bluuebunny/crossref_metadata_2025 huggingface dataset:
Well Succeeded Application of Acoustic Technology for Pipelines (Single Phase and Multi Phases) Leak Detection in More Than 40 Pipelines in Brazil
Authors: Alonso Julio
Published: December 2008

In 2001 was installed the first ALDS-Acoustic Leak Detection System in Brazil, in a multiphase (slug) production pipeline (crude oil + gas + water) in the middle the rain forest. This Leak Detection System was approved and gained confidence from the pipeline community in this country. After this, many other Acoustic Systems were installed in other multiphase pipelines, single phase as crude oil and natural gas and Naphtha, in buried and submarine pipelines. The confidence against false alarms made many pipelines operators to request the Acoustic Technology for their pipelines protection. Also, the ALDS has high sensitivity, detecting small holes. Very important consideration also deserves the leak detection speed; due the acoustic technology, the ALDS alarms the leak in seconds! This action made possible to shutdown pumps avoiding big disasters. The ALDS is also able to locate the leak, with precision of meters, even in buried or submarine pipelines. Brazil has one of the strongest laws to protect the environment (9605, from February 13th, 1998) in the word and requires leak detection system to protect any pipeline before the government approval. The ALDS is being systematically required as the most effective leak detection system.
Friction Stir Welding in Pipeline Applications
Authors: Steel Russell , Sterling Colin , Nelson Tracy , Packer Scott
Published: December 2008

Friction stir welding (FSW) is a relatively new joining process which has exhibited many advantages over traditional arc welding processes such as the elimination of solidification defects and reduced distortion. With the introduction of new tool material technology such as the use of polycrystalline cubic boron nitride, materials such as steels, stainless steels, and nickel base alloys have successfully been FSW. Though there are many advantages to friction stir welding, there has been very little work in applying the process to out of position welds, such as those found in pipelines. This study outlines the progression from linear friction stir welding to initial work consisting of the rotation of pipe coupons on a turn table and finally to the design of a portable FSW machine able to weld 305 mm (12 inches) diameter line pipe. A brief summary of FSW weld characteristics are given for API grades X65, X80, and X100 steels.
Pilot Project for Acquisition System of Chromatograph Signals and Custody Measurements Via Web
Authors: Cerqueira de Santana Jose´ Paulo , Fonseca Ose´ias Boettcher
Published: December 2008

This article defines a very cheap alternative for acquisition of chromatograph signals and/or custody measurements in the process plants of oil and gas pipelines. The devices possess standards and diverse communication ports, demanding a modular architecture to acquire the values of the devices and provide the signals by Web/Intranet, using corporative network, dial-up PSTN line, leased line or cellular phone. This solution is applicable to sets of field devices that need to collect data in real time or in periods of time pre-configured and provide the information for visualization by a browser, load in a database or monitor the devices remotely by the supervision central. The architecture has the following characteristics: • Modularity; • Conversion of the out signal of the devices into standard Ethernet; • The Modbus-rtu is a network protocol; • Provide the signals by Web/Intranet; • Visualization of the signals in Browser; • Historical register of the data read in web Server devices; • Operational environment Windows 2000, Windows CE; • Configuration of the time of frequency of the equipments signals; • Allow integration with supervisory system; • Allow integration with corporative Data Base. To validate the architecture, we made tests in a Pilot Project, carried through in a PETROBRAS receiving station of Natural Gas, using the hardware and software components described in the article.
Facilities and Controls in a Heated Bitumen Pipeline
Authors: Pardo Carlos , Dickau Ralph
Published: December 2008

World scale deposits of oil sands (bitumen) in Northern Alberta, Canada are being developed to extract hydrocarbons from the sand using surface mining processes and new techniques such us Steam Assisted Gravity Drainage (SAGD) or “SagDee” as it is commonly referred to in the industry. This method employs numerous steam injection wells to heat the bitumen to reduce its viscosity and separate it from the sand particles. The heavy tar-like bitumen must either be upgraded to a light synthetic crude on site or diluted with natural gas condensate or a light oil to be able to pump the blend over long distances through pipelines to refineries for upgrading. The cost of this process and the decreasing availability of diluent led to the development of a pilot project to pump the bitumen in a raw heated state. This paper describes the special facilities and controls that were designed to move high viscosity heated bitumen from this remotely operated pump station. Extended loss of heat to the pump station and pipeline would result in a bitumen viscosity increase from which there is no recovery resulting in a permanent failure of the facility. For this reason, the equipment installed required a high degree of reliability. New receipt and blending facilities were also designed and constructed at the end of the pipeline to dilute the bitumen such that the blend could be pumped down conventional pipeline facilities. The pump station was manufactured as modules in Edmonton, Alberta, and then transported 500 km (315 mi) to site for assembly. Startup procedures were developed to fill the pipeline in controlled stages and to commission the new facilities. Redundant systems were employed to ensure the availability of the pump station at all times.
A Risk-Based Approach to Maintenance Planning Utilizing In-Line Inspection Data
Authors: Fenyvesi Louis L. , Colquhoun Iain , Kania Richard , Gu Bill
Published: December 2008

A common approach to the management of external corrosion in the pipeline industry is to perform an In-Line Inspection, followed by repairs of defects that fail a deterministic criterion, and then leave the line in service until a prescribed time interval has elapsed, at which point another reinspection is performed. However, many companies have found that as a result of the uncertainty associated with MFL defect sizing and corrosion growth rates, a deterministic repair and reinspection process may often result in unnecessary maintenance expenditures while occasionally failing to identify and address critical features. When the rare feature ‘slips through’ the deterministic process, companies often respond by adding conservatism to the process, leading to increased spending with little additional benefit. A better approach for evaluating corrosion defects is to view the process as an analysis of a set of stochastic variables instead of deterministic values. Through such an approach, the sensitivity of a defect’s failure probability can be more effectively evaluated, facilitating a decision process that is better able to find the ‘exceptions’ that are not addressed by a deterministic process. This paper outlines an approach to analyzing MFL data with stochastic variable using computer simulation, along with a process for continuously improving the characterization of each variable through a feedback loop. Alternative methods to Monte Carlo, such as Importance Sampling are briefly outlined to minimize the analysis time required without sacrificing simulation accuracy. Finally, acceptance criteria are required to interpret the calculated failure probability in order to inform maintenance decision making. This is presented in a risk-based context using a previously published risk management framework. Through this process, defect repair decisions and the evaluation of the benefit of MFL re-inspection can be better optimized. Examples are drawn from actual maintenance programs to illustrate this approach.
Gas Compressor Service With Turbo Compressors
Authors: Pereira dos Santos Sidney
Published: December 2008

Gas pipeline projects are capital intensive and normally are developed under scenarios of uncertainty. Such uncertainties vary from closing take-or-pay, ship-or-pay or delivery-or-pay agreements to those uncertainties related to the acquisition of equipments, material and construction and assembling contracts. Natural gas compression service contracts with compressor station using gas motors and reciprocating compressors have been widely adopted at PETROBRAS as economically feasible against holding the stations as part of the pipeline asset as well as providing an effective approach to mitigate risks inherent to the gas business and associated to the compressor stations. Although compression service contracts with turbo compressors (gas turbine drivers and centrifugal compressors) have not yet been accomplished at PETROBRAS for gas pipeline projects, studies and preliminaries discussions shows that, taken into consideration certain relevant aspects, they will also present great opportunity to be adopted and will generate the same advantages already perceived for the compression service contracts with stations that uses gas motor drivers and reciprocation compressors. This paper has the objective of presenting an economic approach and a business model addressing the main points that must be considered while doing feasibility analysis between the alternatives of holding property of the compression station asset against the opportunity of having a compression service contract as operating cost for the project. Questions such as how to address depreciation, overhaul costs and tailor made equipment, such as centrifugal compressors, are raised and answered.
Pipeline Integrity Analysis Based on Interdisciplinary Cooperation
Authors: Barham Perry , Brown Bryce , Fingerhut Martine , Porter Patrick
Published: December 2008

For many years, BP Pipelines, North America has used high-resolution Magnetic Flux Leakage (MFL) in-line inspection (ILI) technology to help maintain the integrity of their pipelines. The improvements in this technology that now allow an Operator to make integrity decisions also bring challenges. Reports from ILI can list thousands, or even hundreds of thousands, of individual anomalies or features. When combined with data from NDT field measurements and existing pipe tallies, it can become overwhelming. Methods had to be developed to distill this information for further analysis. BP Pipelines NA encouraged cooperation between all parties involved in the integrity process to adapt reporting requirements and work procedures to provide the best available information for integrity analysis and to ensure continued improvements. This cooperation is a key part of the integrity equation and essential to a successful program. This paper presents an overview of the validation process undertaken on a 51 km (32-mile) section of 457 mm (18-inch) pipeline. This pipe section was inspected in 1999 and again in 2003 by the same inspection company. This provided an opportunity to evaluate improvements in inspection technology, assess repeatability of performance and develop an engineering based approach to review, analyze, and validate high-resolution metal loss MFL data. Field verification and data validation included the use of a several NDE techniques to acquire field measurements to overlay and compare to the ILI inspection data. Anomaly classification and distribution is examined and methods of selecting validation locations for future inspection developed. In addition to the primary goal outlined, the 2003 repair program provided an opportunity to evaluate the performance of the composite sleeve reinforcements applied in 1999, after 4 years of service.
Challenges in Circumferential Magnetisation: A FEA Point of View
Authors: Ireland R. C. , Torres C. R.
Published: December 2008

Integrity of pipelines is of vital importance to their performance. This entails routine inspection using a variety of different inspection tools. One of the most popular type of tools is based upon Magnetic Flux Leakage (MFL). In this technique, the MFL tool magnetically saturates the pipe and in locations where defects exist, flux leaks out of the pipe and is detected by a set of on-board sensors. There are two different geometric configurations of an MFL tool, namely, axial and circumferential. Understanding the magnetic behaviour of these tools is critical is the MFL technique is to be successful. This paper details 2D and 3D finite element (FE) modelling of a circumferential magnetiser at rest and at typical operating speeds. 2D modelling of a stationary MFL tool indicates that pipe saturation can occur for a variety of pipe dimensions provided the magnets are correctly sized. However, this 2D modelling assumes a constant cross-sectional area and thus neglects tool and effects. This is rectified by the creation of several 3D models. It can be seen from these 3D models that end effects are significant and that pipe saturation is not as easily achieved as it was in 2D. Further, it is shown that when the MFL tool moves at constant speed down the pipe, the magnetic field profile in the pipe observed under stationary conditions is significantly altered. The significance of this effect depends on the operational speed of the tool, the material properties of the pipe and the dimensions of the pipe (pipe diameter and wall thickness). The 3D modelling presented suggests that under certain conditions the level of flux in the pipe is less than ideal (i.e. lacking the required magnetic intensity and homogeneity) and, for these conditions, the circumferential MFL technique may have difficulty detecting and sizing pipe anomalies.
Monitoring Slope Deformation With Quadrilaterals for Pipeline Risk Management
Authors: Keaton Jeffrey R. , Gailing Richard W.
Published: December 2008

Ground displacements, strains, and tilts can be calculated by repeated measurements of the lengths of six chords and relative elevations of an array of four points, known as a quadrilateral. Quadrilateral measurements allow ground-surface deformation and strain to be calculated. Typically, soil-pipeline interaction results in pipeline strain being less than ground strain. Strain gauges traditionally have been used on pipelines in landslide areas to aid in managing pipeline risk. Quadrilaterals may be economical alternatives to placing strain gauges on existing pipelines in areas of active or potential slope movements. A threshold ground deformation or strain is used to trigger more expensive means of evaluating pipeline integrity. Quadrilaterals are relatively inexpensive to install, but must be carefully located and founded deep enough to avoid seasonal shrink-swell effects of the soil. Measurements must be taken with precise instruments (tape extensometer) so that small changes can be detected with acceptable errors. Three contiguous quadrilaterals were installed in Spring 2003 in a landslide-prone area of southern California to aid in monitoring a slope between the main scarp of a recently active landslide and a pipeline bridge foundation. Engineering geologic evaluation supported a conclusion that the rate of headward crest advancement would be slow, but a method of detecting and quantifying slope deformation was needed for operational risk management.
Designing Offshore Pipeline Systems Divided Into Sections of Different Design Pressures
Authors: Staurland Gunnar , Aamodt Morten
Published: December 2008

Norwegian waters have been a main arena for development of subsea pipeline technology over the last 25 year. The gas transportation systems from Norway to continental Europe comprise the largest and longest sub sea pipelines in the world. Codes traditionally require a pipeline to be designed with a uniform design pressure between stations with overpressure protection capabilities. However, the downstream part of a very long gas transmission pipeline may, after commissioning, rarely, if ever, see pressures near the pressure at the upstream end. There is, therefore, a potential for cost reduction and capacity improvement if two, or several, sections of different design pressure could be used without having to implement sub sea pressure regulation and overpressure protection facilities at the point of transition between the different sections of design pressure. In determining the lower design pressure the shutdown of the pipeline outlet facilities, at any point in time allowing for a practicable, achievable delay for closure of the upstream inlet valve has to be taken into account. The settle out pressure in a “normal” shut-in situation shall then not exceed the lower design pressure. In addition, deep water pipelines are often designed to withstand buckling due to bending and external pressure during installation, and may therefore locally tolerate a much higher internal pressure than the pipeline was designed for. Transmission pipelines crossing deepwater areas may therefore be designed for two or more operating pressures along the pipeline, thereby optimizing the cost. Even more important, for already existing pipelines, the capacity may be significantly increased by utilizing the upstream heavy wall sections. The operating pressure range for a long offshore gas transmission pipeline is very wide compared to an onshore line, typically between an upstream pressure of 150–250 bar, and a downstream pressure of 60 to 80 bar over a distance of several hundred kilometers. It may take hours to notice the closure of a downstream valve on the upstream pressure. Unless the pipeline is extensively packed, it is obvious that the pressure drop along the pipeline may be taken into account by allowing a lower design pressure for downstream part than for the upstream part. Thereby, the investment cost can be reduced. This paper describes the principles of designing a pipeline system divided into sections of different design pressures from a hydraulic point of view. The basis is the offshore standard for designing submarine pipeline systems, DNV OS-F101. The focusing will be on improvements in transportation efficiency, cost reductions and operational issues.
Mathematical Approach to Foresee the Oil Volume Leaked From a Submarine Pipeline in Case of Accident
Authors: Baptista Renan Martins , Machado Ricardo Antonio Francisco , Quadri Marintho Bastos , Nogueira Andre´ Lourenc¸o , Lopes Toni Jefferson
Published: December 2008

Even considering the high standards of safety involved, the significant and continuous increase in offshore oil exploitation rise the risks of a pipeline rupture, leading to oil spills. If an oil leakage occur, it is necessary to accurately quantify the volume released to correctly foresee the potential environmental impacts and define actions to soften them and clean up the oil spill. The present article introduces a mathematical alternative approach, based on the theories of perturbation and unstable immiscible displacement, to evaluate the occurrence or not of oil leakages through the advective migration phenomenon and estimate the oil volume released. According to preliminary results, the model shows to be promising in accurate estimate the oil volume leaked from a submarine pipeline in case of accident.
Development and Properties of Ultra-High Strength UOE Linepipe
Authors: Asahi Hitoshi , Hara Takuya , Tsuru Eiji , Morimoto Hiroshi , Terada Yoshio , Sugiyama Masaaki , Murata Masahiko , Doi Naoki , Miyazaki Hideki , Yoshida Tatsuya , Ayukawa Naoshi , Akasaki Hiroo
Published: December 2008

High-pressure operation through high strength linepipe reduces long distance transportation cost of natural gas. In order to maximize the cost reduction, X120 UOE pipe has been developed. Low C-Mo-B steel with fine-grained lower bainite (LB) microstructure realizes high strength, excellent low temperature toughness and good weldability. The technology was verified in small-scale commercial production or “mini-rolls”. Suitability for use as linepipe was demonstrated through an extensive development program that covers burst test, fracture toughness evaluation, girth welding technology, etc. A demonstration line was successfully constructed using the pipes manufactured in the “mini-rolls”.
Evaluation of Weld Metal Strength Mismatch in X100 Pipeline Girth Welds
Authors: Pisarski Henryk G. , Tkach Yuri , Quintana Marie
Published: December 2008

A relatively simple method based on standard fracture mechanics flaw assessment procedures, such as BS 7910, but modified using published mismatch limit load solutions is described. It is used to illustrate the effects of weld width and strength mismatch on CTOD requirements for girth welds in Grade X100 strength pipeline material subjected to axial stress. It is shown that fracture toughness requirements based on standard analyses not allowing for mismatch effects can be unnecessarily conservative when either undermatched or overmatched welds are present. Adverse effects of undermatching, in reducing the allowable stress, can be mitigated by reducing weld width. It is shown that even small amounts of overmatching (e.g. 10%) can be beneficial by allowing axial stress to exceed the SMYS of the parent pipe and reducing CTOD requirements.
A Geomorphic Approach to the Design of Pipeline Crossings of Mountain Streams
Authors: Jakob Matthias , Porter Michael , Savigny K. Wayne , Yaremko Eugene
Published: December 2008

Several hydrological methods are available to determine flood discharge and scour of streams at pipeline crossings. These methods are appropriate for streams dominated by purely hydrological processes, but fail where other, more hazardous processes occur within the design recurrence interval. Several investigations have shown that scour, impact and aggradation associated with debris flows, outburst floods or related phenomena may fundamentally change the parameters needed for proper pipeline crossing design. Depending on the process type, the peak discharge of the hazardous process can exceed that of the design flood (typically 50 to 200 year return period) by a factor of 2 to 50. Similarly, scour or aggradation by a non-fluvial process can exceed the hydrologically-derived estimates by several factors. It is therefore recommended that a geomorphic approach be taken in recognizing and quantifying the potential for non-fluvial processes and that the findings be integrated in the design of pipeline crossings.
Evaluation of Below Ground Emergency Shutdown Valves in Sour Gas Pipelines
Authors: Shulhan Guy M.
Published: December 2008

The purpose of emergency shut-down valves (ESDVs) is to provide the capability of dividing sour gas pipelines into segments, which can be individually isolated during upsets or ruptures by closure of the ESDVs. CIMARRON Engineering Ltd. (CIMARRON) performed a study in 2003 to evaluate installing ESDVs below ground for sour gas pipelines. The direct burial advantages of easier pigging, reduction in pipeline stresses, smaller surface footprint, less visibility, lower installation and maintenance costs, less chance of vandalism, and less chance of unauthorized operation are all desirable. This direct burial option, using weld neck valves, is contrary to the conventional above ground installation with flanged valves, which dominates the practice in Western Canada. CIMARRON has used the criteria of feasibility, benefits, and limitations in evaluating the option of direct burial. To these three (3) criteria have been added measures to mitigate any identify limitations or constraints. In addition, piggability for cleaning and in-line inspection is considered to be a required feature for all sour gas pipelines. CIMARRON has reviewed and gathered extensive field data and background case studies for the preparation of this paper. In addition to the industry standard of above ground ESDVs, they are also occasionally installed in vaults. However, entry into any vault constitutes a “confined space entry” with its associated implications on safety. CIMARRON contends that if certain capabilities are provided for functional access from the surface to a buried ESDV, then compliance with all requirements of the governing legislation is possible without being able to physically see or access the buried valve. Enhancements to the responsiveness of ESDVs to pipeline upsets and failures are important. Using SCADA at both wellsites and ESDV sites can provide a significant advantage in limiting any potential sour gas releases. The simplifications associated with buried ESDVs can constitute a significant advantage. Taking all these aspects into consideration, there are substantial benefits to burying ESDVs when compared to both the above ground and vaulted options.
A Statistical Model for the Prediction of SCC Formation Along a Pipeline
Authors: Youzwishen Oliver O. , Van Aelst Audrey , Ehlers Peter F. , Nettel Alberto
Published: December 2008

Near-neutral stress corrosion cracking (SCC) is an operational integrity problem experienced by pipeline transporation companies since the 1970’s. Current in-line inspection (ILI) technology allows for the detection of SCC in pipelines using ultrasonic measurement. However, these tools have size limitations (not available for small diameter pipelines) and can only accurately detect cracks above a certain threshold dimension. Predictive modeling of SCC has been used when direct detection was not feasible. To date, predictive models have focused mainly on establishing quantitative relationships between environmental factors and SCC formation or growth. In general, models used to predict SCC growth have been more successful than models used to predict the location of SCC formation. A model to predict locations of SCC formation has been developed, in conjunction with a pipeline operator, by statistically analyzing data related to locations where SCC was either found or not found during investigative digs on a particular pipeline. Data acquired at the investigative dig sites (such as soil conditions, drainage patterns and local geography) was incorporated into the analysis. In addition, data acquired for the entire length of the pipeline (such as geometry, metal loss features, close-interval cathodic protection readings and operating pressures) was combined with the dig site data in the analysis process. The combined data set was analyzed using statistical regression techniques and various multi-variable logistic regression models were created. Misclassification analysis and regression tress were used to determine the most accurate model for application to the pipeline. The model was then applied to the pipeline to determine probabilities of SCC at specified increments along its length (approximately every 20 metres). Ten locations with high SCC probabilities were selected for verification excavation. In addition, one site with a lower SCC probability was chosen for excavation. Of the ten high-probability locations, SCC was discovered at seven sites. At the lower probability site, SCC was not discovered. The combined success rate of themodel was 73%, a significant improvement over predictive models previously applied to the pipeline. Additional investigative digs are planned to further test the model and to compare its predictions to SCC detected by a recently developed ultrasonic ILI tool. By examining the occurrence of SCC using statistical methods, the ability to make an unbiased prediction of the probability of SCC along a pipeline of interest has been achieved. The pipeline operator has gained an increased ability to assess the likelihood of SCC along its pipeline, showing due diligence in mitigating the risks associated with this pipeline integrity concern.
Development of High-Strength Heavy-Wall Sour-Service Seamless Line Pipe for Deep Water by Applying Inline Heat Treatment
Authors: Arai Yuji , Kondo Kunio , Hamada Masahiko , Hisamune Nobuyuki , Murao Nobutoshi , Osako Hajime , Murase Tsuneo
Published: December 2008

High strength heavy wall sour service seamless line pipe suitable for deep water applications has been developed by Sumitomo Metal Industries, Ltd.,. This paper describes the concept of developing these pipes applying inline heat treatment technology, equipped in a newly constructed, medium-size seamless mill. Increasing hardenability through inline heat treatment achieved higher strength (X70) for heavy wall pipe (40mm) even though carbon equivalent was lower than in a conventional Q&T process. Good toughness was obtained by the control of microalloying elements such as titanium or sulfur. The produced pipe passed the hydrogen-induced cracking (HIC) test conducted according to NACE TM 0284 solution A. Controlling the microstructure and suppressing maximum hardness, utilizing the uniform quenching facility during inline heat treatment, contributed to the test result. Satisfactory data on weldability for practical use were also obtained.
Conversion of Old Crude Oil Pipeline to Product Service
Authors: Agarwal Subhash Chandra
Published: December 2008

Due to capacity expansion of one of our refineries located in Western India, there was a need to evacuate additional products. Pipeline, being the most economical, reliable and environment friendly mode of transportation was the obvious choice. Laying a new pipeline would have required making substantial initial capital investment. However, a crude oil pipeline, owned by another oil company, was terminating at the refinery and was not in regular use. It was decided to convert this pipeline to product service. The pipeline was taken on lease, extensively cleaned, tested and successfully converted to product service with necessary hook-up/modifications at both the ends and in-between. The paper covers the experience gathered during the process of conversion of the crude oil pipeline to product service, including modifications carried out in the pipeline system, methodology adopted for cleaning, hydro-testing and commissioning of the system, and the lessons learnt.
Effect of Thermomechanical Processing Parameters Upon Texture Development and Anisotropy of Mechanical Properties of API-X80 Line Pipe Steels for Spiral-Welded Pipes
Authors: Bae Jin-Ho , Choi Shi-Hoon , Kim Ki Soo , Kang Ki Bong
Published: December 2008

This study has been conducted to analyze the effect of texture and microstructure on the anisotropy of yield strength and Charpy fracture toughness of an X80 line pipe steel. The texture and microstructure were investigated by X-ray diffractometer and electron backscattered diffraction (EBSD). The yield strength and impact energy were measured along 0° (longitudinal), 30° and 90° (transverse) to the rolling direction. It was found that the microstructure of the developed steel consisted of fine acicular and polygonal ferrite with small pearlite and MA constituents. The major components of textures were {332} <113> and {113} <110> orientations. In order to investigate the effect of both morphological and crystallographic texture on yield strength anisotropy, the prediction of the plastic property was carried out by using a visco-plastic self-consistent (VPSC) polycrystal model. The predicted anisotropy of yield strength with VPSC model assuming ellipsoidal grain shape was in a good agreement with experimental observation. EBSD results showed that the density of {100} cleavage planes of Charpy specimen, 30 degree to rolling direction, was the highest compared with that of other specimens. Therefore, the highest susceptibility to the cleavage fracture, i.e. increased ductile-brittle transition temperature, can be seen in the 30 degree direction.
Experimental Study on SCC Susceptibility of X60 Steel Using Full Pipe Sections in Near-Neutral pH Environment
Authors: Kim Bong Am , Zheng Wenyue , Williams G. , Laronde M. , Gianetto J. A. , Shen G. , Tyson W. R. , Oguchi Noritake , Hosokawa Yuji
Published: December 2008

Stress corrosion cracking (SCC) tests were performed using the pipe section buried in a clay type of soil with the pH adjusted to near-neutral range. Pipe specimens with various sizes of fatigue pre-cracks ahead of artifical notch tips on the outer surface were subjected to cyclic loading tests. Maximum level of hoop stress was 105% SMYS, and R-value (Ratio of minimum load to maximum load) was 0.5. Growth of cracks was observed from the fatigue crack tips. Fractographic and metallographic examination has confirmed the quasi-cleavage nature of the transgranular SCC that is typically observed in near-neutral pH SCC. Crack depth measurement using DCPD method revealed the relatively high crack growth rate up to 10−5 mm/s. Metallographic examinations showed the existence of many micro-cracks associated with MnS inclusions in the highly strained field ahead of the initial crack tips. The relatively high crack growth rate may be caused by MnS inclusions. The loading rate, dJ/dt, was calculated for each crack condition in order to correlate qualitatively the crack growth rate with the loading rate. J-integral was calculated through non-linear FEM analyses for semi-elliptical cracks based on the stress-strain relationships obtained from the tensile tests using the same X60 steel specimen. Linear relationship was then obtained between the crack growth rate and the loading rate, and therefore the possibility to predict crack growth rates for various loading condition in the field was demonstrated.
Cyclic Deformability of Steel Pipes With Local Metal Loss and Repaired Pipes
Authors: Miwa Masataka , Oguchi Noritake , Okajima Yutaka , Kurobe Takayuki
Published: December 2008

Cyclic deformability of steel pipes with local metal loss was studied. Full-scale tests were conducted using X42 and X52 pipes with diameters of 762.0 to 609.6mm. Each test pipe specimen contained an artificial metal loss of rectangular shape and uniform depth on the external surface, and inner pressure and cyclic axial strains were applied with constant amplitudes up to 7 cycles. Buckling deformation was observed in the metal loss region during compressive loading, and it induced a load reduction. The experimental results were analyzed by cyclic elastoplastic FE analysis. The effectiveness of the FE analysis was validated and parametric studies were performed. Buckling was strongly affected by the dimensions of the defect. Through these experiments and FE analyses, we suggested fitness-for-service criteria for buried pipes with external metal loss, taking into account large ground movement during strong earthquakes. Similarly, we examined the aseismic performance of three repair methods for the metal loss region—patch-welding, full-encirclement hot sleeve and weld deposition—through full-scale tests using X42 and X52 pipes with a 609.6mm diameter. We found that patch-welding and weld deposition performed sufficiently well, while the sleeve on the pipe induced buckling near the circumferential fillet weld due to constraint in the radial direction.
Purging and Load Operations of Bolivia - Brazil Gas Pipeline
Authors: Frisoli Caetano , Carvalho de Faria Jose´ Aure´lio , Ennes Senna Fernando Jose´
Published: December 2008

Through a pioneer method in Brazil, the Brazilian side of Bolivia-Brazil gas pipeline had its northern and south branches successfully purged and loaded. Pigs were not utilized in this procedure and the method is based on high injection flow rates of natural gas. Results proved this method to be suitable and safe for purging natural gas pipeline into service.
A Life Time Extension of a Natural Gas Transmission System
Authors: Jager Eric , Zanting Jeroen
Published: December 2008

In order to ensure safe and reliable gas transmission, the natural gas infrastructure should be kept in an excellent shape to transport natural gas as successful in the next decades as in the decades behind. Extra challenges in this process are the liberalisation of the energy markets (reducing the amount of money available) and increasing legislation on safety (increasing the safety expectancy of society). The way Gastransport Services deals with these challenges is explained in this paper.
Practical Method of Updating Stochastic Remaining Life of Pipelines Using ILI Data
Authors: Malyukova Margarita G. , Timashev Sviatoslav A. , Maltsev Igor L.
Published: December 2008

The paper describes a new practical method of updating the stochastic remnant life of pipelines with defects using ILI data. The paper describes a comprehensive algorithm for assessing pipeline remnant life taking into account the stochastic results of in-line inspection (ILI). It is assumed that the pipeline segment wall has a longitudinal external crack of semi-elliptical form and is described by the J-integral. The limit state function (LSF) is described as the difference of the critical and current value of the J-integral. The latter is calculated for the current time of pipe performance and is assumed known due to monitoring of the pumping equipment. The critical crack depth is defined using the notion of fracture toughness and the J-integral approach. The algorithm contains solutions of three sequentially interconnected problems. First, the deterministic problem of fatigue crack growth (FCG) is analyzed. Then the stochastic FCG is analyzed. The probability of failure assessment algorithm is designed on the basis of the authors’ version of the adaptive important sampling (AIS) procedure. The main steps of the AIS algorithm are described in detail. The samples are generated in such a way, that at all times a majority of samples belong to the fracture region. Finally, the results of the latest ILI are fused into the algorithm, providing best possible assessment of pipeline remnant life as a random variable. The remnant life update for pipeline segment with crack-like defects using ILI data takes into account three possible outcomes: defect not discovered: defect is discovered but not measured; defect is discovered and measured. This result permits solving most important problems of pipeline maintenance: prioritization of pipeline segments for repair/rehabilitation; optimization of the time between ILI; minimization of pipe operational risk. Two real cases are described of assessing the probability of fracture/leak of a pipeline section with an external crack at different periods of its performance. The described approach currently is being generalized for the case of multiple stress corrosion SC cracks.
Evaluation of the Uncertainty in Measurement Versus the Limit of Specification: Qualitative and Quantitative Aspects of Compliance
Authors: Cruz de Oliveira Elcio , Fernandes de Aguiar Paula
Published: December 2008

In many cases, the declaration of compliance of a result of measurement is not clear. This is observed when there is a partial superposition of the expanded uncertainty of a quantity with its limit of specification. In these cases, a judgment is required based in pre-established criteria between the client and the supplier. The consequences of an inadequate decision may be disastrous. Either the supplier will have financial losses or it will lose credibility with its client. This work demonstrates how to calculate the probability, for an appropriate confidence level, that the uncertainty associated with the measurement is within the limits that were established in a contract, declaring the compliance or non-compliance relative to the specification, and study two methodologies for helping the claimer to take the decision of compliance or non-compliance, using as example the heat capacity of natural gas, calculated from its gas chromatography. This approach encourages the client/supplier relationship. This occurs because the results are reported to both parts with a probability of compliance instead of a single value. The first methodology is based on the increase in the size of the sample. The second proposal is based in the calibration of the chromatograph against certificate reference materials with more exact and precise uncertainty values.
The Risk Assessment Module PSL as an Obvious Part of an Integral Pipeline (Integrity) Management System
Authors: Hordijk Ad Pijnacker , Zanting Jeroen , Kornalijnslijper Rien , Kuik Robert
Published: December 2008

This paper will give an overview of the history of PiMS and the new developments within Gastransport Services regarding the implementation of an integral Pipeline (integrity) Management System and especially and also in more detail the implementation, testing and verifying of a Risk Assessment tool, as an obvious part of PiMS. The design of the pipeline network in the Netherlands was based on the ASME B31G guidelines, as a sound engineering practice. The construction started early 1960 in a very rapid tempo. The control and maintenance in those years was executed on a paper based system with steady state frequencies of measurements uniformly distributed all over the network. With the nowadays databases and computer systems all kind of analyses beyond the capacity of a pipeline engineer can be carried out. These analyses have been made possible by outstanding Research of different companies, Joint Industry Programs and international investigations executed by a variety of different well known groups. At that time however an integration of all the data and stand-alone models into one single (PiMS-)system with one or more linked databases and controlled by one process control system was not a major option due to a lack of IT-possibilities and management objectives. Due to very fast developments in IT, recent incidents in the industry all over the world, the change in management objectives to have a faster and a better control over the pipeline safety, reliability and associating costs a strong desire for a PiMS-process control system was born.
A Critical View on the Significance of HAZ Toughness Testing
Authors: Liessem Andreas , Erdelen-Peppler Marion
Published: December 2008

Within the heat affected zone (HAZ) along the weld seam of LSAW linepipes discrete microstructural regions of reduced toughness can not be avoided and are commonly designated with the term Local Brittle Zones. The nature of these LBZ has been intensively investigated and the gathered knowledge is exploited in today’s steel technology, plate processing and pipe manufacturing. The HAZ toughness has been improved in general by reducing MA constituents and by austenite grain refinement. Nevertheless local areas of low toughness within the CGHAZ can not be avoided completely. They are statistically distributed in every pipe. Furthermore it seems to be widely accepted that the structural reliability of LSAW linepipe produced and inspected with state-of-the-art technology is not influenced as these areas of low toughness have a limited size and distribution. This has been demonstrated by numerous investigations including small scale (CVN, CTOD), wide plate and burst tests. The essence of these investigations is that the failure behaviour of linepipe containing part wall defects in the HAZ is toughness independent. So far researcher’s world is clear and in good shape. Nevertheless many linepipe specifications tend to stipulate stringent test requirements with regard to acceptance criteria for the HAZ. In the occurrences of test failures a re-test procedure for test lot acceptance is carried out. As a matter of fact the LBZ are present along the weld seam over limited areas in each pipe. Therefore such a re-test procedure is regarded to be inappropriate in terms of quality inspection as it randomly sorts out pipes just by the statistical chance. With regard to HAZ toughness the pipes failed by this test do not differ from those pipes accepted and released for dispatch. As a final conclusion it can be stated that the existing test procedures for the HAZ toughness testing of the main standards and specifications do not reflect the current developments with regard to improved HAZ toughness achieved by the development of optimised steel composition and with regard to the enhanced defect detection probability along with modern NDT inspection methods. An amendment of the current test procedures in this direction is proposed. Therefore proposals are made as start for a common discussion.
Construction of New Tie-In in the Bolivi´a-Brasil Gas Pipeline Using Hot Tapping Techniques - High Pressure 92 Bar
Authors: Frisoli Caetano , Frota Cristiane , Casano Ismael , Loba˜o Jesualdo , Saavedra Marcelo
Published: December 2008

To meet the request of supply of 2,4 MMm3/d of natural gas to Treˆs Lagoas Thermal Electric Plant in Treˆs Lagoas city, it was necessary to install a 12 in. branch in the 32 in. main line of the Bolivia-Brazil Gas Pipeline. The most efficient method for the execution of branch and maintenance repairs in gas pipeline is using the hot-tapping technique, where all work is performed with no need for stoppage and clearance of the line, maintaining the gas flow. This paper covers the entire project, specifications, planning and a detailed job execution to carry out this new city-gate using a fully reinforced T (split sleeve) welded into the pipeline, from the retaining of the company up to the safety measures adopted in the operation. The specifies of the complex and innovative welding procedure, still unprecedented in Brazil, that was performed in the API 5L X70 steel piping at an internal pressure of 9022 kPa, as well as the detailing of tests and inspections performed are also presented herein.
Theoretical and Experimental Investigation on the Flow Induced Vibrations of a Centrifugal Pump
Authors: Benra Friedrich-Karl , Dohmen Hans Josef
Published: December 2008

The transport of fluids which include a lot of impurities is often done by special single-stage pumps. In order to avoid clogging of the pumps, the impellers have only one blade. This minimum blade number brings strong disadvantages during the pump operation. The rotation of the impeller in the pump casing produces a strongly uneven pressure field along the perimeter of the casing. The resulting periodically unsteady flow forces affect the impeller and produce radial deflections of the pump shaft which can be recognized as vibrations at the bearing blocks or at the pump casing. These vibrations will also be transferred to the pump casing and attached pipes. In a numerical approach the hydrodynamic excitation forces of a single-blade pump were calculated from the time dependent flow field. The flow field is known from the numerical simulation of the three-dimensional, viscous, unsteady flow in the pump by using a commercial computer code determining the Reynolds averaged Navier-Stokes equations (URANS). The periodically unsteady flow forces were computed for a complete impeller revolution. This forces affect the rotor of the pump and stimulate it to oscillations. The computed forces were defined as external forces and applied as the load on the rotor for a structural analysis. The resulting oscillations of the rotor were calculated by a transient analysis of the rotors structure using a commercial FEM-Method. To verify the calculated results, experimental investigations have been performed. The deflections of the pump rotor were measured with proximity sensors in a wide range of pump operation. Measurements of the vibration accelerations at the pump casing showed the visible effects of the transient flow. To minimize the vibration amplitudes the energizing forces have been reduced by attaching a compensation mass at the impeller. This procedure can be used as “operational balancing” of the pump rotor for a certain point of operation.
A Modeling Approach to High pH Environmentally Assisted Cracking
Authors: Been J. , King F. , Fenyvesi L. , Sutherby R.
Published: December 2008

A model is described for predicting the incidence of high-pH SCC on gas pipelines. The model is mechanistic and is based on a film rupture mechanism of crack growth. Based on field pressure cycle data, the model determines the crack tip strain rate and the occurrence of film rupture events at the crack tip during operating pressure cycles. Crack aspect ratio data were obtained from field data. Probabilistic distribution functions were assigned to input parameters and a Monte Carlo method was used to produce probabilistic crack growth rate distributions. The model grows a crack to failure while considering the effects of temperature and potential.