bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Robotic Technology for Cast Iron Pipeline Repair
Authors: Elliott Ron , Szilard Steve , Prattinger Gunther 
Published: October 2016

Prior to the introduction of plastic pipe many gas utilities used cast iron to build their gas distribution network. Currently, there is approximately forty thousand kilometres of cast iron pipe in service in North America and a further two hundred thousand kilometres in Europe. Mostly found in dense urban locations, the cost of replacing these systems can be significantly high, such that extending the life of these systems is now a common strategy. The main problem has been leakage from bell and spigot joints caused by road vibration, freeze/thaw cycles of the ground, and the swelling and drying of clay soils.
Repair technologies have evolved from mechanical joint clamps, to elastomeric seals, to shrink sleeves, to encapsulants and finally to anaerobics. The most advanced of these technologies involve the use of anaerobic sealants which are injected into the jute packing by drilling into the pipe bells. These sealants have been studied at Cornell University for longevity, and are predicted to withstand many years of service.
The use of anaerobics has been adapted to work with robotics that allows the injection to take place from the inside of the pipeline while the gas main is in operation. This technology allows 24 joints to be sealed from a single excavation. The robot is a tethered electro-mechanical device that allows visual location of the joint, internal drilling into the jute packing, and injection of the sealant. A semi-rigid umbilical cable contains the electrical, hydraulic, and communication lines, and a unique drive mechanism that allows for remote operation and positioning.
The development of this prototype technology was conducted by Engineering Services Inc. (ESI) of Toronto at the request of Enbridge Consumers Gas and was co-funded by Consolidated Edison of New York. Over 2000 joints have been successfully sealed in the last two years and the system is expected to be commercially available within the next year. Internal robotic repair of live mains is an industry first and has the potential to significantly reduce both costs and disruption of road excavations in urban areas.
Development of an Alternative Criterion for Residual Strength of Corrosion Defects in Moderate- to High-Toughness Pipe
Authors: Stephens Denny R. , Leis Brian N. 
Published: October 2016

This paper presents the development of a new, simplified criterion, known as PCORRC, for prediction of the remaining strength of corrosion defects in moderate- to high-toughness pipeline steels that fail by plastic collapse. Comparisons against an experimental database indicate that, when toughness is sufficient, the PCORRC criterion reliably predicts the remaining strength of blunt defects using only the maximum depth and maximum length of the defects with less excess conservatism than existing criteria. The value of PCORRC is demonstrated in comparisons that show it capable of reducing excess conservatism significantly in the class of defects that fail by plastic collapse, potentially resulting in significant reductions in pipeline maintenance and repair costs. This new criterion was developed at Battelle under sponsorship of the Line Pipe Research Supervisory Committee of PRC international.
The new simplified criterion was developed from a finite-element software analysis model. The analysis software was applied in a parametric investigation to evaluate the influence of geometry and material characteristics on the remaining strength of corrosion defects in moderate- to high-toughness steels that fail by plastic collapse. The model development and parametric investigations demonstrated that:
• The failure of this class of defects is controlled by the ultimate tensile strength rather than yield strength or flow stress;
• Defect depth and length are the most critical defect geometry variables;
• Defect width and material strain hardening are of lesser importance.
The Conception, Design and Implementation of 36″ by 48″ Dual Diameter In-Line Cleaning and Inspection Tools in a Crude Oil Transmission System
Authors: Couchman Peter , Bhatia Arti , Ronsky Daryl 
Published: October 2016

Enbridge operates the world’s longest hydrocarbon transmission system. The pipeline infrastructure has experienced additions over its 50 years of operation. The expansions were implemented as successively larger pipe sections upstream from pumping stations. After completing three lines (20″, 24″ and 34″) in parallel configuration, 48″ sections were installed upstream from pumping stations in 1972 and 1973. In order to accommodate future throughput requirements, part of the Enbridge’s 1998 Terrace Expansion Project was designed to connect the 48″ pipe sections into a continuous line with 36″ pipe sections.
The first Terrace Expansion design included sending and receiving traps for both the 36″ and the 48″ sections. An intricate network of crossover piping and mainline valves would allow in-line tools to be both launched and received at the diameter transition point without impacting flow. Since the transition points occur anywhere from 10 to 40 kilometers upstream from pumping stations, more aboveground facility locations would be added.
Enbridge approached vendors of the different in-line inspection technologies to conduct feasibility studies for building 36″ by 48″ dual diameter tools for pipeline cleaning, geometry and metal loss inspection applications in January 1998. Enduro Pipeline Services, Williamson Industries (TD Williamson) and Pipeline Integrity International (PII) were selected to assemble the working tools based on the viability of their technical presentations and cost estimates. The development of 36″ by 48″ dual diameter cleaning and inspection tools would save Enbridge time and money by eliminating the need to install traps and associated valving at the transition areas. As a result, the accelerated schedule and targeted project completion for inspection in Enbridge’s Terrace Expansion line within a twelve-month time frame was accepted by all parties.
This paper discusses the phases of the project from the technical feasibility studies, original and progression of design concepts, test loop execution and actual field use and validation of the tool performance and information.
Comparison of Estimates From a Growth Model 5 Years After the Previous Inspection
Authors: Worthingham Robert , Morrison Tom , Desjardins Guy 
Published: October 2016

A corrosion growth modelling procedure using repeated inline inspection data has been employed as part of the maintenance program planning for a pipeline in the Alberta portion of the TransCanada system. The methodology of matching corrosion features between the different in-line inspections, and estimating their severity at a future date, is shown to be an excellent proactive cost saving methodology.
Throughout this paper estimated 80% confidence intervals for tool measurement error, total prediction error and growth methodology error are given. In this abstract the values have been rounded. For maximum penetration, for the features reported on three inspections, the confidence interval for total prediction error varies from ±12% to ±17%, and for the growth methodology from ±8% to ±10% of the wall thickness (for the 1998 and 1999 dig programs respectively). For features reported on two inspections the confidence interval varies from ±19% to ±22% for total prediction error (1998 and 1999 digs respectively), and is about ±17% for the growth methodology (for both dig programs).
The estimated confidence interval for prediction error in failure pressure is about ±560 kPa for the 1998 dig program. For the 1999 dig program a good estimate of the confidence interval for total prediction error could not be obtained. Assuming the failure pressure data obtained from field measurements were perfect, the estimate of the maximum confidence interval was ±850 kPa.
For the laser profile measurement field tool, compared to an ultrasonic pencil probe, the confidence interval for penetration is less than ±2% of the wall thickness.
The true confidence interval values in some cases are expected to be smaller than reported above for several reasons discussed in this paper.
Laboratory Study of Local Buckling, Wrinkle Development, and Strains for NPS12 Linepipe
Authors: Das Sreekanta , Cheng J. J. Roger , Murray David W. , Wilkie S. A. , Zhou Z. Joe 
Published: October 2016

Buried pipelines are subjected to fluid pressure (oil/gas/water), axial loads, moments, and complex load combination histories. As a result, they may develop large compressive strains and curvatures leading to formation of localized buckles or wrinkles in the pipe shell. Recently, full-scale tests on 12.75″ diameter (NPS12) energy pipes have been carried out at the University of Alberta to study the behavior of wrinkle development and the ultimate limiting strains at the wrinkle locations. Different internal pressures, and axial loads were applied to produce a wrinkle, followed by load variations intended to produce fracture that could develop in buried pipelines in the field.
Three different axially loaded tests are reported. Two different internal pressures were applied, namely, (i) 0.8py and (ii) 0.4py, where py is the required internal pressure to cause the yield stress of the pipe material to be developed in the circumferential direction. Also, two different specimen lengths were adopted. They are: (i) 406 mm (16 inch) and (ii) 736 mm (29 inch). All specimens were loaded axially until the wrinkle formed. It was observed that the pipes are highly ductile and very large compressive strains can be developed without fracture or leakage in the pipe wall.
Because the pipe specimens of the first two tests did not fail (i.e. fracture) under monotonically increasing displacements and strains, the third wrinkled specimen was subjected to load histories involving strain reversals. This load history resulted in a low cycle failure after a very few cycles. The paper addresses test procedures, buckling and post-buckling behavior of NPS12 energy pipelines and relates them to three different types of strain measures, namely, material strain, wrinkle strain and overall strain as observed from these tests.
Analytical Simulation and Field Measurements for a Wrinkle on the Norman Wells Pipeline
Authors: Yoosef-Ghodsi Nader , Cheng J. J. Roger , Murray David W. , Doblanko Rick , Wilkie Scott 
Published: October 2016

In laboratory testing of full-sized pipe subjected to combined axial load, internal pressure and bending, the normal failure mode consists of local buckling on the side of the maximum compressive fiber. If loading is continued beyond the initiation of buckling, and if the pipe is pressurized internally, the pipe retains its integrity while it develops a wrinkle in which very large deformations occur. Buried pipelines should behave in the same way. The paper presents the analyses carried out to assist in the interpretation of Geopig field evidence that, in September of 1997, a wrinkle existed on Slope 92 on the Norman-Wells Pipeline.
A finite element analysis of a shell model of a segment of the pipe confirmed that the wrinkle should exist. A subsequent pipe dig uncovered the wrinkle which had a configuration remarkably similar to those observed in the laboratory and to the form predicted by the analysis. Supplementary geotechnical investigations, a review of operational procedures on the line, and additional testing to determine strains within wrinkles, are presented in companion papers elsewhere in this conference. These combined papers provide a thorough documentation relative to this most interesting case history.
Effect of Microstructure on Near-Neutral-pH SCC
Authors: Bulger Jeffrey , Luo Jingli 
Published: October 2016

Three components are required for stress corrosion cracking: stress, an environment and a susceptible alloy. The environment that causes near-neutral-pH SCC has been established as a dilute bicarbonate environment and the effect of stress on this type of SCC has received a considerable amount of research; however, the third component, the susceptible alloy, has received little research.
The effect of microstructure on near-neutral-pH SCC was investigated using the slow strain rate test. The effect of the microstructure on the corrosion properties is also investigated using polarization resistance tests, potentiodynamic scans and electrochemical impedance spectroscopy. The results indicate that the microstructure influences both the SCC and corrosion behaviour.
Initiation of Stress Corrosion Cracking on X-65 Linepipe Steels in Near-Neutral pH Environment
Authors: Elboujdaini M. , Wang Y.-Z. , Revie R. W. 
Published: October 2016

Initiation and early growth of stress-corrosion cracking of X-65 linepipe steel in near-neutral pH environment were studied in NS-4 solution saturated with N2/5%CO2. The occurrence of SCC is discussed in terms of:
1. Generation of an environment that causes cracks to initiate;
2. Initiation and early growth of cracks; and
3. Effect of the mechanical loading spectrum.
SEM observations of cracks at specimen surfaces showed that stress-corrosion cracks were initiated at bottoms of corrosion pits. Pits that lead to initiation of SCC can develop from surface discontinuities, which can be geometrical, such as surface roughness, or metallurgical, such as inclusions, second phase particles, etc. The formation of large cracks resulting from coalescence of micro-cracks was studied.
Effect of Surface Scratch Roughness and Orientation on the Development of SCC of Line Pipe Steel in Near Neutral pH Environment
Authors: He Daxiong , Chen Weixing , Luo Jingli , King Fraser , Jack Tom , Krist Kevin 
Published: October 2016

This research has focused on the effect of surface roughness and surface scratch orientation on the development of neutral pH SCC on pipeline steels. The susceptibility to neutral pH SCC was assessed in this study using slow strain rate testing on X-65 line pipe steel. The surfaces of the test samples were ground using either #240 or #600 sandpaper to introduce different scratch roughness. Scratches were produced with an orientation parallel, perpendicular and inclined at 45° to the loading direction, respectively. The test samples were exposed to a synthetic neutral pH ground water at both open circuit potential (OCP) and −800 mV (SCE).
It has been found that the reduction in ductility due to a near neutral pH environment was more than 20% larger for the specimens with perpendicular scratches than those with parallel scratches, either at OCP or −800 mV (SCE). Roughness appeared to have little effect on the ductility of the specimen with parallel scratches. However, it has some effect on the sample with perpendicular scratches. For these samples, a finer scratch caused more reduction in ductility than the rougher scratches, particularly under cathodically protected conditions. The reduction in ductility for the specimen with scratches 45° inclined to stress axis was in between those with parallel and perpendicular scratches.
The difference in ductility arising from scratch roughness and orientation was consistent with the observation of the surface conditions after test. For samples with perpendicular and angle scratches, cracks were seen to coincide with scratch lines. For those with parallel scratches, only short cracks developed in a direction approximately 45° to the stress axis. Mechanisms concerning this scratch-facilitated crack formation are discussed.
Hydrate and Wax Prevention in Flowlines by Electrical Heating
Authors: Lervik Jens Kristian , Kulbotten Harald , Klevjer Gunnar , Iversen Øyvind 
Published: October 2016

Traditional chemical treatment methods have considerable operation costs and represent a risk to the environment. Since 1987 Norwegian oil companies have been investigating alternative electrical heating methods for prevention of hydrate and wax plugs. A joint industry project ‘Concept Verification – Direct Heating of Oil & Gas Pipelines’ was initiated in 1996 and terminated in October 1999. During this work an electrical heating system was proved to be feasible on several fields in the North Sea. It will be installed on 7 flowlines of 13% Chromium (Crl3) with lengths between 6 km and 16 km. Electrical heating is used to maintain or raise the thermally insulated steel pipe temperature above the critical value for hydrate formation (typically 15–25 °C) or wax formation (typically 20–40°C). A single-phase power supply for the heating system is based on commercial components and connected to the platform power supply. The qualification work for the direct heating system has included full scale testing for single and parallel pipes, end termination at the template, bypass of a template and aspects concerning corrosion control. The rating of the system is dependent on the magnetic and electrical characteristics of the steel material. Such data is not commonly available.
Measurements performed during the qualification program confirm that the magnetic characteristic may vary within a wide range for a specific steel quality and that mechanical stress and heat treatment can effect the magnetic characteristic. The difference in magnetic characteristic of individual Crl3 pipes results in variation of the pipe temperature and problems concerning differential pressure during melting. The problem can be handled by dividing the pipeline into a number of sections, each with a limited variation of the magnetic characteristic, thus keeping the temperature for the whole pipeline within acceptable limits. As a part of the pipe specification both electrical and magnetic characteristic should be available. These data can be determined by measuring arrangements in the production line of the mill. Measures to limit the variation of magnetic characteristic should be discussed.
Pipeline Survey Scheduling Through Structural Reliability Analysis
Authors: Espiner Richard J. , Edwards Alan M. , Francis Andrew 
Published: October 2016

In order to reduce the risks associated with the occurrence of free spans, offshore pipelines are subject to external survey on a periodic basis. The true impact of this strategy on safety and reliability is generally unknown.
This paper describes a structural reliability-based assessment that was carried out to investigate the probability of failure of an offshore pipeline due to the presence of free spans and develop a survey strategy that ensures a quantified and acceptable level of reliability.
The probabilities of failure of free spans of varying lengths are evaluated using a structural reliability based approach. Then, the probability of occurrence of free spans as a function of time is evaluated in order to quantify the overall time-dependent reliability of the pipeline. Finally, the influence of the survey frequency is investigated. The outcome of the study is a recommended strategy for future surveys of the pipeline.
Rational Modeling of Ultimate Pipe Strength Under Bending and External Pressure
Authors: Nogueira André C. , Lanan Glenn A. 
Published: October 2016

The capacity of pipelines to resist collapse or local buckling under a combination of external pressure and bending moment is a major aspect of offshore pipeline design. The importance of this loading combination increases as oil and gas projects in ultra deep-water, beyond 2,000-m water depths, are becoming reality. The industry is now accepting, and codes are explicitly incorporating, limit state design concepts such as the distinction between load controlled and displacement controlled conditions. Thus, deep-water pipeline installation and limit state design procedures are increasing the need to understand fundamental principles of offshore pipeline performance.
Design codes, such as API 1111 (1999) or DNV (1996, 2000), present equations that quantify pipeline capacities under combined loading in offshore pipelines. However, these equations are based on empirical data fitting, with or without reliability considerations. Palmer (1994) pointed out that “it is surprising to discover that theoretical prediction [of tubular members under combined loading] has lagged behind empirical prediction, and that many of the formula have no real theoretical backup beyond dimensional analysis.”
This paper addresses the ultimate strength of pipelines under combined bending and external pressure, especially for diameter-to-thickness ratios, D/t, less than 40, which are typically used for deep water applications. The model is original and has a rational basis. It includes considerations of ovalization, anisotropy (such as those caused by the UOE pipe fabrication process), load controlled, and displaced controlled conditions. First, plastic analysis is reviewed, then pipe local buckling under pure bending is analyzed and used to develop the strength model. Load controlled and displacement controlled conditions are a natural consequence of the formulation, as well as cross section ovalization. Secondly, external pressure effects are addressed. Model predictions compare very favorably to experimental collapse test results.
Stability Problems for Deep-Water Gas Pipelines: The “Blue Stream” Project
Authors: Kharionovsky V. V. 
Published: October 2016

OAO “GAZPROM” in collaboration with SNAM and Saipem have developed the first stage of the “Blue Stream” Project, which when completed will be unique for the world gas industry in terms of its parameters and route conditions. During this feasibility stage of the project the following new Research and development tasks were addressed:
- deep water collapse problems (the depths reach 2150 m), including buckle propagation;
- the problem of pipeline protection against an H2S environment (in the near bottom zone H2S concentration reaches more than 14 mg/1);
- the problem of installing a reliable pipeline having a diameter of 610×31.8 mm at gas pressures of 25 Mpa while taking into account the subsea currents;
- construction problems associated with the specified parameters.
Solving such problems required an elaborate and complex set of design tasks and experiments with materials and construction conditions. Special requirements were developed for the pipes and fittings, external anti-corrosion coatings, and the cathodic protection of the pipeline. New procedural documents were developed for deep water pipelining that included: the calculation for determining the strength and stability of the offshore pipelines; an instruction manual for the onshore section of the pipeline designed to carry a gas pressure of 25 Mpa; the necessary software for thermal and hydraulic calculations for the gas pipeline under extremely high pressures.