bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulating Pressure Setpoints in Pipeline Pressurizing
Authors: Federico Heitor Honda , Torci Douglas Estevam , Garcia Cláudio Rogério
Published: December 2014

Automation projects concerning the operation of long pipelines aim to not just improve the operational activities but also contribute to the safety of the facilities and reduce any potential environmental impact of the activity. It is common knowledge that oil companies need to have their pipelines flowing fully pressurized so that its contents can be controlled and accounted for. Therefore, many companies have installed automated control valves at arrival point of the pipelines in order to guarantee that the pressure inside the pipeline is optimal and controlled. This operation has led to important studies in control theory and Proportional, Derivative and Integrative control systems PID.

Several articles study methods and optimal gains for the precise positioning of the control valve. The problem presents itself when the valve is required to compensate a severe change in the pressure set point. For instance, if one pump is disconnected from the pipeline by a safety-automated measure in a multi-pump scenario, the rapid movement of the control valve may result in an undesired large overshoot and stabilization period. This can be observed in small diameter or short pipelines in which the system responds fast to any alteration in the control valve position. This behavior can not always be compensated by altering the gains of the PID controller as they are set to work on the most common scenario and can only be expected to correctly respond when the changes in pressure are sufficiently small.

Faced with this problem in a pipeline, the engineers and technicians of an oil company installed a pressure set point curve in order to avoid the described behavior of the valve, even if momentarily depressurizing the pipeline. Throughout this article, the results of this alteration are described and it is suggested ways to further improve the control system without jeopardizing the safety of the pipeline operation.
Building a Risk Based Decision Support System for Midstream Shale Gas Assets
Authors: Murray Jake , Landry Matt
Published: December 2014

In order to support its goals of zero incidents through risk-based asset management, Access Midstream (Access) requires a solution for providing decision support by modeling integrity threats that indicate potential safety and environmental incidents on all of its pipeline assets. The objective is to tailor existing pipeline risk methods to properly account for the unique conditions inherent to midstream gathering assets while still being flexible enough to account for traditional gas transmission and liquids transportation lines.

Access has created a unique risk-based spatial decision support system (RB-SDSS), customized to the needs of a gas gathering company that also owns and operates incidental gas transmission and hazardous liquids pipelines. Access’ business needs call for a comprehensive solution that includes a risk model that can handle a diverse asset base. Most of the company’s pipelines are unregulated, but risk-based management and decision-making are still desired for regulated and non-regulated pipelines alike. Access has designed a decision support system that automatically retrieves and integrates data, estimates risk with directly and indirectly related inputs in its algorithm, and disseminates the data to business users across the enterprise. The processing model is calibrated for risk assessment and is capable of distinguishing between high and low risk lines. It is able to generate results that can be understood and upon which appropriate action can be taken. These results are refreshed monthly as new assets are constructed or purchased and existing asset attributes are updated. Access’ decision support system is repeatable and scalable owing to maximum use of automated processes.

The focus of this paper is to outline Access’ approach to building a risk assessment solution for its pipeline assets. Each component of the RB-SDSS is reviewed: (1) Data Integration, (2) Risk Modeling, and (3) Organizational Utilization. This includes strategies for assessing traditional pipeline threats, geospatial techniques used to infer data, how to assess data quality and completeness, challenges, lesson’s learned, and future improvements.
Evaluation of Design Premises and Uncertainties on the Thermo-Mechanical Behavior of a Subsea Pipeline
Authors: Antunes Bruno Reis , Solano Rafael Familiar , Hansen Alexandre
Published: December 2014

Buckle formation process is a key subject for the design of subsea pipelines laid on the seabed and operating under high pressure and high temperature (HP/HT) conditions. When the controlled lateral buckling methodology is adopted triggers are placed along pipeline route in order to increase the buckle formation probability in specific locations, sharing pipeline expansion between these sites and reducing the level of stress and strain in each buckle.

Despite of its importance, buckle formation process is influenced by several parameters such as the seabed bathymetry, engineered triggers, lateral out-of-straightness (OOS) and pipe-soil interaction. While the first two items above can be defined with reasonable accuracy at previous stages of design, lateral OOS will only be known with tolerable confidence after pipeline installation. The level of uncertainty related to pipe-soil interaction is also considerable since pipeline embedment and friction factors are estimated using equations that include empirical correlations and field collected data. In addition these parameters are influenced by the installation process. Due to these uncertainties, conservative premises are usually assumed in order to obtain a robust pipeline thermo-mechanical design.

After pipeline installation and/or start of operation an investigation can be performed in order to confirm the assumptions considered in the design. This paper presents a comparison of premises adopted during design stage of a pipeline based on the controlled lateral buckling methodology and the feedback obtained with the post-lay survey performed. After a brief introduction, pipeline embedment, global buckling at crossings, lateral OOS and sleepers’ height are some of the subjects addressed. Finally, conclusions and recommendations are presented in order to support future similar projects.
A Novel Approach for Monitoring Pipeline Corrosion Under Disbonded Coatings
Authors: Varela Facundo N. , Tan Mike Y. J. , Forsyth Maria
Published: December 2014

Underground pipeline corrosion monitoring is a complex technical challenge. Currently there is no corrosion monitoring probe that is able to provide in situ information on corrosion under disbonded coatings. This paper presents a proof of concept of a novel corrosion monitoring probe intended to simulate corrosion under disbonded pipeline coatings and monitor its rate under Cathodic Protection (CP). The probe’s capabilities to measure corrosion rates and simulate disbonded coating conditions are illustrated by a typical experiment that involved testing of the probe in 0.1M NaCl at −850mVCSE. Estimated metal thickness losses based on results measured by the probe were compared against corrosion patterns and profilometry measurements of control specimens exposed to the same conditions.
Development of a Probabilistic Pipeline Risk Assessment Software for Mexico’s Oil State Company
Authors: Solis Roberto Ramirez , Simon Arturo Godoy , Gonzalez Jose Luis Martinez , Muhlbauer W. Kent , Lugo Angel Alva
Published: December 2014

Pipeline risk assessment has been a major concern for Mexico’s Oil Sate Company (PEMEX) for the last couple of decades. During this period of time, isolated efforts from the different subsidiary bodies (upstream, midstream, and downstream) have been made regarding this matter, including the implementation of powerful software tools. However, due to several factors, none of these has provided an optimum solution for the company until now as they do not serve specific needs from PEMEX according to the country’s social and geographical environments. Besides that, a different software tool has been used by each subsidiary body, generating variations in practice and dissimilar criteria when assessing risk.

A project sponsored by the Ministry of Energy in Mexico and the National Council of Science and Technology seeks to address these issues by developing a unique and customized software solution for pipeline risk assessment in PEMEX. This paper presents the progress made so far regarding the development of this tool.
An Evaluation Procedure for Crack Driving Forces in Mismatched Welds and its Applicability to ECA Analysis of Undermatched Clad Pipe Girth Welds
Authors: de Souza Rodolfo F. , Ruggieri Claudio
Published: December 2014

Structural integrity of submarine risers and flow lines transporting corrosive and aggressive hydrocarbons represents a key factor in operational safety of subsea pipelines. Advances in existing technologies favor the use of C-Mn steel pipelines (for example, API X65 grade steel) either clad or mechanically lined with a corrosion resistant alloy (CRA), such as Alloy 625, for the transport of corrosive hydrocarbons. However, while cost effective, specification of critical flaw sizes for their girth welds become more complex due to the dissimilar nature of these materials. In particular, effective fracture assessments of undermatched girth welds remain essential to determine more accurate acceptable flaw sizes for the piping system based upon engineering critical assessment (ECA) procedures. This work focuses on development of an evaluation procedure for the elastic-plastic crack driving force (as characterized by the J-integral) in pipeline girth welds with circumferential surface cracks subjected to bending load for a wide range of crack geometries and weld mismatch levels based upon the GE-EPRI framework. The study also addresses the effects of an undermatching girth weld on critical flaw sizes for a typical clad pipe employed in subsea flowlines having an Alloy 625 girth weld. The extensive 3-D numerical analyses provide a large set of solutions for J in cracked pipes and cylinders with mismatched girth welds while, at the same time, gaining additional understanding of the applicability of ECA procedures in welded cracked structural components.
The Reliability of Acoustic Emission Inspection on the Storage Tank Floor
Authors: Guo Zhenghong , Kang Yewei , Chen Hongyuan , Xu Huatian , Liu Mo
Published: December 2014

It is difficult to inspect a tank floor when tank is in service. The conventional inspection of a tank floor after it is opened and cleaned is time-consuming and is a high cost. So the in-service inspection of above-ground storage tank floors with Acoustic Emission (AE) technique is accepted by petrochemical industry more and more. Until now more than 70 tanks have been inspected with AE technology in PetroChina Pipeline Company. In this paper our method is introduced and the influencing factors for AE testing are discussed. The reliability of AE testing is mainly concerned by comparing the results of AE testing with the one of conventional nondestructive testing (NDT). The study concluded that the AE inspection is a useful and economic tool for prioritizing the tank maintenance.
An Updated Fracture Resistance Dataset of Pipeline Ductile Fracture Propagation Based on High Speed DWTT Tests
Authors: Duan Da-Ming , Ferguson James , Zhou Joe , Uddin Mohammed , Shim Do-Jun
Published: December 2014

One of the major research topics in the area of gas pipeline fracture control is the suitability of using Charpy energy for ductile fracture control for modern and/or high strength line pipes. A common understanding is that, for pipe body crack self-arresting, the deviation of the actual required Charpy energy from those predicted using the traditional procedure of Battelle Two-Curve Method (TCM) is getting larger with higher strength pipes. DWTT is being paid more attention to because of its larger and full thickness specimen that can better capture the fracture process than a Charpy specimen does. Previous work at TransCanada indicated that various fracture speeds can be achieved in DWTT specimens and it is the steady-state fracture speed that is representative to the actual fracture propagation in a gas pipeline. It has also been found that the steady-state fracture toughness, in terms of either fracture energy or CTOA, is fracture speed dependent with lower fracture toughness for higher fracture speeds. Previous analysis also indicated by considering the speed dependent toughness, better predictions can be obtained for both self-arresting fracture toughness requirement and the fracture propagation speed. Previous DWTT fracture toughness data published by the authors exhibited a strong speed dependence and it was demonstrated that if the actual speed dependence is plugged into the modified TCM, both the fracture toughness and fracture speed would be over predicted. The assumption was that the original TCM was calibrated using pipe fracture data that also had speed dependent fracture toughness but the speed dependence was less strong than those for the modern pipes.

This paper presents an updated DWTT fracture dataset that expands the previously published data by adding high speed DWTT test results of modern line pipe steels with a range of grades X70-X100 and three old vintage pipe materials that is representative to the pipes that were used for the original TCM testing and calibration. The toughness data for the low grade pipes also shows speed dependence which purports the previous assumption.
A Stress Check Procedure for Pipe Lowering-In Process During Pipeline Construction
Authors: Duan Da-Ming , Jurca Thomas , Zhou Charles
Published: December 2014

The quality of pipeline construction is determined by the effort of controlling the pipe stress level. Constraints may include various factors, such as pipe size, side boom lifting capacity, the number of side booms, side boom spacing and the lifting height profile. The use of girth weld flaw size limit established by Engineering Critical Assessment (ECA) for a given construction condition, makes the accuracy of pipe stress even more important. This is not only because stress level is one of the controlling parameters of the ECA results, but also because in some cases, such as low girth weld fracture toughness, stress level must be controlled with a very narrow window to keep a meaningful ECA that leads to a reasonable weld repair rate. An optimized pipe lifting height profile can be obtained from stress analysis using finite element method based on available construction equipment capabilities. From a practical perspective, an optimized pipe lowering-in plan may not be executable in the construction field. It is thus desired that a practical approach be provided that captures the key feature of construction practice and at the same time makes the key measures recordable.

This paper provides a set of stress check equations derived using beam deformation theory. The calculation results using these equations show that for normal pipe lowering-in practice, pipe stress level can be effectively controlled by checking and controlling the lifting height of just one or two points. The approach proposed is to be used in conjunction with case specific finite element analysis.
Establishing the Correlation Between Charpy Impact Energies for Different Sized Specimens of Modern Pipeline Steels
Authors: Nonn Aida , Brauer Holger
Published: December 2014

The safety assessment of flawed pressurized pipes requires the knowledge of toughness properties which are usually provided in terms of impact energy from standard full-sized CVN notch specimens. For pipes with wall thickness less than 10mm different Charpy standards allow for the application of sub-sized specimens. However, it is still not fully clear how the impact energy from sub-sized specimens can be used to evaluate the fracture resistance of the pipes and how this energy correlates to the one from the full-sized specimen. Although different empirical correlations between sub-sized and full-sized specimens exist in the literature their validity is questionable since they are based on the results for older generation of steels. In the recent years the application of damage mechanics models has been promoted to assess the fracture behavior and deformation capacity of pipelines. The main advantage of these models can be found in their capability to link the damage evolution and the underlying stress/strain condition.

In this paper damage mechanics approach is applied to describe fracture behavior of X65 pipeline material. Within the damage mechanics approach, Gurson-Tvergaard-Needleman (GTN) model is considered to be adequate for the simulation of ductile fracture. For brittle fracture, GTN model is extended by a propagation criterion which examines if the cleavage fracture stress is reached by the maximal principal stresses. The model parameters are calibrated and verified by means of load-displacement curves obtained from instrumented impact tests on different sized CVN specimens. This damage model is subsequently employed to simulate ductile-brittle transition behavior.
How to Assure Fracture-Propagation Control for Seamless Gas Pipelines?
Authors: Nonn Aida , Erdelen-Peppler Marion , Wessel Waldemar , Harksen Silke , Mahn Denise
Published: December 2014

Fracture propagation control in gas transmission gas pipelines belongs to the major design requirements for safe operation at high internal pressures. However, the current tests such as Drop-Weight-Tear Test (DWTT) and full-scale West-Jefferson (WJ) test reach the limits of their applicability with respect to transition temperature evaluation for seamless quenched and tempered small diameter pipes reflecting nowadays alloying concepts related to mechanical properties. Hereby, different geometry and material effects are evident which might lead to misinterpretation and unreliability of testing results. This paper aims to discuss open issues addressed in the literature and in own experimental findings with respect to reliability and transferability of testing methods, fracture parameters and their representativeness of seamless quenched and tempered pipeline behavior. By applying damage mechanics approach, it is possible to quantify the prevailing stress state and thus to understand the mechanisms controlling specific fracture appearance (ductile or brittle). Furthermore, studies were performed with objective to quantify the effect of different parameters (geometry, material and loading) on the fracture performance of the pipeline. The results from these investigations will serve as a basis for a safe pipeline design against propagating fracture.
Recent Development of HFW Linepipe With a High-Quality Weld Seam Suitable for Sour Service Environments
Authors: Toyoda Shunsuke , Goto Sota , Kato Yasushi , Yabumoto Satoru , Sato Akio
Published: December 2014

Based on the appreciable progress being made in quality control and assurance technology for the electric resistance welding process, the number of applications for high-frequency electric resistance welded (HFW) linepipe in highly demanding, severe environments, such as offshore and sour environments, has gradually increased. Resistance to hydrogen-induced cracking (HIC) is the most important property for a linepipe to possess for use in sour environments. However, resistance to HIC, especially along the longitudinal weld seam, has not yet been fully related to metallurgical factors.

In this study, to clarify the effects of inclusions on the sour resistance properties of X60- to X70-grade steels, their resistances to HIC were numerically simulated. For the simulation, the steels were assumed to have a yield strength of 562 MPa and a tensile strength of 644 MPa. To estimate the effect of nonmetallic inclusions, a virtual inclusion was situated at the center of a 10-mm-thick HIC test specimen. Tests were performed using NACE test solution A.

The crack propagation rate was calculated as a function of the content of diffusible hydrogen, the diameter of the inclusion, and the fracture toughness of the matrix after hydrogen absorption. In the propagation calculation, the resistance to chemical reactions at the interface of the inclusion matrix was also considered to be a delaying factor. By assuming a resistance to chemical reactions at the interface, the crack propagation rate could be fitted to the actual HIC propagation rate.

Based on the numerical simulation results, HFW linepipe with a high-quality weld seam was developed. Controlling the morphologies and distributions of oxides generated during the welding process is the key factor for improving the resistance to HIC. Using a combination of optimized chemical composition, microstructure and oxide content, the weld seam of the developed X70-grade HFW steel pipe showed excellent resistance to HIC.
Combining Speed Control Function and Wye Passage in a Long Subsea Gas Line: A Case Study
Authors: Lindner Hubert , van Remmerden Hans , Shamgar Amit
Published: December 2014

Challenging conditions for pipeline inspection can be caused by several different parameters and conditions (length, diameter changes, installations and operating conditions). Very often the real challenge is resulting from a combination of these influencing parameters. For example, a very long pipeline becomes particularly critical for battery lifetime if the flow rate is low. Each single individual parameter does not necessarily constitute such challenge. Some basic examples and a particular combination of pipeline parameters and operational conditions are presented in this article.

The crucial parameters of the regarded pipeline are: 36″, about 700 km length, high wall thickness, high pressure and flow rates and a subsea wye piece. Some of these requirements are already demanding for former inspection tools. But the complex interaction of the features increases the challenge for the tool design significantly. Particularly the combination of high flow, high wall thickness and the wye piece passage required special attention.

The article describes the pipeline properties and run conditions and the consequences for the entire cleaning and inspection program. Notably the interactions of the parameters regarding the MFL inspection are highlighted and the resulting tool concept is presented as well as the run results.
Pipeline Integrity Analyses for Construction in Mountainous Areas
Authors: Zhang Fan , Liu Ming , Wang Yong-Yi , Surface Ryan , Phillips Adam
Published: December 2014

The construction of a pipeline in mountainous terrain often exposes great challenges compared to that on flat land. To accommodate the terrain and resultantly complex route, the pipeline design must incorporate a large quantity of cold bends and elbow fittings. A recently constructed project provides a prime example of a pipeline crossing such terrain. The challenging construction conditions and the bends and elbows make the assessment of stress impacting long-term pipeline integrity critical, yet difficult. This paper focuses on three specific aspects of long-term integrity for construction in mountain areas using advanced finite element analysis (FEA).

The first scenario is tie-in welding. Tie-in welding connects separate pipeline segments constructed independently. In general practice, considerable lengths of pipe are left unburied to reduce the potential resultant stress due to the misalignment between the pipes at the tie-in weld location. However, in mountainous terrain the length of unburied pipe may be constrained by field conditions of the tie-in location. The implications are amplified at a tie-in adjacent to bends or elbows.

The second scenario is hydrostatic testing. The gravitational weight of water generates additional internal pressure in the pipeline segments at low elevations. In areas of significant elevation change, hydrostatic test section design defines the segments based on the maximum allowable hoop stress level calculated for straight pipe. However the bends and elbows often encounter increased combined stresses at such locations that may not be adequately considered.

The last scenario is ratcheting. Exacerbated by complex routing and profile, pipelines constructed in mountainous areas are at risk to develop significant uplift in the soil at bend locations during hydrostatic testing and initial operating cycles. If such uplift displacement accumulates during subsequent operating cycles, a phenomenon known as ratcheting, the pipe may eventually fail by upheaval buckling.

This paper evaluates the above scenarios of a NPS 30 section of pipeline consisting of several segments with wall thicknesses varying from 12.0 mm through 19.6 mm, and contains frequent bends and elbows. The pipeline route is mountainous with slopes exceeding 70 degrees, and includes a tunnel immediately adjacent to water crossings and steep slopes. Tie-in welds are made in tight confines at either end. Analysis based on this project profile provides detailed information and insight into the design and construction of pipelines in mountainous terrain.
Development of an Effective Pipeline Material Traceability and Compliance Program
Authors: Vogt Brett D. , Owen Les
Published: December 2014

As regulations and technology change, an alternative to paper-based construction records for material traceability, document management and regulatory compliance is required. The optimum solution provides a material traceability system that utilizes electronic data capture to drive the creation of a detailed and searchable database comprising of regulatory and company required project documents. By implementing a traceability and compliance program that includes material barcoding, mobile field data collection, mobile inspection reports, an electronic document management system and a compliance review by experienced personnel, pipeline operators are able to meet current regulatory requirements and derive benefits during construction. This enhanced traceability system minimizes transcription and seeks to replace many paper-based pipeline records. It also offers functionality to capture and manage existing paper-based documents, allowing this system to incorporate old and new methodologies simultaneously. System tools allow accelerated comparisons such as; all welds have a complete Non-Destructive Examination (NDE) record; all welders have a valid qualification test; or all pipe segments have a valid hydrostatic test record. The success of an effective pipeline traceability and compliance system requires innovative technology, the dedication and knowledge of experienced pipeline professionals, and most importantly, the lessons-learned implementing prior solutions.
Reducing Human Error Using a Human Factors Life Cycle Approach
Authors: Harron Lorna , Attwood Dennis
Published: December 2014

Reduction of human error can have a significant impact on the potential for spills and leaks and translate into better safety performance and financial gains for an organization. As important as the technical components of a design, construction, operation, and maintenance program is the human component of the activities being performed.

In the Pipeline Industry, human factors can create the potential for a human error at many points along the life cycle of a pipeline. Using a life cycle approach to manage human factors can provide an organization the capability to integrate human factors into programs, standards, procedures and processes using a disciplined approach. This paper reviews the life cycle of a pipeline and identifies areas where the potential for human error can have catastrophic results. Guidance is provided on the development of a human factors life cycle for the organization and illustrates available industry resources as well as opportunities for further research and development.
The Interwell Pressure Matching Analysis of Different Topologies in the Gathering and Transporting System
Authors: Zhou Jun , Li XiaoPing , Cheng Mengya , Zhou Shiwei , Gong Jing
Published: December 2014

Interwell pressure matching (IWPM) refers to the mutual effects of flow parameters between wells under a certain topology. In a low pressure gathering and transporting (G&T) system, the wellhead pressures drop at different rates, leading to discordance. If the wellhead pressure cannot reach the system pressure, the gas would flow backward, which impedes normal production. Currently this issue has increasing attention from engineers; however, they only describe this issue qualitatively. In structure design of a G&T system, only the economy of different topologies, such as star topology (ST), concatenated topology (CT) and main line access topology (MLAT), have been considered; different topologies’ influence on interwell matching has been ignored. The author first defined the IWPM, further divided the concept into node pressure matching (NPM), structure pressure matching (SPM) and type pressure matching (TPM). NPM refers to the influence of one node’s parameter change on other nodes; SPM reflects the influence of one node on the whole network; TPM shows the matching difference of different topologies. Secondly, quantitative evaluating functions and evaluating method are developed. The evaluating method is that given changing rules of wellhead parameters, using a steady-state network program to simulate the system condition in a production period, then calculate the values of the evaluating functions. Last is a case study of a low pressure CBM system. The wellhead pressure can be low as 0.2MPa. The wellhead parameters rely on the extraction system. With this evaluation method, the author systematically analyzed NPM, SPM and TPM of 11 structures under 3 pipe topologies, and each structure connects 2–4 wells. The results show that, as far as NPM is concerned: in ST, the interference of one well would not influence others; in CT, the interference of a node would only affect adjoining nodes; in MLAT, any interference would affect all the wells. Because of the symmetry of ST, the interference of each well would influence the structure to the same degree (value of 1.74); yet the other two topologies have different influencing degrees caused by interference of different nodes. The SPM value range of the other two topologies are 6–16 and 15–45. Among all three topologies, the TPM value of star is 1.74, main line access 11.74, concatenation 32.56. With different topologies the anti-interference capabilities are different. ST is prior to MLAT, which precedes CT. This technique for the first time offers a tool to analyze IWPM and provides supports for the development and design of G&T system.
Venting of a 32 km NG Pipeline: Field Measurements and CFD Simulations
Authors: Godbole Ajit , Michal Guillaume , Lu Cheng , Liu Xiong , Venton Philip , Laidlaw Noel
Published: December 2014

This paper describes two separate field experiments involving the venting of natural gas pipelines. The pipelines were 32 km and 60 km in length respectively. The studies were carried out as part of an investigation of the phenomenon of Low Temperature Excursions (LTE) under the aegis of the Energy Pipelines Cooperative Research Centre (EPCRC), Australia. When a highly compressed gas is allowed to escape from a pipeline, the large drop in pressure is accompanied by a significant drop in the temperature of the gas. The general impression is that the pipeline material is also cooled to a comparable extent. This has often led to over-specification of the properties of the pipeline material. Theoretical and CFD studies have shown that although the gas undergoing severe decompression can indeed attain very low temperatures, the adjacent pipe wall does not experience cooling to a comparable extent. This appears to be in part due to the short time scales involved, and due to frictional effects at the gas-pipe wall interface [1].

In the field experiments described, in-situ measurements of gas pressure and pipe wall temperature were carried out. One of the field experiments also involved thermal imaging of the vent pipe surface. The measurements showed that even the most susceptible parts of the vent pipe were not excessively cooled during the event, i.e. much less than the cooling experienced by the gas at the corresponding location. CFD simulations of the highly transient flow in one of the field studies suggest that this may be due to a combination of the time scales involved, and frictional dissipation in severe pipeline decompression, i.e. rapid decompression from an initially high pressure level.

Based on the above findings, work is in progress to improve the temperature calculations in computer applications.
Numerical Modeling of Pipe-Soil Interaction Under Transverse Direction
Authors: Farhadi Bahar , Wong Ron C. K.
Published: December 2014

Based on the Winkler method, a pipe can be treated as a beam, and pipe-soil interactions can be represented by soil springs in the axial, horizontal and vertical directions. Pipe deflection and resultant forces are correlated by coefficient K in the equation F=Kδ, where F is the resultant force and δ is the pipe displacement. This paper studies pipe-soil interaction for pipelines buried in clay and sand subjected to displacements in oblique directions. The objective is to measure the effect of soil parameters on coefficient K as well as the maximum soil resistance. Pipe-soil behavior has been studied using the finite element software ABAQUS/CAE. There are 48 models in total with varying soil parameters, pipe burial depth and pipe-soil interaction friction for the investigation of the effect of each variable on pipe-soil behavior. In addition, the finite element results have been compared to the analytical results from American Lifelines Alliance guideline (ALA, 2001) and proposed failure envelopes in previous studies.
Conditioning TRANSPETRO’s Gas Pipeline Network to the Baía de Guanabara LNG Terminal New Regasification Profile
Authors: Krause Philipe B. , Carnevale Marcos Bruno B. , dos Santos Denis F. , Jardim Rodrigo B. L.
Published: December 2014

Petrobras Transporte S.A. – TRANSPETRO’s Gas Pipeline System, composed by 7.3 thousand kilometers, 135 delivery stations and 21 compressor stations, has a very seasonally dependent operation. Highly linked with the Brazilian energy grid, during the dry season of the year a large part of the 77.3 million cubic meters of natural gas daily transportation are used to generate around 6.4 gigawatts to power the country. Additionally, the ever increasing number of power plants and distribution companies around the country demand more and more gas to be offered to supply the system. Among the different sources of natural gas available, the LNG is the most flexible for such seasonal operation.

In order to support this current demand and to attend future demands, the regasification ability of Baía de Guanabara LNG Terminal was increased in December 2012, by changing the regasification vessel that supplies the southeast portion of the gas pipeline network, from 14 to 20 million cubic meters per day. To prepare to receive the new ship, some tests were performed to determine the operational limits on system survival time without LNG supply during vessel exchange. This assessment involved two different issues. The ship change operation occurred during a period of high consumption, when the LNG terminal was needed to sustain the network inventory. A long period without this supply, caused by the exchange of LNG vessel, would affect the deliveries. On the other hand, the new ship’s commissioning curve would introduce a large amount of natural gas into the system during a short period of time, demanding that the deliveries absorbed such volume. Four planning scenarios were assessed based on some expected pipeline supply and delivery conditions. The work was important as a reference for future changes on operating supply units of TRANSPETRO gas pipeline system, showing the importance of pipeline simulation both as a planning tool for pipeline logistic problems and as operational support.
A Risk Approach for Distribution Pipeline Systems
Authors: Mihell James , Augustine Chad , Hasham Zaheed , Leewis Keith
Published: December 2014

Unlike the circumstance associated with transmission pipelines, where variables that are attributes of risk are typically widely available in GIS systems or in other databases that are geo-referenced to linear assets, risk data for distribution systems are not typically linearly referenced to what is essentially a network system. Therefore the manner in which risk is calculated and displayed for distribution systems must differ significantly from the way these functions are performed on transmission pipelines. In distribution systems, failure (defined as the loss of containment) and the contributors to the likelihood of failure, is often highly correlated to system-specific circumstances, such as type of material used, installation era, and operating environment. These correlations between cause-and-effect as they relate to failure likelihood in distribution systems are not widely recognized on a universal basis, such as they might be in transmission pipeline environments, but are typically unique to each operating system.

Because system data for distribution networks is not typically available in a manner that can be linearly geo-referenced to pipeline coordinates the way it is for transmission systems, the convention of mapping risk to pipeline dynamic segments as a function of risk attributes that exist within those dynamic segments is not achievable for distribution systems the way that it is for transmission systems. Therefore, the most effective strategy for performing risk assessments in distribution systems is to create a database in which existing incident data can be correlated to system attributes, and then to use those correlations to create cause-and-effect relationships between system attributes and failure likelihood. Consequences are characterized in terms of the operating environment (e.g., wall-to-wall, residential, etc.), leak magnitude, type of facility (mains vs. service lines), and special mitigating or exacerbating factors, such as availability of excess flow valves, or the presence of inside meters.

A risk assessment methodology has been developed that accommodates the above constraints and that meets the stated objectives, and which is well-suited to the distribution system data infrastructure that is typical of most operators. Because the risk assessment approach leverages existing databases and incident reporting structures, it lends itself to automation, and re-evaluation on a regular basis. Reporting is facilitated by a ‘heat map’, which provides immediate insight as to the drivers of risk for each system sub-group having similar design, materials, and operating characteristics.
Real-Time Pig Tracking Using a Fibre Optic Pipeline Monitoring System
Authors: Espiner Richard , Pickburn Alastair
Published: December 2014

The use of fibre optic based monitoring systems is becoming more common for new onshore pipelines. These systems are typically intended to provide leak detection and third party interference surveillance for long lengths of pipeline.

Between 2006 and 2008 BP and OneSubsea™ developed the optical technology that provides the basis for a fibre optic pipeline monitoring system (presented in IPC2008-64549). Subsequently BP installed the system on its Khazzan Extended Well Test (EWT) pipeline system in a remote location in Oman. In addition to the originally designed leak detection and third party surveillance capability, operating experience gained by OneSubsea on a variety of pipeline projects has demonstrated the ability of the system to track the movement of pipeline pigs. The monitoring system interface has been upgraded to integrate this additional functionality.

The paper describes the capabilities of the fibre optic monitoring system and through a case study illustrates the accuracy and operational benefits of the pig tracking capability.
Strain-Based Pipeline Design in Harsh Environments Using Large Diameter High Strain Line Pipes
Authors: Suzuki Nobuhisa , Arakawa Takekazu , Arabey Andrey
Published: December 2014

This paper outlines the draft recommendations to be issued by Gazprom that deals with the advanced strain-based pipeline design to ensure pipeline integrity in harsh environments using stress-strain curve controlled high-strain line pipe (SSLP). The draft recommendations have been provided to employ the new design concept to some future pipeline projects. The analytical solution was adopted in the draft as the solution is useful to improve strain capacity by controlling the longitudinal tensile properties without increasing wall thickness. The concept was validated through full-scale bending test using X70, 1220 mm SSLPs. FEA clarified that the strain capacity in compression or bending of X70, 1420 mm SSLP, 9.8 MPa, is high compared to that of the standard line pipe (STLP). The strain demand required for the SSLP pipeline in the harsh environments shall be small compared to that for the STPL pipeline. The SSLP pipeline shall be beneficial for ensuring the pipeline integrity in the harsh environments.
Ductile Crack Extension Analysis for X80 Bending Deformation Using Damage-Based Model
Authors: Igi Satoshi , Ohata Mitsuru , Sakimoto Takahiro , Oi Kenji , Kondo Joe
Published: December 2014

This paper presents experimental and analytical results focusing on the strain limit of X80 linepipe. Ductile crack growth behavior from a girth weld notch is simulated by FE analysis based on a proposed damage model and is compared with the experimental results. The simulation model for ductile crack growth accompanied by penetration through the wall thickness consists of two criteria. One is a criterion for ductile crack initiation from the notch-tip, which is described by the plastic strain at the notch tip, because the onset of ductile cracking can be expressed by constant plastic strain independent of the shape and size of the components and the loading mode. The other is a damage-based criterion for simulating ductile crack extension associated with damage evolution influenced by plastic strain in accordance with the stress triaxiality ahead of the extending crack tip.

The proposed simulation model is applicable to prediction of ductile crack growth behaviors from a circumferentially-notched girth welded pipe with high internal pressure, which is subjected to tensile loading or bending (post-buckling) deformation.
Fast Detection and Localization of Small Leaks in Toxic Pipelines Using Distributed Fibre Optic Sensors
Authors: Inaudi Daniele , Walder Roberto , de Bont Rob
Published: December 2014

Over the past decades, several major industrial accidents led the chemical industries handling large quantities of dangerous substances and national regulation bodies to reinforce the safety and prevention measures of their installations, in compliance with local laws such as the Seveso II directive in Europe. Indeed, leakages of chemicals can be at the origin of toxic releases, which can have severe consequences on the installations as well as on the environment and nearby inhabitants. Industries are prompted to take all possible measures to reduce the occurrence of such catastrophic events by implementing additional technical safety barriers in order to prevent or mitigate any potential danger on their key structures such as pipelines, reactors, storages, transfer lines, etc. Pipeline leakages may have different origins, such as corrosion, fatigue, material flaws, shocks, abnormal temperatures, extreme pressures, or excessive deformations caused by ground movement. In the case of liquefied or pressurized gases, leakages can be detected by the rapid drop of temperature due to the evaporation of the released liquid and its evaporation gases or due to gas expansion. These local thermal anomalies can be reliably detected by a fiber-optic distributed temperature sensing system able to detect temperature changes of the order of 1°C, with 1m spatial resolution and 10s response time. A fiber optic cable is installed all along the whole length of the pipeline and is connected to a measurement system that can automatically detect temperature anomalies which are telltale of leakages and generate an alert to initiate appropriate response actions on the affected pipeline section. Such a system has been permanently deployed at several industrial and chemicals sites were functional and operational tests have also been carried out. This paper will present the system architecture and installation at an ammonia production, storage, shipping and processing site. Results of simulated leakage detection tests on ammonia pipeline and long-term operation in normal conditions will also be presented.
High Energy Natural Gas Internal Corrosion Susceptibility Analysis
Authors: Owen David , Schapira Simon
Published: December 2014

Alliance Pipeline operates an integrated Canadian and U.S. high-pressure, rich natural gas transmission pipeline system. Rich natural gas pipelines are unique in that the product transported in these pipelines contains greater amounts of higher molecular weight hydrocarbons than would be transported in a dry natural gas pipeline. The specifications for gas quality however are very similar and require the product to contain less than sixty five mg/m3 water, no free liquids and/or objectionable materials such as bacteria, ashphaltene, gum, etc. The acid gases, carbon dioxide and hydrogen sulphide, are also required to be below certain values (see Table 1). Corrosion is not expected to occur under these conditions due to the lack of free water available for the development of an electrochemical corrosion cell. However, there are instances where the gas quality may vary and this gas enters facility piping for short periods of time. A method has been developed by Pipeline Research Council International (PRCI) to determine the internal corrosion susceptibility for dry gas natural gas pipelines but there are currently no industry accepted models which determine the internal corrosion susceptibility for high energy natural gas (HENG) pipeline systems. Accordingly, it is important for operators of pipelines with high energy natural gas (HENG) to collect and analyze these off specification events and develop a method to determine the relative impact on internal corrosion susceptibility. It is perhaps more important for operators to use this method to develop a strategy to prioritize facility piping for inspection and confirm the absence of internal corrosion. An Internal Corrosion Susceptibility Assessment (ICSA) method has been developed for HENG which considers off specification water, carbon dioxide, and hydrogen sulphide contents in the HENG. The analysis has been enhanced to also consider low temperature operation and hydrocarbon dew-point variations. The model has been effectively trialed over the last number of years to prioritize inspections and has been further tested against PRCI research and models developed for dry gas internal corrosion susceptibility. All internal corrosion models need to identify free water as prime contributor to susceptibility, thus the subject model is considered adaptable to other gas pipeline systems. This paper discusses the methods used to develop the model, the challenges encountered and results of the field inspections conducted.
Effect of Girth Welding on Strain Capacity of X80 SAW Pipes
Authors: Shitamoto Hidenori , Tsuru Eiji , Nagayama Hiroyuki , Takahashi Nobuaki , Nishi Yuki
Published: December 2014

Application of API X80 grade line pipes has been promoted to reduce a construction cost of the pipeline. Assessment of the strain capacity of X80 submerged arc welded (SAW) pipe is required for strain-based design (SBD). Long distance gas pipelines are usually constructed using girth welded line pipes. In the assessment of the strain capacity, it is important to keep over-matching at girth welds. However, since strength variation exists in base metal and girth weld metal, the value of the matching ratio also changes. In this study, X80 SAW pipes produced by the UOE process were welded under slightly over-matching condition and full-scale pipe bending test of the girth welded pipe was performed to evaluate the effect of the matching ratio on the strain capacity.