Double Jointing Technology for Strain-Based Design (SBD) Pipelines

2016 ◽  
Author(s):  
Neerav Verma ◽  
Doug P. Fairchild ◽  
Andrew J. Wasson ◽  
Timothy D. Anderson ◽  
Fredrick F. Noecker
Keyword(s):  
Welding Process ◽  
Cost Savings ◽  
High Strength ◽  
High Productivity ◽  
Weld Properties ◽  
Weld Metal Microstructure ◽  
Welding Consumable ◽  
Metal Microstructure ◽  
Longitudinal Strains ◽  
Submerged Arc

Pipelines may experience significant longitudinal strains when subjected to large ground motions, such as seismic activity, landslides, etc. For these conditions, a strain-based design (SBD) approach can be used. The use of higher strength steels (like X80) for SBD approach can enable significant construction cost savings. Costs can be further reduced through the use of a double jointing process in order to reduce the amount of field welding. However, it is challenging to achieve adequate girth weld properties for SBD scenarios involving higher strength steels by using conventional double jointing processes such as submerged arc welding (SAW). Acicular ferrite interspersed in martensite (AFIM) has been previously identified as an advantageous high strength weld metal microstructure that can be applied in field pipeline construction. In this paper, a double jointing technology for X70+ SBD applications will be discussed. Excellent strength and toughness properties were achieved in double joint welds by using an optimized AFIM welding technology that included a tailored welding consumable wire and a high productivity GMAW-P weld process. Welding procedures are discussed along with mechanical properties achieved. Productivity comparisons suggest that a fully optimized GMAW-P welding process in the 1G-rolled welding position can have productivity comparable to a conventional SAW double jointing process.

Advanced Strain-Based Design Pipeline Welding Technologies

2014 ◽  
Author(s):  
Neerav Verma ◽  
Doug P. Fairchild ◽  
Fredrick F. Noecker ◽  
Mario L. Macia ◽  
Nathan E. Nissley
Keyword(s):  
Cost Savings ◽  
High Strength ◽  
Pipeline Construction ◽  
Major Activity ◽  
Welding Technology ◽  
Discontinuous Permafrost ◽  
Weld Metal Microstructure ◽  
Pipeline Welding ◽  
Metal Microstructure ◽  
Longitudinal Strains

To meet the increasing worldwide demand for natural gas, there is a need to safely and economically develop remotely located resources. Pipeline construction is a major activity required to connect these remote resources to markets. Such pipeline routes may cross areas containing geohazards such as discontinuous permafrost, active seismicity and offshore ice gouging. These pipelines may be subjected to longitudinal strains above 0.5%. To safely design pipelines for such conditions, a strain-based design (SBD) approach can be used in addition to conventional allowable stress designs (ASD). Significant pipeline construction cost savings can be achieved with the use of higher strength steels (X70+) due to reduced pipe wall thicknesses (less steel) and faster girth welding. However, a robust welding technology for higher strength SBD pipelines is often a technology gap depending on the target level of longitudinal strain that needs to be accommodated, since such applications often demand excellent weld toughness at low temperatures (−15°C) and high tensile strength (>120ksi). This paper discusses the development of an enabling welding technology that offers a superior combination of strength and toughness compared to commercially available technologies. Acicular ferrite interspersed in martensite (AFIM) has been previously identified as a useful high strength weld metal microstructure that can be applied in field pipeline construction. This paper describes how this microstructure has been used to create welds with excellent strength overmatch and good ductile tearing resistance for X80 SBD pipelines. This approach has been implemented for mainline, double-joining and repair welding applications. This paper describes the welding procedures, mechanical properties achieved, estimated strain capacities, and the results of a full-scale pipe strain capacity test.

Application of Electric Current in Friction Stir Welding

2010 ◽  
Author(s):  
Matthew Pitschman ◽  
Jacob W. Dolecki ◽  
Garret W. Johns ◽  
Jun Zhou ◽  
John T. Roth
Keyword(s):  
Friction Stir Welding ◽  
Electric Current ◽  
Mechanical Energy ◽  
Welding Process ◽  
High Strength ◽  
Work Piece ◽  
Friction Stir ◽  
Weld Metals ◽  
Weld Properties ◽  
Electrically Enhanced

Friction Stir Welding (FSW) is a relatively new joining technique and has many applications. In FSW, heat generated due to friction between FSW tool and work-piece material softens the material and allows the materials in work-pieces to be stirred and joined together. FSW allows the work-pieces to be joined without reaching the melting point of the material, thus resulting in better welds. However, a large amount of mechanical energy has to be consumed for FSW of high-strength, difficult-to-weld metals such as titanium alloys. Hence, new FSW methods should be investigated to reduce the required energy. In this study, an innovative electrically-enhanced friction stir welding (EEFSW) has been developed. Electric current is passed in welding coupons of Aluminum 6061 plates and its effect on welding process and welds are examined. The results indicate that, with the aid of electric current, improvement in welding speed and reduction in energy consumption is obtainable, which enhances the productivity and widens the range of applications of FSW. Weld properties are found to be affected by the introduced current as well.

Tensile and Toughness Properties of Pipeline Girth Welds

2006 ◽  
Author(s):  
J. A. Gianetto ◽  
J. T. Bowker ◽  
R. Bouchard ◽  
D. V. Dorling ◽  
D. Horsley
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Strain Curve ◽  
High Strength ◽  
Primary Objective ◽  
Stress Strain ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Girth Welds ◽  
Metal Microstructure

The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.

Effect of Ti on the Microstructures and Toughness of TMCP-600 Steel Weld Metals

2013 ◽  
Vol 746 ◽  
pp. 462-466
Author(s):  
Jin Hyun Koh ◽  
Bok Su Jang
Keyword(s):  
Weld Metal ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Gas Metal Arc Welding ◽  
Control Process ◽  
High Strength ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
The Impact ◽  
Ti Content

The Ti addition effect on the characteristics of weld metal, such as impact energy, microstructure and nonmetallic inclusions, was investigated to develop a suitable gas metal arc welding wire for the high strength of TMCP (Thermo Mechanical Control Process)-600 steel. The fraction of acicular ferrite which was known to be a favorable weld metal microstructure for toughness was increased with Ti content from 0.002% to 0.025%, The impact energy of weld metal was increased whereas the ductile to brittle transition temperature was decreased with increasing Ti content. The size of nonmetallic inclusion was decreased while the density of inclusions was decreased with increasing Ti content. It was found that Ti content on the weld metal toughness had a plus effect by increasing the fraction of acicular ferrite in the weld metal microstructure.

Advanced Pipeline Welding Technologies for Strain-Based Design

2016 ◽  
Author(s):  
Andrew J. Wasson ◽  
Doug P. Fairchild ◽  
Fredrick F. Noecker ◽  
Mario L. Macia ◽  
Nathan E. Nissley
Keyword(s):  
Weld Metal ◽  
Energy Demand ◽  
Oil And Gas ◽  
Cost Savings ◽  
High Strength ◽  
Weld Strength ◽  
Pipeline Construction ◽  
Welding Technology ◽  
Discontinuous Permafrost ◽  
Longitudinal Strains

In order to meet the increasing worldwide energy demand, there is a need to economically develop remote oil and gas resources. Construction of pipelines is required to connect these resource locations to markets. Such pipeline routes may cross areas of large ground motions such as regions of active seismicity, discontinuous permafrost, and offshore ice gouging. All of these features can subject pipelines to significant longitudinal strains. For these conditions a strain-based design (SBD) approach may be required to maintain pipeline integrity. Welding technology is a key component of pipeline construction. Significant pipeline construction cost savings are enabled with the use of higher strength steels (X80+). Higher strengths enable reduced pipe wall thicknesses, which reduces both weight and girth welding time. However, robust welding technology for high strength SBD pipelines remains challenging. Such applications demand welds with both high strength (>120ksi) and low temperature (−15°C) toughness, combinations that are at the limits of, or beyond, existing commercial technology. This paper discusses the development of an enabling welding technology which offers a superior combination of strength and toughness properties. An iron-nickel (FeNi) martensitic weld metal with a refined mixed cellular microstructure has been developed as a promising high strength weld metal that can be applied for field pipeline construction. This paper describes how this technology has been applied to create welds for X80 strain-based pipelines requiring significant weld strength overmatch and superior ductile tearing resistance. The welding technology can also be applied to X70 grade strain-based pipelines where high toughness is required. This approach has been developed for mainline girth, tie-in girth, and girth repair welding scenarios. Welding procedures are discussed and examples of the mechanical properties achieved and calculated strain capacities are described.

Development of Welding Procedures for X90-Grade Seamless Pipes for Riser Applications

2012 ◽  
Author(s):  
Hiroyuki Nagayama ◽  
Masahiko Hamada ◽  
Mark F. Mruczek ◽  
Mark Vickers ◽  
Nobuyuki Hisamune ◽  
...  
Keyword(s):  
Weld Metal ◽  
Arc Welding ◽  
Mechanical Test ◽  
Welding Process ◽  
High Strength ◽  
Submerged Arc Welding ◽  
Welding Parameters ◽  
Flux Cored Arc Welding ◽  
Welding Procedure ◽  
Submerged Arc

Ultra-high strength seamless pipes of X90 and X100 grades have been developed for deepwater or ultra-deepwater applications. Girth welding procedure specifications (WPSs) should be developed for the ultra-high strength pipes. However, there is little information for double jointing welding procedure by using submerged arc welding process for high strength line pipes. This paper describes mechanical test results of submerged arc welding (SAW) and gas shielded flux cored arc welding (GSFCAW) trials with various welding consumables procured from commercial markets. Welds were then made with typical welding parameters for riser productions using high strength X90 seamless pipes. The submerged arc weld metal strength could increase by increasing alloy elements in weld metal. The weld metal with CE (IIW) value of 0.74 mass% achieved fully overmatching for the X90 pipe. The weld metal yield strength (0.2% offset) was 694 MPa, and the ultimate tensile strength was 833 MPa. It was also confirmed that the reduction of boron in weld metal can improve low temperature toughness of high strength weld metal. Furthermore, it was confirmed that the HAZ has excellent mechanical properties and toughness for riser applications. In this study GSFCAW procedures were also developed. GSFCAW can be used for joining pipe and connector material for riser production welding. The weld metal with a CE (IIW) value of 0.54 mass% could meet the required strength level for X90-grade pipe as specified in ISO 3183. Cross weld tensile testing showed that fractures were achieved in the base metal. Good Charpy impact properties in weld metal and HAZ were also confirmed.

A Decade of Progress in Underwater Wet Welding Using the SMAW Process (1990-2003)

2004 ◽  
Author(s):  
Stephen Liu
Keyword(s):  
Weld Metal ◽  
Nickel Content ◽  
Cost Savings ◽  
Significant Cost ◽  
Electrode Coating ◽  
Underwater Wet Welding ◽  
Recent Developments ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
Repair Techniques

It is well established that underwater wet welding (UWW) offers significant cost savings over other repair techniques for submerged structures such as petroleum production platforms, ships, and piers. Due to the deleterious effect of increased pressure on weld quality, innovative consumables are required for the production of quality wet welds. Manganese was added to the electrode coating to replenish its loss from the weld pool. Titanium and boron were added to control the molten metal oxygen potential and refine the as-solidified and reheated weld metal microstructure. Rare-earth metals (REM) were added to control the weld metal oxygen content. Finally, weld metal nickel content was optimized to improve impact toughness. Selected results of these approaches are presented in this work. These recent developments clearly demonstrate that it is possible to achieve significant progresses in wet welding using shielded metal arc (SMA) consumables, if these are designed following sound metallurgical principles.

Effects of Nitrogen on Weld Metal Microstructure and Toughness in Submerged Arc Welding

2007 ◽  
Vol 539-543 ◽  
pp. 3906-3911 ◽  
Author(s):  
Kook Soo Bang ◽  
Woo Yeol Kim ◽  
Chan Park ◽  
Young Ho Ahn ◽  
Jong Bong Lee
Keyword(s):  
Impact Toughness ◽  
Weld Metal ◽  
Nitrogen Content ◽  
Arc Welding ◽  
Solid Solution Hardening ◽  
Microstructural Changes ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
Submerged Arc ◽  
Metal Impact

The effects of nitrogen content on weld metal impact toughness in submerged arc welding were investigated and interpreted in terms of microstructural changes and solid solution hardening. The weld metal impact toughness in as-welded condition decreased with increasing nitrogen content from 110 to 200 ppm. The weld metal microstructure changed with increasing nitrogen content; ferrite with second phase increased at the expense of tough acicular ferrite. In addition to microstructural changes, the microhardness of acicular ferrite increased gradually with the nitrogen content. Therefore, the loss of impact toughness can be attributed to a combination of the effects of microstructural changes and solid solution hardening.

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