Assessment of the Remaining Strength of Corroded Small Diameter (Below 6”) Pipelines and Pipework

2012 ◽  
Author(s):  
Troy Swankie ◽  
Vinod Chauhan ◽  
Robert Owen ◽  
Robert Bood ◽  
Geoffrey Gilbert
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Ductile Failure ◽  
Corrosion Damage ◽  
Full Scale ◽  
Alternative Methods ◽  
Low Grade ◽  
Numerical Work ◽  
Line Pipe ◽  
Failure Pressure

Internal and external corrosion damage is a major cause of pipeline failures worldwide. When corrosion features in pipelines are detected by in-line inspection (ILI), a decision whether to replace, repair or accept and monitor must be made. Extensive experimental and numerical work has been undertaken to develop methods for assessing the remaining strength of corroded transmission pipelines. Common methods used by the pipeline industry include ASME B31G, modified ASME B31G and LPC. These methods are semi-empirical and have been developed using a modified version of a toughness independent ductile failure criterion for pressurized pipes containing axially orientated surface breaking defects. The validity range of these models is dominated by large diameter (10 to 48″), thin walled, low grade (API 5L grade A to X65) and low yield to tensile ratio line pipe. Smaller diameter (not greater than 6″), thick walled pipelines and pipework located, for example, at above ground installations, compressor and pressure reduction stations are very common. The use of ASME B31G, modified ASME B31G or LPC may not be appropriate when assessing the remaining strength of small diameter pipelines and pipework. No alternative methods are available in the public domain and hence a program of work was undertaken to derive appropriate defect acceptance limits by conducting a series of full-scale burst tests on small diameter pipe with simulated corrosion defects. It was concluded that the LPC method gave the most accurate prediction of failure pressure when compared with the results of the full-scale tests, and the most conservative predictions of failure pressure were obtained using the ASME B31G method.

Simulation of Dynamic Crack Propagation and Arrest Using Various Types of Crack Arrestor

2016 ◽  
Author(s):  
Mohammed Uddin ◽  
Gery Wilkowski
Keyword(s):  
Crack Propagation ◽  
Large Diameter ◽  
Small Diameter ◽  
Full Scale ◽  
Fe Model ◽  
Ductile Crack ◽  
Burst Test ◽  
Ductile Crack Growth ◽  
Diameter Pipe ◽  
Linepipe Steels

In linepipe steels, there has been a growing interest in using damage mechanics that provides physical models of the fracture process which are embedded into a two- or three-dimensional finite element (FE) model. Among the various damage models, the cohesive zone model (CZM) has recently been used to simulate the ductile crack growth behavior in linepipe steels because of its computational efficiency and it requires only two parameters which can be determined in experiments. While CZM is not yet to be used as predictive tool, but it has a great application in crack arrestor design as well as in providing insight to ductile crack propagation. In this paper, the authors have demonstrated some practical applications of CZM in linepipe steels. The CZM was used to simulate the ductile crack propagation in full-scale pipes which was able to capture the global deformation as well as the experimental crack speed. The model was then used to determine the effect of anchor blocks at the end of the pipe in a large diameter full-scale burst test. Later, the model was used to simulate two small diameter pipe tests with steel crack arrestors to mimic two arrestor cases with one showing crack propagation and the other showing crack arrest. The CZM model was also applied to demonstrate the circumferential ring-off behavior of a small diameter pipe test with rigid crack arrestor. The arrestor model was then extended to simulate a large diameter full scale Mojave burst test with “soft crack arrestor (SCA)”. A single element FE model was developed to verify the SCA material which was later extended with stain-based failure criteria. Finally, ductile crack growth in full-scale pipe with SCA was demonstrated to show that the FE CZM model can be used to optimize the design of SCA.

Ruptures in Gas Pipelines, Liquid Pipelines and Dense Phase Carbon Dioxide Pipelines

2012 ◽  
Author(s):  
Andrew Cosham ◽  
David G. Jones ◽  
Keith Armstrong ◽  
Daniel Allason ◽  
Julian Barnett
Keyword(s):  
Large Diameter ◽  
Saturation Pressure ◽  
Fracture Propagation ◽  
Full Scale ◽  
Gas Pipeline ◽  
Thick Wall ◽  
Dense Phase ◽  
Line Pipe ◽  
Rich Mixture ◽  
High Toughness

Ruptures in gas and liquid pipelines are different. A rupture in a gas pipeline is typically long and wide. A rupture in a liquid pipeline is typically short and narrow, i.e. a slit or ‘fish-mouth’ opening. The decompression of liquid (or dense) phase carbon dioxide (CO2) immediately after a rupture is characterised by a rapid decompression through the liquid phase, and then a long plateau. At the same initial conditions (pressure and temperature), the initial speed of sound in dense phase CO2 is greater than that of natural gas and less than half that of water. Consequently, the initial decompression is more rapid than that of natural gas, but less rapid than that of water. A question then arises … Does a rupture in a liquid (or dense) phase CO2 pipeline behave like a rupture in a liquid pipeline or a gas pipeline? It may exhibit behaviour somewhere in-between the two. A ‘short’ defect that would rupture at the initial pressure might result in a short, narrow rupture (as in a liquid pipeline). A ‘long’ defect that would rupture at the (lower) saturation pressure might result in a long, wide rupture (as in a gas pipeline). This is important, because a rupture must be long and wide if it is to have the potential to transform into a running fracture. Three full-scale fracture propagation tests (albeit shorter tests than a typical full-scale test) published in the 1980s demonstrate that it is possible to initiate a running ductile fracture in a CO2 pipeline. However, these tests were on relatively small diameter, thin-wall line pipe with a (relatively) low toughness. The results are not applicable to large diameter, thick-wall line pipe with a high toughness. Therefore, in advance of its full-scale fracture propagation test using a dense phase CO2-rich mixture and 914×25.4 mm, Grade L450 line pipe, National Grid has conducted three ‘West Jefferson Tests’. The tests were designed to investigate if it was indeed possible to create a long, wide rupture in modern, high toughness line pipe steels using a dense phase CO2-rich mixture. Two tests were conducted with 100 mol.% CO2, and one with a CO2-rich binary mixture. Two of the ‘West Jefferson Tests’ resulted in short ruptures, similar to ruptures in liquid pipelines. One test resulted in a long, wide rupture, similar to a rupture in a gas pipeline. The three tests and the results are described. The reasons for the different behaviour observed in each test are explained. It is concluded that a long, wide rupture can be created in large diameter, thick-wall line pipe with a high toughness if the saturation pressure is high enough and the initial defect is long.

Fracture Resistance in Line Pipe

1965 ◽  
Vol 87 (3) ◽  
pp. 265-278 ◽  
Author(s):  
G. M. McClure ◽  
A. R. Duffy ◽  
R. J. Eiber
Keyword(s):  
Fracture Behavior ◽  
Large Diameter ◽  
Full Scale ◽  
Laboratory Studies ◽  
Research Committee ◽  
Line Pipe ◽  
Diameter Pipe ◽  
On Line ◽  
Fracture Tests ◽  
Scale Behavior

The program of research on line pipe under the sponsorship of the A.G.A. Pipeline Research Committee is a comprehensive effort to investigate the important properties of pipe used in gas transmission. Several different phases are involved in this project, ranging from fundamental laboratory studies to fracture-behavior experiments on large-diameter pipe. This paper discusses the full-scale experimental parts of the program in which the fracture toughness of line pipe is being studied. Some of the factors that influence full-scale fracture behavior are discussed—material properties, fracture speed, temperature, wall thickness, nominal stress level, and type of backfill. Laboratory fracture tests that are being run and correlated with full-scale behavior are also described.

Interactions among seedling diameter grade, weed control, and soil cultivation for Pinusradiata in South Africa

1993 ◽  
Vol 23 (10) ◽  
pp. 2078-2082 ◽  
Author(s):  
David B. South ◽  
J. B. Zwolinski ◽  
D. G. M Donald
Keyword(s):  
South Africa ◽  
Weed Control ◽  
Standard Method ◽  
Seedling Survival ◽  
Large Diameter ◽  
Small Diameter ◽  
Diameter Growth ◽  
Low Grade ◽  
Soil Cultivation ◽  
Better Than

A study was established in the southern Cape Province, South Africa, to examine survival and growth in response to seedling grade and various methods of site preparation. Second-year performance was examined in relation to (i) initial groundline diameter, (ii) intensity of weed control, and (iii) method of soil cultivation. Weeds were controlled with (i) manual release 1 year after planting (the standard method used by the Department of Water Affairs and Forestry) or (ii) total weed control for 1 year involving the use of herbicides and additional hoeing. Soil cultivation treatments included (i) pitting by hand, (ii) pitting with a mechanical auger, (iii) ripping, and (iv) ripping plus disking. The influence of initial seedling diameter on survival was significant. Seedlings with a 2-mm groundline diameter averaged 62% survival, whereas 5-mm seedlings averaged 85% survival. Use of large-diameter stock improved survival regardless of soil cultivation or weed control treatments. For survival, there was an interaction between soil cultivation treatments and the use of herbicides. Total weed control with herbicides and hoeing improved survival for plots that received ripping or disking treatments. However, seedling survival was decreased where herbicides were used on plots where pits were used. On average, seedlings with larger diameters grew better than those with smaller diameters. However, small-diameter seedlings with total weed control grew better than large-diameter seedlings with standard weed control. Average seedling volume after 2 years was 33% greater for high-grade seedlings (2.4 dm3) than for low-grade seedlings (1.8 dm3). However, there were interactions between soil cultivation and weed control treatments for height and diameter growth. With the standard method of weed control, ripping improved height and diameter growth. Total weed control with herbicides and hoeing greatly improved growth for all treatments, and as a result, little or no differences in average seedling volume were observed between pitting and ripping treatments.

Analysis of Data From a Full-Scale Burst Test on 1219 mm OD Grade 550 Pipe: Implications for the Prediction of Fracture Velocity

2016 ◽  
Author(s):  
Brian Rothwell ◽  
Cindy Guan ◽  
Satoshi Igi
Keyword(s):  
Traditional Approach ◽  
Large Diameter ◽  
Crack Tip ◽  
Management Program ◽  
Full Scale ◽  
Correction Factors ◽  
Long Distance ◽  
Line Pipe ◽  
Fracture Arrest ◽  
Fracture Velocity

In recent years, considerable doubt has arisen over the prediction of the level of toughness required to arrest a propagating fracture in higher-strength line pipe. It has been clear for many years that the most widely used traditional approach, the Two-Curve Method (TCM) developed at Battelle in the early 1970s, could not be applied directly when the required toughness, expressed as full-size Charpy energy, exceeded about 80–90 J. Initially, this issue was addressed by the adoption of empirical correction factors, but more recently, there have been indications that this approach is no longer effective for modern, high-strength materials. Additional information, which in general can only be derived from well-characterized burst tests, is essential to furthering understanding of the fracture arrest problem under conditions that are typical of modern, long-distance, large-diameter pipeline design. In the context of the Coastal GasLink (CGL) project, TransCanada has carried out a program of full-scale burst testing at the Spadeadam test site of DNV GL. The tests were supported by LNG Canada and the TransCanada Technology Management Program. These tests are described in another paper at this conference [1]. Though most of the testing was directed towards the assessment of different crack arrestor designs, one half of one test contained a run of four pipes of progressively increasing Charpy energy, up to a very high level (over 450 J). The fracture was observed to run through all four pipes, before being arrested by a crack arrestor fitted to a fifth pipe having lower toughness. Nearly all approaches to determining requirements for fracture arrest depend, directly or indirectly, on relationships between fracture velocity (for given levels of fracture resistance) and the driving force, generally considered to be directly related to the pressure in the plane of the crack tip. By comparing measured fracture velocity with the crack tip pressure determined either directly at pressure transducer locations or by comparison with propagation velocities within the expansion wave, conclusions can be drawn regarding the accuracy of existing relationships. Most previous work regarding correction factors has been based simply on discrepancies between predicted and observed propagation and arrest behaviour. Direct comparisons of observed and predicted fracture speed potentially provide much more data and focus more clearly on where model deficiencies may lie. The current analysis focuses on comparisons with the predictions of the traditional TCM and those of a transient model developed by JFE. While data from the present work are clearly limited, this approach appears to present a way of recalibrating fracture velocity formulations that may extend the range over which traditional, Charpy-based approaches can be applied. For the future, the incorporation of additional results from other recent, well-characterized burst tests would be extremely valuable in this respect.

Development of Modern High Strength Heavy Plates for Linepipe Applications

2012 ◽  
Author(s):  
Heike Meuser ◽  
Florian Gerdemann ◽  
Fabian Grimpe ◽  
Charles Stallybrass
Keyword(s):  
Mechanical Properties ◽  
High Pressures ◽  
Large Diameter ◽  
High Strength ◽  
Alternative Methods ◽  
Accelerated Cooling ◽  
Processing Conditions ◽  
Line Pipe ◽  
Heavy Plate ◽  
Shear Area

High strength linepipe steels have to fulfil increasing property demands in modern pipeline applications. The transport of large gas volumes at high pressures from remote areas to the market is achieved in the most economical way by large diameter pipelines. For the last 30 years, high strength heavy plates for pipes and pipe bends were developed and produced at Salzgitter Mannesmann Grobblech. These products were steadily improved for example in terms of toughness and fracture behaviour at low temperatures. This is a strong focus of materials development around the world. Modern high-strength heavy plates used in the production of UOE pipes are generally produced by thermomechanical rolling followed by accelerated cooling (TMCP). The combination of high strength and high toughness of these steels is a result of the bainitic microstructure realised by TMCP and are strongly influenced by the rolling and cooling conditions. This paper gives an overview of the development of high strength plates for line pipe application at Salzgitter Mannesmann Grobblech. From comparably thin-walled X80 plates with no or medium DWTT requirements to recent requirements for approx. 28 mm thick X80 plates with requirements of 75/85% shear area fraction at −30°C and more than 250 J Charpy energy at −40°C the development work and the result of the last five years are described and presented. Classical light-optical characterisation of the microstructure of these steels is at its limits because the size of the observed features is too small to allow reliable quantitative results. Therefore Salzgitter Mannesmann Grobblech and Salzgitter Mannesmann Forschung (SZMF) developed alternative methods with the aim of a quantification of microstructure features and a correlation of those with the mechanical properties and processing conditions. In several investigations, the information is related to the mechanical properties of the plate material. It was found that a variation of the processing conditions has a direct influence on parameters that are accessible through the EBSD method and correlates with mechanical properties. The detailed correlations vary depending on steel grade and TMCP strategy. The results have to be carefully interpreted and help understanding the connection between processing and properties. Consequently this can be used as valuable input for the definition of the processing window for heavy plate production with optimized properties.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Analysis Influence of Pile Embedded Depth and Diameter on Pile Tip Resistance

2013 ◽  
Vol 353-356 ◽  
pp. 459-462
Author(s):  
Ying Jie Zheng ◽  
Bin Fang ◽  
Lian Xiang Li
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Stiffness Ratio ◽  
Initial Stiffness ◽  
Tip Resistance

Pile tip absolute settlement curves and relative settlement curves of several working cases were analyzed. It is found that load-settlement curve characteristic related to the selection standard. The tip resistance initial stiffness of each case was analyzed. Results show that the small diameter pile has higher initial stiffness than large diameter pile, embedded depth has little influence on initial stiffness ratio, but increment of initial stiffness is linear with embedded depth growth.

Development of X80M Line Pipe Steel for Spiral Welded Pipes With Low Temperature Toughness and Excellent Weldability

2014 ◽  
Author(s):  
Nuria Sanchez ◽  
Özlem E. Güngör ◽  
Martin Liebeherr ◽  
Nenad Ilić
Keyword(s):  
Low Temperature ◽  
Life Cycle Cost ◽  
Volume Fraction ◽  
Large Diameter ◽  
Pipe Production ◽  
Strain Accumulation ◽  
Long Distance ◽  
Line Pipe ◽  
Low Temperature Toughness ◽  
Welded Pipe

The unique combination of high strength and low temperature toughness on heavy wall thickness coils allows higher operating pressures in large diameter spiral welded pipes and could represent a 10% reduction in life cycle cost on long distance gas pipe lines. One of the current processing routes for these high thickness grades is the thermo-mechanical controlled processing (TMCP) route, which critically depends on the austenite conditioning during hot forming at specific temperature in relation to the aimed metallurgical mechanisms (recrystallization, strain accumulation, phase transformation). Detailed mechanical and microstructural characterization on selected coils and pipes corresponding to the X80M grade in 24 mm thickness reveals that effective grain size and distribution together with the through thickness gradient are key parameters to control in order to ensure the adequate toughness of the material. Studies on the softening behavior revealed that the grain coarsening in the mid-thickness is related to a decrease of strain accumulation during hot rolling. It was also observed a toughness detrimental effect with the increment of the volume fraction of M/A (martensite/retained austenite) in the middle thickness of the coils, related to the cooling practice. Finally, submerged arc weldability for spiral welded pipe manufacturing was evaluated on coil skelp in 24 mm thickness. The investigations revealed the suitability of the material for spiral welded pipe production, preserving the tensile properties and maintaining acceptable toughness values in the heat-affected zone. The present study revealed that the adequate chemical alloying selection and processing control provide enhanced low temperature toughness on pipes with excellent weldability formed from hot rolled coils X80 grade in 24 mm thickness produced at ArcelorMittal Bremen.

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