bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Coating Thickness on Tribological Performance of CrN in Dry Sliding Contact
Authors: Lorenzo Martin C. , Ajayi O. O. , Torrel S. , Demas N. , Erdemir A. , Wei R.
Published: July 2013

One of the most commonly used tribological thin-film coatings is Chromium Nitride (CrN), typically deposited by PVD process. Examples of current applications of this coating include cutting and forming tools: ICE piston ring, hydrodynamic pumps, etc. In selecting coating for tribological applications, one of the critical parameter is the coating thickness. In the present work, we experimentally studied the effect of coating thickness on friction and wear performance of CrN coatings under unidirectional sliding. Test were conducted with ∼ 1, 5 and 10 microns thick coatings deposited on a hardened H-13 steel substrate by plasma enhanced magnetron sputtering (PEMS) process. The friction behavior was strongly dependent on coating thickness, especially at relatively low loads. At higher load however, the thinner coating (1 μm) was quickly worn through while the thicker ones (5 and 10 μm) remained intact. Wear in both, the counterface WC material and the coating was also observed to depend on coating thickness. The observed effect on coating thickness on tribological behavior is attributed to differences in the microstructure and mechanical behaviors of coatings as function of thickness.
Two Dimensional Modified Reynolds Equation Including Pressure Dependent Viscosity Effect
Authors: Lee Jung Gu , Palazzolo Alan
Published: July 2013

The Reynolds equation plays an important role for predicting pressure distributions for fluid film bearing analysis, One of the assumptions on the Reynolds equation is that the viscosity is independent of pressure. This assumption is still valid for most fluid film bearing applications, in which the maximum pressure is less than 1 GPa. However, in elastohydrodynamic lubrication (EHL) where the lubricant is subjected to extremely high pressure, this assumption should be reconsidered. The 2D modified Reynolds equation is derived in this study including pressure-dependent viscosity, The solutions of 2D modified Reynolds equation is compared with that of the classical Reynolds equation for the ball bearing case (elastic solids). The pressure distribution obtained from modified equation is slightly higher pressures than the classical Reynolds equations.
Using a 3-Dimensional Viscoelastic Finite Element Model to Analyze the Effects of Floor Roughness, Sliding Speed and Material Properties on Shoe-Floor Friction
Authors: Singh Gurjeet , Hasija Vikas , Menezes Pradeep L. , Beschorner Kurt
Published: July 2013

Slip and fall accidents are a major occupational health concern. Important factors affecting shoe-floor friction is critical to identifying and resolving unsafe surfaces and designing. Experimental studies have indicated that several factors including floor roughness, sliding speed and shoe materials affect shoe-floor friction although the precise nature of the mechanism behind this phenomenon is not well understood. In addition, recent studies have suggested that boundary lubrication is highly relevant to slipping and that adhesion and hysteresis are the main contributing factors to boundary lubrication. The purpose of this study is to perform the numerical simulations to analyze the effects of floor roughness (asperity height), sliding speed and material properties on ratio of real area of contact and normal force (relevant to adhesion friction) and hysteresis friction for a viscoelastic shoe material interacting with a hard floor surface. A 3D shoe model and 3D vinyl floor model was simulated with speed 0.01 m/s, 0.5 m/s, 0.75 m/s and 1 m/s in three different floor surfaces. The material property was also varied in the numerical simulations. The study showed that roughness affects both the hysteresis and adhesion friction whereas sliding speed and material property affects the adhesion friction only. The dependence of adhesion and hysteresis friction on roughness, sliding speed and material property is useful in understanding the shoe-floor friction phenomenon and development of slip resistant sports and work shoes.
Determination of Dynamic Coefficients in a Hydrodynamic Journal Bearing Based on the 3-D Navier-Stokes Equations and Considering Cavitation Effects
Authors: Xing Changhu , Braun Minel J.
Published: July 2013

Dynamic coefficients are very important for the stability of a hydrodynamic journal bearing and therefore for its design. In order to determine the stiffness, damping and added mass coefficients of the hydrodynamic bearing, the finite perturbation method around its stabilization position was employed. Based on the Reynolds equation with Gumbel cavitation algorithm, the maximum magnitude of the perturbation was judged by comparing results from finite perturbation (numerical way) to those from infinitesimal perturbation (additional analytical equations need to be derived based on order analysis), as well as theoretical analysis. Using the determined perturbation amplitude, the full three-dimensional Navier-Stokes equations in CFD-ACE+ were used to evaluate coefficients from an actual lubricant and compare to those obtained with Reynolds equation. Finally, a homogeneous gaseous cavitation algorithm is coupled with the Navier-Stokes equation to establish the pressure distribution in the bearing. When gas concentration was varied, the pressure distribution as well as the dynamic coefficients changed significantly.
On Simulation of Multi-Particle Impact Interactions in the Cold Spray Process
Authors: Yıldırım Baran , Hulton Andrew , Alavian Seyed Ali , Ando Teiichi , Gouldstone Andrew , Müftü Sinan
Published: July 2013

The cold spray process consists of coating build-up by sequential impact, deformation and bonding of many particles. Therefore, formation and properties of a deposited layer are not only affected by the impact behavior of a single particle, but also by subsequent impact events. To investigate the material behavior under such conditions, impact of multiple particles in cold spray was studied here by the finite element method. Effects of high strain rates and temperature on material yield and failure criteria were considered. Particle conditions prior to impact were derived from fluid dynamics calculations. To predict sticking behavior of the particle, an interfacial cohesive strength parameter was defined between the particle and the substrate. The effects of temperature and particle positioning were examined for three particle impacts. In addition, simulations involving 100 consecutive particle impacts were carried out, and findings were compared with experimental observations. Results showed that subsequent impacts have a large effect on the previously impacted particles for cohesion, degree of deformation, and residual stresses.
Self-Organization and Friction During Sliding
Authors: Menezes Pradeep L. , Kishore  , Kailas Satish V. , Lovell Michael R.
Published: July 2013

In self-organized sliding processes, the surfaces align to each other during sliding. This alignment leads to a more ordered contact state and significantly influences the frictional behavior. To understand the self-organization sliding processes, experiments were conducted on a pin-on-plate reciprocating sliding tester for various numbers of cycles. In the experiments, soft magnesium pins were slid against hard steel plates of various surface textures (undirectional, 8-ground, and random). Experimental results showed that the transfer layer formation on the steel plates increased with increasing number of cycles for all surfaces textures under both dry and lubricated conditions. The friction also increased with the number of cycles under dry conditions for all of the textures studied. During lubricated conditions, the friction decreased for unidirectional and 8-ground surfaces and increased for random surfaces with the number of cycles. Furthermore, the friction and transfer layer formation depend on the surface textures under both dry and lubricated conditions during the first few sliding cycles. Later on, it is less dependent of surface textures. The variation in the coefficient of friction under both dry and lubrication conditions were attributed to the self-organization process that occurred during repeated sliding.
New Method for In-Trench Pipeline Support
Authors: Connors Geoff W.
Published: July 2013

Protection of the pipe during and after pipeline construction is of paramount importance for safety and pipeline integrity. Areas of rock and stone are often encountered during construction of new pipelines. Even with modern pipeline coatings, additional protection for the pipe is necessary where rock or stone exposure is significant.

Historically, additional pipe protection used in these types of situations is achieved through adding either a significant layer of sand or select backfill above and below the pipeline (sand padding) and/or by attaching a high-impact resistant, poly-type rock shield around the pipeline during the pipeline installation process.

To accommodate sand padding, some form of intermittent support of the pipeline is generally required to elevate the pipeline off the trench bottom. Similar intermittent support is also recommended practice when using poly-type rock shields to keep the pipeline from fully resting on trench rocks.

Current methods of in-trench support involve sand piles, sand bags, spray foam and individually formed foam pillows — each with drawbacks:

i) Sand Piles are difficult to install and often oval or dent the pipe when improperly placed.

ii) Sand bags require hand placement for proper support. In open trenches, this can be time consuming and unsafe. Improper placement can cause the pipe to oval or dent.

iii) Spray-in foam is considered to be an obstruction of cathodic protection currents. Newly constructed pipelines full of hydrostatic test water and one metre cover can cause foam to compress excessively.

iv) Foam pillows are light and easily placed — but can float out of position and compress or crack under heavy loads. As with all foam, cathodic shielding is always a concern.

A new, engineered method of in-trench pipeline support is now available — the Structured Pipeline Pillow (SPP).

SPP’s are injection molded and made from high strength, environmentally inert polypropylene or polyethylene resins. Designed to support any size pipeline, SPP’s are most effective with larger diameter, heavier pipelines. One SPP is engineered to carry a single 40′ joint of heavy wall pipeline filled with hydrostatic test water.

Compared with current methods, SPP’s:

i) Stack tightly for transport.

ii) Are light enough for installation from outside the trench and resist floatation when ground water is present.

iii) Help ensure the pipeline is centered in the trench during the pipeline installation.

iv) Maintain long-term pipe clearance above rocky trench bottoms.

v) Ovality and denting concerns are reduced.

vi) Allow cathodic protection an easy path to the pipeline.

vii) Will never biodegrade.

In their extended stacking mode, SPP’s tested well as an effective alternative to wooden skids for many situations such as pipe stockpiling; stringing along the rights-of-way (ROW); and even for some low level skidding during the welding process.
Evaluation and Zoning by Mass Removal Phenomena (MRP) Along the Ecuadorian Heavy Crude Oil Pipeline Route
Authors: Mendoza Carlos H. , Gibbons Eddie M. , Reinoso Pablo A. , Bermeo Ramiro E.
Published: July 2013

The occurrence of MRP is related to the external geodynamics of the Earth’s crust, which are the most common processes occurring each year around the world. In the case of Ecuador, these events, within the ROW (Right Of Way), have affected the integrity of the ROW, bringing dangerous OCP pipe bursts and thus oil spills affecting the surrounding terrain and water bodies.

Landslides are phenomena subject to a degree of uncertainty due to the different geological – geotechnical areas involved; this research tries to determine the susceptibility of the terrain to landslide using these intrinsic factors, environmental properties (topography, moisture, lithology) and other variables that could trigger these conditions (e.g. rain, earthquakes). Each factor defines an index of influence for a given site when combined and correlated to the threat of a specific severity, which allows for a value to be ratesed on its susceptibility.

The recognition of the threats and the susceptibility of the terrain to landslide is a very useful tool to identify and divide the land into homogeneous areas and scale them according to their actual or potential threat.

The mapping is performed on an area where there is occurrence data of the events or phenomena. This data can then be extrapolated to determine the potential threat in areas where no data exists. The collected information is processed using GIS software to be spatially represented information.

Maps generated with this methodology are used and applied as key tools in decision making processes for land use planning. The result of their application also increases the understanding of natural phenomena in the study area, leading to an efficient and sustainable development.

This methodology is not intended under any circumstances, to ignore the geotechnical field and laboratory data, and it can not predict the kind of slippage that could occurs.
Ultrasonic Guided Wave for Pipeline and Storage Tank Corrosion Defect Inspection
Authors: Wang Weibin , Tong Haolin , Dong Hongjun , Ai Muyang , Wu Kai , Feng Zhanjun
Published: July 2013

Pipeline and storage tank corrosion defect inspection is one of the most important concerns for integrity management of oil & gas storage and transportation industry. Besides the internal inspection for pipeline, tri-axis high-resolution magnetic leakage inspection technique which is applied for trunk line inspection, long range ultrasonic guided wave technique based on Lamb wave is adopted for inaccessible part inspection in technique package for pipeline inspection in PetroChina. Corrosion in the tank floor and wall is a serious threat for environmental and economic safety. Owing to the capabilities of ultrasonic guided wave which are long-range, in-plane propagation, in-service storage tank floor/wall inspection becomes possible by employing an array of SH wave transducers mounting on the edge of the outer storage tank floor. At this point, ultrasonic guided wave shows its capability for pipeline and storage tank corrosion defect inspection. With the advancement of high-performance transducer, its capability will be boosted for even longer and remoter detection. Currently, ultrasonic guided wave system for pipeline could detect defect 200 m away in ideal case while 3∼6 m for storage tank floor in practical case. The complexity of the application of ultrasonic guided wave in tank floor inspection lies in the object containing multiple lap joint welds along the large diameter of the tank (up to 100 m) and the complicated reconstruction of the two-dimensional defect distribution information. The prototype of ultrasonic guided wave system for storage tank is able to detect defects along the edge of storage tank floor. Once the propagation mechanism at overlap joint welds is broken through, the system capability is believed to be greatly improved. The main scope of the paper is to introduce the ultrasonic guided wave principles and the system design of the inspection systems for pipeline and storage tank, respectively, including the system electrical module, hardware program and the module of data acquisition, analysis and processing. Besides, the field application study cases are included to show the capability of both systems and their potential for integrity management in oil & gas storage and transportation field.
Hydrogen Assisted Cracking Failures of Girth Welds in Oil and Gas Pipelines
Authors: Amend W. E. , Quickel G. T. , Bruce W. A. , Beavers J. A.
Published: July 2013

There are more than 2.5 million miles of oil and gas pipelines in the United States, totaling over 330 million girth welds below ground. During construction, girth welds are susceptible to the formation of various defects, one of which is hydrogen-assisted cracks. The synergistic impact of tensile stress, a susceptible microstructure, and atomic hydrogen can lead to hydrogen embrittlement and the formation of hydrogen cracks. This paper reviews hydrogen cracking of girth welds in carbon steel pipelines made during new construction and provides examples involving hydrogen cracking in which failure analysis techniques were used to establish the metallurgical cause of failure.
Semi-Empirical Correlation to Quantify the Effects of Pipe Diameter and Internal Surface Roughness on the Decompression Wave Speed in Natural Gas Mixtures
Authors: Botros K. K. , Carlson Lorne , Rothwell Brian , Venton Philip
Published: July 2013

GASDECOM is typically used in the design of gas pipelines for calculating decompression speed in connection with the Battelle two-curve method used throughout the pipeline industry for the control of propagating ductile fracture. GASDECOM idealizes the decompression process as isentropic and one-dimensional, taking no account of pipe wall frictional effects. Previous shock tube tests showed that decompression wave speeds in smaller diameter and rough pipes are consistently slower than those predicted by GASDECOM for the same conditions of mixture composition and initial pressure and temperature. Preliminary analysis based on perturbation theory and the fundamental momentum equation showed a correction term to be subtracted from the ‘ideal’ value of the decompression speed. One parameter in this correction term involves a dynamic spatial pressure gradient of the outflow at the rupture location. While this is difficult to obtain without a shock tube or actual rupture test, data from 14 shock tube tests, as well as from 14 full scale burst tests involving a variety of gas mixture compositions, were analyzed to quantify the variation of this pressure gradient with gas conditions and outflow Mach number. A semi-empirical relationship was found to correlate this pressure gradient parameter with two basic parameters representing the natural gas mixture, namely the molecular weight of the mixture and its higher heating value (HHV). For lean gas mixes, the semi-empirically obtained correlation was found to fit very well the experimentally determined decompression wave speed curve. For rich gas mixes, the correlation fits both branches of the curve; above and below the plateau pressure.

This paper provides the basis for the derived semi-empirical correlation, and suggests a procedure (with examples) to correct the ‘ideal’ (frictionless) GASDECOM prediction to account for both the effects of pipe diameter and pipe internal wall surface roughness.
Design and Application of Monitoring Device for Valve Chamber
Authors: Cai Yongjun , Tan Dongjie , Chen Pengchao , Li Zhengbin , Zhao Yingbo , Jin Shijiu
Published: July 2013

There are a lot of valve chambers without protective measure along oil & gas pipeline. The interval of valve chamber is usually about thirty kilometers. Patrol is the main and only method in security protect, there are no technologies in valve chamber guard. Operator can’t ensure valve chamber under the controlled condition all the time. It’s a potential safety hazard.

One kind of monitoring device was designed for valve chamber security protection. Image and combustible gas concentration can all be obtained by this monitoring device. Pyroelectric infrared sensor and Microwave sensor combined are used for theft-proof so as to realize automatic detection and pre-warning. Once illegal intrusion is detected or combustible gas concentration exceed standard, the monitoring device would be activated. It takes a Snapshot of the valve chamber and sent the field image to administrators by MMS (Multimedia Messaging Service).
Fatigue Life Assessment for NPS30 Steel Pipe
Authors: Silva Jorge , Ghaednia Hossein , Das Sreekanta
Published: July 2013

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Aging and corrosive environment may lead to formation of various defects such as crack, dent, gouge, and corrosion. The performance evaluation of field pipelines with crack defect is important. Accurate assessment of crack depth and remaining fatigue life of pipelines with crack defect is vital for pipeline’s structural integrity, inspection interval, management, and maintenance. An experimental based research work was completed at the University of Windsor for developing a semi-empirical model for estimating the remaining fatigue life of oil and gas pipes when a longitudinal crack defect has formed. A statistical approach in conjunction with fracture mechanics was used to develop this model. Statistical analysis was undertaken on CT specimen data to develop this fatigue life assessment model. Finite element method was used for determining the stress intensity factor. The fatigue life assessment model was then validated using full-scale fatigue test data obtained from 762 mm (30 inch) diameter X65 pipe. This paper discusses the test specimens and test data obtained from this study. Development and validation of the fatigue life assessment model is also presented in this paper.
Research on Infrared Laser Leak Detection for Natural Gas Pipeline
Authors: Xu Bin , Yu Dongliang , Wu Jiayong , Wang Hongchao , Tan Dongjie , Wang Likun
Published: July 2013

An airborne infrared laser leak detection technology is proposed to detect natural gas pipeline leakage by helicopter which carrying a detector that can detect a high spatial resolution of trace of methane on the ground. The principle of the airborne infrared laser leak detection system is based on tunable diode laser absorption spectroscopy. The system consists of an optical unit including the laser, camera, helicopter mount, electronic unit with GPS receiver, a notebook computer and a pilot monitor. And the system is mounted on a helicopter. The principle and the architecture of the airborne infrared laser leak detection system are presented. Field test experiments are carried out on West-East Natural Gas Pipeline of China, and the results show that the airborne laser leak detection method is suitable for detecting gas leak of pipeline on plain, desert and hills but unfit for the area with large altitude diversification.
Meeting the New Regulatory Requirements for Pipeline Control Room Management
Authors: Kieba Max , Coy Byron
Published: July 2013

The U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) has amended the U.S. pipeline safety regulations to prescribe safety requirements for controllers, control rooms, and Supervisory Control and Data Acquisition (SCADA) systems used to remotely monitor and control pipeline operations. The objective of Control Room Management (CRM) is to help assure the controllers will continue to be successful in maintaining pipeline integrity and safety, and help reduce the number and consequences of shortfalls in control room management practices and operator errors when remotely monitoring and controlling pipelines and responding to abnormal and emergency conditions. CRM helps to address this by prescribing safety requirements intended to verify that procedures, systems, and equipment are well thought out and function as intended. CRM also intends to help assure that pipeline operators are addressing human fatigue risks and other human factors inside the control room that could inhibit a controller’s ability to carry out the roles and responsibilities the operator has defined for the safe operation of the pipeline. This paper will go over the background and elements of the rule, additional guidance and resources that have been provided publically, and lessons learned through the development and roll out of the new requirements.
Effect of Taper Angle on Plastic Collapse of Pipe Joint With Different Wall Thickness and Strength
Authors: Baek Jong-hyun , Kim Young-pyo , Kim Woo-sik
Published: July 2013

The plastic collapse behavior of the pipelines with the different wall thickness and different strength was evaluated by using the finite element analyses. Joint designs of the API X65-API X80, API X42-API X65 and API X42-API X80 were employed to investigate the plastic collapse under tensile, internal pressure or bending load.

The wall thickness ratios of the pipe joint combinations with an outer diameter of 762 mm (30 inch) were 1.22, 1.54 and 1.89. End face of the pie joint with the different wall thickness was machined with a taper angle between 4° ∼ 45° along the longitudinal direction of the lower strength and thicker pipe.

A parametric study was shown that the tensile strength and moment of the pipe joint with the wall thickness ratio less than 1.5 were not influenced by the wall thickness ratio and taper angle; however those of the pipe joint with the wall thickness ratio more than 1.5 considerably decreased at the low taper angle. The failure pressure of the pipe joint with the different wall thickness was not influenced by the wall thickness ratio and taper angle.
Application of Laser Profilometry for Fitness-for-Service Assessment on Pressure Vessel External Corrosion
Authors: Nelson Grant , Bradley Ian , Fingerhut Martin , Yu Deli
Published: July 2013

In order to safely extend the life of damaged in-service components, Fitness-For-Service (FFS) assessments are used to evaluate structural integrity. These FFS assessments largely depend upon the quality of the inspection data. Compared to traditional inspection methods such as pit gauge or ultrasonic techniques, laser profilometry provides faster results with higher resolution and accuracy. Improved inspection data enables more precise FFS assessments and leads to fewer unnecessary repairs and non-conservative assessments.

This paper examines how laser profilometry measurements were taken of several corrosion areas on the exterior shell of a pressure vessel in order to complete a FFS assessment equivalent to an API 579 Level 2 assessment. The results of the FFS assessment show how laser profilometry data may be used in a detailed structural integrity analysis to consider a vessel safe for continued use. A discussion of how laser profilometry data could also be used for an API 579 Level 3 assessment, using finite element analysis, in areas not acceptable for Level 1, or 2 assessments is included.
Modelling of Wind Turbine Fall-Induced Vibrations Near Buried Steel Transmission Pipelines: An Updated RAMCES Software Extension
Authors: Fernandez Charles , Bourgouin Laurent , Riegert Frederic , Pecker Alain
Published: July 2013

At CRIGEN, the GDF SUEZ research center for gas and new energies, a project on risk management on gas infrastructures (MARTHO project) is aimed, among other goals, at protecting the pipelines against external aggressions such as vibrations. Over the past few years, extensive construction of wind turbines has taken place all around the world in areas where many steel pipelines are already buried. The possible fall of these heavy machines may induce damageable vibrations to the pipeline. The common threshold used by the industry, established by the American Gas Association, is stated at PPV ≤ 50 mm.s−1. A more accurate and less conservative model of vibration propagation has been developed and validated by extensive field measurements coupled with a nonlinear 2D-finite element model for the soil. An experimental soil characterization through MASW tests coupled with vibration measurements was performed in a representative soil. As a result, safety distances between wind turbines and pipelines were considerably shortened compared to the previous model. The updated model is now part of the RAMCES software which has been developed for more than a decade at CRIGEN and is widely used in France by transmission operators.
A Bayesian Approach to Assessment of In-Line-Inspection Tool Performance
Authors: McCann Roger , McNealy Richard , Haines Harvey
Published: July 2013

This paper discusses a method based on Bayes’ Theorem to estimate the probability that performance of an In-Line-Inspection tool satisfies stated sizing accuracy specifications. This leads to a new method for accepting or rejecting tool performance that is entirely different from methods based on confidence intervals.
The Flexural Behavior of Buried Steel and Composite Pipes Pulled Relative to Dense Sand: Experimental and Numerical Investigation
Authors: Almahakeri Mohamed , Moore Ian D. , Fam Amir
Published: July 2013

The flexural behavior of flexible buried pipelines subjected to lateral earth movements is investigated. Two types of pipeline materials, steel and then glass-fiber reinforced polymers (GFRP), are examined. Bending tests are conducted, where two parallel cables attached to a hydraulic actuator load the buried pipe. The study investigated three burial depth-to-diameter ratios (H/D = 3, 5, and 7) representing shallow to deep burial depths commonly used in energy pipeline construction. A three dimensional finite element model for this loading case has also been developed. Data from the numerical simulations are presented and compared to the experimental measurements. This paper provides an overview of the outcomes for this project. For example, while soil resistance was very similar for the two pipe types, the GFRP pipes demonstrated superior flexibility in longitudinal bending compared to the steel pipe. Furthermore, the finite element analyses were able to depict both this similarity in soil resistance, and the significant difference in flexural behavior of the two different pipe materials, the same phenomena observed during testing.
Non-Standard HIC and SSC Testing Under More Severe Test Conditions
Authors: Schmidt Tanja , Haase Thomas , Bosch Christoph
Published: July 2013

The challenging environment appearing in recent and moreover future deep offshore explorations promoted the development of linepipe steel grades with reliable sour service resistance. Severe sour conditions such as the combination of elevated production temperature, increasing pipeline pressures and high stress loads initiated by modern laying methods or introduced during service are leading to increasing corrosion demands. Steel pipelines used for the transport of media containing wet Hydrogen Sulphide (H2S) are faced with the danger of the cracking phenomena HIC (Hydrogen Induced Cracking) and SSC (Sulphide Stress Cracking). To prove resistance to HIC and SSC, test specimens are typically tested according standardised test methods. The exposure of test specimens in a sour test solution to a H2S pressure of 1 bar for 96 h, as described in NACE TM0284 is used to prove HIC resistance. Commonly four-point bend testing as described in EFC publication no. 16 is performed for SSC resistance testing with the appliance of a specific load, typically 80% of the actual yield strength.

Within this work HIC testing at test conditions representing higher H2S partial pressures (up to 5 bar) and longer test durations (up to 6 months) have been performed on seamless quenched and tempered line pipe steel of grade X65 and X70 produced by VALLOUREC & MANNESMANN TUBES by plug and continuous mandrel mill process. Beside material in as delivered condition also pre-strained material was tested. SSC four-point bend testing has been performed on specimens which were strained up to 10% of plastic strain in longitudinal direction.
Quantitative HAZOP Risk Analysis for Oil Tanks Using the Fuzzy Set Theory
Authors: Cao Tao , Zhang Huabing , Zheng Honglong , Yang Yufeng , Wang Xin
Published: July 2013

Oil storage tanks are identified as the major hazard installations because of the hazard of huge fire & explosion. Evaluating the risk and controlling the danger is the advancement of accident prevention and the compulsory requirement of laws. HAZOP (Hazard and Operability Analysis), is a simple but intensive, systematic, qualitative risk analytical method, is an important technique for the identification of hidden hazards in operation of tank facility. It can only qualitatively account for potential risks, but cannot quantify their possibility and severity. Thus, research involving HAZOP quantitative analysis has become an area of focus. Due to uncertainty of deviation probability in the traditional HAZOP analysis, this paper discusses a new approach of HAZOP quantitative analysis, combining HAZOP with fuzzy set theory to calculate the possibilities of deviation and consequence quantitatively. The evaluation process and technique route of risk analysis is also brought forward in this paper.

Based on the traditional HAZOP analysis, the typical outputs of a HAZOP analysis can be achieved, including identification of possible deviation states, identification of the possible causes for deviations and probable worst case consequence. Next, according to fuzzy evaluation of some HAZOP experts on deviation by means of their knowledge, the triangular fuzzy-number is introduced in this paper to conduct quantitative calculation. Based on the fuzzy set theory, combining Delphi method and judging matrix method, the linguistic values are transformed into triangular fuzzy numbers. The probability of deviation is evaluated by fuzzy cut and raking method of fuzzy numbers. Finally, the probability of consequence caused by deviation is evaluated.

A complete quantitative risk analysis example for oil tank is conducted, the probabilities of deviations and incident consequence are computed, the quantitative risk is determined and reasonable mitigations of the storage tanks are given. It is shown that the proposed approach is advanced and practicable to make a quantitative assessment on the risk of existing deviation, which is helpful for risk managers to bring forward the suggested measure and regulate the hidden hazards.
Development of Offshore X65/70 Steels for Deep Water Application
Authors: Ro Yun-Jo , Chon Seung-Hwan , Yoo Jang-Yong , Kang Ki-Bong
Published: July 2013

Heavy gauge X65/70 steels have been developed for deep-water offshore application. As the thickness of linepipe steels is increased, Mo, Ni, V alloying elements are generally employed to improve the low temperature toughness and strength balance. However, the price of such alloying element has been rapidly increased. Hence, in the present work, a lean composition is designed to achieve thick X65/70 grade steels with better strength and toughness balance. To prevent the degradation of toughness or strength due to a lean alloying composition, the authors optimize processing parameters, such as a rolling stop temperature or accelerated cooling patterns. By in large, two strategies have been applied to develop linepipe steels; i) cooling starts in γ + α region, and iii) rolling stops in γ + α region. These strategies promote ferrite+bainite dual phase microstructures exhibiting a good low temperature toughness and strength balance. Such dual phase microstructures are characterized by using EBSD (electron back scattered diffraction) technique. The result shows a percentage of DWTT shear area is strongly correlated with effective grain size (misorientation ≥ 15°). As a result, the present work demonstrates that heavy gauge API steels grade X65/70 can be achieved with Mo+V free or small addition of Mo alloying elements.
Achieving Dependability Value for Pipelines and Facilities
Authors: Van Hardeveld Thomas , Kiang David
Published: July 2013

In today’s competitive and changing environment, it is crucial that pipelines and associated facilities create and sustain value for their stakeholders. This value can only be achieved by incorporating dependability into the pipeline system, in whole or in part. Dependability characteristics address not just availability and reliability as the probability of successful performance, but also identify other potential risk exposures such as degradation and wear-out that advocate the need for maintenance and logistic support to sustain “problem free” pipeline and facility operation. Dependability engineering provides practical means and measurable targets for achieving value, which are then implemented by sound operational risk assessment practices. Dependability management is needed to present viable business success options on risk avoidance, prevention, and mitigation; and where applicable, provides cost-effective risk treatments to support pipeline operation and enhance facility management. Characterizing the value of dependability focuses on two key issues: (1) what is the value of dependability, and (2) what is required to achieve it. This paper establishes a unified approach for understanding the dependability principles and practices, and enunciates how dependability value can be ascertained and assured in real life situations. It presents a general framework and provides implementation guidelines for ensuring that dependability value can be achieved in practical application for pipelines and facilities.
Performance Degradation Monitoring of Centrifugal Compressors Using Deviation Analysis
Authors: Jasmani Mohd Shahrizal , Van Hardeveld Thomas , Bin Mohamed Mohd Faizal
Published: July 2013

Performance degradation monitoring of centrifugal compressor provides a means for the operators predict the behavior of their machines. Understanding the key principles in performance evaluation is essential for operators to benefit from this approach. In this paper, common performance degradation mechanisms found in centrifugal compressors for the oil and gas industry are outlined and related to their associated performance characteristics. Various analysis and evaluation techniques and approaches are elaborated with relevant requirements and assumptions for practical site application. A case study is also presented to demonstrate the application of performance degradation monitoring in a real-life operating environment. The benefits and limitations of the approach are also discussed. When combined with other condition monitoring approaches, this method provides a powerful tool to analyze and monitor centrifugal compressor performance which will then lead to useful recommendations for maintenance and operational interventions.
Multiple Data Set ILI for Mechanical Damage Assessment
Authors: Goller Chris , Simek James , Ludlow Jed
Published: July 2013

The purpose of this paper is to present a non-traditional pipeline mechanical damage ranking system using multiple-data-set in-line inspection (ILI) tools. Mechanical damage continues to be a major factor in reportable incidents for hazardous liquid and gas pipelines. While several ongoing programs seek to limit damage incidents through public awareness, encroachment monitoring, and one-call systems, others have focused efforts on the quantification of mechanical damage severity through modeling, the use of ILI tools, and subsequent feature assessment at locations selected for excavation. Current generation ILI tools capable of acquiring multiple-data-sets in a single survey may provide an improved assessment of the severity of damaged zones using methods developed in earlier research programs as well as currently reported information. For magnetic flux leakage (MFL) type tools, using multiple field levels, varied field directions, and high accuracy deformation sensors enables detection and provides the data necessary for enhanced severity assessments. This paper will provide a review of multiple-data-set ILI results from several pipe joints with simulated mechanical damage locations created mimicing right-of-way encroachment events in addition to field results from ILI surveys using multiple-data-set tools.
Reliability Scorecards for Operating Pipelines
Authors: Jones Brad , Ferrari André-Michel
Published: July 2013

Scorecards are generally used to track operational performance in various fields of work and direct the management team toward correcting the observed deviations. Generally, a Scorecard is made up of specific metrics which have been carefully identified against defined operating objectives. In this paper, the Scorecard examined uses a reliability growth indicator in combination with other traditional factors to measure speed of progress to a target level. As a leading liquid pipeline operator, Enbridge Pipelines Inc. (hereafter “Enbridge”) holds established and comprehensive management systems governing all aspects of its operations. In essence the Reliability Scorecard adds enhanced capabilities to the existing systems.

In September 2010, using current throughput performance and failure historical data, the Reliability Team in Enbridge developed a quarterly Reliability Scorecard for its pipeline network. Metrics for each pipeline consisted of utilization, adherence to shipping schedules and a unique reliability growth indicator of the overall line as well as the top ten failure modes. This enabled not only the tracking of performance levels but also the direction and speed of improvement or decline in those metrics. The analysis was conducted using the Crow-AMSAA Analytical Process. Using the throughput impact (e.g. barrels not shipped), level of reliability performance and magnitude of reliability improvement for each failure mode on all pipelines, it became easy to select targets for improvement. Unacceptable deviations were those having more than a 10% share of throughput volume impact per failure mode combined with a Crow AMSAA growth factor (Beta) of 1.2 or greater.

The advent of this Reliability Scorecard has improved the organizational focus on areas with greatest impact on pipeline performance and revenue generation. Having a solid indication of the issues affecting each pipeline system, the Reliability Team was able to target its efforts accordingly. For example, for a specific high impact failure mode, a formal Root Cause Analysis would be conducted to identify the causes and implement a corrective action plan. Additionally, systematic lack of improvement for one failure mode over multiple quarters would be shared with relevant teams as awareness of specific threats to performance in their area.

In essence, if well-defined and accepted, an effective Scorecard can be a powerful driver for improvement in an organization. It can assist in channeling the efforts of individuals, departments or the overall organization in addressing real threats to performance specific fields. Management can also use this tool to justify where appropriate resources need to be allocated. Finally, as demonstrated in this case, in addition to traditional operational targets, an improvement or regression factor can also be used to measure the progress or decline of specific scorecard metrics.
DEH Cable System Preventive Protection With Distributed Temperature and Strain Sensors
Authors: Ravet Fabien , Børnes Atle , Borda Carlos , Tjåland Even , Hilde Halfdan , Niklès Marc
Published: July 2013

Hydrate and wax formation in subsea flowlines is a major cause of production impairment. Among various approaches used to minimize the risk, Direct Electrical Heating (DEH) is being applied. DEH is based on passing a current through the pipe wall to mitigate heat losses from the fluid to the surroundings during events which require flow assurance measures. The Piggyback Cable, a high voltage cable attached to the DEH pipeline, is during operation exposed to thermal and mechanical loads which may be critical for the integrity of the DEH system. The overall safety requirement is that any potential Piggyback Cable fault is detected and disconnected from the power source before damage is caused to the pipeline.

Conventional cable fault detection methods based on current measurements give adequate protection for the main part of the pipeline. However, for the far end of the Piggyback Cable complementary fault detection is required. A method based on fiber break monitoring has been qualified for this purpose. The new method is implemented in the North Sea on two DEH pipelines operated by Statoil, 43 and 21 km long respectively. The protection is facilitated by standard single-mode fibers integrated into the DEH cables.

Although not basis for the design the integrated fibers open up possibilities for temperature and strain sensing using stimulated Brillouin scattering. Sensing has been performed on a 43 km DEH pipeline using the DITEST AIM (Distributed Temperature and Strain Asset Integrity Monitoring). Analysis of the sensing results reveal that distributed fiber optic sensing is capable of pin-pointing thermal events and strain induced loads for an object of this length.
Upheaval Buckling of Small Diameter Pipelines Induced by Strong Ground Shaking
Authors: Horikawa Hiroyuki , Tsunasawa Yoji , Shinkai Hajime , Suzuki Nobuhisa
Published: July 2013

Upheaval buckling of small diameter gas pipeline occurred due to strong seismic excitation during the 2007 Niigata-ken Chuetsu-Oki earthquake whose diameters were 4″ and smaller. This paper deals with investigation of the upheaval buckling of gas pipes conducted by Ministry of Economy, Trade and Industry of Japan to establish seismic design guidelines to mitigate upheaval buckling.

Sand box and field tests were conducted using small diameter pipes to simulate the upheaval buckling behaviors and construct a simple finite element model. The results clarified that the tensile properties of pipe material and pipe-soil interaction were the most effective parameters to explain the buckling behaviors.

Interaction curve of pipes can be found in the relationship between compression and bending moment in the combined loading tests. The deformation behaviors of the buried pipe tests followed the interaction curve and local buckling of buried pipes occurred in lower bending moment than that of pipes not buried.
Steel Catenary Risers at Touchdown Zone: A Fluid Dynamics Approach to Understanding the Water-Riser-Soil Interaction
Authors: Fouzder Anup , Zakeri Arash , Hawlader Bipul
Published: July 2013

The critical location for fatigue damage in Steel Catenary Riser’s (SCR’s) often occurs within the Touchdown Zone (TDZ), where cyclic interaction of the riser with the seabed takes place. Riser-fluid-soil interaction at the TDZ is a complex phenomenon. In this study, Computational Fluid Dynamics (CFD) technique is used to investigate the velocity field and suction forces during riser-fluid-soil interaction for a two-dimensional cross section of 0.10 m diameter SCR at TDZ. Numerical simulation shows that the suction forces at the bottom of the riser are high enough to pull the clay upward when it departs from the seabed during the heave action. The influence of suction and water on trench formation mechanism is discussed.