bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncertainty Quantification of Nondestructive Techniques to Verify Pipeline Material Strength
Authors: Kornuta Jeffrey A. , Ames Nicoli M. , Louie Mary W. , Veloo Peter , Rovella Troy 
Published: November 2018

The Pipeline and Hazardous Materials Safety Administration (PHMSA) Notice of Proposed Rulemaking (NPRM), with Docket No. PHMSA-2011-0023, substantially revises 49 CFR Part 191 and 192. Notable among these changes was the addition of §192.607, verification of pipeline material. This section calls for the verification of material properties of pipe and fittings located in either high consequence areas, class 3, or class 4 locations where traceable, verifiable, and complete records do not exist. Material properties include grade (yield strength, YS, and ultimate tensile strength, UTS) and chemical composition. The proposed regulations include an independent third-party validation for non-destructive testing (NDT) methods to determine material strength and require an accuracy of within ±10% of an actual strength value.
Among the NDT technologies currently available to pipeline operators to estimate material strength is instrumented indentation testing (IIT). IIT is based on the principal that there exists a relationship between the indentation response of a material and its stress-strain curve. The indentation response is measured during the IIT process whereby an indenter is sequentially forced into the material during testing. The link between the indentation response and the material stress-strain curve is established often through the use of iterative Finite Element Analysis (FEA). The IIT vendor’s proprietary software performs this calculation, converting force-displacement measurements into an estimate of YS and UTS.
In this study we extracted force-displacement data from IIT performed using FEA on an idealized steel. This data was then coupled with literature algorithms developed at Seoul National University (Kwon et al.). Parametric sensitivity analysis was then performed on estimated YS with respect to the algorithm parameters. Preliminary results indicate that while variations in the indenter constant, ω, used to estimate surface deformation do not significantly alter the predicted UTS or YS, the sensitivity to deviations in the empirical constant, Ψ, relating normal load to representative stress was more pronounced due to an effect on the calculated power-law constant, K.
PHMSA’s NPRM accuracy requirements for NDT to establish yield and tensile strength should be driven by a rigorous understanding of material inhomogeneities, uncertainties in actual tensile strength determination, experimental uncertainty, and modeling uncertainties. The analysis performed in this paper provides part of this rigorous framework to establish realistic accuracy requirements for NDT that must drive federal rulemaking. In addition, this research highlights the need for pipeline operators to establish controls on the algorithms adopted by commercial NDT vendors.
Is Public Safety Impacted by the Multiple Regulatory Regimes for Gas Pipelines and Networks?
Authors: Hayes Jan , Chester Lynne , King Dolruedee Kramnaimuang 
Published: November 2018

Gas pipelines and networks are subject to multiple regulatory governance arrangements. One regime is economic regulation which is designed to ensure fair access to gas markets and emulate the price pressures of competition in a sector dominated by a few companies. Another regime is technical regulation which is designed to ensure pipeline system integrity is sufficient for the purposes of public safety, environmental protection and physical security of supply. As was highlighted in analysis of the San Bruno pipeline failure, these two regulatory regimes have substantially different orientations towards expenditure on things such as maintenance and inspection which ultimately impact public safety.
Drawing on more than 50 interviews, document review and case studies of specific price determinations, we have investigated the extent to which these two regulatory regimes as enacted in Australia may conflict, and particularly whether economic regulation influences long-term public safety outcomes. We also draw on a comparison with how similar regulatory requirements are enacted in the United Kingdom (UK).
Analysis shows that the overall orientation towards risk varies between the two regimes. The technical regulatory regime is a typical goal-setting style of risk governance with an overarching requirement that ‘reasonably practicable’ measures are put in place to minimize risk to the public. In contrast, the incentive-based economic regulatory regime requires that expenditure should be ‘efficient’ to warrant inclusion in the determination of acceptable charges to customers. How safety is considered within this remains an open question.
Best practice in performance-based safety regimes such as those used in the UK and Australia require that regulators adopt an attitude towards companies based on the principle of ‘trust but verify’ as, generally speaking, all parties aim for the common goal of no accidents. Equally, in jurisdictions that favor prescriptive safety requirements such as the United States (US) the common goal remains. In contrast, stakeholders in the economic regulatory regime have significantly diverse interests; companies seek to maximize their individual financial returns and regulators seek to exert downward price pressures. We argue that these differences in the two regulatory regimes are significant for the management of public safety risk and conclude that minimizing risk to the public from a major pipeline failure would be better served by the economic regulatory regime’s separate consideration of safety-related from other expenditure and informed by the technical regulator’s view of safety.
An Optimization Model for UAV Inspection Path of Oil and Gas Pipeline Network
Authors: Yan Yamin , Zhang Haoran , Zhang Wan , Wang Bohong , Liao Qi , Liang Yongtu 
Published: November 2018

Currently, the oil and gas pipeline network is a key link in the coordinated development of oil and gas upstream and downstream cohesion. To ensure the reliability and safety of oil and gas pipeline network operation, it is necessary to inspect the pipeline periodically to minimize the risk of leakage, spill and theft, as well as documenting actual incidents and the effects on the environment. Traditional manpower inspection is extremely labor-intensive and inefficient. Through the use of UAV (unmanned aerial vehicle) inspection, it is possible to greatly increase efficiencies by reducing the amount of manpower and resources required by traditional inspection methods.
The integrated optimization for UAV inspection path of oil and gas pipeline networks, including physical feasibility, performance of mission, cooperation, real-time implementation, three-dimensional (3-D) space, et al, is a strategic problem due to its large-scale and complexity. Aimed at improving inspection efficiency and maximizing economic benefits, this paper proposes a novel mix-integer linear programming model which could be used for inspection path planning. Minimizing the total inspection time is the objective function of this model. The constraints of the mission scenario and the safety performance of UAV are taken into account. By using evolutionary genetic algorithm, each candidate route can be measured through the evaluation function that takes into account the cost of the route, the mission scenario as well as the cooperative and coordinative requirements among the unmanned aerial vehicles constraints.
Finally, the proposed approach is applied to a virtual oil and gas pipeline network. Compared with the traditional inspection approach, the proposed method is 66.48% less in inspection cost and 22.07% shorter in total inspection time, verifying the rationality and superiority of the model.
Vibration and Fatigue Failures at Pipeline Facilities
Authors: Matta Lawrence M. , Szasz Gyorgy 
Published: November 2018

Vibration related issues can be a challenging part of pipeline integrity management, because they are frequently difficult to predict, diagnose, and remediate. Often, vibrational issues are not even considered until pipe movement is observed or failures occur. A wide variety of vibration problems are associated with pumps and compressors, and piping at pumping stations are often susceptible to vibration related issues. Excessive piping vibration may result in leaks at connections and flanges, and fatigue failures can occur, leading to leaks that present safety and environmental concerns.
The energy responsible for pipeline vibration is usually provided by rotating or reciprocating pumping equipment, and is transmitted to the piping either by direct mechanical contact, pressure pulsations, or turbulence in the pumped fluid. Vibration problems usually occur when a mechanical natural frequency of the piping system, an acoustic natural frequency of the contained fluid, or both, is excited by the driving force.
In this paper, a brief overview of vibration issues that occur in pipeline facilities is presented. Next, a selection of case studies is provided to illustrate some of the types of vibration induced failures that have been observed at pipeline facilities, and how they were addressed and resolved. These examples provide some insight into how to potentially avoid such issues, or if they occur, how to identify and mitigate them.
The Effect of Material Strain Hardening on the Determination of CTOD R-Curves Using SENB Specimens
Authors: Moore Philippa L. , Khor Wee Liam 
Published: November 2018

In ductile materials the fracture toughness is usually characterised by a tearing resistance curve, or R-curve, plotting the fracture toughness in terms of J or CTOD against crack extension. Recent research has evaluated the methods to determine CTOD in engineering alloys with a wide range of yield to tensile (Y/T) ratios for single point CTOD. This work develops the investigation into R-curves, and reviews the assumptions about SENB specimens deforming under rigid rotation, the evaluation of CTOD from J for R-curves, and the nature of tearing initiation in low Y/T ratio stainless steel, from comparisons against a series of silicone replicas cast from the SENB specimen notch during fracture toughness tests.
For CTOD R-curves, the methods based on CTOD from J in ISO 12135 and ASTM E1820 gave lower and less accurate R-curves than the rigid rotation methods in BS 7448-4 and WES 1108. However, the accuracy of the BS 7448-4 formula varied for the different strain hardening materials, and overestimated the R-curves in the low tensile ratio stainless steel.
Investigations into the effect of the assumption about rigid rotation in different strain hardening materials led to a rotational factor function of tensile ratio, rp sh, to be developed from numerical modelling. When this function was substituted into standard equations in place of the fixed value of rp an improvement in the accuracy of BS 7448-4 R-curves compared to replica measurements was seen for the range of strain hardening investigated, but it did not significantly improve the accuracy of the WES 1108 formula, which accounts for strain hardening in other parameters.
A combination of the elastic CTOD part of the WES 1108 formula, with the plastic CTOD incorporating the modified rotational factor, was concluded to offer the optimum method to determine CTOD R-curves for a range of strain hardening materials.
Quality Assurance for Quenched and Tempered Pipeline Fittings: A Regulator’s Perspective and Plan of Action
Authors: van Schalkwyk Negar , Wang Hong , Colquhoun Iain , Paviglianiti Joe 
Published: November 2018

Heat treated pipeline fittings (principally elbows, tees, and reducers) require careful process control. For example, furnace temperature, placement of the fittings in the furnace, transfer time to quenching tank, adequacy of quench or tempering time can all impact the fittings’ mechanical properties if not done properly.
In recent years, the National Energy Board (NEB) became aware of instances of quenched and tempered (Q&T) pipe and fittings having mechanical properties that did not meet Canadian Standards Association (CSA) or similar standards, being installed on pipeline systems under NEB and other regulatory bodies’ jurisdiction. In 2013, a pipeline rupture occurred on an NEB-regulated pipeline. Although failure to meet mechanical specifications was not the cause of the incident, the investigations revealed that there were fittings installed on the pipeline with yield strength of less than Specified Minimum Yield Strength (SMYS). The NEB undertook further investigations to determine if this low yield issue might indicate a systemic problem. In the cases examined, contrary to the recorded information in the Material Test Reports (MTRs), not all fittings met the specified mechanical properties requirements, and this was due to inadequate controls in the Quality Assurance Programs (QAPs) of different stakeholders. It is also important to note that MTR results based on a coupon test may not always reflect the properties of each fitting produced following that process.
The NEB has taken several actions in order to address this potential issue including:
- Issuing industry-wide Safety Advisories
- Issuing Orders to all companies under its jurisdiction
- Commissioning a third party to investigate and write a technical paper on this issue
- Hosting a technical workshop to facilitate broad dialogue between various stakeholders (using the technical paper as a seed document)
In this paper, the authors first review the manufacturing process of Q&T fittings. Then case studies are discussed involving four instances of nonconforming fittings. Lastly the authors propose solutions for different stakeholders to effect improvement in Quality Assurance (QA) of pipeline fittings. The authors also recommended enhancement of applicable clauses in related standards and initiation of several research and development (R&D) projects.
Industry Best Practices for Hot Tap Branch Connections
Authors: Bruce William A. , Etheridge Brad , Gould Melissa , Boring Matt , Fleck Patrick 
Published: November 2018

When faced with an opportunity to install a branch connection using the “hot tapping” technique, pipeline operating companies have a wide variety of choices when it comes to branch connection design and installation practices (e.g., welding procedure options) depending on the application. The objective of a recently-completed joint industry project (JIP) was to develop industry best practices for hot tap branch connections, including a compendium of properly qualified procedures, guidance pertaining to specification of branch connection design for specific applications, and guidance pertaining to related areas of concern for which there was not widespread agreement.
The core group of welding procedures that was developed and qualified for branch groove welds and sleeve fillet welds all involve the use of shielded metal arc welding (SMAW) and conventional low-hydrogen electrodes. There are applications for which other welding processes and consumables have advantages, so procedures for a broader range of applications were also developed and qualified. All of the procedures were qualified in accordance with the requirements of a range of relevant industry codes, including the Twenty-first Edition of API Standard 1104.
The various options for branch connection design include integrally-reinforced fittings (e.g., Weldolets®), fabricated branch connections, and full-encirclement pressurized tees (e.g., Stopple® fittings). Some designs are better suited to some applications than to others. The guidance for specifying branch connection designs focused on geometric parameters, such as branch diameter, header diameter, and branch-to-header diameter ratio. Several antiquated branch connection designs that should no longer be used were also identified.
The related areas of concern for which guidance was developed included the need for sleeve end fillet welds, burnthrough prediction for in-service welding on thin-wall pipelines, pressure limits/pressure reduction requirements, flow rate limits, heat-affected zone (HAZ) hardness limits, welder qualification requirements, branch connection location and fit-up, pipeline support requirements, branch connection welding sequence, preheating for in-service welds, fillet weld size requirements, extent of welding required for integrally-reinforced fittings, inspection/non-destructive testing (NDT) requirements, delay time prior to inspection for hydrogen cracking, pressure testing prior to tapping, and grouting of larger diameter, larger diameter-ratio branch connections. This guidance, along with the branch connection design guidance, was used to develop a generic company specification for installing hot tap branch connections in the field. The use of this guidance and the compendium of properly qualified welding procedures that was developed during the JIP will reduce the cost of installing hot tap branch connections, increase safety during installation, and increase the reliability of completed connections.
An Investigation Into the Benefits of Employing Multiple Assessments Methods for High Risk Pipelines
Authors: McMahan Tara , Graf Eric , Bubenik Thomas 
Published: November 2018

Selecting the appropriate assessment method for a pipeline system requires an understanding of the pipeline segment, the potential threats to the pipeline segment, and the various assessment methods and technologies available along with their performance capabilities. Each assessment method has its own set of advantages and disadvantages depending on the pipeline and threat being assessed.
In most cases, the assessment of a pipeline segment using one method is sufficient for the management of that threat or threats. However, for high risk pipelines (driven by likelihood, consequence, or both), this paper explores the potential benefits of leveraging one or more assessment methods by examining a number of scenarios with a specific focus on the management of cracks within a pipeline segment. It looks at the benefits of multiple assessment methods employed at the same intervals but in varying order.
Development and Experiences of a Circumferential Stress Corrosion Crack Management Program
Authors: Bates Neil , Brimacombe Mark , Polasik Steven 
Published: November 2018

A pipeline operator set out to assess the risk of circumferential stress corrosion cracking and to develop a proactive management program, which included an in-line inspection and repair program. The first step was to screen the total pipeline inventory based on pipe properties and environmental factors to develop a susceptibility assessment. When a pipeline was found to be susceptible, an inspection plan was developed which often included ultrasonic circumferential crack detection in-line inspection and geotechnical analysis of slopes. Next, a methodology was developed to prioritize the anomalies for investigation based on the likelihood of failure using the provided in-line inspection sizing data, crack severity analysis, and correlation to potential causes of axial or bending stress, combined with a consequence assessment. Excavation programs were then developed to target the anomalies that posed the greatest threat to the pipeline system or environment.
This paper summarizes the experiences to date from the operator’s circumferential stress corrosion cracking program and describes how the pipeline properties, geotechnical program, and/or in-line inspection programs were combined to determine the susceptibility of each pipeline and develop excavation programs. In-line inspection reported crack types and sizes compared to field inspection data will be summarized, as well as how the population and severity of circumferential stress corrosion cracking found compares to the susceptible slopes found in the geotechnical program completed. Finally, how the circumferential SCC time-average growth rate distributions were calculated and were used to set future geohazard inspections, in-line inspections, or repair dates will be discussed.
Mechanical Behaviour of Intercritically Reheated Coarse-Grained Heat Affected Zone in High Strength Line Pipe Steels
Authors: Mandal Madhumanti , Poole Warren J. , Garcin Thomas , Militzer Matthias , Collins Laurie 
Published: November 2018

Multipass welding of high strength steels used for fabrication and joining of transmission pipelines presents a number of metallurgical challenges. A key concern is both the strength and toughness of the heat affected zone (HAZ) adjacent to both seam and girth welds. In this work, a systematic study has been conducted on regions of the heat affected zone in the base metal where the first welding pass produces a thermal excursion which results in a coarse-grained heat affected zone (CGHAZ). The subsequent weld pass involves intercritical annealing of this region, i.e. a microstructure associated with intercritically reheated coarse grain heat affected zone (ICCGHAZ). The small ICCGHAZ region is often identified as being particularly susceptible to crack initiation. This work was undertaken to understand microstructure development in this zone and how the ICCGHAZ may affect the overall performance of the HAZ.
Gleeble thermomechanical simulations have been conducted to produce bulk samples representative of different welding scenarios. Charpy impact tests and tensile tests have been performed over a range of temperatures. It was found that when a continuous necklace of martensite-austenite islands form on the prior austenite grain boundaries (i.e. for a M/A fraction of ≈10%), the Charpy impact toughness energy is dramatically decreased and the ductile brittle transition temperature is significantly raised. Detailed studies on the secondary cracks have been conducted to examine the fracture mechanisms in the different microstructures. The results show that the lower bainite microstructures obtained after the 1st thermal treatment, representative of CGHAZ have excellent impact properties. The impact toughness of the microstructures typical of ICCGHAZ is strongly dependent on the composition as well as morphology and spatial distribution of the resulting martensite-austenite (M/A) islands transformed from inter-critically formed austenite. This zone can play a significant role in fracture initiation and thus needs to be considered in alloy and welding process designs.
Advanced EMAT Crack Tool for Unpiggable Pipelines
Authors: Bondurant Phillip , Farrag Khalid , Kannajosyula Haraprasad , Droessler Maureen , Mactutis Tony 
Published: November 2018

This paper presents the development and testing of an Electro-Magnetic Acoustic Transducer (EMAT) sensor prototype to detect and quantify longitudinal cracks in small diameter and difficult to inspect or unpiggable gas pipelines. The development of the system was a collaborative and jointly-funded work between Quest Integrated, Gas Technology Institute, Operations Technology Development, and US DOT, Pipeline Hazardous Material Safety Admin (PHMSA).
The initial focus for the project was to inspect 8-inch (200 mm) diameter pipes with robotic or tethered towing, with the eventual goal of a free-swimming tool. A bench scale lab prototype has been successfully completed and tested in Phase 1 of the project in 2016. The prototype demonstrated the basic approach of a EMAT tool for crack detection and sizing that could be packaged into a single module, had reasonable flaw depth sensitivity, was bidirectional, and could negotiate a 1.5 D bend.
Phase 2 focused on identifying and solving additional implementation issues, developing a more hardened tool for field pull testing, improving flaw sizing, and the necessary internal electronics and processing algorithms. The prototype recently developed in Phase 2 was tested in an extended length of 8-inch diameter steel pipe with pre-set and controlled longitudinal cracks. The results demonstrated the applicability of the integrated prototype in locating and sizing multiple flaws in the axial direction.
This paper discusses the EMAT sensor development and results of the laboratory testing program.