bluuebunny/crossref_metadata_2025 huggingface dataset:
Manufacture and Qualification of Small Diameter / Thickwall Reelable DSAWL Linepipe
Authors: Hall Stephen , Connelly Martin , Alderton Graham , Hill Andrew , Wen Shuwen
Published: November 2016

Tough market conditions have seen the price of oil drop which with the subsequent uncertainty surrounding the industry have seen the oil and gas industry concentrate on reducing the cost of designing, installing and operating pipelines. A critical process for the industry is the procurement, manufacture and installation of appropriate linepipe. The method of installation is often dictated by the pipe size and the water depth that the pipe is to be laid in, however there are times when the choice of lay method is due to vessel availability and relative costs for each technique.

In early 2014, Tata Steel successfully manufactured and delivered 16"OD × 0.875”WT X65 submerged arc welded longitudinal (SAWL) linepipe for installation via the reel lay method. Notable features about this fact were the size, which represents the thickest 16” external diameter UOE pipe yet delivered by Tata Steel, and that this was to be the first UOE pipe to be installed by the reel lay method in the North Sea. The ability to manufacture small diameter thickwall linepipe was only possible due to recent operational developments including an established tooling programme and a fully validated Finite Element (FE) model of the UOE process, along with years of experience of integrating these tools into the manufacturing process.

This paper discusses the manufacturing challenges for small diameter thickwall linepipe, and how with the aid of modelling tools, innovative thinking and previous experience in supplying small diameter thickwall linepipe into two reel-installed projects, the pipe was manufactured and delivered with the properties shown to be compliant with DNV OS-F101 Supplementary Requirement P.
Full-Scale Stress Corrosion Crack Growth Testing of an X70 Spiral-Welded Pipe in Near-Neutral pH Soil Environment
Authors: Kang Jidong , Bibby Darren , Blanchard Romain , Zheng Wenyue
Published: November 2016

Stress corrosion cracking (SCC) in near-neutral pH environment remains a major concern for high pressure pipelines transporting oil and gas in Canada since its first discovery in 1980s. A variety of laboratory experiments and models have been developed to address different aspects of this complex problem. Full-scale pipe SCC testing using soil box that mimics the condition in the field can directly assess crack growth in terms of pressure level, range of pressure fluctuation, soil conditions, etc. This type of test also offers the most direct validation of SCC models.

A state-of-the-art full-scale SCC pipe testing facility has been established at CanmetMATERIALS Hamilton Laboratory. The facility includes a new hydraulic power unit (HPU), an upgraded 500 kN fatigue frame, and a new 2000 psi (14MPa) pressurization system. In addition, a 24-channel direct current potential drop (DCPD) unit has been refurnished for in-situ monitoring of crack growth.

The full-scale pipe SCC testing facility has been successfully used to measure crack growth in an X-70 (Grade 483) large diameter (914 mm or 36” OD) spiral seam-welded pipe. Six axial cracks were made using saw cutting and fatigue pre-cracking in the base metal and across the spiral-weld metal. All cracks were buried under two types of soil boxes with soil obtained from a near-neutral pH SCC pipeline failure site mixed with distilled water or NS4 solution. The pH of the solution was maintained between 6.9 and 7.2 throughout the testing. Several loading conditions were tested and DCPD was used to monitor SCC growth rate during all the tests.

No detectable growth was observed in the cracks of weld area during all the tests mainly due to over-matching strength. Crack growth was also not detected for the base metal until the maximum pressure was raised up to 95% SMYS with R = 0.7. The threshold of the range of stress intensity factor, (ΔK)th for SCC is thus estimated to be between 11.53 to 13.52 MPa m1/2. The measured average crack growth rate was 5.98×10−7 mm/s.
Analysis of a Dense Phase Carbon Dioxide Full-Scale Fracture Propagation Test in 24 Inch Diameter Pipe
Authors: Cosham Andrew , Jones David G. , Armstrong Keith , Allason Daniel , Barnett Julian
Published: November 2016

A third full-scale fracture propagation test has been conducted using a dense phase carbon dioxide (CO2)-rich mixture (approximately 10 mole percent of non-condensables), at the DNV GL Spadeadam Test & Research Centre, Cumbria, UK, on behalf of National Grid, UK.

The first and second tests, in 914 mm (36 inch) outside diameter pipe, also conducted at the Spadeadam Test & Research Centre, showed that predictions made using the Two Curve Model and the (notionally conservative) Wilkowski et al., 1977 correction factor were incorrect and non-conservative. An additional correction was required in order to conservatively predict the results of the two tests.

A third full-scale test was necessary to evaluate the fracture arrest capability of the line pipe for the proposed 610 mm (24 inch) outside diameter Yorkshire and Humber CCS Cross-Country Pipeline, because the predictions of the first and second tests were non-conservative, and it was unclear if and how the results of these tests could be extrapolated to a different diameter and wall thickness.

The third test was designed to be representative of the proposed cross-country pipeline, both in terms of the grade and geometry of the pipe, and the operating conditions.

The test section consisted of seven lengths of pipe: an initiation pipe and then, on either side of the initiation pipe, one transition pipe and two production pipes. The (in total) four production pipes are representative of the type of line pipe that would be used in the proposed cross-country pipeline.

A running ductile fracture was successfully initiated; it propagated through the transition pipes on both sides, and then rapidly arrested in the production pipes. The result of the test demonstrates that a running ductile fracture would arrest in the proposed Yorkshire and Humber CCS Cross-Country Pipeline.

The main experimental data, including the layout of the test section, and the decompression and timing wire data, are summarised and discussed.

Furthermore, the implications of the three tests, in two different pipe geometries, for setting toughness requirements for pipelines transporting CO2-rich mixtures in the dense phase are considered.
Leak Detection and Operations Management in Offshore Pipelines
Authors: Zhang Jun , Kane Adrian
Published: November 2016

This paper will demonstrate that with limited instruments at the terminals and platforms only, it is feasible to monitor the integrity of offshore pipelines effectively. Some examples of applications will be shown, including both crude oil and natural gas pipelines.

The statistical volume balance technology based on flow and pressure measurements at the inlets and outlets only provides the detection and location of leaks. The paper describes the performance of these leak detection systems for incidents ranging from small leaks to pipeline rupture.

To help operators run pipelines safely and cost effectively, real-time transient models are used to calculate the flow, pressure, temperature, density and other fluid properties along the pipeline. Instead of using measured flow and pressure, the operators rely on these calculated values to take operational decisions. The combination of hydraulic modelling and statistical leak detection provides the operators with the information and confidence in the integrity of their pipelines. In the event of any incident the operators can take actions quickly and correctly to minimize the consequences.
Development and Implementation of a Risk Based Prioritization Methodology for MAOP Reconfirmation of Gas Transmission Facilities
Authors: Sloterdijk Wytze , Hommes Martin , Coster Roelof , Rovella Troy , Herbison Sarah
Published: November 2016

As part of Pacific Gas and Electric Company’s (PG&E) on-going commitment to public safety, the company has begun a comprehensive engineering validation of its gas transmission facilities that will ultimately support the reconfirmation of maximum allowable operating pressure (MAOP) for these assets.

In addition to 6,750 miles of line pipe, PG&E’s gas transmission system contains over 500 station facilities. Since this set of facilities is not only large but diverse, and the validation effort for these facilities is expected to be an extensive, multi-year process, a methodology for the prioritization of the facilities needed to be developed to facilitate planning of the process for the efficient mitigation of risk. As a result, DNV GL was retained to develop and implement a risk-based prioritization methodology to prioritize PG&E’s gas transmission facilities for the engineering validation and MAOP reconfirmation effort. Ultimately, a weighted multiple criteria decision analysis (MCDA) approach was selected and implemented to generate the prioritization.

This MCDA approach consisted of the selection of relevant criteria (threats) and the weighting of these criteria according to their relative significance to PG&E’s facilities. Relevant criteria selected for inclusion in the analysis include factors that are important in order to assess both the short- and long-term integrity of the facility as a whole as well as the integrity of features for which design records cannot be located. The criteria selected encompass stable threats, time-dependent threats, as well as environmental impact. Enormous amounts of data related to design, operations, maintenance history and meteorological and seismic activity in addition to other environmental data were evaluated with this newly developed methodology to assess the relative risks of the facilities. Pilot field visits were performed to validate the selection of the various criteria and to confirm the outcome of the analysis.

The novelty of this approach lies in the prioritization of facilities in a coherent risk-based manner. The described approach can be used by operators of oil and gas facilities, either upstream, midstream or downstream.
Development of Key Performance Indicator for Management of Under Deposit Corrosion (UDC)
Authors: Garcia Alfonso , Place Trevor , Wood Stephen
Published: November 2016

Hydrocarbons transported in transmission pipelines contain solid particles with micro-attached water. Subjected to flow conditions, these particles may have sufficient density to reach the pipe floor and enable bacteria growth and local Under-Deposit Corrosion (UDC), with this form of corrosion being one of the principal threats to the integrity of oil and gas transmission pipelines. NACE International has published a variety of UDC related standard practices to manage corrosion in the oil industry such NACE 61114, but few of them are representative of, or applicable to, low water cut hydrocarbon transmission pipelines. Further, there are presently no industry recognized key performance indicators (KPIs) suitable for managing UDC in low water cut hydrocarbon transmission pipelines.

Enbridge (the “Company”) operates North America’s largest interconnected liquid hydrocarbon transmission pipeline network. For the purposes of this paper, when the word ‘transmission’ is used to modify ‘crude oil’, ‘hydrocarbons’, or ‘pipelines’, it implies medium to long distance transport (100’s to 1000’s of km) as well as clean, “refinery-ready” crude oil (oil containing less than 0.5% sediment and water). This quality of oil renders it generally non-corrosive at pipeline operating conditions. However, if water wet particulates accumulate on the pipe floor, it can lead to UDC. The Company collects sludge samples produced during pigging operations on a regular basis to establish the composition of these materials and quantify bacterial population/activity. These solids represent an amalgamation of material removed from the pipe floor, and thus can be used as an indicator of the UDC threat in the pipeline. This paper builds upon previous work of the Company [1] by considering a larger data set in order to generate a more meaningful assessment of bacteria population/activity and provide better correlations with crystalline compounds, water content and elements found in the sludge.

This paper presents these data and associated statistical analysis, and proposes KPIs for evaluating the UDC threat based on numerous variables, including in-line inspection Magnetic Flux Leak (MFL) data (through signal to signal corrosion growth rates), sludge analysis, flow conditions and pipeline operation; this paper also suggests mitigation activities and intervals relative to these KPIs.

Personnel involved in pipeline integrity management (e.g. field operations, technical and management staff) may find the concepts, strategies and correlations presented herein to be useful in developing their own UDC management programs.
Analysis of Pressure Test Failure Performance for Vintage Pipe
Authors: Chen Jenny Jing , Williams Dan , Leewis Keith , Aguiar David
Published: November 2016

Systemic manufacturing defects in select vintage pipe pose challenges when assessing the integrity of pipeline systems comprised of such pipe. The common manufacturing technology and quality control practices in place at the time of manufacturing left some vintage line pipe prone to imperfections which could remain even after passing pressure tests in the mill or after construction. The lack of complete and reliable manufacturing records for some vintage line pipe limits granularity and adds integrity assessment uncertainties.

Up until 1984, the United States Department of Transportation (USDOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) required operators to report incidents related to failed pressure tests for all pipelines at the time of installation. Performance with respect to the manufacturer and year of manufacture can therefore be extracted from these reported incidents. These performance records are essential when re-establishing the MAOP (or MOP) and confirming the fitness for service of older pipelines. The pressure test failure performance in the early incident records provides insight into pipeline integrity prioritization and mitigation activities for managing pipeline safety based on pipe manufacturer, production date and seam type.
Identification of Repair Coatings on Pipelines Using In-Line Inspection Technologies
Authors: Greig Andrew , Grillenberger Jörg
Published: November 2016

One of the major issues in the pipeline industry is coating disbondment. A very large percentage of external corrosion and SCC is observed under disbonded coatings that shield Cathodic Protection (CP). This has been an ongoing issue with coated and cathodic protected pipelines since the initial use of these two protection methods. The various coating types and their typical failure scenarios, under various harsh environmental conditions, as well as their compatibility with cathodic protection when disbondment occurs, play a major role for recoating programs and selection of the coating type used for repairs and re-coating programs.

With the continued development and improvements of the “Electro-Magnetic Acoustic Transducer” (EMAT) in line inspection technology it is possible to locate disbonded coatings, without the need of exposing the pipeline. This way operators can assess the condition of the coatings applied to their pipeline systems at a comparable low cost. Inline inspection tools equipped with the “EMAT” technology are also capable of identifying the various coating types and coating conditions.1 The coating type identification process is not limited to coating types applied to whole joints. Field applied coatings covering the girth weld area or coating changes within a joint such as repairs can be identified as well. In the presented case study, the challenge was the identification of different coating types used as repairs or for re-coating procedures, within the 60 year history of the inspected pipeline system. At the beginning of the project the main coating types and obvious repairs were identified based on EMAT in line inspection data. In a combined effort, operator and in line inspection vendor compared the initially identified coating types with the known repair history of this pipeline system. Based on this shared combined information the coating type analysis could be finetuned and additional areas could be identified as repaired or re-coated.

The paper will outline different coating repair methods described by the operator and subsequently identified by the EMAT tool. This paper will also describe for each coating repair method the associated risks for the pipeline integrity.
Backfilling Onshore Abandoned Pipelines With Paste
Authors: Longo Sue , Cull Joshua
Published: November 2016

According to the 2015 AER database there are approximately 473,000 km of high pressure pipelines in Alberta alone, ∼93,000 km of which have been discontinued. Of these 93,000 km of discontinued lines approximately half have been abandoned. When a pipeline is abandoned it is typically flushed out, marked and has all corrosion protection and monitoring systems removed.

In the absence of corrosion protection all pipelines will inevitably corrode. This can create long term issues for abandoned pipelines. Two of the critical issues are potential ground subsidence and the creation of unintended water conduits. Ground subsidence is caused when an abandoned pipeline corrodes to the point of allowing the surrounding soil to fall into the empty pipe. Ground stability issues can result depending on the size and depth of the pipeline. Stability issues can appear suddenly in the form of sinkholes, slow slumping troughs or cracks in the earth and anything in between. Regarding unintended water conduits the main concern centres on a pipeline under or near water crossings or in areas of saturated soil. The pipeline corrosion can eventually provide a mechanism for water (or other constituents) to enter and migrate through the empty pipe and then be discharged further down the line. This uncontrolled migration can potentially have environmental impacts depending on what gets transported and where it ends up being discharged.

One common industry method to protect abandoned lines from the issues described above is to backfill them with foam or grout. Backfilling areas of abandoned lines can help protect against ground instability and subsidence as the line corrodes away. Creating plugs or cutting/capping abandoned pipelines can protect against the possibility of water conduits. The use of paste technology is not common to the industry in this regard however it can provide many benefits over current foams and grouts. This paper will discuss paste technology and it use as a backfill option for pipeline abandonment.
Modeling Conflicts and Batch Quality Impacts in Pipeline and Crude Oil Storage Terminal
Authors: Juergensen Birgit , Ewanicke Ivan , Xi Thomas
Published: November 2016

The problem of identifying and forecasting potential scheduling conflicts and the impact to quality and delivery targets is a very real and complex problem. The most effective way to meet the above business objective is to develop a terminal simulation model that combines elements of a mass balance system (MBS), operational rules/procedures and operator behavioral patterns.

This paper is a case study describing the approach in designing a detailed pipeline tank terminal simulation model with an objective to identify and quantify complex and possibly unresolvable operating conflicts/events occurring given a current pipeline, tank or terminal configuration and then comparing this with other configuration options. In addition, the model will be able to measure quality impacts (measured by quantifying the volume of degraded product) that results from resolving the operating conflicts for each evaluated configuration.

We will demonstrate how the resultant model allows a terminal operator to effectively understand quality impacts to batches delivered through the pipeline tank terminal as a function of operational procedures and system configuration changes.
Determination of Brittle-to-Ductile Transition Temperatures of Large-Diameter TMCP Linepipe Steel With High Charpy Energy by Use of Modified West Jefferson Testing
Authors: Hioe Y. , Wilkowski G. , Fishman M. , Myers M.
Published: November 2016

In this paper the results will be presented for burst tests from a Joint Industry Project (JIP) on “Validation of Drop Weight Tear Test (DWTT) Methods for Brittle Fracture Control in Modern Line-Pipe Steels by Burst Testing”. The JIP members for this project were: JFE Steel as founding member, ArcelorMittal, CNPC, Dillinger, NSSMC, POSCO, Tenaris, and Tokyo Gas.

Two modified West Jefferson (partial gas) pipe burst tests were conducted to assess the brittle-to-ductile transition temperature and brittle fracture arrestability of two 48-inch diameter by 24.6-mm thick X65 TMCP line-pipe steels. These steels had very high Charpy energy (350J and 400J) which is typical of many modern line-pipe steels. In standard pressed-notch DWTT specimen tests, these materials exhibited abnormal fracture appearance (ductile fracture from the pressed notch prior to brittle fracture starting) that occurs with many high Charpy energy steels. Such behavior makes the transition temperature difficult to determine.

The shear area values versus temperature results for these two burst tests compared to various modified DWTT specimens are shown. Different rating methodologies; DNV, API, and a Best-Estimate of steady-state fracture propagation appearance were evaluated.
Casing and Inserted Pipe Inspection Program on the San Francisco Peninsula Using Robotic ILI
Authors: Liddicoat Robert , Janvier Jeffrey
Published: November 2016

Pacific Gas & Electric Company (PG&E) operates multiple gas transmission pipelines on the San Francisco Peninsula, a significant portion of which operate at low Maximum Allowable Operating Pressure (MAOP), typically below 300 psig and are challenging to inspect using traditional ILI technology. This paper describes PG&E’s use of Non-Traditional robotic ILI technology to inspect numerous cased pipelines located in High Consequence Areas in the highly populated and dense urban area between the San Francisco International Airport (SFO) and central San Francisco. Examples will be provided for pipeline segments installed in various casing types, including sections inserted through utility infrastructure that was made available for use as a gas pipeline casing. Examples include pipe that was installed in the 1940’s and cased pipe installed without corrosion test stations. In some instances, the length of cased pipe sections were several hundred feet long and traversed locations difficult to access, such as major highway crossings and cased spans above water crossings. These inspections were executed in 2015 on 24 separate pipeline segments totaling more than 12,000 feet of pipeline. This paper explains how the inspection team utilized current technology and identified Non-Traditional ILI (NT ILI) as the preferred method. It also explains how the locations were scoped, project parameters and program strategy were developed, NT ILI tool selection, project outcomes, and lessons learned. An overview of the advantages of NT ILI methods to perform these cased pipeline inspections in-lieu of External Corrosion Direct Assessment (ECDA) and Traditional ILI will be discussed. This paper is applicable to Track 3 (Pipelines & Facilities Integrity) and also to Track 2 (Project Management, Design, Construction & Environmental Issues), and will be of interest to Pipeline Operators, Integrity Management Engineers, and Project Managers. The intent is to share PG&E’s experience utilizing Non-Traditional robotic ILI tools to perform difficult pipeline inspections in casings, as well as practical advice on scoping, planning, and execution of non-traditional ILI projects.
Technical and Operational Guidelines When Using Strain Gauges to Monitor Pipelines in Slow Moving Landslides
Authors: Dewar Douglas , Tong Andy , McClarty Edward , Van Boven Greg
Published: November 2016

Vibrating wire (VW) strain gauges have been used by the pipeline industry for over 50 years as part of landslide hazard management programs. This paper provides technical and operational guidelines for the use of these strain gauges based on 20 years of experience managing active but slow moving landslides. Guidelines are provided for the use of strain gauges during 1) routine monitoring 2) cut outs and 3) strain relief. Examples of expected strain gauge responses are provided along with technical considerations for interpreting data. Given the relatively small size of the gauges in relation to the length of pipeline within most landslides, techniques are provided to best locate the gauges including the use of 1) visual/on-site geotechnical assessments, 2) geotechnical monitoring technologies and 3) smart pigging technologies (caliper, IMU and axial strain technologies). Limitations, reliability, and alternatives to VW gauges are also discussed.
Retarding Crack Growth by Static Pressure Hold for Pipeline Steel Exposed to a Near-Neutral pH Environment
Authors: Yu Mengshan , Chen Weixing , Chevil Karina , Van Boven Greg , Been Jenny
Published: November 2016

From extensive investigations for over 30 years since the discovery of near-neutral pH stress corrosion cracking (NNpHSCC), the physical processes of crack initiation and growth have been determined, despite that some details in various aspects of crack initiation and growth are still to be understood. The growth curve is a function of crack growth by direct dissolution of steels at localized areas on pipe surface during initiation or at the tip of a crack during early stage of crack growth (the dissolution growth curve), and by a process involving the interaction of fatigue and hydrogen embrittlement (corrosion fatigue, the hydrogen enhanced fatigue growth curve) in Stage II after crack initiation and early stage of crack growth. For the latter case, recent research shows that crack growth rate can be substantially enhanced by variable amplitude cyclic loading. One of the most severe scenarios of cyclic loading in terms of crack growth rate is the underload type of pressure fluctuations that is often found within 30 km downstream of a compressor station. This investigation is aimed to evaluate pressure scenarios that could reduce or retard crack growth during pipeline operation. Specifically, the effect of pressure holds was investigated. Different periods of static hold were performed to an X65 pipeline steel exposed to a near-neutral pH solution. It was found that a static hold at the maximum load for one hour immediately after a large depressurization-repressurization cycle (underload cycle) yielded the lowest crack growth rate, which was about one third of that of constant amplitude fatigue without the static hold. Static holds for a period shorter or longer than one hour have yielded higher crack growth rates. This observation can be applied to field pipelines during operations to retard crack propagation.
Application of Load Sequence to Control Crack Growth in Steel Pipelines Under Near Neutral pH SCC
Authors: Tehinse Olayinka , Chen Weixing , Been Jenny , Chevil Karina , Keane Sean , Van Boven Greg
Published: November 2016

Pipelines are designed to operate below a maximum operating pressure in service. However, there are pressure fluctuations during operation. The presence of pressure fluctuations creates a drive for crack growth in steel pipes. In order to prevent catastrophic failure of pipelines, there is need for better understanding of the contribution of pressure fluctuations to crack growth rate in steel pipelines. Analysis of pressure fluctuation data in oil and gas pipelines shows that there are different types of fluctuations in a pipe due to friction loss with distance from the pump or compressor station. All these fluctuation types show a form of variable amplitude loading classified in this research as underload, mean load and overload. Studies of some structural systems shows that underload can cause acceleration of crack growth while retardation of crack growth is observed after an overload. This research aims to apply pressure fluctuations to manage integrity of steel pipelines through a novel approach of load sequence involving underload and overload in near neutral pH environment. Clear knowledge of the effect of load interaction involving load sequence of underload and overload is vital to control crack growth in steel pipelines under near neutral pH environment. The result of crack growth rate under different load sequence on X65 steel indicate that increase in overload ratio of 2, 3 and 4 caused an increase in crack growth rate of 1.68E−3, 1.89E−3 and 2.31E−3 mm/block respectively. These results are compared with results from other tests under variable amplitude without load sequence. Analyses were carried out on the morphology of the crack tip and the fracture surface after the test.
The Use of Hydrotesting and EMAT Inline Inspection Technology for the Integrity Management of Stress Corrosion Cracking (SCC) in Gas Pipelines
Authors: Hryciuk Pedro M. , Carzoglio Eduardo , Minellono Jose A. , Martinetto Leonardo , Guillen Pedro M. , Grillenberger Joerg
Published: November 2016

This paper describes the activities and stages completed as part of the Integrity Management Program for SCC in the natural gas system of Transportadora de Gas del Norte (TGN-Argentina) which started in 2000. This document focuses in a pipeline section of the system, which suffered an in-service failure in 2002 due to high pH SCC.

This event triggered a series of activities, whose results are detailed in this paper. These activities involved soil analysis to determine the susceptibility to develop SCC along the system pipelines. For susceptible sections, the program included hydrostatic testing to levels of 100% and 110% of SMYS followed by replacement of degraded coating.

The paper also details the experience in the use of new internal inspection tools with EMAT technology. The capability of the EMAT tool to detect and size SCC defects and the possibility of discriminating between SCC colonies that have been recoated and those that may still be active due to degraded coating is discussed. Finally, the severity of SCC cracks detected by in-line inspection is assessed using API 579 methodology, and the feasibility of using this assessment results to determine the critical SCC defect sizes for detection by ILI tools is analyzed.
Methane Detectors Challenge: Low-Cost Continuous Emissions Monitoring
Authors: Siebenaler Shane P. , Janka Adam M. , Lyon David , Edlebeck John P. , Nowlan Aileen E.
Published: November 2016

Natural gas leakage from unmanned facilities, such as compressor stations, gathering sites, and block valve locations, can pose significant economic and safety impacts. Additionally, methane, the primary constituent of natural gas, is a powerful greenhouse gas with 84 times the global warming potential of carbon dioxide on a mass basis over a 20-year period (IPCC 2013). Due to the remote location of many of these facilities, fluid leaks can persist for extended periods of time. Continuous leak detection systems would facilitate rapid identification and repair of leaks. However, existing technologies, such as infrared cameras, are cost-prohibitive to be installed at a high number of sites and are instead used in periodic monitoring as part of leak detection and repair programs. Such periodic monitoring does not provide for quick detection of “fat tail” leaks that dominate the emissions from gathering and transportation systems (Mitchell et al. 2015, Subramanian et al. 2015).

A unique and innovative arrangement of various stakeholders was utilized to initiate a technology development and testing program aimed at expedited deployment of low-cost technologies at high numbers of sites. The technologies targeted for this work were low enough in cost to economically justify the installation of such sensors at every gas gathering and transportation site. This work was driven by an environmental advocacy organization under a partnership with eight different oil and gas companies and technical oversight from various universities, non-profits, and government agencies to give a wide perspective on the needs of such technology.

Four different technologies were developed and tested in realistic release environments. The technologies ranged from sensors modified from automobile-based technology to laser-based systems used for monitoring gases in coal mines. The systems were treated as “end-to-end” units whereby all components (e.g., sensor, data acquisition, enclosures, etc.) needed to perform according to the provided specifications. The testing involved controlled releases under numerous environmental conditions and with different gas compositions. The largest focus of the testing was on outdoor releases where the systems had to detect the transient nature of gas plumes.

The primary objectives of the testing were to determine the readiness of the technologies for pilot testing in the field and identify continuous improvement opportunities. The project demonstrated that there are newly-developed technologies that could be deployed as low-cost continuous monitoring solutions for the gas industry.
Characterization of Al2O3 and ZnO multilayer thin films deposited by low temperature thermal atomic layer deposition on transparent polyimide
Authors: Song Seung Hak , Lee Myoung Youb , Lee Gyeong Beom , Choi Byoung-Ho
Published: November 2016

Recently, flexible and stretchable displays with organic light emitting diodes are one of hottest technical issues in electronic industries. Therefore, the application of polymer substrates is required because current glass-based materials cannot meet the required properties of flexible and stretchable displays. But there are some limitations for using polymers in display substrate such as inferior surface characteristics such as low scratch resistance, low hardness, and so on. Polymers have many additional technical issues like low stiffness, low heat resistance, low barrier properties, and high sensitivity to degradation compared with glass material. The low temperature atomic layer deposition (ALD) can be a good solution as a functional coating on the polymer substrate to resolve such surface characteristic issues. In this study, two oxide thin films, i.e., Al2O3 and ZnO, are deposited on a transparent polyimide (TPI) film substrate using a low temperature thermal ALD technique. To fabricate a reliable and high quality thin film, the pretreatment using O2 plasma was conducted on the surface of TPI. Two oxide thin films are deposited as multilayer thin films by layer-by-layer process to investigate the effect of multilayer deposition of oxide thin films on mechanical properties. Surface morphologies of the deposited thin films are observed using optical microscopy and scanning electron microscope. Chemical characteristics of the deposited thin film are analyzed using x-ray photoelectron spectroscopy. The physical and mechanical characteristics of the Al2O3 and ZnO multilayer thin film are investigated using nanoindentation and microtensile tests.
Kirchhoff approximation for backscattering from a partially exposed rigid sphere at a flat interface
Authors: Gunderson Aaron M. , Marston Philip L.
Published: November 2016

The Kirchhoff approximation (KA) is used to model backscatter of sound from a partially exposed, rigid sphere at a flat free interface of two homogenous media. Scattered wavefields are calculated through numerical integration on the sphere of the Kirchhoff integral, requiring detailed knowledge of the illuminated region for each scattering path. This approach avoids amplitude discontinuities resulting from geometric transitions in the number of reflected rays. Reflections from the interface are modeled through use of an image source, positioned symmetrically relative to the real source. Results are compared to experimentally obtained backscattering records from elastic spheres at an air–water interface, as well as to an exact partial wave series for a half exposed sphere. These comparisons highlight the omission of Franz-type reflections from consideration within the KA, and the consequences of this omission are discussed. The results can be extended to boundary conditions beyond the ideal free surface limit, and are applicable to the problem of scattering by underwater objects partially buried in sand.
Serum Bactericidal Antibody Responses of Adults Immunized with the MenB-4C Vaccine against Genetically Diverse Serogroup B Meningococci
Authors: Giuntini Serena , Lujan Eduardo , Gibani Malick M. , Dold Christina , Rollier Christine S. , Pollard Andrew J. , Granoff Dan M.
Published: November 2016

MenB-4C is a meningococcal vaccine for the prevention of serogroup B disease. The vaccine contains factor H binding protein (FHbp) and three other antigens that can elicit serum bactericidal antibodies (SBA). For vaccine licensure, efficacy was inferred from the SBA responses against three antigen-specific indicator strains. The relation between those results and broad protection against circulating genetically diverse strains is not known. Twenty adults were immunized with two doses of MenB-4C given 1 to 2 months apart. SBA activity against 3 reference strains and 15 serogroup B test strains (6 from college outbreaks) was measured. Compared to the preimmunization titers, 70%, 95%, and 95% of subjects had ≥4-fold increases in the titers of anti-PorA P1.4, anti-NadA, and anti-FHbp antibodies against the reference strains, respectively. In contrast, only 25 to 45% of the subjects had ≥4-fold increases in responses to 10 of the 15 test strains, including 8 that expressed one to three of the antigens in the vaccine. At 1 month, the majority of subjects with <4-fold titer increases had serum titers of ≥1:4, which are considered sufficient for protection. However, the titers against four strains declined to <1:4 by 4 to 6 months in one-third to greater than 50% of the subjects tested. Clinically relevant isolates are often more resistant to SBA than the indicator strains used to measure antigen-specific SBA. A working model is that the percentage of subjects with titers of ≥1:4 at 1 month postimmunization correlates with short-term protection against that strain, whereas the percentage of subjects with ≥4-fold titer increases represents a more robust response. (The protocol used at the Oxford Vaccine Group has been registered at ClinicalTrials.gov under registration no. NCT02398396.)
Biotinylation in vivo as a sensitive indicator of protein secretion and membrane protein insertion
Authors: Jander G , Cronan J E , Beckwith J
Published: November 2016

Escherichia coli biotin ligase is a cytoplasmic protein which specifically biotinylates the biotin-accepting domains from a variety of organisms. This in vivo biotinylation can be used as a sensitive signal to study protein secretion and membrane protein insertion. When the biotin-accepting domain from the 1.3S subunit of Propionibacterium shermanii transcarboxylase (PSBT) is translationally fused to the periplasmic proteins alkaline phosphatase and maltose-binding protein, there is little or no biotinylation of PSBT in wild-type E. coli. Inhibition of SecA with sodium azide and mutations in SecB, SecD, and SecF, all of which slow down protein secretion, result in biotinylation of PSBT. When PSBT is fused to the E. coli inner membrane protein MalF, it acts as a topological marker: fusions to cytoplasmic domains of MalF are biotinylated, and fusions to periplasmic domains are generally not biotinylated. If SecA is inhibited by sodium azide or if the SecE in the cell is depleted, then the insertion of the MalF second periplasmic domain is slowed down enough that PSBT fusions in this part of the protein become biotinylated. Compared with other protein fusions that have been used to study protein translocation, PSBT fusions have the advantage that they can be used to study the rate of the insertion process.
Growth suppression in early-stationary-phase nutrient broth cultures of Salmonella typhimurium and Escherichia coli is genus specific and not regulated by sigma S
Authors: Barrow P A , Lovell M A , Barber L Z
Published: November 2016

We have studied the growth suppression seen in early-stationary-phase LB broth cultures of Salmonella typhimurium. Multiplication of small numbers of an antibiotic-resistant S. typhimurium mutant was prevented when the mutant was added to 24-h cultures of the antibiotic-sensitive parent strain, whereas an antibiotic-resistant mutant of an Escherichia coli strain added to the same culture grew well. A 24-h E. coli culture produced a similar specific bacteriostatic inhibition against E. coli. In older cultures, a specific bactericidal effect similar to that observed by M. M. Zambrano and R. Kolter (J. Bacteriol. 175:5642-5647, 1993) was also observed. Whether incubated statically or shaken, sufficient nutrients were present in the filtered supernatants of 24-h cultures for small inocula of the same strain to multiply to ca. 10(9) CFU/ml after reincubation. Introduction of the rpoS mutation had no effect on the specific bacteriostatic inhibition. Similar specific inhibition was also observed in strains of Citrobacter freundii, Klebsiella pneumoniae, Enterobacter agglomerans, and Shigella spp. Experiments in which the 24-h culture was physically separated from the antibiotic-resistant mutant by using a dialysis membrane were carried out. These results indicated that the inhibition might be mediated by a diffusible but labile chemical mediator.
Modeling and measuring the elastic properties of an archaeal surface, the sheath of Methanospirillum hungatei, and the implication of methane production
Authors: Xu W , Mulhern P J , Blackford B L , Jericho M H , Firtel M , Beveridge T J
Published: November 2016

We describe a technique for probing the elastic properties of biological membranes by using an atomic force microscope (AFM) tip to press the biological material into a groove in a solid surface. A simple model is developed to relate the applied force and observed depression distance to the elastic modulus of the material. A measurement on the proteinaceous sheath of the archaebacterium Methanospirillum hungatei GP1 gave a Young's modulus of 2 x 10(10) to 4 x 10(10) N/m2. The measurements suggested that the maximum sustainable tension in the sheath was 3.5 to 5 N/m. This finding implied a maximum possible internal pressure for the bacterium of between 300 and 400 atm. Since the cell membrane and S-layer (wall) which surround each cell should be freely permeable to methane and since we demonstrate that the sheath undergoes creep (expansion) with pressure increase, it is possible that the sheath acts as a pressure regulator by stretching, allowing the gas to escape only after a certain pressure is reached. This creep would increase the permeability of the sheath to diffusible substances.
Regulatory proteins and cis-acting elements involved in the transcriptional control of Rhizobium etli reiterated nifH genes
Authors: Valderrama B , Dávalos A , Girard L , Morett E , Mora J
Published: November 2016

In Rhizobium etli the nitrogenase reductase genes are reiterated. Strain CE3 has three copies; nifHa and nifHb form part of nifHDK operons with the nitrogenase structural genes, while nifHc is linked to a truncated nifD homolog. Their sequences are identical up to 6 residues upstream from a sigma54-dependent promoter. A remarkable difference among them is the absence of canonical NifA binding sites upstream of nifHc while a canonical binding site is located 200 bp upstream of nifHa and nifHb. To evaluate the transcriptional regulation of the reiterated nifH genes, we constructed fusions of nifHa and nifHc with the lacZ gene of Escherichia coli. Both genes were expressed at maximum levels under 1% oxygen in free-living cultures, and their expression declined as the oxygen concentration was increased. This expression was dependent on the integrity of nifA, and nifHc was expressed at higher levels than nifHa. The same pattern was observed with root nodule bacteroids. Expression of both genes in E. coli required sigma54 in addition to NifA bound to the upstream activator sequence. In vivo dimethyl sulfate footprinting analyses showed that NifA binds to the canonical site upstream of nifHa and to a TGT half-site 6 nucleotides further upstream. NifA protected an imperfect binding site upstream of nijHc at position 85 from the promoter. The integration host factor stimulated each gene differently, nifHa being more dependent on this protein. The above results correlate the asymmetric arrangement of cis-acting elements with a differential expression of the reiterated nifH genes, both in culture and during symbiosis with bean plants.
The Agrobacterium tumefaciens VirB7 lipoprotein is required for stabilization of VirB proteins during assembly of the T-complex transport apparatus
Authors: Fernandez D , Spudich G M , Zhou X R , Christie P J
Published: November 2016

The Agrobacterium tumefaciens virB7 gene product is a lipoprotein whose function is required for the transmission of oncogenic T-DNA to susceptible plant cells. Three lines of study provided evidence that VirB7 interacts with and stabilizes other VirB proteins during the assembly of the putative T-complex transport apparatus. First, a precise deletion of virB7 from the pTiA6NC plasmid of wild-type strain A348 was correlated with significant reductions in the steady-state levels of several VirB proteins, including VirB4, VirB9, VirB10, and VirB11; trans expression of virB7 in the delta virB7 mutant partially restored the levels of these proteins, and trans coexpression of virB7 and virB8 fully restored the levels of these proteins to wild-type levels. Second, modulation of VirB7 levels resulted in corresponding changes in the levels of other VirB proteins in the following cell types: (i) a delta virB7 mutant expressing virB7 and virB8 from isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible Plac and other virB genes from acetosyringone (AS)-inducible PvirB; (ii) a delta virB operon mutant expressing virB7 and virB8 from Plac and virB9, virB10, and virB11 from PvirB; and (iii) a delta virB operon mutant expressing virB7 from IPTG-inducible Pklac and virB9 from an AS-inducible PvirB. Third, the synthesis of a VirB7::PhoA fusion protein in strain A348 was correlated with a significant reduction in the steady-state levels of VirB4, VirB5, and VirB7 through VirB11; these cells also exhibited a severely attenuated virulence phenotype, indicating that synthesis of the fusion protein perturbs the assembly of VirB proteins into a stabilized protein complex required for T-complex transport. Extracts of AS-induced cells electrophoresed under nonreducing conditions possessed undetectable levels of the 32-kDa VirB9 and 4.5-kDa VirB7 monomers and instead possessed a 36-kDa complex that cross-reacted with both VirB7 and VirB9 antisera and accumulated as a function of virB7 expression. Our results are consistent with a model in which VirB7 stabilizes VirB9 by formation of a covalent intermolecular cross-link; in turn, the VirB7-VirB9 heterodimer promotes the assembly of a functional T-complex transport machinery.