bluuebunny/crossref_metadata_2025 huggingface dataset:
Salinity risk assessment using fuzzy multiple criteria evaluation
Authors: Buchanan S. , Huang J. , Triantafilis J.
Published: October 2016

For agricultural productivity, primary salinity constitutes a hazard. Understanding the risk of secondary salinization is also important and it is necessary to map all these hazards and the overall risk. One approach is digital soil mapping. We have developed hazard maps of root zone (0–2 m) and subsurface (6–12 m) salinity, as well as groundwater height, using empirical best linear unbiased prediction using proximal and remotely sensed ancillary data. To convert the hazards into salinity risk maps and account for some uncertainty, fuzzy membership functions (FMF) were used in conjunction with semantic import models that consider the vulnerability of agricultural crops. Therefore, we developed memberships (μ) to three salinity risk classes and created maps of each, including root zone (μRSR) and subsurface (μSSR) salinity, and depth to groundwater (μGTR). To estimate groundwater (μGSR) and overall salinity risk (μOSR), fuzzy multiple criteria evaluation was undertaken. To account for μGSR, the μSSR and μGTR were combined using a t‐norm operator, and μOSR was accounted for by combining μRSR and μGSR using a t‐conorm operator. The approach was applied to an area growing irrigated cotton. Cross‐validation shows predicted μOSR was good, with an agreement rate of 70.6%. The predicted μOSR was consistent with that of many areas affected by point‐source salinity. The method provides an effective way of mapping salinity hazard and risk. Incorporation of FMF provides a meaningful continuum of membership and allows the incorporation of uncertainty. Salinity risk can be calculated relative to any vegetation community and locations where management actions to moderate soil salinization can be identified.
Experience with miltefosine for persistent or relapsing visceral leishmaniasis in solid organ transplant recipients: A case series from Spain
Authors: Pérez‐Jacoiste Asín Maria A. , Carrasco‐Antón Nerea , Fernández‐Ruiz Mario , San Juan Rafael , Alonso‐Moralejo Rodrigo , González Esther , Andrés Amado , López‐Medrano Francisco , Aguado Jose M.
Published: October 2016

The incidence of visceral leishmaniasis (VL) after solid organ transplantation (SOT) is increasing. The optimal therapy for post‐transplant VL remains unclear, as relapses after liposomal amphotericin B (L‐AmB) are common. Miltefosine has been shown to be effective for treating VL in immunocompetent patients, although data in the specific population of SOT recipients are lacking. In the setting of an outbreak of leishmaniasis occurring in Southwest Madrid, we reviewed our experience in 6 SOT recipients with persistent or relapsing VL who received a 28‐day course of miltefosine (2.5 mg/kg/day) as salvage therapy. All patients had been treated previously with L‐AmB as first‐line therapy. The incident episode of VL occurred at a median of 14 months after transplantation. Two patients experienced persistent infection and the remaining 4 had a relapse after a median interval of 168 days since the completion of the course of L‐AmB. All the patients had an apparent initial clinical improvement with miltefosine. However, VL relapsed in 3 of them (after a median interval of 46 days), which required retreatment with L‐AmB‐based regimens. Miltefosine therapy was followed by a prolonged secondary prophylaxis with L‐AmB in the only 2 cases with sustained clinical response and ongoing immunosuppression. No adverse effects associated with miltefosine were observed. Albeit limited, our experience suggests that miltefosine monotherapy likely has a limited utility to obtain a long‐lasting clinical response in complicated (persistent or relapsing) forms of post‐transplant VL, although its role in association with L‐AmB‐based secondary prophylaxis may merit further investigation.
Pipelining in a Changing Competitive Environment
Authors: Jones E. Glynn , Wishart Donald M.
Published: October 2016

The changing competitive environment for the pipeline industry presents a broad spectrum of new challenges and opportunities: international cooperation; globalization of opportunities, organizations and competition; an integrated systems approach to system configuration, financing, contracting strategy, materials sourcing, and operations; “cutting edge” and emerging technologies; adherence to high standards of environmental protection; an emphasis on safety; innovative approaches to project financing; and advances in technology and programs to maintain the long term, cost effective integrity of operating pipeline systems.

These challenges and opportunities are partially a result of the increasingly competitive nature of pipeline development and the public’s intolerance to incidents of pipeline failure. A creative systems approach to these challenges is often the key to the project moving ahead. This usually encompasses collaboration among users of the pipeline, pipeline owners and operators, international engineering and construction companies, equipment and materials suppliers, in-country engineers and constructors, international lending agencies and financial institutions.
Unleashing the Hidden Value of a Pipeline Through the Use of Visual Communications
Authors: Connor Paul B.
Published: October 2016

How does the communication of information affect the pipeline industry? People are becoming more aware of the pipeline industry and how it may affect individuals and landowners in the future. Corporations are producing commuications tools to alleviate the lack of knowledge and the hidden value of energy pipelines.

This case study examines two projects: “Passing through Edson” examines a winter pipeline construction job in Edson, Alberta. The story is told by the people on the job. We examine the environmental issues, economic impact, Native employment, and winter construction techniques. The “Boy Chief” video examines the impact of an archaeological dig on the prairies. In this program we have insight into the aboriginal history of the area and how the pipeline company is helping people learn more about the Native way of life.

The paper examine how communication tools like these, allow employees access to information when communicating to stakeholders.
Target Reliability Levels for Pipeline Limit States Design
Authors: Zimmerman T. J. E. , Chen Q. , Pandey M. D.
Published: October 2016

The limit states design appendix currently being developed for inclusion in the Canadian Standards Association pipeline design code, Z662, Oil and Gas Pipeline Systems contains preliminary partial safety factors that were selected on the basis that they result in designs similar to those produced using the existing working stress design standards.

This paper suggests an approach for selecting partial factors for limit states design of pipelines based on formal reliability analysis. Such an approach recognizes that consistent safety levels can be achieved for different pipeline sections by varying the target reliability as a function of the severity of failure consequences, where consequences are measured in terms of public safety, economic costs, and damage to the environment. Where the consequences of failure are more severe, higher reliability is required. Where the consequences are less severe, lower reliability can be tolerated, with the same risk level being achieved.

This paper reviews the limit states design method and discusses the selection of target reliability levels and the reliability analysis procedures used to calibrate partial design factors.
Pipeline Maintenance Planning Based on Quantitative Risk Analysis
Authors: Stephens M. J. , Nessim M. A.
Published: October 2016

The integrity of aging pipeline systems is a major concern for operating companies. Because maintenance budgets are limited by economic constraints, operators must decide on how to best allocate the available maintenance resources. Optimal resource allocation involves the identification of high risk segments, and the determination of integrity maintenance activities for those segments that will lead to the highest reduction in overall operating risk.

To identify high risk segments it is necessary to quantify the probability of line failure and to evaluate the consequences associated with different types of failure. To identify optimal maintenance activities for high risk segments it is also necessary to quantify the reductions in failure probabilities associated with various candidate integrity maintenance activities. Under the sponsorship of a number of pipeline companies and Government Agencies, C-FER has initiated a Joint Industry Program (JIP), to develop quantitative risk-based models and software tools for estimating the current level of operating risk and the risk reduction potential associated with distinct segments of pipe within a pipeline system.

The key steps in the methodology are system prioritization and maintenance optimization. At the prioritization stage, segment-specific attributes are processed to provide an estimate of the failure rate for individual segments, and an estimate of the potential consequences of line failure. The failure rates are then combined with the loss potential into a measure of risk, and used to rank segments according to the calculated level of operating risk. At the maintenance optimization stage, a formal decision analysis approach is employed to identify the best maintenance strategy for high risk segments based on a comparison of the costs and risk reductions associated with each available option.
Quality and Risk Management: Complementary Management Techniques to Assist Pipeline Life Cycle Integrity
Authors: Fowlie Bruce E.
Published: October 2016

In recent years, numerous management techniques have come forward. Many of these techniques are perceived as independent and not complementary to each other. This may have led many people to suggest that the various techniques are nothing more than buzzwords and flavor of the month philosophies. Understanding the various techniques and their complementary aspects is perhaps the greatest tool for the management of a pipeline system throughout its life cycle.

This paper discusses the main features of quality management and risk management. It also demonstrates the advantage of merging these two techniques thereby causing the organization to better manage life cycle design, operation and cost. Lastly, this paper illustrates that external communications can be improved by communicating both the quality and risk management aspects of the work.
Public Safety Risk Assessment of Natural Gas Liquids Pipelines
Authors: Zelensky Michael J. , Springer W. Arthur J.
Published: October 2016

Public safety risks are becoming an important issue in the planning of new pipelines and the operation of existing pipelines. Pipelines are initially routed to avoid densely populated areas. However, new developments may encroach on existing pipelines. Risks to the public can be estimated to determine an adequate setback distance.

The methodology for risk assessment is described using a Canadian case study. Ethane, propane, butane and pentanes are commonly transported as liquids in pipelines. These compounds have a high vapour pressure, and when accidentally released, may form a flammable dense gas cloud. If the cloud is ignited, a flash fire or vapour cloud explosion may occur. Consequences and frequencies of the selected hazardous incidents are provided. Individual risk levels in rural and urban areas along the pipeline are presented and compared to the risk-based land use planning guidelines of the Major Industrial Accidents Council of Canada.
Manufacture, Properties, and Installation of X80 (550 MPa) Gas Transmission Linepipe
Authors: Kostic M. Milos
Published: October 2016

Steel for a large-scale commercial production of X80 (550 MPa) gas transmission linepipe was made in a scrap-based, electric arc furnace shop. Thermo-mechanical processing of skelp was completed in a Steckel mill. Successful pipe manufacture (1219 mm OD, 12.0 mm WT) and efficient field construction demonstrated that suitable steel making and processing controls can eliminate potential detrimental effects of residual chemical elements in electric steel.
Comparison of Ring Expansion vs Flat Tensile Testing for Determining Linepipe Yield Strength
Authors: Saikaly Wahib E. , Bailey William D. , Collins Laurie E.
Published: October 2016

Ring expansion testing has been compared to conventional tensile testing as a means to evaluate the circumferential yield strength of pipe products. It was found that ring expansion testing provides a more accurate determination of hoop yield stress than tensile testing of flattened pipe samples. In addition, ring testing was found to be more sensitive to the metallurgical condition of the steel. Tests were conducted on ERW and Spiral pipes. Different grades and diameter to thickness (D/t) ratios were evaluated.

In comparison to tensile testing on flattened specimens, ring expansion tests gave: a) higher yield strength; and b) reduced standard deviation in test data. The difference in yield strength measured by ring and tensile tests increased with increasing grade and lower D/t. The higher yield strength measured in the ring test is a result of reducing the Bauschinger effect associated with flattening tensile samples. The reduced standard deviation is due to the elimination of flatness and machining variations that occur on a flattened tensile specimen. It was concluded that ring testing provides a true measure of pipe circumferential yield stress.
The Use of Thermoplastic Lined Pipelines for Aggressive Hydrocarbon Service
Authors: Woodward Kenneth A. , Al-Hassan Tariq
Published: October 2016

This study is related to the use of thermoplastic liners to control corrosion of new and rehabilitated pipelines carrying aggressive hydrocarbon products. The aim is to investigate the technical and safety issues involved in introducing a thermoplastic liner into an existing carbon steel pipeline for aggressive hydrocarbon service at temperatures up to 150°C and internal pressures up to 34 MPa (5000 psi). The principal objective is to provide design data for thermoplastic lined pipelines. The scope combines the use of liner insertion techniques with thermoplastic materials widely used in onshore pipelines and demonstrates the effectiveness of thermoplastic linings.

The results indicate that thermoplastic liners can be used to control corrosion of pipelines in aggressive hydrocarbon environments.
Predictive and Preventive Maintenance of Oil and Gas Production Pipelines in the Area North Monagas-Venezuela
Authors: Pérez Miguel Angel Lugo
Published: October 2016

Predictive maintenance of oil and gas production pipelines has allowed tp predict operational failures. Specially due to the thermodynamic behavior of the produced fluids, contaminants present in the oil and gas such as sand, water, H2S and CO2, asphaltene deposition, high temperatures and pressures, phisicochemical characteristics of the soil, etc. that would lead to risks of the installations.

In order to minimize risks of failures, we have stablish a control and monitoring preventive program of the variables that influence this conditions, such as: non-destructive testing, wall thickness measurements and two dimensional B Scan measurements to detect impurities, laminations and inclusions in the pipeline material, corrosion evaluation of pipelines, characterization of the soil corrosive potential of flow stations and compressing plants.

Aditionally, we have implementede predictive control through the application of external corrosion prevention techniques such as cathodic protection and coatings. For internal corrosion, the use of corrosion inhibitors, asphaltene dispersants and material selection. Increasing the protection through preventive and predictive maintenance we can reduce the operational risks involved for the oil and gas production.
Assessment of Long Corrosion Grooves in Line Pipe
Authors: Cronin Duane S. , Roberts K. Andrew , Pick Roy J.
Published: October 2016

Due to coating disbondment long corrosion grooves can develop in line pipe. For simple corrosion geometries current methods of assessing the residual strength of the pipe are adequate but conservative, particularly if only the nominal material strength is considered. In the case of long corrosion grooves which contain pits the application of current assessment procedures can lead to a variation in the degree of conservatism, depending on the importance applied to the pitting. This paper reviews existing methods of assessing long corrosion and describes the result of a finite element study of pits within long corrosion grooves.
The Evaluation and Restoration of a Deteriorated Buried Gas Pipeline
Authors: Dovico Ricardo , Montero Eduardo
Published: October 2016

Historically, the Argentine gas transmission and distribution industry was owned and operated by the State. In 1992, by government decree, this entire industry was transferred to private owners and operators, and divided into two Gas Transmission Companies (TGN and TGS) and eight Gas Distribution Companies.

The pipelines and related facilities had been left in an operating condition, however major capital investments were required to assure that the integrity, reliability and operability of the facilities were intact. These capital expenditures were mandatory in many areas as part of the privatization.

Maintenance and rehabilitation tasks were developed for the entire transmission system, with the intent to reduce the number of unscheduled outages, optimize system maintenance costs, increase operation safety, and upgrade the pipeline to ensure compliance with the international code.

Transportadora de Gas del Norte (TGN), operated by Nova Gas International of Calgary, Canada, consists of two major pipeline transmission systems. The North Line, which transports gas from Northern Argentina and Bolivia to markets south to Buenos Aires is a 24 inch, 3,000 Km system constructed in 1960. It was constructed using a field applied asphalt coating system. The Center West Line, which transports gas from central Argentina (Neuquen) to markets in the western part of the country and also to the Buenos Aires area, is a 30 inch, 1,400 Km system constructed in 1981. It was constructed using a field applied polyethylene tape coating system.
Evaluation of Stray Current Effect on the Cathodic Protection of Underground Pipeline
Authors: Park K. W. , Cho Y. B. , Jeon K. S. , Lee S. M. , Kho Y. T.
Published: October 2016

Two types of stray current which affect the cathodic protection of underground pipeline are discussed. One is the stray current by DC transit system and the other is that originated from the nearby cathodic protection system. The popular evaluation methods of the pipe-to-siol potential measurement was undertaken to evaluate the corrosion activity of pipeline. In case when the pipe was affected by the stray current, the measured pipe-to soil potential was significantly deviated from the mean value resulting in normal distribution. Analysis of such distribution pattern has revealed that the pipe under investigation was in the condition of insufficient protection (noble mean potential and high asymmetry coefficient) due to the considerable effect of stray current (high standard deviation value). It was also confirmed that the efficiency of drainage system was so low (<10%) due to the improper selection of drainage point. Simultaneous measurement of the magnitude and direction of the sheath current resulted in information about the place where stray current entered into pipe and escaped to soil. For the second case of stray current problem, it is shown that it has been caused by the combined interference from nearby CP system.
Corrosion and Cathodic Protection at Disbonded Coatings
Authors: Payer J. H. , Fink K. M. , Perdomo J. J. , Rodriguez R. E. , Song I. , Trautman B.
Published: October 2016

The effectiveness of cathodic protection to control corrosion and the resulting corrosion rate of pipelines arc determined by the chemical and electrochemical conditions at local areas along the pipeline. The disbonding of coatings and tapes is also controlled to a large extent by the chemical and electrochemical conditions. Processes that occur on the metal surface and their effect on corrosion and cathodic protection are discussed with respect to real pipeline conditions. Disbonded coatings on steel can interfere with the current distribution from cathodic protection. Shielding the current under disbonded coatings can affect the level of protection, the corrosion behavior and the disbonding of coatings. A major thrust in our laboratories has been the use of laboratory measurements and computational models to determine the changes in the corrosive environment that occur beneath disbonded coatings as a function of applied potential, disbonded area geometry, prior corrosion products and wet/dry cycles. These results are summarized here.
Hydrogen-Induced Stress Corrosion Cracking of Pipe Lines of Russia
Authors: Sergeyeva Tatyana K. , Tychkin Igor A. , Vasiliev Gennady G.
Published: October 2016

The results of expert studies of large diameter pipes damaged due to external stress corrosion cracking are presented in the report. These data obtained in the 1993–1995 are typical for various regions of Russia. The results of laboratory studies of the stress-corrosion mechanism for pipe steels in suspensions of soils from the places where the operating failure had occurred are given in the report also. The mechanism of hydrogen-induced stress-corrosion cracking (HISCC) realizing through local hydrogenation of steel during plastic deformation has been determined by means of the technique of slow strain rate test (SSRT) of samples in the soil under cathodic, anodic and free corrosion potentials in combination with hydrogenation and hydrogen distribution analyses along length of a sample. No hydrogenation of volumes of pipes non-subjected to cracking was observed but hydrogenation took place in the zones subjected to stress corrosion.
Factors Influencing Stress Corrosion Cracking of Gas Transmission Pipelines: Detailed Studies Following a Pipeline Failure: Part 2 — Pipe Metallurgy and Mechanical Testing
Authors: Wilmott Martyn J. , Diakow David A.
Published: October 2016

Following a failure caused by stress corrosion cracking (SCC) on an NPS 8 pipeline in the Nova Gas Transmission (NGTL) system, a detailed investigation was undertaken to understand the contributing factors resulting in the failure. Studies included site characterization using the NOVAProbe, followed by a detailed excavation, sampling, pipe replacement and subsequent metallurgical analysis. In total, 1.1 km of pipe was inspected and replaced. This paper will detail the results of pipe inspection, mechanical testing and metallurgical analysis following excavation. Possible correlation of the results with potential SCC severity is discussed.
Restoring the Supporting Capacity of Compressor Station (CS)’s Framework With Pipe Surface Defects
Authors: Kurganova I. N. , Zayets A. F.
Published: October 2016

In the technologic pipeline framing of CS shop there are revealed defect sections which emerging is caused by tearing-out of pipeline support channels in their places of welding to supports. Because of it there emerged defects like cavities, fissures Russian CS pipelines are related to highly dangerous ones and there are no regulative materials for exploitation of such systems with defects. But removing of all defect places in this binding equals to its disassemblying and building of new one, this is existing defects.

With this aim there are conducted complex surveys and developed repair method, considerably increasing capacity of technologic framing without cutting of defect places. Complex measures include long-term nature measurings of stress-strain state in vicinities of defects; cyclic longevity (remaining capacity) tests of soil with defects cut from operating framework; calculation-theoretical developments patent workings-up, creation of new repair method and its approbation in CS conditions.

As results of nature and cyclic tests there are gotten factual value of stress polus on pipe and remaining capacity data. On basis of gotten results there are made static calculations on crack-resisting and load-bearing capacity of designs with defects and dynamic calculation for remaining capacity. There is developed repair method of pipeline binding, preconcerted with exploitation situation and allowing to lift framing’s reliability level up to project one.
Heavy Oil Transportation by Pipeline
Authors: Gerez John M. , Pick Archie R.
Published: October 2016

More of the crude oil being produced in the world is heavy oil. It was reported by Meyer and Dietzman (1979) that world annual production of heavy crude oil was about five percent of other oil produced. They forecast that heavy crude oil production would increase. Canadian heavy oil production cumulative to 1979 was reported to be 197 million barrels. By 1996 Canadian daily production levels have risen to the levels shown in Table 1, with annual production of heavy oil and bitumen exceeding cumulative totals produced to 1979.
Reconstruction of Gas Distribution Pipelines in MOZG in Poland Using PE and PA Pipes
Authors: Borowicz Waldemar , Podziemski Tadeusz , Kramek Elzbieta
Published: October 2016

MOZG - Warsaw Regional Gas Distribution Company was established in 1856. Now it is one of six gas distribution companies in Poland and covers about a quarter of the area of our country. We serve 1.8 million customers in total. The total length of our distribution network is approximately 20,000 km and the quality of the greater part of our pipelines is suitable for the current level of demand. However, approximately 150 km of our network is made of steel or cast iron constructed pre 1955. Additional some 3000 km of piping is between 15 to 40 years old. Due to steadily increasing safety demands, some of the pipelines will need reconstruction. The majority of the substandard piping is located in urban areas. It is common to find gas pipes buried under roads and pavements along with other utilities (water, sewage, power and communications) leaving these underground areas crowded. Also due to the recent increase in “traffic volume” it has become more and more difficult to conduct pipeline reconstruction by conventional “trench excavation” pipe replacement techniques.
The Development of a Pipeline Blowdown Strategy Using a Decision and Risk Analysis Model
Authors: Karwacki L. , Murray M. A.
Published: October 2016

Providing safe working access to natural gas pipelines often involves removing gas from those portions of the pipeline affected by the activity. A number of means exist for performing this task, with varying impacts to the environment in terms of noise and air pollution and at various costs to the shippers of the gas. The paper briefly describes a number of ways in which the environmental impact can be minimised, and then places these within a Decision and Risk Analysis model in order to obtain the most cost effective strategy over a fifteen year period.
Recommissioning NPS 30 Pipeline
Authors: Saad Ziad A. , O’Rourke Dan J.
Published: October 2016

This paper will discuss all the steps taken to reclaim an 80 kilometre (50 Mile) NPS 30 (30″) pipeline loop, including the project planning, the labour requirements, the techniques utilized to complete the various stages of the project, some of the unique problems encountered, as well as, some options that were examined for hydrostatic test leak detection and water treatment.

This project was a component of the Trans Mountain, Cdn $30 million, Stage II capacity expansion. This component of Stage II resulted in an increase of 3,000 m3/d (18,909 barrel/d) to the overall pipeline capacity achieving a 36,300 m3/d sustainable pipeline pumping capacity1 (230,000 barrel/d).
Problems of Restructurisation and Renewal of Old Gas Distribution Network in Wroclaw
Authors: Rygier Jan
Published: October 2016

Changing environment, growing demand for gas for heating, and shut down of old gas plant, cause necessity of restructurisation of the old gas distribution network in the city.

Aging distribution network, replacement of manufactured gas by natural gas and rapid growth in number of leaks cause urgent necessity of replacement and rehabilitation of the old gas pipelines.

Modern materials and technologies have enabled rehabilitation gas pipelines in the narrow busy streets of the city.
Pipeline Reliability Evaluation and Design Using the Sustainable Capacity Methodology
Authors: Chmilar W. S.
Published: October 2016

A reliability evaluation methodology, referred to as Sustainable Capacity, has been developed to quantify reliability expectations and provide a basis for the explicit consideration of reliability in pipeline design. The methodology, which has been adapted from one widely used in the electric power industry, is based on the representation of the load and capacity processes, which define reliability, with Markov models. These models generate time-series of simultaneous load and capacity profiles which are evaluated to determine reliability expectations. A cost-benefit methodology which recognizes the variation in the value attributed to pipeline reliability by individual customers is then used to assess the economic efficiency of any proposed facility addition. Further to its application as a design tool, the Sustainable Capacity methodology can also provide support in other areas such as operations and maintenance planning.
Establishing the “Fitness for Use Criteria” for Pipe Line Variable Frequency Drives
Authors: Spencer Roy C. , Rivera Arnold
Published: October 2016

“Fitness For Use”[1] criteria are used to define project quality. This paper documents how to establish the “Fitness For Use” criteria for pipe line variable frequency drives (VFD’s). A Pipe Line VFD project’s life cycle process together with the technical requirements” determine its “fitness for use”. Effective definition and management of these “life cycle requirements”, therefore ensures a quality result.

In summary, this paper documents how the “Fitness For Use Criteria” methodology was successfully used on the IPL Capacity Expansion Program to:

(a) establish the project process;

(b) engineer, procure, construct, commission and start-up the VFD systems; and

(c) carry out training plus technically support the pipe line’s early operation phase.

The Canadian section of IPL’s Line 13 is powered by eight pump stations containing five 3750 hp and three 6250hp, current source inverter (CSI)[2] based VFDs; this equipment was installed and commissioned in 1994, and has been in operation for 18 months.
Analysis for Wrinkling Behavior of Girth-Welded Line Pipe
Authors: Souza Luiz T. , Murray David W.
Published: October 2016

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.
Polyurethane Foam Use in Pipeline Construction
Authors: Ellis Douglas S. , Belding James
Published: October 2016

The use of polyurethane foam in Pipeline Construction in North America has been widely accepted by the Industry during the past twenty years. Recent aggressive sales attempts are being made to enter the International market which includes South America. The use of foam is far superior to out-dated sandbag methods to prevent soil erosion. Many other uses have since come to be utilized for the pipeline construction.
Gas Turbine Compressor Unit Repowering
Authors: Taylor Joe S.
Published: October 2016

This paper presents how a major U.S. gas transmission and storage company restored gas storage peaking capacity by repowering obsolete gas turbine compressor units. Consumers Power Company’s Ray Field located in Macomb County, Michigan, USA, was developed as a 44 BCF working capacity gas storage field in 1966. Due to the high deliverability, the field is operated as a peaking reservoir, handling rates as high as 500 MMCFD on injection and 1,200 MMCFD on withdrawal. Ten (10) 2,750 horsepower gas turbine driven 4-stage centrifugal compressor units were installed in the mid to late 1960’s at the field. The compression is operated 2, 4 and 8 stage, as needed, to cover storage pressures of 450 to 1800 psig.

Each centrifugal compressor is driven by a Pratt Whitney (PW) GG-12 Gas Generator firing into a Cooper-Bessemer (CB) RT-27 Power Turbine. By 1980 parts and maintenance services for the PW GG-12 Gas Generator became very expensive to non-existent. Aircraft use of the GG-12 (JT-12) had been phased out. Consumers Power, with 13 of these turbines on their system, was becoming the only remaining user. In the mid 1980’s four (4) of the Ray Field gas turbine compressor units were replaced with two (2) 6,000 horsepower reciprocating engine compressor units. These replacements maintained the deliverability of the field and provided salvageable engines and other parts to maintain the six (6) remaining turbines. However, by 1993 maintenance parts returned as a major problem as well as unit availability on the 6 remaining turbine units.

In 1994 Consumers Power committed to a gas turbine unit repowering program as the preferred choice over unit replacement. Two (2) refurbished Solar Centaur T4500 Gas Turbine drives were purchased and installed to repower 2 of the obsolete turbine units. These installations have been very successful. Existing compressors, foundations, piping, coolers and auxiliary systems were re-used with only minor modification. The complete installed cost for repowering was about 33% of the cost experienced for replacement. Installation was completed within eight (8) months of project commitment. The low emission rates from the Solar SoLoNOx Combustors allowed short lead time (6 months) on air emissions permit. New sound attenuation enclosures met the new local noise ordinance and replaced equipment that had been a source of local complaint. PLC based controls improved reliability and flexibility of operation. The additional horsepower available from the T4500 Turbine (4,300 vs 2,750) allows for increased future capacity.

Because of the success of the Ray Turbine Repowering Project, Consumers Power has committed to 2 more refurbished Solar Centaur T4500 Units to repower PW/CB Turbines at the St Clair Compressor Station. Solar is scheduled to delivery these 2 units by year-end 1995 for installation in 1996.
Dry Gas Seal Developments and Contamination Prevention
Authors: Uptigrove Stan O. , Eakins Paul S. , Sears John E.
Published: October 2016

Dry gas seals have become the pipeline industry standard for sealing of centrifugal gas compression equipment. Recent applications have pushed the limits of materials used in their construction from exposure to ever increasing levels of pressure, speed and temperature. This provides the focus for a discussion of recent advances with the use of advanced materials, higher pressure, speed and temperature applications and bidirectional designs.

Operating experience has been very favourable, enough to make dry gas seals a preferred standard, but the failures that have occurred raise two fundamental questions. The first concerns the resistance of gas seals to contamination and the second is their influence upon rotor dynamic behavior. Both of these predominant issues are reviewed along with advancements and preventive measures now available to address these concerns.
Experiences With Simulation of Reciprocating Compressor Valve Dynamics
Authors: Howes Brian , Lin Leonard , Zacharias Val
Published: October 2016

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling.

Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance.

Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life.

Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow.

Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.
PC Based Leak Detection
Authors: Mactaggart Ross H. , Myers Richard M.
Published: October 2016

Software based leak detection has a reputation of being very complex and requiring large amounts of computing power to be effective. This makes it impractical for application on small pipelines. This paper will discuss implementation of a software based leak detection system on a small crude oil gathering pipeline. The leak detection system uses a more practical approach to the problem than traditional methods and was implemented on a PC under the Windows operating system.
Application of Higher-Order TVD Resolution for Investigation of Transients Problems in Natural Gas Pipelines
Authors: Ibraheem Sarafa O. , Adewumi Michael A.
Published: October 2016

A higher-order numerical procedure is applied to simulate typical transient phenomena in natural gas transportation. Reliable modeling and prediction of transients features in transmission pipelines are desirable for optimal control of gas deliverability, design and implementation of active controls, and modeling of operational behavior of network peripheral equipment (e.g., chokes, valves, compressors, etc.). As an alternative to the Method of Characteristics (MOC) that is widely used presently, a higher-order Total Variation Diminishing (TVD) method is used to model some transient problems. This, class of methods has the capability to capture fine-scale phenomena and provides a better resolution of frontal discontinuities. In this study, the TVD method is utilized in conjunction with upwind methods. Also, in order to ensure a stable time-stepping scheme over a wide range of Courant-Friedrich-Lewy (CFL) number, a special Runge-Kutta method is employed as the base solution algorithm to integrate the highly non-linear, hyperbolic equations which govern the transportation of natural gas in pipelines. The overall procedure is stable, robust and accurate when applied to solve practical problems with simulated pressure waves.
Evaluating the Effective Friction Factor and Overall Heat Transfer Coefficient During Unsteady Pipeline Operation
Authors: Price Glenn R. , McBrien Robert K. , Rizopoulos Sandy N. , Golshan Hossein
Published: October 2016

This paper presents a method to determine the effective friction factor and overall heat transfer coefficient for a high pressure, natural gas pipeline during fully transient flow conditions. Time varying SCADA (Supervisory Control And Data Acquisition) measurements at the pipeline boundaries (i.e., inlet and outlet) provide boundary conditions for a transient flow model as well as additional information that is utilized to determine these parameters. The resulting friction factor and overall heat transfer coefficient minimize the least-squared difference between the additional SCADA measurements at the pipeline outlet and the corresponding values predicted from the transient flow model. This concept is referred to as parameter estimation. The transient flow model is based on a numerical solution of the one-dimensional, unsteady flow equations (i.e., continuity, momentum and energy) which are discretized using a highly accurate compact finite-difference scheme.

The transient flow model and parameter estimation are incorporated into a computer program that is initially tested on a simple pipeline with steady flow conditions. Here, the predicted outlet pressure and temperature, using the estimated friction factor and overall heat transfer coefficient, exactly matches the corresponding prescribed values. Subsequently, a portion of the Foothills Pipe Line Ltd. transmission system in Alberta is considered using time varying SCADA flow measurements. The resulting outlet pressure and temperature from the transient flow model are in good agreement with SCADA measurements at this location.
The Importance of Dynamic Simulation on the Design and Optimization of Pipeline Transmission Systems
Authors: Mohitpour M. , Thompson William , Asante Benjamin
Published: October 2016

Traditionally, pipeline transmission systems have been designed using steady state simulations. Steady state simulations are sufficient for optimizing a pipeline when supply/demand scenarios are relatively stable. In the case of a gas pipeline, it is also important that flows in and out of storage are not highly variable. In general, steady state simulations will provide the designer with a reasonable level of confidence when the system is not subject to radical changes in mass flow rates or operating conditions.

However, situations do arise which require more than a conventional analysis such as large load factors, surges in mass flow rates, the loss of facilities and facility operation (e.g. pigging procedures). In these and other instances, the designer will want to perform a dynamic (or transient) analysis to test the capability of the system, choose the system components and maintain the appropriate level of safety.

This paper will illustrate the importance of transient simulations when designing transmission systems subject to aggressive conditions. Example scenarios, taken from current major projects, are used to depict a diverse range of dynamic problems. The examples help identify the need for a transient analysis and exemplify the downfalls in a system when the analysis is not employed during the optimization and design process.
Rehabilitation of Pipelines in Seismic Regions
Authors: Gershtein Mark
Published: October 2016

The susceptibility of oil and gas pipelines to seismic damage has been demonstrated in earthquakes everywhere around the world. The latest examples of the dangerous failures are the ruptures of gas pipelines caused by Los-Angeles earthquake 1994 and oil pipelines caused by Sakhalin earthquake 1995.

A significant part of oil and gas pipelines were designed some decades ago. Earthquake design specifications acting today are more restrictive than before. That is why pipelines built more than ten years ago are of major concern to managers and engineers.

Basic approaches to the aseismic design of new pipelines and retrofitting of buried pipes and above-ground transmission pipelines and piping systems located in high risk seismic regions represent the main topic of the paper.

A realistic assessment of earthquake damage potentials is needed to develop construction and retrofitting procedures. Supporting this type of constructing and rehabilitation activity for pipelines requires a better definition of key input parameters like area seismicity, the identification and characterization of ground moving hazards.

The nonlinear approach for predicting spatial bending, torsion, and upheaval buckling of curved pipeline is applied for stress and stability analysis of buried pipelines under operational and seismic loading. The example of calculations useful for retrofit design of pipelines is given.

An experience of damping devices application to mitigate seismic movement of above-ground pipelines has demonstrated an excellent ability to prevent damages during earthquake and operational dynamic loading. These devices are useful for above-ground pipeline retrofitting.

To reduce uncertainty regarding the ability of a pipe to continue to hold pressure after seismic damages and retrofitting measures, it is important to develop the test programs, which should include investigations of buried and above-ground pipeline samples.
Laboratory Investigation of Pipeline/Soil Interactions Using X-Ray Computer Assisted Tomography
Authors: Kantzas Apostolos , Trigg Allan
Published: October 2016

X-ray Computer Assisted Tomography (CAT or CT) Scanning has been used successfully for the determination of physical properties of porous rocks and for flow visualization in a variety of porous media including soils. CAT scanning has also been demonstrated as an effective tool for the visualization of different stress conditions in porous rocks with greater accuracy when dealing with unconsolidated media. This success was the motivation in trying to expand the diagnostic capabilities of CAT scanning in the phenomena associated with pipeline / soil interactions. For this purpose, a physical model was built. The model consisted of a x-ray transparent holder which had two pistons, one at each end. The pistons were mounted on a cylindrical rod of variable diameter. The holder was then filled with sand. The entire apparatus was placed in the CAT scanner gantry. A series of experiments were performed whereby the rod was forced through the sand pack. The holder was scanned from end to end and the images of various cross-sections were acquired and analyzed for bulk density and porosity. The experiments were coupled with calibration experiments where a uniformly packed sand was loaded under hydrostatic load in given increments. As the sand pack compacted, its bulk density increased. The normalized change in density (strain) was monitored as a function of the pressure load (stress). The results of the calibration tests were used to identify the levels of stress on the sand surrounding the moving rod. It was discovered that areas of compaction ahead of the moving rod and dilation behind the moving rod could be successfully identified and mapped. The stress / strain calibration data allowed the translation of the bulk density images into stress maps around the pipeline. Although the system and materials used in this work were utilized only for demonstration, it was evident that this type of experimental work could be successfully used to calibrate complicated field scale computer models that are very difficult to tune because of the lack of experimental data.