bluuebunny/crossref_metadata_2025 huggingface dataset:
Best practices for veterinary toxicologic clinical pathology, with emphasis on the pharmaceutical and biotechnology industries
Authors: Tomlinson Lindsay , Boone Laura I. , Ramaiah Lila , Penraat Kelley A. , von Beust Barbara R. , Ameri Mehrdad , Poitout‐Belissent Florence M. , Weingand Kurt , Workman Heather C. , Aulbach Adam D. , Meyer Dennis J. , Brown Diane E. , MacNeill Amy L. , Bolliger Anne Provencher , Bounous Denise I.
Published: July 2013

The purpose of this paper by the Regulatory Affairs Committee (RAC) of the American Society for Veterinary Clinical Pathology (ASVCP) is to review the current regulatory guidances (eg, guidelines) and published recommendations for best practices in veterinary toxicologic clinical pathology, particularly in the pharmaceutical and biotechnology industries, and to utilize the combined experience of ASVCP RAC to provide updated recommendations. Discussion points include (1) instrumentation, validation, and sample collection, (2) routine laboratory variables, (3) cytologic laboratory variables, (4) data interpretation and reporting (including peer review, reference intervals and statistics), and (5) roles and responsibilities of clinical pathologists and laboratory personnel. Revision and improvement of current practices should be in alignment with evolving regulatory guidance documents, new technology, and expanding understanding and utility of clinical pathology. These recommendations provide a contemporary guide for the refinement of veterinary toxicologic clinical pathology best practices.
Jet-Penetration in Prechamber-Ignited Lean Large-Bore Natural Gas Engines
Authors: Kammerstätter S. , Bauer S. , Sattelmayer T.
Published: July 2013

Combustion in lean large-bore natural gas engines is usually initiated by gas-scavenged prechambers. The hot reacting products of the combustion in the prechamber penetrate the main chamber as reacting jets, providing high ignition energy for the lean main chamber charge. The shape and intensity of the reaction zone in these jets are the key elements for efficient ignition and heat release in the main chamber. The influence of geometrical and operational parameters on the reaction during jet penetration was investigated in detail. As the periodically chargeable high pressure combustion cell used in the study provides full optical access to the entire main chamber the evolution of the spatial distribution of the reaction zones was investigated in terms of OH*-chemiluminescence. As jet penetration is a very fast and highly transient process the emission of OH* was recorded at a frequency of f = 30000 Hz. The macroscopic reaction zone parameters in the jet region (penetration length and angle, reacting area and light emission) reveal the influence of orifice size and prechamber gas injection on the heat release in the shear layer between the jet and the lean charge in the main chamber. In addition, the influence of the development of the reaction in these zones on the ignition probability and the main chamber pressure rise is shown. With an appropriate selection of the combination of the prechamber orifice geometry and the operating parameters significant improvements of ignition probability and heat release in the main chamber were obtained.
The Low Load Limit of Gasoline Partially Premixed Combustion Using Negative Valve Overlap
Authors: Borgqvist Patrick , Andersson Öivind , Tunestål Per , Johansson Bengt
Published: July 2013

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions.

The objective is to investigate different multiple-injection strategies in order to further expand the low load limit and reduce the dependency on negative valve overlap in order to increase efficiency. The question is, what is the minimum attainable load for a given setting of negative valve overlap and fuel injection strategy. The experimental engine is a light duty diesel engine equipped with a fully flexible valve train system. The engine is run without boost at engine speed 800 rpm. The fuel is 87 RON gasoline.

A turbocharger is typically used to increase the boost pressure, but at low engine speed and load the available boost is expected to be limited. The in-cylinder pressure and temperature around top-dead-center will then be too low to ignite high octane number fuels. A negative valve overlap can be used to extend the low engine speed and load operating region. But one of the problems with negative valve overlap is the decrease in gas-exchange efficiency due to heat-losses from recompression of the residual gases. Also, the potential temperature increase from the trapped hot residual gases is limited at low load due to the low exhaust gas temperature. In order to expand the low load operating region further, more advanced injection strategies are investigated.
Methyl Oleate Evaluation as a Model Fuel for Peanuts FAME, in an Indirect Injection Diesel Engine
Authors: Soloiu Valentin , Weaver Jabeous , Duggan Marvin , Ochieng Henry , Vlcek Brian , Williams David , Jansons Marcis
Published: July 2013

This study investigates the combustion characteristics of methyl oleate (oleic FAME) produced from oleic acid. This compound is the main fatty acid component of peanut FAME, a potential renewable biofuel. Methyl oleate has been suggested in our previous work as a reference fuel or surrogate for biodiesel for advanced research (simulation and experiments), or as an enrichment compound to improve biodiesel’s fuel properties. This investigation compares the combustion and emissions characteristics of methyl oleate to peanut FAME and ultra-low sulfur diesel No. 2 (ULSD), in a single-cylinder indirect injection diesel engine intended for use as an auxiliary power unit. The dynamic viscosity of peanut FAME (P100) and Methyl Oleate (O100) was found to be 5.2 cP and 4.3 cP, respectively, at 40°C. It was determined from the ASTM standards for biodiesel that up to 50% FAME could be run in the engine. The lower heating value of P100 and O100 was 36 MJ/kg and 37 MJ/kg respectively, compared to 42.7MJ/kg for ULSD. With a combustion time of 2ms, P50 and O50 have shown similar combustion characteristics with ignition delays of about 1 ms at 2200rpm, 6.2 imep (100% load). The P50, O50, and ULSD heat release, with premixed phase combining with diffusion combustion, produced maximum values of 20.3 J/CAD, 22.7 J/CAD, and 21.9 J/CAD respectively. The heat fluxes were calculated by the Annand model, and a 2% increase in maximum total heat flux was observed for O50 compared with a maximum value of 1.95 MW/m2 for ULSD and P50. The mechanical efficiency of 77% was similar for all tested FAME blends and ULSD. The NOx increased for P20 by 6% compared with ULSD while for P50 it was similar to the ULSD values. The NOx emissions of methyl oleate showed a similar trend with that of ULSD. The soot values were relatively constant for all of the methyl oleate blends and increased by 14% for P50 when comparing both fuels to ULSD.

The findings support the use of methyl oleate as a reference or model fuel for combustion modeling, and as a compound for enriching biodiesel.
Influence of Hydrodynamic Fluid Pressure and Shoe Tread Depth on Available Coefficient of Friction
Authors: Singh Gurjeet , Beschorner Kurt
Published: July 2013

Slip and fall accidents are a major occupational health concern. Identifying the lubrication mechanisms affecting shoe-floor-contaminant friction under biofidelic (testing conditions that mimic human slipping) conditions is critical to identifying unsafe surfaces and designing a slip-resistant work environment. The purpose of this study is to measure the effects of varying tread design, tread depth and fluid viscosity on underfoot hydrodynamic pressure, the load supported by the fluid (i.e. load carrying capacity), and the coefficient of friction (COF) during a simulated slip. A single vinyl floor material and two shoe types (work shoe and sportswear shoe) with three different tread depths (no tread, half tread and full tread) were tested under two lubrication conditions: 1) 90% glycerol and 10% water (219 cP) and 2) 1.5% Detergent-98.5% (1.8cP) water solutions. Hydrodynamic pressures were measured with a fluid pressure sensor embedded in the floor and a forceplate was used to measure the friction and normal forces used to calculate coefficient of friction. The study showed that hydrodynamic pressure developed when high viscosity fluids were combined with no tread and resulted in a major reduction of COF (0.005). Peak hydrodynamic pressures (and load supported by the fluid) for the no tread-high viscous conditions were 234 kPa (200.5 N) and 87.63 kPa (113.3 N) for the work and sportswear shoe, respectively. Hydrodynamic pressures were negligible when at least half the tread was present or when a low viscosity fluid was used despite the fact that many of these conditions also resulted in dangerously low COF values. The study suggests that hydrodynamic lubrication is only relevant when high viscous fluids are combined with little or no tread and that other lubrication mechanisms besides hydrodynamic effects are relevant to slipping like boundary lubrication.
A Fluid-Structure Interaction Modeling Approach of Lubricated Bearing-Type Sliding Contacts
Authors: Mpagazehe Jeremiah N. , Higgs C. Fred
Published: July 2013

In many tribological applications, such as journal bearings and gears, a fluid film is used to accommodate velocity between moving surfaces. To model the behavior of this film and to predict its ability to carry load, the Reynolds equation is predominantly employed. As computational processing power continues to increase, computational fluid dynamics (CFD) is increasingly being employed to predict the fluid behavior in lubrication environments. Using CFD is advantageous in that it can provide a more general approximation to the Navier-Stokes equations than the Reynolds equation. Moreover, using CFD allows for the simulation of multiphase flows as could occur during bearing contamination and bearing exit conditions. Because the bearing surfaces move relative to each other as they obtain equilibrium with the fluid pressure, there is a need to incorporate the moving boundary into the CFD calculation, which is a non-trivial task. In this work, a fluid-structure interaction (FSI) technique is explored as an approach to model the dynamic coupling between the moving bearing surfaces and the lubricant. The benefits of using an FSI approach are discussed and the results of its implementation in a lubricated sliding contact model are presented.
Variation of the Thermal Properties During Friction Under Shock Conditions
Authors: Peillex G. , Le Tallec P. , Dambakizi F.
Published: July 2013

During friction under shock conditions, interface is submitted to very strong heat flux. Thus, it may reach a temperature as high as melt temperature of one of the materials constituting the contact. As a consequence, the income and outcome of heat at the interface governs the friction and the contact behavior. This article exposes a model that resolves the non-linear heat equation in the vicinity of the interface. This way, it takes into account the variations of thermal properties of materials constituting the interface. First results indicate that such variations influence the tribological behavior of the contact.
Description of the Integrated Electronic Security System – SISE Implemented at OCP (Heavy Crude Oil Pipleine) in Ecuador
Authors: Mendizábal Andrés , Montalvo Francisco
Published: July 2013

The OCP (Oleoducto de Crudos Pesados - Heavy Crude Oil Pipeline) pipeline in Ecuador crosses through several regions determined by unique characteristics and threats. The pipeline runs almost parallel and at some points close (30km) to the border with Colombia, country with a very active group of illegal armed forces. It is also known that the logistics of these illegal groups operate within Ecuador. Within this context, and also considering minor delinquency within Ecuador, OCP Ecuador S.A. emphasized on the need to have a Security Management Model that addresses the security threats to which the pipeline is vulnerable. Under this model the company has invested in the implementation of an Integrated Electronic Security System (SISE) in order to monitor and control security of terminals, pumping and pressure reduction stations, block valve sites and other specific sites along the pipeline. This paper describes the SISE, its equipment and how it is managed in order to present a security model to other pipeline operators with similar threats.
Prediction of Gas Turbine Performance Degradation Between Soakwashes in Natural Gas Compressor Stations
Authors: Chatterjee R. , Botros K. K. , Golshan H. , Rogers D. , Samoylove Z.
Published: July 2013

Gas Turbine (GT), like other prime movers, undergoes wear and tear over time which results in performance drop as far as available power and efficiency is concerned. In addition to routine wear and tear, the engine also undergoes corrosion, fouling etc. due to the impurities it breathes in. It is standard procedure to ‘wash’ the engine from time to time to revive it. However, it is important to establish a correct schedule for the wash to ensure optimal maintenance procedure. This calls for accurate prediction of the performance degradation of the engine over time. In this paper, a methodology is presented to predict the performance degradation in a GE LM2500 Gas Turbine engine used at one of TransCanada’s pipeline system, Canada. Emphasis is laid on analyzing the degradation of the air compressor side of the engine since it is most prone to fouling and degradation. Although the results presented are for a specific engine type, the general framework of the model could be used for other engines as well to quantify degradation over time of other components within the GT engine. The present model combines Gas Path Analysis (GPA) to evaluate the thermodynamic parameters over the engine cycle followed by parameter estimation to filter the data of possible noise due to instrumentation errors. The model helps quantify the degradation in the engine performance over time and also indicates the effectiveness of each engine wash. The analysis will lead to better scheduling of the engine wash thereby optimizing operational costs as well as engine overhaul time.
Living With HIC Damaged Pipeline
Authors: Al-Mithin Abdul Wahab , Al-Sulaiman Saleh , Safri Shabbir , Humphrey Stephen , Meinzer Thomas
Published: July 2013

A 41 km. (25.5 mile) long, 508 mm (20″) Fuel Gas pipeline (FG048) was in service to supply Fuel Gas to oil gathering centers (GC) in the West Kuwait area since 1968. It was required to convert the pipeline for reverse flow of HP Gas from a new gas gathering center in West Kuwait. During MFL-ILI survey prior to conversion, several undefined anomalies were detected along with other internal and external corrosion. Repair work was initiated based on ASME B31G criteria. During repair work, sections having unidentified anomalies were cut out and inspected internally. Internal blistering and HIC damage were observed. Further investigation revealed severe HIC damage and internal blistering at different areas throughout the pipeline length. Since the pipeline was crucial in commissioning gas collection and compressor facility operation, and was required to be in service for transporting gas within a short time, a program of failure investigation, inspection, data analysis and repair work was implemented. This paper demonstrates how a severely HIC damaged pipeline, crucial for gas transportation was put back into service using inspection, analysis, hydrotest and repair techniques through the collaborative efforts of different agencies.
Metallurgical Design and Development of High-Grade Line Pipe
Authors: Hara Takuya , Fujishiro Taishi , Shinohara Yasuhiro , Tsuru Eiji , Doi Naoki , Yamashita Eiichi , Miyazaki Hideki , Asahi Hitoshi , Terada Yoshio , Murata Masahiko
Published: July 2013

The application of high-strength line pipes has enabled pipelines to operate at high pressure, generating cost savings for both gas transportation and construction. In general, high-strength line pipes require crack initiation resistance and crack arrestability at low temperatures, as well as field weldability. High strength and deformability for strain-based design and excellent sour resistance are also required. Moreover, composite properties are often required for high-strength line pipes. This paper describes our progress in this field with regard to metallurgical design and development. Metallurgical design aimed at achieving a good balance between strength, low temperature toughness and deformability for strain-based design is also described from the perspectives of grain refinement, microstructure and chemical composition. Metallurgical design focused on a good balance between strength and sour resistance in limited low chemical composition is described from the perspectives of microstructure and control to chemical composition and center segregation. These efforts have led to the development of high-strength heavy wall line pipes of API X60 to X100 grades offering excellent low temperature toughness and high deformability for stain-based design, while API grades X65 to X70 with good sour resistance have also been developed.
Effect of Plastic Deformation on Occurrence of Abnormal Fracture During DWTT
Authors: Fujishiro Taishi , Hara Takuya , Aihara Shuji
Published: July 2013

Demand for natural gas using LNG and pipelines to supply the world’s gas markets is increasing. Under the large demand for high-strength linepipe, crack arrestability is one of the most important properties. DWTT (Drop Weight Tear Test) is the major test method for evaluating crack arrestability. Generally, a DWTT shear area of 85% or higher is required as the acceptance criteria, such as those of the API (American Petroleum Institute). In high-toughness linepipe steels, the abnormal fracture frequently occurs in DWTT. Abnormal fracture is defined as a cleavage fracture on the hammer side. However, the mechanism for occurrence of the abnormal fracture during DWTT has not been fully clarified. This paper describes the effect of plastic deformation on occurrence of abnormal fracture during DWTT using various steels with different microstructures. Each DWTT was carried out at the same test temperature using 20 mm plates with approximately the same tensile strength. This paper describes the deformation during DWTT, which consists of deformation caused by hammer impact, bending compression, and bending tension. The deformation due to the impact of the hammer during DWTT on a 20 mm plate was limited, and the location affected by the hammer impact did not correspond to that where abnormal fracture occurred. Moreover, the equivalent plastic strain from bending deformation was dominant as compared with that of hammer impact regardless of the microstructure. This suggests that abnormal fracture occurred by exceeding the critical equivalent plastic strain due to the bending deformation.
A System Based Approach to Achieve Long Term Integrity of Gas Facilities
Authors: Sloterdijk W. , Hommes M.
Published: July 2013

In today’s challenging environment, the priority for many oil and gas operation companies is to design, build and safely operate facilities at optimum cost efficiency. This means that new facility designs must consider critical facility integrity and that existing facilities are operated well beyond their intended design life. Main gas transmission systems are now some 50 years old and operate for longer periods than anticipated during design and construction for reasons such as; the transition to renewables with another 50 years of service foreseen, and; gas transmission systems that operate satisfactorily, have very low failure rates and for which the planned safe life time extension is expected to be the lowest cost option.
High Pressure Gas Pipeline Installation Inside a Long Length and Small Cross-Section Mountain Tunnel
Authors: Sumikura Yuya
Published: July 2013

The gas pipeline called “Mie-Shiga Pipeline” (60km total length, 610mm diameter, 7MPa maximum pressure, grade L450 (X65)) is under joint construction between Chubu Electric Power Co., Inc. and Osaka Gas Co., Ltd. This pipeline is planned to start supplying gas in 2014. Since the main part of our construction area is in a mountainous area called Suzuka Mountains, the mountain tunneling method is adopted in part of the mountainous area (about 7.5km in length) for gas pipeline installation to shorten the construction period. This paper discusses the design concept and the highly efficient technique for installing pipeline inside a long length and small cross-section mountain tunnel, as well as the application of an internal watertight wall, which is a task specific to the mountain tunnel.
Development of the New Welding Control Method for HF-ERW Pipes: Advanced Welding Process of HF-ERW 1
Authors: Fukami Toshisuke , Mizuhashi Nobuo , Hasegawa Noboru , Hamatani Hideki , Hasegawa Yasushi , Asano Takuya , Motoyoshi Suguru , Miura Takao , Tanaka Kimiharu , Nakaji Tomohiro , Yamamoto Kazuto
Published: July 2013

In recent years, the key application requirement of the ERW line pipe has been its toughness, including the weld seam.

It is known that, among defects generated at the weld seam, the penetrator defect affects toughness and is difficult to control by welding condition[1–4].

Generally speaking, ERW pipes are welded with exposure to air, and oxides are produced on the surface of the melted metal during the process. The discharge of this melted metal by electromagnetic force and squeezing produced at the current welding route is effective in eliminating the penetrator, and constantly optimizing the welding heat input means this defect can be constantly reduced.

To optimize the welding heat input, therefore, it is important to determine the welding phenomena occurring at the welding spot and contrast them with the defect area ratio. We have studied (examined) the welding phenomena, optimum heat input power and the welding defect generation mechanism. Consequently, it was revealed that by varying the welding speed, Vee convergence angle and welding heat input, etc., a new categorization of welding phenomena as Types 1, 2, 3, and 2′ was possible.

In the case of Type 2 and 2′ welding phenomena, the welding defect area ratio decreases, which resulted in a sound seam weld with high toughness. If these two welding phenomena are compared, the wider heat input power range of Type 2′ is preferable for the HF-ERW manufacturing process. The higher heat input of Type 2′ compared to Type 2 compensates for the abutting surface angle fluctuation, meaning it is also preferable for pipe manufacturing. Consequently, the control of the Type 2′ welding phenomenon is preferable for the HF-ERW manufacturing process.
Increased Robustness in Hyperbaric Welding of Subsea Pipelines by Introducing Copper Backing
Authors: Fostervoll Hans , Akselsen Odd Magne , Berge Jan Olav
Published: July 2013

Hyperbaric tie-in and repair welding of pipelines at the seabed is performed as full penetration TIG butt welding. Variations in pipe end fit-ups make the root pass welding challenging with relatively low robustness. The present investigation concerns with exploiting copper backing to increase the root pass welding robustness. Initial welding experiments are performed at 15.4bara ambient pressure with the TIG process based on the technique and procedures used by the Statoil PRS (Pipeline Repair System). The results demonstrate that significant increase in robustness can be achieved, which can be an important contribution in the strive for cost reductions. Mechanical testing and microstructure examination of the weld metal revealed no negative influence of the copper backing. Initial MIG root pass welding experiments at 11bara are also performed as a part of the development of hyperbaric MIG butt welding of pipelines. These results are promising and demonstrate that by exploiting copper backing can robust procedures be developed, which opens for deep water MIG butt welding in the future.
Using Quantitative Risk Assessment to Justify Location Class Changes: Case Study
Authors: Rumney Paul , Goodfellow Graham
Published: July 2013

Expansion of existing residential and commercial areas, or the construction of new developments in the vicinity of high pressure gas transmission pipelines can change a Location Class 1 into a Class 2 or Class 3 location. Operators are left with a pipeline that no longer meets the requirements of its design code.

Reducing the maximum allowable operating pressure of a pipeline, or re-routing it away from the population, can meet the requirements of a design code, such as CSA Z662 or ASME B31.8, but such options have both high costs and significant operational difficulties.

Quantitative risk assessment has been employed successfully for many years, by pipeline operators, to determine risk based land use planning zones, or to justify code infringements caused by new developments. By calculating the risk to a specific population from a pipeline, and comparing it with suitable acceptability criteria, a pipeline may be shown to contribute no more risk to a population than other pipelines operating entirely in accordance with the design codes.

Risks may be demonstrated to be ‘as low as reasonably practicable’, through the use of cost benefit analysis, without additional mitigation, allowing precious pipeline maintenance funds to be spent most effectively in areas where they will have the highest impact on risk.

This paper shows how quantitative risk assessment may be used to justify continued safe operation of a pipeline at its original operating stress following a change of class designation, illustrated with a case study from Western Europe.
Pressure Test Planning to Prevent Internal Corrosion by Residual Fluids
Authors: Place Trevor , Sasaki Greg , Cathrea Colin , Holm Michael
Published: July 2013

Strength and leak testing (AKA ‘hydrotesting’, and ‘pressure testing’) of pipeline projects remains a primary method of providing quality assurance on new pipeline construction, and for validating structural integrity of the as-built pipeline [1][2][3]. A myriad of regulations surround these activities to ensure soundness of the pipeline, security of the environment during and after the pressure testing operation, as well as personnel safety during these activities. CAN/CSA Z662-11 now includes important clauses to ensure that the pipeline designer/builder/operator consider the potential corrosive impacts of the pressure test media [4].

This paper briefly discusses some of the standard approaches used in the pipeline industry to address internal corrosion caused by pressure test mediums — which often vary according to the scope of the pipeline project (small versus large diameter, short versus very long pipelines) — as well as the rationale behind these different approaches. Case studies are presented to highlight the importance of considering pressure test medium corrosiveness. A practical strategy addressing the needs of long-distance transmission pipeline operators, involving a post-hydrotest inhibitor rinse, is presented.
Development of a Probabilistic Model for Stress Corrosion Cracking of Underground Pipelines Using Bayesian Networks: A Concept
Authors: Jain Swati , Ayello Francois , Beavers John A. , Sridhar Narasi
Published: July 2013

Stress corrosion cracking (SCC) continues to be a safety concern, mainly because it can remain undetected before a major pipeline failure occurs. SCC processes involve complex interactions between metallurgy, stress, external soil environment, and the electrolyte chemistry beneath disbonded coatings. For these reasons, assessing SCC failure probability at any given location on a pipeline is difficult.

In an attempt to assess the SCC probability, a Bayesian network model was created. The model links events by cause-consequence connections. The strengths of these connections are adjusted using expert knowledge, analytical models, and data from the field. Bayesian network modeling was chosen because it takes into account the high degree of uncertainty in the input parameters. Other models have been developed to assess SCC: such as indexing methods, heuristics models, and mechanistic models. However, their main limitation is the uncertainty of the input parameters. One other strength of the Bayesian model is that calculations can be run in two directions: the forward direction from cause to consequence and the backward direction from observation to causative factors. In the forward direction, the model evaluates the probability of SCC failure using various input probabilities of factors that are important to SCC. In the backward direction, the model can evaluate the effect of any known occurrence of SCC failure on the probabilities of causative factors and thus condition the Bayesian network to evaluate the future failure probability.

In this paper, we discuss a Bayesian network model for high-pH SCC. The conceptual framework, acquisition of data, and the inclusion of uncertainties are described. In addition, an example of the model application to high pH SCC is given. The effects of service and field conditions such as soil type, soil chemistry, coating type, surface preparation techniques, stresses, residual stress due to pipe manufacturing conditions, welds, dents, location such as proximity to rivers, wetting and drying cycles, etc. on the SCC probability can be assessed with the model. The model details shown in this publication will only cover the stress affect due to surface preparation, welds, dents, and manufacturing conditions and temperature effect. The effects of other factors and validation against field experience will be discussed in future publications.
Assessment of the Remaining Strength of Corroded Small Diameter (Below 6”) Pipelines and Pipework
Authors: Swankie Troy , Chauhan Vinod , Owen Robert , Bood Robert , Gilbert Geoffrey
Published: July 2013

Internal and external corrosion damage is a major cause of pipeline failures worldwide. When corrosion features in pipelines are detected by in-line inspection (ILI), a decision whether to replace, repair or accept and monitor must be made. Extensive experimental and numerical work has been undertaken to develop methods for assessing the remaining strength of corroded transmission pipelines. Common methods used by the pipeline industry include ASME B31G, modified ASME B31G and LPC. These methods are semi-empirical and have been developed using a modified version of a toughness independent ductile failure criterion for pressurized pipes containing axially orientated surface breaking defects. The validity range of these models is dominated by large diameter (10 to 48″), thin walled, low grade (API 5L grade A to X65) and low yield to tensile ratio line pipe. Smaller diameter (not greater than 6″), thick walled pipelines and pipework located, for example, at above ground installations, compressor and pressure reduction stations are very common. The use of ASME B31G, modified ASME B31G or LPC may not be appropriate when assessing the remaining strength of small diameter pipelines and pipework. No alternative methods are available in the public domain and hence a program of work was undertaken to derive appropriate defect acceptance limits by conducting a series of full-scale burst tests on small diameter pipe with simulated corrosion defects. It was concluded that the LPC method gave the most accurate prediction of failure pressure when compared with the results of the full-scale tests, and the most conservative predictions of failure pressure were obtained using the ASME B31G method.
Characterization of X80 Grade Linepipe Steel Coil With 24 mm Thickness
Authors: Sanchez Nuria , Ilić Nenad , Liebeherr Martin
Published: July 2013

High strength and high toughness at low temperatures on heavy wall thickness skelp is required to build high pressure gas transportation pipelines. Detailed mechanical and microstructural characterization was carried on 24mm thick ArcelorMittal X80 coils in order to identify the microstructure control required to reach high toughness as determined by the shear fracture appearance after DWTT testing. Detailed microstructural characterization through thickness reveals that the microstructure gradient described by a systematic increase of the average grain size between surface and middle thickness of the strip and the increment of the volume fraction of M/A (martensite/ retained austenite) are the key microstructural parameters to control in order to ensure the adequate toughness of the material. The obtained high toughness of the coils indicates that the microstructure, controlled by an optimized rolling and cooling practice, is homogeneous through thickness of heavy wall linepipe grades.
Qualification of an Application System for In-Field External Reinforcement of Pipelines Using Helical Steel Wrap
Authors: Miles David J.
Published: July 2013

A solution, known as XHab™, has been developed for external repair and reinforcement of pipelines using ultra high strength steel strip. This method involves wrapping multiple layers of strip in a helical form continuously over an extended length of pipeline using a dedicated forming and wrapping machine. The reinforcement provided by the strip can be used to:

a) Restore the original maximum allowable operating pressure to a section of defective pipe (e.g. external corrosion or denting), or

b) Reinforce an intact but de-rated section of pipeline (e.g. a Location Class change through encroachment) to maintain reduced hoop stress in the base pipe as required by codes and regulations, but allow reinstatement of the original operating pressure by carrying the additional load in the strips.

This paper describes the full-scale qualification testing, including in-field proving runs, and design analysis necessary to demonstrate the field-readiness of the application system and reinforcement product. This includes wrapping and pressure testing of pipe with machined external wall defects. The potential for XHab repair of stress corrosion cracking (SCC) is also discussed for an upcoming series of tests on pipe samples with electrical discharge machined notches.

To demonstrate reinforcement of intact pipe, a 40ft joint of 26-inch vintage flash-butt seam welded pipe, instrumented with hoop and axial strain gages, has been wrapped by the XHab machine with sufficient reinforcement to simulate a change from Location Class 1, Div. 2 to Location Class 3 (ASME B31.8). This pipe has been subjected to pressure cycling and ultimate burst alongside an identical unwrapped pipe sample which provides a baseline. The test results are presented and compared to finite element analysis.
Potential Components of an Effective LSW Integrity Management Program
Authors: Podnar Tara , Bubenik Thomas A. , Andrew Jim , Hicks Dyke
Published: July 2013

Det Norske Veritas (U.S.A.), Inc. (DNV) has had the opportunity to observe and contribute to a significant number of longitudinal seam weld integrity management programs. DNV has used these opportunities to identify activities with a positive impact on the integrity management of the longitudinal seam welds for which they are implemented.

The Integrity Assessment activities identified by DNV include those pertaining to hydrostatic pressure testing, in-line inspection data, and in-line inspection technology. The Anomaly Review and Prioritization activities include excavation prioritization, control excavations, and investigative excavations. The Excavation and Repair Program activities include non-destructive examination techniques, technologies and validation, repair methods, and safety measures. The Tool Validation activities include in-line inspection specification and vendor feedback. The Reassessment activities include those pertaining to in-line inspection validation, operations, and reassessment interval calculation methodologies.

Not all longitudinal seam weld integrity management activities are appropriate for all pipelines. In these cases, the correct combination of integrity management activities will result in an effective longitudinal seam weld integrity management program.
ILI Based Dent Screening and Strain Based Analysis
Authors: Tinacos Katina , Cazenave Pablo , Gao Ming , Krishnamurthy Ravi , Seman Dan , Jones Charley
Published: July 2013

Pipeline operators often deal with the large numbers of dents that require further consideration, and are required to prioritize these dents for further investigation and repair. Code guidance is clear on the relative severity of dents based on a depth or associated with welds, corrosion, gouging or cracking. It allows the pipeline operators to prioritize their dig lists and limit the number of “investigative digs” by omitting plain and shallow dents. However, the dent depth criterion has limitations, experiences learned in the past have shown that a dent prioritization based on depth alone, may still leave a significant number of dents in the pipeline which may pose a threat, particularly from local static strain and fatigue.

In recent years, strain and fatigue analyses have been included in the assessment of severity of dents in order to better prioritize and effectively repair dents which represent a threat to the structural integrity of pipelines. However, strain analyses require tedious calculation of dent curvature at each data point from ILI reported dent profile. When a large numbers of dents require to be prioritized by strain severity, using this detail calculation is impractical. Therefore, a screening methodology is required to reliably identify candidate dents that require detail strain assessment.

In this paper, an aspect-ratio based screening methodology is developed and applied to over 7,000 dents reported by an In-Line Inspection (ILI) caliper tool for a 265 miles long pipeline section. A total of 263 shallow dents which could have injurious strain level were identified and ranked for detail strain and fatigue calculations.

In-ditch investigation of 20 dents with LaserScan profiling showed that the developed screening methodology provides an effective tool to capture all the dents with strain equal and 6.5% at 95% confidence level.
Development and Evaluation of a Steel-Composite Hybrid Composite Repair System
Authors: Alexander Chris , Brooks Carl
Published: July 2013

Composite materials are widely recognized as a resource for repairing damaged pipelines. The fibers in conventional composite repair systems typically incorporate E-glass and carbon materials. To provide greater levels of reinforcement a system was developed that incorporates steel half shells and an E-glass composite repair system. In comparison with other competing composite technologies, the hybrid system has a significant capacity to reduce strain in corroded pipeline to a level that has not been seen previously. Specifically, the hybrid system was used to reinforce a pipe sample having 75% corrosion subjected to cyclic pressure at 36% SMYS. This sample cycled 767,816 times before a leak failure developed. Furthermore, recent testing has demonstrated that the hybrid system actually places the pipeline in compression during installation. This paper will provide results on a series of specifically-designed tests to evaluate the performance of the hybrid system and the implications in relation to the service of actual pipelines.
CVN and DWTT Energy Methods for Determining Fracture Arrest Toughness of High Strength Pipeline Steels
Authors: Zhu Xian-Kui , Leis Brian N.
Published: July 2013

Battelle two curve model (BTCM) was developed in the 1970s and successfully used for determining arrest toughness for ductile gas transmission pipelines in terms of Charpy vee-notched (CVN) impact energy. Practice has shown that the BTCM is accurate only for pipeline grades up to X65, but not for high strength pipeline grades X70 and above. Different methods to improve the BTCM were proposed over the years. This paper reviews the BTCM and its modified methods in terms of CVN energy or drop weight tear test (DWTT) energy for determining arrest toughness of ductile gas pipeline steels, particularly for high strength pipeline steels X80 and beyond. This includes the often-used Leis correction method, the CSM factor method, Wilkowski DWTT method and others. The CVN and DWTT energy-based methods are evaluated and discussed through the critical analysis and comparison with full-scale experimental data. The objective is to identify reasonable methods to be used for determining the minimum fracture toughness required to arrest a ductile running crack in a modern high strength, high pressure gas pipeline. The results show that available nonlinear models to correlate the standard DWTT and CVN energies are questionable, and the Leis correction method is a viable approach for determining arrest toughness for high strength pipeline steels, but further study is needed for ultra-high pipeline grades. Suggestions for further improving the BTCM are discussed.
Online Application of Hydraulic Simulation Software to Gassco’s Subsea Pipeline Network
Authors: Birchenough Eadred , Munro James , Zhang Jun , Hansen Dagfinn , Rinde Ola , Sakariassen Vidar , Velde Ben
Published: July 2013

This paper addresses the on-line application of ATMOS SIM simulation software, integrated with ABB Network Manager WS500, to a subsea pipeline network of 7,800 km (4,847 mile) length — see Figure 1. The pipeline system is operated by Gassco Norway, and it delivers an annual volume of approximately 100 billion standard cubic meters of Norwegian gas to customers in Western Europe. One of the main challenges to such a great subsea pipeline system is the limited measurements available. For nearly all of the pipelines, the only location where flow, pressure and temperature are measured is at the inlet and outlet which could be more than 800 km (497 mile) apart.

The following applications will be addressed in this paper:

• IT architecture. User controls including Common Alarm List.

• Data validation overview.

• Pipeline inventory calculation.

• Continuous calculation of settle-out-pressures for (sub)sections of pipelines to provide information for emergency shutdown systems.

• Integration of ambient seabed temperatures as provided by UK Met.

• Composition tracking including the possibility to track user specified trace components.

• Estimated arrival times and volumes of “off-specification” gas.

• Tracking of the parentage of batches such that the party responsible for off-spec gas can be identified (polluter pays principle).

• Facilities to restart models from historic data with the possibility to remove erroneous inputs.

• Continuous running of look-ahead cases based on user defined transient time series and nominations for contractual exit points.

• Using larger network models to plan and monitor mixing of gasses to prevent off-spec gas.

Comparisons between simulated and measured values will be made to illustrate the accuracy of the hydraulic models. In addition, the application of Maximum Likelihood State Estimation will be discussed to demonstrate its effectiveness in overcoming measurement errors.
Detection of Trace Hydrocarbons and Toxic Components in the Environment
Authors: Knoblach Walter , Bryce Peter W.
Published: July 2013

The risk of hydrocarbon and toxic spills increases with the aging of oil and chemical plant related infrastructure. The need for early detection of hydrocarbon and toxic chemical pollution is paramount, particularly in view of potential environmental damage, cleanup costs, and the loss of public confidence in industry’s ability to quickly respond to leaks.

Rigorous right-of-way monitoring, control of third party activities within proximity of pipelines, in conjunction with a robust preventative maintenance program is key to leak prevention. The first line of defense in the event of a leak is early detection and operational response to limit product loss from the pipe. Sophisticated mathematical modeling of flow regimes coupled with multiple pressure sensory relay devices in pipelines has increased the sensitivity of these leak detection technologies. However, despite these technological improvements significant leaks have occurred recently on major pipeline systems with damaging consequences.

Operators are challenged to interpret and respond to leak alarms in the absence of corroborating information. Frequent false or ambivalent “indications” can foster complacency, and worse, inaction.

The authors contend that reliance on a single technology for detecting leaks is imprudent and unacceptable in certain environments given the consequences of a late response to a loss of product from the line. Leak detection can be significantly enhanced by the application of molecular sensory technology in tandem with real time pipeline monitoring systems. The systems are synergistic and do not compete with each other.

This paper describes the development of the LEOS® leak detection system, its application and operational experience in high sensitivity locations. Four distinct applications are described, including: an Arctic subsea pipeline, an arctic above ground pipeline, a river crossing, and a buried onshore pipeline right of way. In the latter, a situation is described where a hydrocarbon leak was discovered on an adjacent third party pipeline not directly monitored by the system.
New Concrete Crosstie Regulations and Rail Cant Measurement
Authors: Clouse Arthur L.
Published: July 2013

The new concrete crosstie rules require, in FRA Class 1-5 track standards, specific performance requirements that address the unique characteristics of fastener reliability, concrete crosstie, and roadbed stability. [Inspectors] should be aware of the three modes of concrete crosstie failure: support, stability, and electrical isolation. The compressive strength of concrete and the amount of prestress in its section composition provide the strength and stiffness necessary to support expected wheel loads. There’s a balance between excessive stiffness that can lead to higher stresses at the bottom of the crosstie and at the rail seat.

Conversely, a loss of stiffness, caused by ever increasing axle loading, can lead to excessive rail deflections and damage to the ballast and subgrade. Inspectors should be aware that failure modes are not isolated to crosstie defects. Combinations of compliant but irregular track and rail geometry, poor drainage, insufficient ballast depth and subgrade soil conditions may contribute to failure or root causal factors.

The new concrete crosstie regulations contained in Part 213.109(d) and a section by section description is as follows:

Part 213—[AMENDED]

§ 213.109 CROSSTIES

d) Concrete crossties counted to satisfy the requirements set forth in paragraph (b)(4) of this section shall not be—

(1) Broken through or deteriorated to the extent that prestressing material is visible;

(2) Deteriorated or broken off in the vicinity of the shoulder or insert so that the fastener assembly can either pull out or move laterally more than 3/8 inch relative to the crosstie;

(3) Deteriorated such that the base of either rail can move laterally more than 3/8 inch relative to the crosstie on curves of 2 degrees or greater; or can move laterally more than 1/2 inch relative to the crosstie on tangent track or curves of less than 2 degrees;

(4) Deteriorated or abraded at any point under the rail seat to a depth of 1/2 inch or more;

(5) Deteriorated such that the crosstie’s fastening or anchoring system, including rail anchors (see § 213.127(b)), is unable to maintain longitudinal rail restraint, or maintain rail hold down, or maintain gage due to insufficient fastener toeload; or

(6) Configured with less than two fasteners on the same rail except as provided in § 213.127(c).