Guidance for Field Segmentation and Welding of Induction Bends and Elbows

2012 ◽  
Author(s):  
William A. Bruce ◽  
Bill Amend ◽  
Steve Rapp
Keyword(s):  
Large Diameter ◽  
Second Phase ◽  
Pipeline Construction ◽  
Work Space ◽  
Optimal Methods ◽  
Recommended Practices ◽  
Construction Practice

The use of cold field bends is not practical for some pipeline construction applications, particularly for large diameter pipelines built with restricted work space. For many reasons, the use of segmented induction bends and long-radius elbows becomes a necessary part of normal construction practice. This paper describes the results of the second phase of a recently-completed joint industry project pertaining to welding of field segmented induction bends and elbows for pipeline construction. In this phase, optimal methods for mapping, cutting, beveling, and transitioning induction bends and elbows were developed. Recommended practices for welding in the field and for a variety of related issues were also developed. The information was summarized and used to develop a generic specification for segmenting and welding of induction bends and elbows.

Impurity Effects in the Growth of 4H-SiC Crystals by Physical Vapor Transport

1999 ◽  
Vol 572 ◽  
Author(s):  
V. Balakrishna ◽  
G. Augustine ◽  
R. H. Hopkins
Keyword(s):  
Electronic Device ◽  
Defect Density ◽  
Growth Parameters ◽  
Large Diameter ◽  
Growth Conditions ◽  
High Resistivity ◽  
Growth Surface ◽  
Second Phase ◽  
Impurity Effects ◽  
Growth Environment

ABSTRACTSiC is an important wide bandgap semiconductor material for high temperature and high power electronic device applications. Purity improvements in the growth environment has resulted in a two-fold benefit during growth: (a) minimized inconsistencies in the background doping resulting in high resistivity (>5000 ohm-cm) wafer yield increase from 10–15% to 70-85%, and (b) decrease in micropipe formation. Growth parameters play an important role in determining the perfection and properties of the SiC crystals, and are extremely critical in the growth of large diameter crystals. Several aspects of growth are vital in obtaining highly perfect, large diameter crystals, such as: (i) optimized furnace design, (ii) high purity growth environment, and (iii) carefully controlled growth conditions. Although significant reduction in micropipe density has been achieved by improvements in the growth process, more stringent device requirements mandate further reduction in the defect density. In-depth understanding of the mechanisms of micropipe formation is essential in order to devise approaches to eliminate them. Experiments have been performed to understand the role of growth conditions and ambient purity on crystal perfection by intentionally introducing arrays of impurity sites on one half of the growth surface. Results clearly suggest that presence of impurities or second phase inclusions during start or during growth can result in the nucleation of micropipes. Insights obtained from these studies were instrumental in the growth of ultra-low micropipe density (less than 2 micropipes cm−2 ) in 1.5 inch diameter boules.

Development of a Hybrid Laser Arc Welding System for Pipeline Construction

2008 ◽  
Author(s):  
D. Begg ◽  
G. Beynon ◽  
E. Hansen ◽  
J. Defalco ◽  
K. Light
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Large Diameter ◽  
Primary Objective ◽  
Construction Costs ◽  
Hybrid Laser Arc Welding ◽  
Pipeline Construction ◽  
Girth Welding ◽  
Pipeline Welding ◽  
Welding Processes

The construction costs for a northern pipeline will represent approximately half of the project costs and will be extremely challenging with much of the work being carried out in harsh winter conditions at temperatures, as low as −55°C. The welding costs are a major component of the overall construction costs and industry continues to seek future generation pipeline welding technologies to achieve additional improvements in productivity and enable significant cost savings. The current state-of-the-art welding processes for onshore pipelines involve mechanized gas metal arc welding (GMAW). The dual tandem pulse GMAW process provides the greatest productivity to date with four welding arcs operating simultaneously on each welding carriage. Based on the progression of laser welding technology, it is highly likely that the next generation of automated pipeline welding equipment will be built around hybrid laser arc welding (HLAW). The primary objective of this project is to develop, test, and validate a “field ready” HLAW system for full circumferential girth welding of large diameter (NPS30 and above) high strength pipe. The system is based on both robotic and direct clamp-on platforms where potential applications include double jointing operations in pipe mills and as well for onshore and offshore pipeline construction projects. The pipe grades evaluated include both X80 and X100, with wall thicknesses of 10.4mm and 14.3mm, respectively. Lab trials include high speed root pass, high speed root pass with laser assisted GMAW for fill and cap passes, and, single pass complete joint penetration girth welding. This paper discusses the approach to the development of the HLAW system, however at the time the paper was submitted no mechanical testing or system validation trials had been completed. It is expected results will be available for the conference presentation.

A Stress Check Procedure for Pipe Lowering-In Process During Pipeline Construction

2014 ◽  
Author(s):  
Da-Ming Duan ◽  
Thomas Jurca ◽  
Charles Zhou
Keyword(s):  
Finite Element ◽  
Stress Level ◽  
Height Profile ◽  
Element Analysis ◽  
Pipeline Construction ◽  
Lifting Capacity ◽  
Calculation Results ◽  
Construction Condition ◽  
Construction Practice

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

The Riser System Challenge for 1,800 Meters: Roncador Field, Offshore, Brazil

2003 ◽  
Author(s):  
Renato Marques Correˆa da Silva ◽  
Marcio Martins Mourelle ◽  
Jose´ Maurico Teixeira da Gama Lima ◽  
Francisco Henrique Ferreira Rodrigues
Keyword(s):  
Feasibility Study ◽  
Oil And Gas ◽  
Large Diameter ◽  
Production Unit ◽  
Base Case ◽  
Second Phase ◽  
Steel Catenary Riser ◽  
Associated Gas ◽  
Main Challenge ◽  
Gas Lift

The paper presents a general overview of the technological challenge posed by the development of the phase 2, module 1A of Roncador field, offshore, Brazil. The field, discovered in 1996, encompasses reserves of 2.1 billion barrels of oil equivalent and is being developed in phases. This second phase, module 1A will be developed using solutions that will be among the world’s larger semi-submersible floating production unit displacement of more than 80,000 tons named Petrobras 52 (P-52). The platform will be moored in 1,800 meters (5905 ft) water depth. Peak production rates are targeted at 180,000 barrels per day (28,618m3/day) of oil and 130 million cubic feet per day (3.7 million m3/day) of natural gas. In addition to oil and associated gas processing capability to export and gas-lift, the unit will provide facilities capable of injecting up to 302,000 barrels per day (48,000 m3/day) of water. The subsea system was devised with all wells wet completed and directly connected to the production unit through around 44 SCRs (steel catenary risers) as base case. Moreover, alternative riser solutions such as flexible and hybrid risers are being screened and should be considered in the construction and installation bid. The gas lift system was defined through three subsea manifolds in order to narrow down the number of risers. The oil and gas export system was envisaged to be done through large diameter pipeline up to a shallow water fixed jacket hub facility which is linked with shore refinery pipeline network. The platform is scheduled for initial production in 2006. The feasibility study for the second phase, module 1A was performed in the third quarter of 2001. The main challenge was to produce an appraisal that mitigates the technology risk and also provides enough robustness to guarantee an attractive return rate. The unique field proven technology available to be considered in the feasibility study for the riser system as base case was the steel catenary riser system. On the other hand, other technologies were also investigated such as the riser tower system — similar to Girassol, West Africa; flexible riser system — to be qualified and the sub surface buoy, an in house solution. This paper describes the technical approach used into the feasibility in-house study that established the design base for the base case as well as the alternatives.

Grain Refinement in Titanium-Erbium Alloys

1974 ◽  
Vol 32 ◽  
pp. 522-523
Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Grain Refinement ◽  
Grain Growth ◽  
Volume Fraction ◽  
Pure Titanium ◽  
Systematic Investigation ◽  
Second Phase ◽  
Titanium Matrix ◽  
Average Size

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

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