Evaluation of UOE and Spiral-Welded Line Pipe for Strain Based Designs

2010 ◽  
Author(s):  
Yankui Bian ◽  
Christopher Penniston ◽  
Laurie Collins ◽  
Robert Mackenzie
Keyword(s):  
Heat Affected Zone ◽  
Work Hardening ◽  
Good Work ◽  
Aging Effects ◽  
Pipe Axis ◽  
Line Pipe ◽  
Advantages And Disadvantages ◽  
Minimum Requirements ◽  
Girth Welds ◽  
Welding Processes

Strain-based designs for Arctic pipelines place stringent demands on properties of the pipe body as well as the girth weld and associated heat affected zone. The pipe body must demonstrate good work hardening behavior in addition to satisfactory strength and toughness properties. Girth welds are required to overmatch the strength of the pipe body; both the weld and heat affected zone must also provide good toughness. In this study, X80 line pipe produced using the UOE and spiral welding processes were compared. The UOE process provides some degree of work hardening resulting from cold expansion. This extra hardening renders the UOE pipe more responsive than the spiral pipe to aging effects associated with pipe coating. However, the UOE pipe has an advantage in balancing LPA (longitudinal to pipe axis) and TPA (transverse to pipe axis) strengths. Greater strengths in the TPA orientation afford the capacity to meet specified minimum requirements of the pipe grade and lower strengths in the LPA orientation facilitate overmatching by girth welds. The two types of line pipe offer both advantages and disadvantages for strain-based designs. It must be emphasized that good work hardening characteristics can be maintained in the UOE pipe when the coating process involves a low temperature, which is an objective of modern coating technologies. It was also observed that aging effects did not affect toughness properties significantly.

Effect of Strain Ageing on Mechanical Properties of Pipeline Girth Welds

2011 ◽  
Author(s):  
Badri K. Narayanan ◽  
Jon Ogborn
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Base Material ◽  
Dynamic Strain ◽  
Pipe Material ◽  
Cored Wire ◽  
Line Pipe ◽  
Strain Ageing ◽  
Girth Welds ◽  
Welding Processes

Pipeline girth welds for on-shore and off-shore pipelines use a variety of arc welding processes. The trend towards strain based designs for line pipe installation and the effect of coatings for off-shore pipelines have resulted in evaluation and testing of pipe material subjected to strain ageing. However, very little work has been done to systematically study the effect on ferritic weld metal. This work details some initial work done on evaluating the effect of strain ageing on ferritic weld metal deposited with a 1.2 mm diameter flux cored wire under 75% Ar −25% CO2 shielding gas. Pipeline girth welds were welded on API Grade X-70 pipe and tested to get all weld metal tensile and Charpy V-Notch properties. The weld metal strength overmatched the base material by 7–9%. The ductile to brittle transition temperature for the weld metal was −40°C. The effect of strain ageing on weld metal properties was evaluated. All weld metal tensile samples were subjected to varying levels of pre-strain and ageing treatments to evaluate the effect on yield strength and post-yield behavior. An increase in yield strength after straining and ageing as well as the re-appearance of yield point is observed. Increase in pre-strain decreases elongation. Increase in ageing temperature delays the appearance of dynamic strain ageing. The activation energy for the increase in strength after strain ageing has been measured by assuming a diffusion controlled mechanism. Charpy V-Notch samples were taken to generate transition curves of weld metal after strain ageing and compared to the as-welded condition.

Microstructure, Mechanical Properties and SSC Susceptibility of Multiple SMAW Repairs in Line Pipe Girth Welds

2008 ◽  
Author(s):  
Oscar E. Vega ◽  
Jose´ M. Hallen ◽  
Agusti´n Villagomez ◽  
Antonio Contreras
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Impact Resistance ◽  
Microstructural Characterization ◽  
Coarse Grained ◽  
Shielded Metal Arc Welding ◽  
Line Pipe ◽  
Metal Arc Welding ◽  
Sulfide Stress ◽  
Girth Welds

Girth welds of seamless API X52 steel pipe containing multiple shielded metal arc welding (SMAW) repairs and one as-welded condition were studied. Microstructural characterization, mechanical behavior and sulfide stress corrosion cracking (SSC) susceptibility of the welded joints were evaluated by means of optical and scanning electron microscopy, hardness, tension, Charpy-V impact resistance and slow strain rate tests (SSRT). The results of this work indicate that increasing the number of welding repairs promotes grain growth in the heat affected zone (HAZ). The yield strength (YS) and ultimate tensile strength (UTS) for the different welding repairs satisfy the specified minimum values of the material. Significant reduction in Charpy-V impact resistance with the increases of the number of repairs was found in the coarse grained heat affected zone (CGHAZ). A high susceptibility to SSC was exhibited by the welded joints and the intercritical heat affected zone was the most susceptible area to SSC.

Effects of Ti, C and N on Weld HAZ Toughness of High Strength Line Pipe

2008 ◽  
Author(s):  
Christopher Penniston ◽  
Laurie Collins ◽  
Fathi Hamad
Keyword(s):  
Low Temperature ◽  
Heat Affected Zone ◽  
Construction Projects ◽  
High Strength Steels ◽  
High Strength ◽  
Construction Costs ◽  
Line Pipe ◽  
C And N ◽  
Welding Processes ◽  
Haz Toughness

As pipeline construction projects seek to implement more efficient welding techniques in order to reduce construction costs, it is important to understand the factors that affect the tolerance of the steel to welding processes. This is particularly true in the case of welding high strength steels (X70 and greater) in which increased alloy content will promote the formation of low temperature phases with limited ductility in the heat affected zone (HAZ). In the present study, the effects of titanium (0.008 to 0.015 wt%), nitrogen (60 to 100 ppm) and carbon (0.035 versus 0.060 wt%) have been examined through welds produced by a robotic gas metal arc welder.

Advanced submerged arc welding processes for Arctic structures and ice-going vessels

2016 ◽  
Vol 232 (1) ◽  
pp. 114-127
Author(s):  
Pavel Layus ◽  
Paul Kah ◽  
Viktor Gezha
Keyword(s):  
Case Studies ◽  
Arc Welding ◽  
Oil And Gas ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
The Arctic ◽  
Correct Selection ◽  
Advantages And Disadvantages ◽  
Welding Processes ◽  
Submerged Arc

The Arctic region is expected to play an extremely prominent role in the future of the oil and gas industry as growing demand for natural resources leads to greater exploitation of a region that holds about 25% of the world’s oil and gas reserves. It has become clear that ensuring the necessary reliability of Arctic industrial structures is highly dependent on the welding processes used and the materials employed. The main challenge for welding in Arctic conditions is prevention of the formation of brittle fractures in the weld and base material. One mitigating solution to obtain sufficiently low-transition temperatures of the weld is use of a suitable welding process with properly selected parameters. This work provides a comprehensive review with experimental study of modified submerged arc welding processes used for Arctic applications, such as narrow gap welding, multi-wire welding, and welding with metal powder additions. Case studies covered in this article describe welding of Arctic steels such as X70 12.7-mm plate by multi-wire welding technique. Advanced submerged arc welding processes are compared in terms of deposition rate and welding process operational parameters, and the advantages and disadvantages of each process with respect to low-temperature environment applications are listed. This article contributes to the field by presenting a comprehensive state-of-the-art review and case studies of the most common submerged arc welding high deposition modifications. Each modification is reviewed in detail, facilitating understanding and assisting in correct selection of appropriate welding processes and process parameters.

scholarly journals The Microstructure and Property of the Heat Affected zone in C-Mn Steel Treated by Rare Earth

2019 ◽  
Vol 38 (2019) ◽  
pp. 362-369 ◽  
Author(s):  
Ming-ming Song ◽  
Yu-min Xie ◽  
Bo Song ◽  
Zheng-liang Xue ◽  
Nan Nie ◽  
...  
Keyword(s):  
Rare Earth ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Steel Matrix ◽  
Impact Properties ◽  
Treated Steel ◽  
The Impact ◽  
Welding Processes ◽  
Mn Steel

AbstractThe microstructures and impact properties of the heat affected zone (HAZ) in steel treated by rare earth (RE) under different welding processes were discussed. The effect of Al on the impact properties of the HAZ in RE treated steel was analyzed. It finds that when the welding t8/5 is smaller than 111 s, the main microstructure in steels is bainite/widmanstatten. The impact toughness of the HAZ is lower than that of the steel matrix. When t8/5 is more than 250 s, the microstructure is mainly acicular ferrite (AF) in the steel treated by RE, and the impact toughness of HAZ is obviously improved. Even under the welding processing with t8/5 about 600 s in RE treated steel can still obtain a lot of AF. While in the steel killed by Al and treated by RE, the main microstructure is parallel cluster of bainite/widmanstatten, and the impact toughness of HAZ is significantly lower than that of low-Al RE treated steel. Al can deteriorate the optimizing of RE treatment on HAZ.

Effect of Welding Processes with High Heat Input on the Microstructure and Toughness of Coarse-Grained Heat-Affected Zone of a High-Strength High-Toughness Steel

2018 ◽  
Vol 937 ◽  
pp. 61-67
Author(s):  
Yu Jie Li ◽  
Jin Wei Lei ◽  
Xuan Wei Lei ◽  
Oleksandr Hress ◽  
Kai Ming Wu
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
High Strength ◽  
High Heat ◽  
Coarse Grained ◽  
Low Temperature Impact Toughness ◽  
The Impact ◽  
Welding Processes

Utilizing submerged arc welding under heat input 50 kJ/cm on 60 mm thick marine engineering structure plate F550, the effect of preheating and post welding heat treatment on the microstructure and impact toughness of coarse-grained heat-affected zone (CGHAZ) has been investigated. The original microstructure of the steel plate is tempered martensite. The yield and tensile strength is 610 and 660 MPa, respectively. The impact absorbed energy at low temperature (-60 °C) at transverse direction reaches about 230~270 J. Welding results show that the preheating at 100 °C did not have obvious influence on the microstructure and toughness; whereas the tempering at 600 °C for 2.5 h after welding could significantly reduce the amount of M-A components in the coarse-grained heat-affected zone and thus improved the low temperature impact toughness.

scholarly journals Prediction of Residual Stresses in a Multipass Pipe Weld by a Novel 3D Finite Element Approach

2018 ◽  
Author(s):  
Hui Huang ◽  
Jian Chen ◽  
Blair Carlson ◽  
Hui-Ping Wang ◽  
Paul Crooker ◽  
...  
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
High Performance ◽  
Large Scale ◽  
Graphics Processing Unit ◽  
Computational Cost ◽  
Three Dimensional ◽  
Processing Unit ◽  
Girth Welds ◽  
Welding Processes

Due to enormous computation cost, current residual stress simulation of multipass girth welds are mostly performed using two-dimensional (2D) axisymmetric models. The 2D model can only provide limited estimation on the residual stresses by assuming its axisymmetric distribution. In this study, a highly efficient thermal-mechanical finite element code for three dimensional (3D) model has been developed based on high performance Graphics Processing Unit (GPU) computers. Our code is further accelerated by considering the unique physics associated with welding processes that are characterized by steep temperature gradient and a moving arc heat source. It is capable of modeling large-scale welding problems that cannot be easily handled by the existing commercial simulation tools. To demonstrate the accuracy and efficiency, our code was compared with a commercial software by simulating a 3D multi-pass girth weld model with over 1 million elements. Our code achieved comparable solution accuracy with respect to the commercial one but with over 100 times saving on computational cost. Moreover, the three-dimensional analysis demonstrated more realistic stress distribution that is not axisymmetric in hoop direction.

Predicting the Brittle-to-Ductile Transition Temperatures for Surface Cracks in Pipeline Girth Welds: It’s Better Than You Thought

2008 ◽  
Author(s):  
Gery Wilkowski ◽  
David Rudland ◽  
Do-Jun Shim ◽  
David Horsley
Keyword(s):  
Transition Temperature ◽  
Surface Crack ◽  
Master Curve ◽  
Crack Depth ◽  
Temperature Shift ◽  
Transition Temperatures ◽  
Surface Cracks ◽  
Line Pipe ◽  
Brittle To Ductile Transition ◽  
Girth Welds

A methodology to predict the brittle-to-ductile transition temperature for sharp or blunt surface-breaking defects in base metals was developed and presented at IPC 2006. The method involved applying a series of transition temperature shifts due to loading rate, thickness, and constraint differences between bending versus tension loading, as well as a function of surface-crack depth. The result was a master curve of transition temperatures that could predict dynamic or static transition temperatures of through-wall cracks or surface cracks in pipes. The surface-crack brittle-to-ductile transition temperature could be predicted from either Charpy or CTOD bend-bar specimen transition temperature information. The surface crack in the pipe has much lower crack-tip constraint, and therefore a much lower brittle-to-ductile transition temperature than either the Charpy or CTOD bend-bar specimen transition temperature. This paper extends the prior work by presenting past and recent data on cracks in line-pipe girth welds. The data developed for one X100 weld metal shows that the same base-metal master curve for transition temperatures works well for line-pipe girth welds. The experimental results show that the transition temperature shift for the surface-crack constraint condition in the weld was about 30C lower than the transition temperature from standard CTOD bend-bar tests, and that transition temperature difference was predicted well. Hence surface cracks in girth welds may exhibit higher fracture resistance in full-scale behavior than might be predicted from CTOD bend-bar specimen testing. These limited tests show that with additional validation efforts the FITT Master Curve is appropriate for implementation to codes and standards for girth-weld defect stress-based criteria. For strain-based criteria or leak-before-break behavior, the pipeline would have to operate at some additional temperature above the FITT of the surface crack to ensure sufficient ductile fracture behavior.

Standardization of Flattening Procedure of Transverse to Pipe Axis Strap Tensile Samples

2018 ◽  
Author(s):  
M. Rashid ◽  
S. Chen ◽  
L. E. Collins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Testing ◽  
Standard Procedure ◽  
Large Diameter ◽  
Spring Back ◽  
Pipe Axis ◽  
Element Analysis ◽  
Line Pipe ◽  
Experimental Approaches

Tensile testing on large diameter line pipe is generally done using strap samples obtained in the transverse to pipe axis (TPA) orientation of a pipe. The strap samples are then flattened and machined prior to testing. Although the standardized tensile testing is well documented, the variability in the reported TPA tensile properties of the same material tested within a lab or at different labs has always been an issue. Recent work conducted at EVRAZ NA research lab has identified flattening as the main source of the variability in reported yield strength (YS) values for line pipe. The lack of a standard procedure for flattening TPA strap samples is a major obstacle to obtaining consistent results. Therefore, the main objective of this current study was to establish a standardized flattening procedure for TPA strap samples. Both finite element analysis (FEA) and experimental approaches were adopted. Various flattening methods and fixtures were studied. Extensive flattening experiments were conducted on TPA samples from different line pipe products. Results showed that the spring back after flattening in a TPA sample is different for pipes with different gauge and grades. It was established that consistent flattening can be achieved using appropriate fixtures for differerent ranges of tubular products defined by grade, diameter and gauges. Evaluation of the flattening fixture designs and experimental results are discussed in this paper.

Effects of Heat-Affected Zone Microstructure on Fracture Toughness of Two X70 Pipe Girth Welds

2017 ◽  
Vol 48 (7) ◽  
pp. 3248-3260 ◽  
Author(s):  
Dong-Yeob Park ◽  
Babak Shalchi Amirkhiz ◽  
Jean-Philippe Gravel ◽  
Yiyu Wang ◽  
Leijun Li ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Heat Affected Zone ◽  
Girth Welds ◽  
Zone Microstructure
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