bluuebunny/crossref_metadata_2025 huggingface dataset:
The First L555 (X80) Pipeline in Japan
Authors: Matsuhiro Yoshiyuki , Oguchi Noritake , Kurumura Toshio , Hamada Masahiko , Takahashi Nobuaki , Shirahama Atsuhi
Published: July 2013

The construction of the first L555(X80) pipeline in Japan was completed in autumn, 2011.In this paper, the overview of the design consideration of the line, technical points for linepipe material and for girth welds are presented.

In recent years the use of high strength linepipe has substantially reduced the cost of pipeline installation for the transportation of natural gas. The grades up to L555(X80) have been used worldwide and higher ones, L690(X100) and L830(X120), e.g., are being studied intensively. In the areas with possible ground movement, the active seismic regions, e.g., pipeline is designed to tolerate the anticipated deformation in longitudinal direction.

In Japan, where seismic events including liquefaction are not infrequent, the codes for pipeline are generally for the grades up to L450(X65). Tokyo Gas Co. had extensively investigated technical issues for L555(X80) in the region described above and performed many experiments including full-scale burst test, full-scale bending test, FE analysis on the girth weld, etc., when the company concluded the said grade as applicable and decided project-specific requirements for linepipe material and for girth weld.

Sumitomo Metals, in charge of pipe manufacturing, to fulfill these requirements, especially the requirement of round-house type stress-strain (S-S) curve to be maintained after being heated by coating operation, which is critical to avoid the concentration of longitudinal deformation, developed and applied specially designed chemical composition and optimized TMCP (Thermo-Machanical Control Process) and supplied linepipe (24″OD,14.5∼18.9mmWT) with sufficient quality. It had also developed and supplied induction bends needed with the same grade.

Girth welds were conducted by Sumitomo Metal Pipeline and Piping, Ltd and mechanized GMAW (Gas Metal Arc Welding) was selected to achieve the special requirements, i.e., the strength of weld metal to completely overmatch the pipe avoiding the concentration of longitudinal strain to the girth weld, and the hardness to be max.300HV10 avoiding HSC (Hydrogen Stress Cracking) on this portion. Both of RT (Radiographic Test) and UT (Ultrasonic Test) were carried out to all the girth welds. These were by JIS (Japan Industrial Standards) and the project-specific requirements.
The 2D Spring Splines Procedure Application With Prescribed Accuracy for Determination of the Global (Pipe Centerline) as Well as the Local (Dent) Curvatures
Authors: Orynyak I. V. , Bohdan A. V. , Lokhman I. V.
Published: July 2013

The problem of smoothing the spatial line based on position measurements of discrete points exists in cases where a) the positions of points are determined with some errors, b) the goal of smoothing is not a continuous position itself but the higher derivatives of it. It is a very common problem in many engineering applications. With respect to the pipeline industry this problem is very prominent at least in two cases but regretfully many researchers do not pay due attention to it at all.

First, the Geopigs are widely used for the determination of spatial position of the pipe centerline points. This information inter alia may be (and in fact are widely) used for the calculation of the global centerline curvatures which are proportional to the global bending strains. Second, the maximum strain levels of the dents are calculated based on the local geometry of the dent as determined by radial sensor measurements from the in line inspection survey. Note, that in both cases mathematically the curvatures are the second derivatives of the function of global (pipeline) or local (dent) positions.

The input information about the global X–Y–Z position of each consecutive point of axis line as well as the local radial position of the dent points are given with some error. This leads to a huge noise in predicted curvatures which can overrun the useful information. The amplitude of errors of calculation is inversely proportional to the squared distance between the points of measurement. The application of any smoothing procedure may lead to the loss of the useful information about real curvatures. Thus tradeoff between the smoothing of the noise and the loss of accuracy presents a big problem in the pipeline industry.

Two quantitative parameters are introduced here to allow performing such a tradeoff. First parameter characterizes the standard deviation (also referred to as standard in the following) of the random value of the position measurement accuracy by the devices, ρ. Second parameter is the requested accuracy of the curvature determination and is defined in terms of the standard deviation of the bending stress, σ or strain, ε. The spatial beam on elastic foundation model is used to fit the measured point positions to the spatial curve. Its main characteristic is the specific compliance of the foundation α which is determined based on two above root-mean-square errors ρ and σ. The corresponding formulas and tables based on the solution for the elastic beam are obtained. The bigger the allowed error in bending stress σ the lesser is required compliance of the foundation, α. In turn this leads to the smaller value of characteristic wave length of solution and the possibility to retain more useful information about the actual short length stresses in the pipeline.

Some practical examples of applications of the procedure are given.
Constraint Effects on Ductile Crack Growth in SE(T) and SE(B) Specimens With Implications for Assessments of Tearing Resistance
Authors: Ruggieri Claudio
Published: July 2013

This work addresses a two-parameter description of crack-tip fields in bend and tensile fracture specimens incorporating the evolution of near-tip stresses following stable crack growth with increased values of the J-integral. The primary objective is to examine the potential coupled effects of geometry and ductile tearing on crack-tip constraint as characterized by the J-Q theory which enables more accurate correlations of crack growth resistance behavior in conventional fracture specimens. Plane-strain, finite element computations including stationary and growth analyses are described for SE(B) and clamped SE(T) specimens having different notch depth to specimen width ratio in the range 0.2 ≤ a/W≤0.5. A computational cell methodology to model Mode I crack extension in ductile materials is utilized to describe the evolution of J with Δa for the fracture specimens. Laboratory testing of an API 5L X70 steel using deeply cracked C(T) specimens is used to measure the crack growth resistance curve for the material and to calibrate the cell parameters. The present results provide additional understanding of the effects of constraint on crack growth which contributes to further evaluation of crack growth resistance properties of pipeline steels using SE (T) and SE(B) specimens.
Technical Challenges of a High Pressure Heavy Wall Hot Tap Connection on the Bord Gáis Éireann Brighouse Bay Project
Authors: Cotter Adrian , Boothby Peter
Published: July 2013

The UK onshore high pressure gas export terminal at Brighouse Bay in south west Scotland is a key strategic facility for Bord Gáis Éireann currently providing the predominant source of gas supply to Ireland via two interconnector pipelines that cross the Irish sea. A high design pressure of 150 barg combined with a low minimum design temperature (−30°C) has led to the use of heavy wall thickness station pipework, i.e. 508 mm outside diameter × 38.1 mm wall thickness ASTM A333 grade 6 (240MPa yield strength) seamless pipe. A requirement for a new hot tap connection at Brighouse Bay to improve security of supply identified several issues that needed to be addressed. Firstly, the normal UK requirement for 2 × carrier pipe thickness for the shell of the full encirclement split tee for the main branch connection could not be achieved due to the impracticality of rolling 76.2 mm thickness material to an internal diameter of only 508 mm to match the carrier pipe. Consequently there was concern that the area replacement ratio achieved by use of a thinner fitting may not be adequate for any additional site specific system loading despite meeting the ASME B31.3 code. Furthermore, the pressurised circumferential fillet welds made between the split tee and the carrier pipe may not be of sufficient size in view of the restricted leg length and hence resultant reduced fillet weld throat thickness. The parameters for the Brighouse Bay pipework in term of pipe material specification, pipe wall thickness and design pressure were also outside the range for which the existing UK hot tap welding procedure had been qualified. Hence a hot tap simulation assembly would need to be fabricated to qualify the welding procedure. In addition, the 38.1mm thickness Brighouse Bay pipework required PWHT in accordance with the ASME B 31.3 design code, but PWHT was not feasible for the hot tap connection. Hence there would be a need to demonstrate adequate toughness and fitness for purpose in the as welded condition. The paper describes the detailed approach taken to address these concerns which included preliminary on-site material sampling and NDE, evaluation and assessment of the project pipe and fitting materials requirements, pipework stress analysis, finite element analysis and engineering critical assessment of the split tee connection, and hot tap weld procedure qualification. The paper concludes by describing the successful hot tap installation phase of the project.
Determination of Significant Risk Threshold of Upstream Pipelines
Authors: Lu Hong
Published: July 2013

The pipeline risk assessment has been part of the integrity management in the industry in today’s environment of increasing regulatory and public oversight. One of the widely used risk assessment method is the score index method. This method has been used for more than two decades and is widely accepted in the pipeline industry. The input data is relatively easy to acquire. The method provides details of mitigation options and relative risk values. However, this method does not provide the simple decision making process.

In risk management, it is always the question to choose the most cost effective mitigation option to use limited resources. On the basis of score index risk assessment method, a method to correlate the probability of failure score with actual failure probability, and leak impact factor score with actual failure consequence in monetary units has been developed. This method applies the monetarily calibrated consequence factor to the probability of failure to obtain a normalized and calibrated risk in monetary unit. By comparing the cost of an estimated mitigation program, the decision can be made.

Recent regulations in Canada require that risk assessment must have a method to determine the significant risk threshold. Even though some industrial standards have some recommended methods or benchmark data for failure probability, there is no published method to determine the threshold of high risk. Some pipeline companies have the in-house personnel to develop an advanced method to meet regulation requirement. However, many pipeline companies need to have a practical and economical method to determine the significant risk threshold to meet regulation requirement, and to effectively allocate resources. This paper develops a method to determine the significant risk threshold that can be used as a decision-making criterion in pipeline risk management.

This process is practical for industrial application, especially for upstream companies where operators have limited resources for advanced risk assessment. A case study is presented using this method based on upstream pipelines.
Tools and Methods for Internal Pipe Coating Evaluation for Gas Transmission Systems
Authors: Botros K. K. , Piazza M. , Abayarathna D.
Published: July 2013

The option of internally coating a new pipeline, or a section of an existing pipeline has emerged in recent years as competition in the energy marketplace grows more intense and coating technologies have advanced from 100% solvent-base to 100% dry-based. Internally coated pipes would mean additional capital cost, but will result in lower pressure losses, hence lower compression power, lower fuel consumption and lower emission. Therefore, there is a trade-off that needs to be assessed, which is the subject of the present paper.

The present paper first provides a proposed standardized method to report the internal wall roughness parameters that could be used to compare bare vs. different coating technologies in a consistent manner. The second part of the paper focuses on evaluating the impact and performance of internal coatings on flow efficiency in energy transmission pipeline systems. A tool and methods were developed to evaluate all of the various options specific to internal pipe coating (including bare pipe option) using a Life Cycle Cost (LCC) economic tool developed for this purpose. The incremental Cumulative Present Value Cost of Service (iCPVCOS) associated with the application of the various coating technologies, as well as quantification of the relative benefits of each compared to a bare pipe, are the main outcome of the tool. This provides an impetus to sound design and selection of the most cost effective technology for internally coating the pipes, whether for new or existing pipeline systems. Examples of various scenarios involving a 2900 km pipeline coated using different internal coating technologies are discussed.
Development of Laminar Plasma Shielded HF-ERW Process: Advanced Welding Process of HF-ERW 3
Authors: Hamatani Hideki , Watanabe Funinori , Mizuhashi Nobuo , Takeuchi Sunao , Hirota Yoshiaki , Matsubayashi Shigeharu , Tsukakoshi Kazumoto , Hasegawa Yasushi , Asano Takuya , Motoyoshi Takashi , Miura Takao , Tanaka Kimiharu , Yamamoto Kazuto , Nose Tetsuro , Solonenko Oleg P. , Smirnov Andrey V.
Published: July 2013

High frequency - electric resistance welded (HF-ERW) pipe has been successfully used for many years for a number of applications. The benefits of HF-ERW pipe are considerable, including a higher dimensional tolerance and lower prices than seamless pipe and UO pipe. The conventional weld seam produced by HF-ERW, however, often has a relatively low toughness. We have developed an automatic heat input control technique based on ERW phenomena that relies on optical and electrical monitoring methods and has been shown to result in a significant improvement in the toughness. Shielding of the weld area must also be considered as a key factor in the formation of a sound weld. It has been shown that an inert cold gas (e.g., at room temperature) shielding technique is effective for maintaining a stable low oxygen state in the weld area that inhibits the formation of penetrator, a pancake oxide inclusions. Compared to the cold gas shielding technique, high temperature gas shielding, due to its higher kinetic viscosity coefficient, should make it easier to sustain a higher laminar flow, thus leading to a rather low air entrainment in the shielding gas. In addition, plasma is a much higher temperature state (∼6000 K), and the dissociated gases can react with the entrained oxygen; plasma jets should, therefore, enhance the overall shielding effects. Moreover, oxides on the strip edges can be expected to melt and/or be reduced by the high temperature plasma jets. Nippon Steel has developed a plasma torch that can generate a long and wide laminar argon – nitrogen – (hydrogen) jet. This paper describes the results obtained from our investigation of the effects of a plasma jet shield on the weld area of high strength line pipe with a yield strength grade of X65. Preliminary attempts in applying this novel shielding technique has been found, as expected, to demonstrate extremely low numbers of weld defects and a good low temperature toughness of the HF-ERW seam.
Evaluation of Leak/Rupture Behavior for Axially Part-Through-Wall Notched High-Strength Line Pipes
Authors: Amano Toshihiko , Makino Hiroyuki
Published: July 2013

Concerning the fracture assessment of high strength linepipes for natural gas transportation, it is necessary to take into consideration not only the crack arrestability of running ductile fractures but also the characteristics of ductile fracture initiation from defects which can cause fracture propagation. The original leak/rupture criteria proposed by Kiefner et al. have been widely used in many industries and worked well for ordinary grade pipes. However, as pointed out by D.-J. Shim et al., recent modern line pipes have some unusual characteristics that differ from older materials. Kawaguchi et al. also revealed that the leak/rupture prediction using Charpy V-notch (CVN) absorbed energy-based equation was not applicable to pipes having CVN energy (Cv) greater than 130 J and flow stress greater than X65.

To verify the leak/rupture criteria using CVN absorbed energy-based equation for high strength linepipes with higher Charpy energy, hydrostatic burst tests were conducted for API 5L X100 linepipes with an axial part-through-wall (PTW) notch. Based on the relationship between the axial PTW notch length/depth and hoop stress, Leak-Before-Break (LBB) criteria was experimentally determined. A series of tests demonstrated that the CVN-based equation underestimates the failure stress for X100 linepipes i.e., the predicted failure stress is 0.943 times the experiment on average and the flow stress dependent equation has a tendency to overestimate the failure stress for longer notched pipes. Concerning the leak/rupture behavior, it is observed that the flow stress-dependent curve for through-wall (TW) notch overestimates the leak/rupture boundary and the toughness-dependent curve for TW notch is relatively close to the leak/rupture boundary.
Failure Investigation of a Natural Gas Transmission Pipeline
Authors: Chauhan Vinod , Fordyce Ian , Gilliver James , Peravali Sudhakar , Connell Andrew , Thompson Ian , Saleh Hadi , Ng Paul , Laksana Arie , Lalan Dadang , Komaruddin M.
Published: July 2013

PT Transportasi Gas Indonesia (TGI) own and operate a 536 km long natural gas pipeline in South Sumatra, Indonesia which transports natural gas from ConocoPhillips’s gas field in Grissik, South Sumatra to Chevron Pacific Indonesia’s station facilities in Duri. On 29th September 2010, an event occurred that resulted in a release of gas from the pipeline. In response to the emergency, the affected section of the pipeline was isolated by closing block valves upstream and downstream of the leak. The incident was brought under control by TGI on the same day and there were no reported injuries or fatalities. Failure was located in a girth weld on a 28 inch diameter pipe section, which had spread into the adjacent pipe material. Subsequently a failure investigation was requested by TGI. The investigation included a fracture examination and materials testing of the failed girth weld and parent pipe; a geotechnical investigation; and an engineering critical analysis (ECA) of the failure. This paper describes the multidisciplinary works undertaken to investigate the cause of the incident.

The primary observation of this failure investigation is that no single factor contributed to the failure that occurred. The pipeline at the rupture location had been subjected to high bending stresses when the pipeline was laid and the stresses were exacerbated following consolidation and creep settlement of the underlying swamp material. The field joint coating had been compromised, leading to the formation of near neutral stress corrosion cracking (SCC). Initial cracking from the SCC had then extended to the point where the remaining ligament then failed by plastic collapse. It was judged that the settlement may also have been enhanced by a recent earthquake.
Essential Elements of an Effective SCC Direct Assessment Program
Authors: Rapp S. C. , Marr J. E. , Martinez F. H. , Vervake G. , Batte A. D.
Published: July 2013

Stress Corrosion Cracking (SCC) Direct Assessment in accordance with the guidance set out in NACE SP0204 is an accepted method for assessing the threat of SCC in High Consequence Areas in the US, as prescribed for gas transmission pipelines by CFR 192 Sub-part O. Although operators have used excavations as part of their integrity management strategies for SCC for many years, the formalized method for gathering, interpretation and application of information that is set out in NACE SP0204 has only been applied for less than ten years.

During a recent Joint Industry Project involving eight major North American natural gas transmission operators, the current status and application of SCC Direct Assessment has been reviewed. Several of these operators have developed in-house procedures incorporating the relevant guidance from NACE, CEPA and ASME, and over 160 SCC Direct Assessment excavations in accordance with the requirements of NACE SP0204 have been undertaken during the last five years. This paper reviews the development of the procedures, their in-field application and the use of the interpreted data to further refine the SCC Direct Assessment processes.
Dynamic Behavior of Spring-Loaded Pressure Relief Valve: Numerical and Experimental Analysis
Authors: Carneiro Leonardo Motta , Pires Luis F. G. , de Souza Cruz Marcelo , Azevedo Luis F. A.
Published: July 2013

The majority of oil and refined-product pipelines in Brazil have their protection system designs based on spring-type pressure relief valves. Thus, the proper design and operation of these valves is essential to ensure the safety of transport pipelines and loading/unloading terminals during any abnormal operation conditions that generate a surge pressure. In simple terms, these valves have a disk which is pressed by a spring against the inlet nozzle of the valve. When the pressure rises, the force generated on the surface of the disc increases and, depending on the pressure relief valve set point, the force due to pressure overcomes the force exerted by the spring, causing the disk to rise and discharge the fluid through the outlet nozzle to the relief line, reducing the pressure level within the pipeline. Despite its importance, most commercial applications do not present a specific model to simulate the transient behavior of pressure relief valves. This paper presents an experimental study aimed at determining the dynamic behavior of a commercial spring-type relief valve. The valve was installed in a pipe loop instrumented with pressure and flow transducers. The transient motion of the valve disc was measured with a fast-response displacement transducer. The transient in the flow loop was generated by the controlled closing of a block valve positioned downstream of the relief valve. The recorded transient data for disc position, upstream and downstream pressures, and discharge flow rates were used to compute the discharge coefficient as a function of opening fraction and the opening fraction as a function of time. Simulation models based on a spring-mass damped system were developed and implemented in a PID-actuator-control valve system. The systems were implemented in a commercial pipeline simulation program modeling the experimental loop employed in the tests. The numerical and experimental data of the block valve closure transient were compared displaying good agreement. Simulations results employing a generic relief valve model frequently used in simulations were also obtained revealing problems associated with this approach.
Using Hardness to Estimate Pipe Yield Strength: Field Application of ASME CRTD - Vol. 91
Authors: Amend Bill
Published: July 2013

The mechanical properties of some operating pipelines are unknown or uncertain, yet pipe yield strength is a required input of design pressure calculations. ASME CRTD -Vol. 91 “Applications Guide for Determining the Yield Strength of In-Service Pipe by Hardness Evaluation: Final Report” [1] describes the means by which the lower bound yield strength of a pipeline segment can be determined based on nondestructive measurements of hardness in the field on randomly selected pipe joints. The procedure allows the lower bound limit of yield strength to be determined at a selected confidence level and with selected percentile limit of pipe that could have yield strengths lower than the calculated lower bound limit of yield strength.

Key steps in the process include:

• Preassessment to ensure that the pipeline segment includes pipe having consistent characteristics.

• Development of a qualified hardness testing procedure that replicates laboratory hardness test results.

• Qualification testing of the test technician.

• Adjustment of the data from randomly selected pipe joints to estimate the lower bound hardness of the pipeline segment.

• Determination of the lower bound yield strength for the pipeline segment based upon the calculated lower bound hardness.

This paper describes the key requirements of ASME CRTD - Vol. 91, the capabilities and limitations of the procedure for estimating yield strength from hardness, and the field application of the procedure.
An Experimental Study on J(CTOD)-R Curves of Single Edge Tension Specimens for X80 Steel
Authors: Wang Enyang , Zhou Wenxing , Shen Guowu , Duan Daming
Published: July 2013

Fracture toughness testing of SE(T) and SE(B) specimens is carried out to experimentally develop J(CTOD)-R curves for the X80 steel based on the unloading compliance method. Six clamped (two shallow-cracked side-grooved, two deep-cracked side-grooved, and two deep-cracked plain-sided) SE(T) and two shallow-cracked side-grooved SE(B) specimens are tested. The impact of crack length on the J(CTOD)-R curves of the SE(T) specimens is investigated. The J(CTOD)-R curves of the shallow-cracked SE(T) specimens are significantly higher than those of the deep-cracked SE(T) specimens once the crack extension exceeds 0.5 mm. A comparison of the J(CTOD)-R curves associated with the SE(B) and SE(T) specimens suggests that the crack tip constraint for the SE(T) specimens is lower than that of the SE(B) specimens with the same nominal initial crack length, and that shallow-cracked SE(T) specimens have less constraint at the crack tip than deep-cracked SE(T) specimens.
Model Error Assessment of Burst Capacity Models for Corroded Pipes
Authors: Zhou W. , Huang G. (Terry) , Zhang S.
Published: July 2013

The model errors associated with five representative burst pressure prediction models, namely B31G, B31G Modified, DNV, PCORRC and RSTRENG, for corroded pipelines are evaluated based on a relatively large number full-scale burst tests on corroded pipes reported in the literature. All the test specimens in the database contain single isolated real corrosion defects. The means, coefficients of variation (COVs) and probability distribution of the model errors for the considered burst capacity models are derived based on the test-to-predicted burst pressure ratios for the collected test data. A numerical example is used to illustrate the impact of the model error on the probability of burst of the corroding pipeline.
An Integrated Model to Predict Microstructure and Mechanical Properties in the Heat Affected Zone for X80 Linepipe
Authors: Poole W. J. , Militzer M. , Garcin T.
Published: July 2013

There is a complex interplay between welding procedures and the steel chemistry which determines the final engineering performance of the heat affected zone in a large diameter girth weld. This work uses a combination of experimentally determined thermal histories from laboratory scale single and dual torch multi-pass gas metal arc welding (GMAW) with phenomenological models to predict microstructure and mechanical properties in the heat affected zone (HAZ) of an X80 steel. The integrated model consists of sub-models for austenite grain growth, dissolution of Nb based precipitates and austenite decomposition. These models have been calibrated with detailed experimental studies using a Gleeble 3500 thermomechanical simulator. The models are fully integrated so that the austenite grain size and the Nb solid solution level are used as inputs into the austenite decomposition model where these two factors strongly affect the final microstructure. The decomposition model includes ferrite and bainite models with suitable criteria for transition from one model to the other and a simple first order empirical relation to predict the final fraction of martensite/retained austenite (MA). The integrated model has been applied to a variety of thermal scenarios which are derived from experimental measurements of thermal histories including dual torch conditions where, for example, the Nb solid solution level has to be tracked through both thermal excursions into austenite. Using the integrated model, microstructure maps of the HAZ can be generated for the different welding scenarios.
A Dynamic Simulation Study of Overpressure for Pigging Process
Authors: Deng Tao , Gong Jing , Li XiaoPing , Zhang Yu , Yao Yanan , Quan Qing
Published: July 2013

With the method of characteristic (MOC) and analysis for the dynamic state of trapped air, this study could be performed on the basic theory of gas-liquid two phase unsteady flow, and cavitation and bubble dynamics, to obtain the overpressure value during pigging. For a long slope pipeline, a severe rupture occurred in the vicinity of a drainage pipe during a segmental pigging process. In contrast to earlier accidents induced by hydraulic transients, the unique combination of topography and geometry of the drainage pipe was a key factor. Generally, a pipeline profile complexity has a significant effect on both the liquid-fill flow behavior and the state of trapped air, both of which are factors contributing to cavitation and water hammer. Pigging is a common technological process that has been studied for many years, but has rarely been analyzed by hydraulic transient methods with consideration for pig motion in a pipeline. From local data, it is shown that transient pig motion has a huge influence on operating conditions, especially outlet pressure. The purpose of this study was to identify the damage mechanism. Following extensive study, it was determined that cavitation and vapor cavity collapse cause instantaneous overpressure due to the interaction of topography, geometry of the drainage pipe, and pig motion. It would be rather difficult to simulate the pig motion by a conventional MOC and the simple water hammer equation for the collapse of large vapor cavities at a high point. Therefore, a new approach which describes the moving boundary with a dual-grid model has been implemented, along with an explicit solution procedure.
CEPA Development of a Metal Loss ILI Acceptance Procedure
Authors: Desjardins Guy , Sporns Ryan , Sahney Reena , Yip Joe
Published: July 2013

This paper presents guidelines to enable a pipeline operator to assess whether the results of a metal loss in-line inspection (ILI) should be deemed acceptable. Acceptance depends on passing two checks, Verification and Validation. Verification is the process which ensures that all planning, preparation, execution, and analysis of the inspection were conducted according to ILI vendor processes to meet specification and prescribed industry standards. It assumes that a successful run is a consequence of good planning, preparation, execution and analysis. Validation is the process by which the results of an ILI run are compared to independent measurements. The Validation process depends on the results of the ILI and available information. Passing both the Verification and Validation checks is required to accept of the ILI run.
Numerical Analysis of High Pressure Cold Bend Pipe to Investigate the Behaviour of Tension Side Fracture
Authors: Cakiroglu Celal , Komeili Amin , Adeeb Samer , Cheng J. J. Roger , Sen Millan
Published: July 2013

The cold bend pipelines may be affected by the geotechnical movements due to unstable slopes, soil type and seismic activities. An extensive experimental study was conducted by Sen et al. in 2006 to understand the buckling behaviour of cold bend pipes. In their experiments, it was noted that one high pressure X65 pipe specimen failed under axial and bending loads due to pipe body tensile side fracture which occurred after the development of a wrinkle. The behaviour of this cold bend pipe specimen under bending load has been investigated numerically to understand the conditions leading to pipe body tension side fracture following the compression side buckling. Bending load has been applied on a finite element model of the cold bend by increasing the curvature of it according to the experimental studies conducted by Sen [1]. The bending loads have been applied on the model with and without internal pressure. The distribution of the plastic strains and von Mises stresses as well as the load–displacement response of the pipe have been compared for both load cases. In this way the experimental results obtained by Sen [1] have been verified. The visualization of the finite element analysis results showed that pipe body failure at the tension side of the cold bend takes place under equal bending loads only in case of combined loading with internal pressure.
Application of FIB/SEM/EBSD for Evaluation of Residual Strains and Their Relationship to Weld Metal Hydrogen Assisted Cold Cracking
Authors: Costin W. L. , Brown I. H. , Green L. , Ghomashchi R.
Published: July 2013

Hydrogen assisted cold cracking (HACC) is a welding defect which may occur in the heat affected zone (HAZ) of the base metal or in the weld metal (WM). Initially the appearance of HACC was associated more closely with the HAZ of the base metal. However, recent developments in advanced steel processing have considerably improved the base material quality, thereby causing a shift of HACC to the WM itself.

This represents a very serious problem for industry, because most of the predictive methods are intended for prevention of HACC in the HAZ of the base metal, not in the weld metal [1].

HACC in welded components is affected by three main interrelated factors, i.e. a microstructure, hydrogen concentration and stress level [2–4].

In general, residual stresses resulting from the welding process are unavoidable and their presence significantly influences the susceptibility of weld microstructures to cracking, particularly if hydrogen is introduced during welding [5]. Therefore various weldability tests have been developed over the years which are specifically designed to promote HACC by generating critical stress levels in the weld metal region due to special restraint conditions [4, 6–8]. These tests were used to develop predictive methods based on empirical criteria in order to estimate the cracking susceptibility of both the heat-affected zone and weld metal [4].

However, although the relationship between residual stress, hydrogen and HACC has received considerable attention, the interaction of residual stresses and microstructure in particular at microscopic scales is still not well understood [5, 9–21].

Therefore the current paper focuses on the development and assessment of techniques using Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction for the determination of local residual strains at (sub) micron scales in E8010 weld metal, used for the root pass of X70 pipeline girth welds, and their relationship to the WM microstructure. The measurement of these strains could be used to evaluate the pre-existing stress magnitudes at certain microstructural features [22].
Development of Grade X70 and X80 for Sour Service Line Pipe Applications
Authors: Staudt Thorsten , Schwinn Volker , Raedersdorf Sven , Pant Martin , Kalwa Christoph , Haverkamp Heiko , Coppey Christian
Published: July 2013

The paper describes the results of elaborated development work and the application of the very latest technology on steel, plate and pipe making, the recent demand on grade API-5L X70 or even API-5L X80 for specific sour service applications can be met. Furthermore the paper will point out the overall production concept which provides the fundament for the production of such steels with consistent and reliable resistance to hydrogen induced cracking (HIC). The essential parameters will be explained. This includes the utilization of an appropriate quality assurance system. Recent achievements in terms of strength level, thickness and sour service conditions will be explained.
Modelling of Slant Failure Using Small Size Specimen
Authors: Thibaux Philippe , Van Wittenberghe Jeroen
Published: July 2013

The instability of a pipeline crack eventually leads to brittle or ductile crack propagation. The resistance to ductile crack propagation is assessed by the energy dissipated in the CVN test. However the Charpy specimen exhibits mainly mode I failure, with no small shear lips, while real failure is a combined mode often described as slant failure. In the present investigation, instrumented Charpy tests with nominal and reduced thickness down to 2.5 mm are carried out. Instrumented Battelle drop weight tear tests where also performed with nominal and reduced thickness, in order to vary the ligament versus thickness ratio. The results of the Charpy tests are simulated by the finite element method. The results are then discussed in terms of energy dissipated during crack initiation and crack propagation. It is shown that by reducing the size of the Charpy specimen, slant failure is promoted, which results in a decrease of the specific energy absorbed. However, most of the difference of absorbed energy is in the crack initiation mode, and only marginally in crack propagation. Consequently, the fraction of the total energy dissipated in crack propagation is increased by reducing the sample thickness, making it a possible tool to assess the resistance of a material to crack propagation, provided that brittle fracture is avoided and no separation is present.
Application and Validation of Statistically Based Corrosion Growth Rates
Authors: Maier Clifford J. , Moreno Pamela J. , Harper William V. , Stucki David J. , Polasik Steven J. , Bubenik Thomas A. , Shanks David A. R. , Bates Neil A.
Published: July 2013

When it comes to managing the integrity of corroded pipelines, operators are confronted with many difficult decisions — one of which is the level of conservatism that is used in pipeline integrity assessments. The financial implications associated with excavation, repair, rehabilitation, and inspection programs typically balance the level of conservatism that is adopted. More conservative approaches translate into more spending, so it is important that repair strategies developed based on the integrity assessment results are effective.

As integrity assessment methodologies continue to evolve, so does the ability to account for local conditions. One development in recent years has been the ability to evaluate multiple MFL in-line inspections to determine areas of active corrosion growth, through the combined use of statistics, inspection signal comparisons, and engineering analysis. The authors have previously outlined one approach (commonly known as Statistically Active Corrosion (SAC)) that has been successfully used to identify areas of probable corrosion growth, predict local corrosion growth rates, and maximize the effectiveness of integrity assessments.[1]

Validation of the SAC-predicted corrosion growth rates is important for establishing confidence in the process. This is achieved through inspection signal comparisons, integrating close interval survey (CIS) results, and (when possible) field verification. The means by which these methods are used for validating the SAC method are described in this paper.
Simulation and Planning of Pipeline Emptying Operations
Authors: Martinoia Thomás , Barreto Claudio Veloso , da Rocha Jose Carlos D. C. , Lavoura João , Henriques Fausto M. P.
Published: July 2013

The pipeline pigging operation for emptying purposes is a common practice in the petroleum and gas transport industry. The emptying operation is employed for removal of the pipeline liquid products and substitution for an inert gas like nitrogen. This operation is necessary before pipeline maintenance or hydrostatic test procedures. The emptying operation applied for oil pipelines usually demands large volumes of nitrogen because of the pressure difference that is necessary to maintain the pig in a velocity that guarantee an efficient and safe operation. The nitrogen that is originally stored inside cryogenic vessels in liquid phase is pumped and vaporized to be injected into the pig launcher, after heating the gas. The gas injection and expansion inside the pipeline propel the pig, delivering the product that was in the pipeline at the receiver station. It is common to cut the nitrogen injection in a certain instant of the operation, before the pig reaches its destination. From then on, the expansion of the gas is able to finish the operation alone.

A dynamic simulator called DESLOCAN2 was developed by SIMDUT/PUC-Rio to simulate the pig motion during emptying operations with nitrogen in TRANSPETRO crude oil and refined products pipelines. In the operation planning phase the simulator is used to evaluate the gas mass flow rate, the inlet gas pressure and the nitrogen cut instant that can propel the pig to its destination with a minimum volume of nitrogen. The outlet liquid pressure is calculated using two simultaneous controllers: outlet flow rate based on maximum pig velocity and minimum outlet pressure that avoids slack line condition. The dynamic simulator also can be used as a forecast monitor of the pipeline pigging operation given the current inlet gas and outlet liquid conditions, allowing the visualization of actual and forecasted pipeline pressure profile, the pig velocity and position, the accumulative gas inside the pipeline and the volume of product removed.

The main objectives of this paper are: Present the mathematical modeling and considerations built in the simulator; Validate the model’s main hypothesis; Present the gained experience on building the model and planning an emptying operation of an existing pipeline: OSBAT 24.
DSE-T: A Program for Strain Based Assessment of Pipeline Dents With Complex Shape
Authors: Guerreiro João N. C. , Garcia Eduardo L. M. , Noronha Dauro B. , Martins Ricardo R. , Fonseca Leonardo G. , Lopes Tuane V. , Costa Marcos F. , Castro Eduardo S.
Published: July 2013

According to ASME B31.8 - Gas Transmission and Distribution Piping Systems, plain dents or dents on ductile welds of any depth are acceptable provided strain levels associated with the deformation do not exceed 6% and 4%, respectively.

Appendix R of the Code presents a method for estimating strains in dents. In order to use this method, some technique is usually necessary to evaluate strains based on the pipe surface contour information captured from in-line inspection (ILI) tools or from direct measurement.

In previous papers the authors have presented techniques based on B-spline curves or B-spline surfaces to evaluate the bending strains on dents which have a “well-behaved” topology or on dents having a complex shape, respectively. The B-splines are used to interpolate the geometry of the dent, to infer its radii of curvature and to calculate the bending strain components using a procedure similar to that suggested on the Appendix R of the ASME B31.8 Code. The strains are combined in order to obtain an equivalent strain field that does not take into account the effect of the membrane strains or include the effect of the longitudinal membrane component through an expression like that contained on the code. These techniques which were implemented in the DSE-B and the DSE-R programs, respectively, make the dent strain estimation based on data coming from in-line inspections (ILI) tools easier and automatic.

This paper presents the DSE-T program, which uses the methodology implemented in the DSE-B program to calculate bending strains, and a dedicated finite element method to estimate membrane strains. Bending and membrane strains are combined to give the total strain fields on the inside and outside surfaces of the indented pipe. The program also enables the user to verify whether the dent is smooth or kinked and to simulate the effects of measuring the dent shape using “virtual” geometric tools with different degrees of resolution. Results obtained using the DSE-T are compared to results from nonlinear finite element analyses.
Improved Comparison of ILI Data and Field Excavations
Authors: Harper William V. , Stucki David J. , Bubenik Thomas A. , Maier Clifford J. , Shanks David A. R. , Bates Neil A.
Published: July 2013

The importance of comparing in-line inspection (ILI) calls to excavation data should not be underestimated. Neither should it be undertaken without a solid understanding of the methodologies being employed. Such a comparison is not only a key part of assessing how well the tool performed, but also for an API 1163 evaluation and any subsequent use of the ILI data. The development of unity (1-1) plots and the associated regression analysis are commonly used to provide the basis for predicting the likelihood of leaks or failures from unexcavated ILI calls. Combining such analysis with statistically active corrosion methods into perhaps a probability of exceedance (POE) study helps develop an integrity maintenance plan for the years ahead.

The theoretical underpinnings of standard regression analysis are based on the assumption that the independent variable (often thought of as x) is measured without error as a design variable. The dependent variable (often labeled y) is modeled as having uncertainty or error. Pipeline companies may run their regressions differently, but ILI to field excavation regressions often use the ILI depth as the x variable and field depth as the y variable. This is especially the case in which a probability of exceedance analysis is desired involving transforming ILI calls to predicted depths for a comparison to a threshold of interest such as 80% wall thickness. However, in ILI to field depth regressions, both the measured depths can have error. Thus, the underlying least squares regression assumptions are violated. Often one common result is a regression line that has a slope much less than the ideal 1-1 relationship.

Reduced Major Axis (RMA) Regression is specifically formulated to handle errors in both the x and y variables. It is not commonly found in the standard literature but has a long pedigree including the 1995 text book Biometry by Sokal and Rohlf in which it appears under the title of Model II regression. In this paper we demonstrate the potential improvements brought about by RMA regression.

Building on a solid comparison between ILI data and excavations provides the foundation for more accurate predictions and management plans that reliably provide longer range planning. This may also result in cost savings as the time between ILI runs might be lengthened due to a better analysis of such important data.
A Large-Scale Model Developed for Predicting the Corroding Conditions of a Carrier Pipe in a Casing
Authors: Song Fengmei , Nordquist Andrew
Published: July 2013

The corroding conditions of a cased carrier pipe segment are difficult to measure in the field. It is hard to know whether or how well the cased pipe segment is cathodically protected. The pipeline industry needs a tool that can predict the in-situ corrosion potential of the carrier pipe in the casing annulus in order to determine the level of cathodic protection (CP). This work reports on a large-scale, three-dimensional computer model developed to make such a prediction. The casing wall may be treated as bare or coated on both or either of the external and internal surfaces. The carrier pipe is coated, and the coating quality inside the annulus may or may not be the same as the outside of the casing segment. The casing annulus is full of electrolytes. The model is used to investigate the effect of several factors on the level of CP imposed on the carrier pipe in the annulus, including the coating quality on the carrier pipe, the casing wall native potentials (both external and internal), the presence of a coating on a casing wall surface, and a metallic contact (between the casing and the carrier pipe) with the contact resistance being a variable. The effect of the voltage variation inside the pipe metal wall is also investigated.