutout decisions of vintage pipelines should be evaluated against the possible use of FFS assessment procedures. FFS assessment provides a quantifiable performance target which is not available through the workmanship criteria. However, necessary inputs to perform FFS assessment may not be readily available. Ongoing work intended to address some of the gaps is briefly described.
Longitudinal Stress Limits in Managing Spans and Other Longitudinal Loads
Authors: Wang Yong-Yi , Sen Millan , Song Peter 
Published: November 2016

Stresses along the length of pipelines, termed longitudinal stresses, are generated by pipeline construction, service conditions, and changes in pipe support conditions. Although there are no explicit federal regulations limiting longitudinal stresses for in-service pipelines, pipeline operators typically reply on design requirements in established standards, such as ASME B31.4, B31.8, and CSA Z662, to manage possible integrity concerns arising from longitudinal stresses.
In this paper longitudinal stress limits in existing standards are reviewed. These standards include CSA Z662, ASME B31.4, ASME B31.8, DNV RP F101 and API RP 1111. These standards provide various formulae or specific values for the longitudinal stress limits. These limits are compared under various levels of internal pressure. Although the potential failure modes addressed by the different standards may be similar, the specific limits on longitudinal stresses differ among the standards. One of the interesting findings is that the limit on compressive longitudinal stress can be very low when the combined stress criteria (von Mises or Tresca) are applied to pipelines operating at a pressure level equivalent to Class 1 design of gas pipelines, i.e., hoop stress being 72% SMYS. The resulting compressive stress limits, at 18–29% SMYS by some standards, are much lower than often quoted 90%, 80%, or 54% SMYS limits. These quoted limits refer to limits for tensile stresses, but sometimes mistaken for compressive stress limits. The low compressive stress limits can be quite difficult to manage for spans after the addition of possible compressive stresses from temperature differential, lateral bending, and other sources.
Alternative stress limits that provide a consistent level of safety and in compliance with the spirits of standards are proposed. The new limits are sound from the viewpoint of safety, yet practical to apply. One possibility of increasing the compressive stress limit is reducing the hoop tensile stress by lowering operating pressure. The other possibility is setting a combined equivalent stress limit that is not overly conservative and preserves a sound level of safety. An Example is provided to illustrate the assessment of a span against the stress limits.
Effect of Residual Forming Stresses on Fracture in ERW Pipe
Authors: Anderson Ted L. , Brown Gregory W. 
Published: November 2016

Many older pipelines contain significant residual stress due to the forming process. Cold expansion or a normalizing heat treatment can virtually eliminate residual forming stresses, but these practices were less common in the past. In the absence of cold expansion or normalization, residual forming stresses can be reduced by hydrostatic testing or operating pressures, but not eliminated entirely. Residual stresses can contribute to fracture in pipelines, particularly when the material toughness is low.
This article presents a series of analyses that seek to quantify the magnitude of residual forming stresses as well as their impact on pipeline integrity. The pipe forming process was simulated with elastic-plastic finite element analyses, which considered the effect of subsequent loading on relaxation of residual stresses. A second set of finite element simulations were used to quantify the effect of residual stresses on fracture behavior.
Simulation of Dynamic Crack Propagation and Arrest Using Various Types of Crack Arrestor
Authors: Uddin Mohammed , Wilkowski Gery 
Published: November 2016

In linepipe steels, there has been a growing interest in using damage mechanics that provides physical models of the fracture process which are embedded into a two- or three-dimensional finite element (FE) model. Among the various damage models, the cohesive zone model (CZM) has recently been used to simulate the ductile crack growth behavior in linepipe steels because of its computational efficiency and it requires only two parameters which can be determined in experiments. While CZM is not yet to be used as predictive tool, but it has a great application in crack arrestor design as well as in providing insight to ductile crack propagation.
In this paper, the authors have demonstrated some practical applications of CZM in linepipe steels. The CZM was used to simulate the ductile crack propagation in full-scale pipes which was able to capture the global deformation as well as the experimental crack speed. The model was then used to determine the effect of anchor blocks at the end of the pipe in a large diameter full-scale burst test. Later, the model was used to simulate two small diameter pipe tests with steel crack arrestors to mimic two arrestor cases with one showing crack propagation and the other showing crack arrest. The CZM model was also applied to demonstrate the circumferential ring-off behavior of a small diameter pipe test with rigid crack arrestor. The arrestor model was then extended to simulate a large diameter full scale Mojave burst test with “soft crack arrestor (SCA)”. A single element FE model was developed to verify the SCA material which was later extended with stain-based failure criteria. Finally, ductile crack growth in full-scale pipe with SCA was demonstrated to show that the FE CZM model can be used to optimize the design of SCA.
Girth Welds Integrity Evaluation on a Vintage Gas Pipeline
Authors: Hryciuk Pedro M. , Minellono Jose A. , Domínguez Verónica 
Published: November 2016

A leak on a girth weld was detected on a 609.6 mm (24 in) diameter transmission gas pipeline while recoating works were being performed. Failure analysis determined that the leak was caused by a pre-existing defect in the girth weld. This pre-existing defect had not been evolving over time. Nonetheless, because of the stress particular condition to which the gas pipeline was subject during the recoating work, the defect destabilized and progressed to failure.
In order to reduce the risk of occurrence of similar failures, a total of 27,000 girth welds were individually analyzed, corresponding to a length of 191 kilometers (118 miles) of the same gas pipeline section. The analysis included evaluation of internal inspection runs and girth welds gammagraphs available from the recoating work. Hence, not only was the data analyzed individually, but a comparison of the different sources of information to find a correlation was also performed.
Features detected in the analysis were classified and prioritized base on comparison with the failed girth weld defect. Also correspondence with crack like indications was considered. Severity of anomalies was categorized on four levels. A set of the highest severe crack like anomalies with potential failure were selected for direct assessment.
The complete process involved the assessment of 399 anomalies in total, revealing cracks on 79 girth welds. Metal reinforcements were installed as permanent repair on 27 girth welds according to repair criteria, and direct assessment findings were used to correlate internal inspection signals with features.
This paper discusses the results of the analysis, the field findings, and the actions taken.
A Study of Crack Interaction Criteria
Authors: Scott Colin 
Published: November 2016

Cracks in close proximity may interact and lead to leaks or ruptures at pressures well below the predicted failure pressures of the individual cracks. Several industry organizations and standards, including CEPA, ASME, API, and British Standards provide guidance on the treatment of potentially interacting cracks. This guidance tends to be very conservative.
This paper is a study of crack interaction, including a discussion of industry guidance, a critical review of failure pressure models, and a review of results of laboratory hydro-testing of pipe sections containing either in-service flaws or simulated flaws. In some cases the industry guidance and current failure pressure models provide inconsistent predictions, and this leads to uncertainty in the assessments used in routine crack management programs. The results of the hydro-testing are discussed in the context of both types of predictions. Understanding and predicting these interactions is important in maintaining an effective and efficient crack management program.
The paper is aimed at engineers involved in integrity assessments and integrity management system process improvement.
Estimating J-R Curve From CVN Upper Shelf Energy and its Application
Authors: Tandon Samarth , Gao Ming , Krishnamurthy Ravi , Kania Richard , Rosca Gabriela 
Published: November 2016

Accuracy in predictions of burst pressures for cracks in pipelines has significant impact on the pipeline integrity management decisions. One of the fracture mechanics models used for failure pressure prediction is API 579 Level 3 FAD ductile tearing instability analysis that requires J-R curves, i.e., crack resistance curves, for the assessment. However, J-R curves are usually unavailable for most pipelines. To overcome this technical barrier, efforts have been made to estimate the J-R curve indirectly from commonly available toughness data, such as the Charpy V-notched Impact Energy CVN values, by correlating the upper-shelf CVN value (energy) to the ductile fracture resistance J-R curve.
In this paper, the theoretical background and studies made by various researchers on this topic are reviewed. Attempts made by the present study to establish correlations between CVN and J-R curves for linepipe materials are then presented. Application of this CVN-JR correlation to API 579 Level 3 FAD tearing instability assessment for failure pressure predictions is demonstrated with examples. The accuracy of the correlation is analyzed and reported.
Re-Routing of an Exposed Subsea Pipeline Using a Double Block and Bleed Intrusive Isolation Technique
Authors: Iyengar Srivatsan K. , Jaiswal Shivram 
Published: November 2016

Oil & Natural Gas Corporation Ltd. (ONGC) operates a 42” gas pipeline that originates from an offshore platform and terminates at an onshore plant. The pipeline has operated for two decades and transmits 17% of India’s gas needs.
Unfortunately, the buried pipeline became exposed at Landfall Beach, likely due to the unpredictable impact of natural forces over a period of time. The shifting shoreline eroded resulting in the pipeline being exposed, which threatened its integrity. Stopgap arrangments were made to protect the pipeline from being hit and moved by continual tides, but that temporary measure also proved ineffective against the forces of the nature. The seasonal tropical storms worsened the situation.
ONGC rose to the challenge and decided to carry out permanent remedial measures, including re-routing of the affected segment of the pipeline and its associated station valve.
The situation presented several challenges. Because the pipeline was responsible for a large percentage of India’s gas needs, it was important to keep the pipeline live. Additionally, the worksite was a popular beach recreation area, so safety was a top priority.
ONGC contacted T.D. Williamson India Private Ltd. (TDW) for an isolation solution using double block and bleed methodogy to meet both of these concerns.
Weight Regain: No Link to Success in a Real-Life Multiday Boxing Tournament
Authors: Reale Reid , Cox Gregory R. , Slater Gary , Burke Louise M. 
Published: November 2016

Purpose:Combat-sport athletes acutely reduce body mass (BM) before weigh-in in an attempt to gain a size/strength advantage over smaller opponents. Few studies have investigated these practices among boxers and none have explored the impact of this practice on competitive success.Methods:One hundred (30 women, 70 men) elite boxers participating in the Australian national championships were weighed at the official weigh-in and 1 h before each competition bout. Regain in BM after weigh-in was compared between finalists and nonfinalists, winners and losers of each fight, men and women, and weight divisions. Boxers were surveyed on their pre- and post-weigh-in nutrition practices.Results:The lightest men’s weight category displayed significantly greater relative BM regain than all other divisions, with no difference between other divisions. BM prebout was higher than official weigh-in for men (2.12% ± 1.62%; P < .001; ES = 0.13) and women (1.49% ± 1.65%; P < .001; ES = 0.11). No differences in BM regain were found between finalists and nonfinalists, winners and losers of individual bouts, or between preliminary or final bouts. BM regain was significantly greater (0.37% BM, P < .001; ES = 0.25) before an afternoon bout compared with a morning bout.Conclusions:Boxers engage in acute BM-loss practices before the official competition weigh-in, but this does not appear to affect competition outcomes, at least when weight regain between weigh-in and fighting is used as a proxy for the magnitude of acute loss. While boxers recognize the importance of recovering after weigh-in, current practice is not aligned with best-practice guidance.