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.

Methodology for Assessment of Surface Defects in Undermatched Pipeline Girth Welds

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Aurélien Pépin ◽  
Tomasz Tkaczyk ◽  
Noel O'Dowd ◽  
Kamran Nikbin
Keyword(s):  
Weld Metal ◽  
Surface Defects ◽  
Analytical Formula ◽  
Strain Curve ◽  
High Strength ◽  
Cost Effective ◽  
Medium Size ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Girth Welds

The demand for subsea transport of highly corrosive constituents has noticeably increased in recent years. This has driven the requirement for high strength pipelines with enhanced corrosion resistance such as chromium stainless steel or bimetal pipes. The latter are carbon steel pipes with a corrosion resistant alloy lining. Reeling is a cost effective installation method for small to medium size subsea pipelines, up to 457.2 mm (18 in.) in diameter. However, plastic straining associated with reeling has an effect on weld defect acceptance criteria. The maximum acceptable defect sizes are typically developed using engineering critical assessment (ECA), based on the reference stress method, which requires that the weld metal is equal to or stronger than the parent metal in terms of the stress–strain curve. However, evenmatch/overmatch cannot always be achieved in the case of subsea stainless or bimetal pipelines. In this work, a parametric finite-element (FE) study was performed to assess the effect of weld metal undermatch on the crack driving force, expressed in terms of the crack tip opening displacement (CTOD). Subsequently, the fracture assessment methodology for reeled pipes was proposed, where the ECA as per BS7910 is first carried out. These acceptable defect sizes are then reduced, using an analytical formula developed in this work, to account for weld undermatch.

The Influence of Diffusible Hydrogen in Weld Metal and Moisture Content Levels in Flux Related With Weld Metal Mechanical Properties in Submerged Arc Welding Process for Line Pipe Manufacturing

2015 ◽  
Author(s):  
Gautam Chauhan ◽  
Piyush Thakor ◽  
Satyanarayana Samavedam ◽  
Ramakrishnan Mannarsamy ◽  
Ashif Sheikh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Weld Metal ◽  
Hydrogen Content ◽  
Welding Process ◽  
Diffusible Hydrogen ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Submerged Arc ◽  
Pipe Manufacturing

The mechanical properties of welding material is correlative with the diffusible hydrogen content in weld metal and level of moisture content in flux. Minitab16program to predict mechanical properties correlated to diffusible hydrogen content in weld metal and level of moisture content in flux, such as yield strength, tensile strength, elongation and average Charpy impact toughness of welding material is established by using submerged arc welding process in line pipe manufacturing. The present paper aims to experiment and investigate the line pipe SAW Flux used for offshore/onshore applications. Flux moisture content has been studied under Karl Fischer Coulometer method. Subsequently, flux was then used to make weld to analysis for ‘diffusible hydrogen content in weld metal’ through mercury displacement method. This detailed study envisages and explains the correlations between the mechanical properties and micro structures of weldments. Evaluating the variance of moisture level in flux and diffusible hydrogen content in weld metal proves the advantage of restricting the moisture content along with good practices to accomplish better weld quality.

Development of Optimized Weld Metal Chemistries for Pipeline Girth Welding of High Strength Line Pipe

2008 ◽  
Author(s):  
Susan R. Fiore ◽  
James A. Gianetto ◽  
Mark G. Hudson ◽  
Suhas Vaze ◽  
Shuchi Khurana ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Yield Strength ◽  
Weld Metal ◽  
High Strength ◽  
Process Variations ◽  
Line Pipe ◽  
Girth Welding ◽  
Dimensional Finite Element ◽  
Initial Work ◽  
Girth Welds

The primary objectives of this program were to provide a better understanding of the factors that control strength and toughness in high strength steel girth welds and to develop optimized welding consumables and welding procedures for high strength pipelines. The initial work on the program involved developing cooling rate models so that optimized weld metal compositions for high-strength pipelines could be developed, ensuring that the ideal balance of strength and ductility, together with tolerance to process variations and resistance to hydrogen cracking is achieved. The model, which was developed under a companion program, uses a two-dimensional finite element approach. Complete details can be found in Reference [1]. The model predicts the cooling rates during various weld passes in narrow groove welding of X80 and X100 pipes. Using this model, along with experimental datasets, a neural network model was developed which has been used to predict weld metal properties for various weld metal compositions. Based on the predictions, eight target compositions were selected and were manufactured by one of the team partners. The results of mechanical property testing showed that it was possible to develop weld metal compositions which exceeded the target yield strength of 820 MPa and also provided excellent toughness (>50J at −60°C). It was also found that the weld metal yield strength measured close to the ID of the pipe was significantly higher than that which was measured closer to the OD of the pipe. Complete mechanical property results, including results for round-bar and strip tensiles, CVN impact toughness, microhardness and more, are presented.

Establishment of Cold Wire Addition Technology® in Multiwire Submerged Arc Welding for Line Pipe Manufacturing to Improve the Weldment Quality

2015 ◽  
Author(s):  
Ramakrishnan Mannarsamy ◽  
S. K. Shrivastava ◽  
Piyush Thakor ◽  
Gautam Chauhan ◽  
S. K. Joshi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Arc Welding ◽  
Welding Process ◽  
High Strength ◽  
Submerged Arc Welding ◽  
Line Pipe ◽  
Cold Wire ◽  
Welding Procedure ◽  
Submerged Arc

For achieving high productivity multiple wire submerged arc welding such as tandem wire, three wires and five wires submerged arc welding was introduced in recent past years. Due to adding of additional wires in a pipe mill faced process difficulties such as controlling the current supply to each wire and further challenges for consumable design in order to give effective slag characteristics and bead shape control at these higher welding speeds and heat inputs. To gain maximum productivity, welding speed must be as fast as possible (in excess of 2 m/min) consistent with reliable high speed wire feeding and the characteristics of the SAW flux considering these factors in determining the balance of heat input, penetration, bead shape, dilution, weld metal chemistry and mechanical properties such as toughness. Steels containing high strength low alloying elements like Manganese, Molybdenum, Titanium and boron have favorable physical properties such as higher subzero toughness, resistance to improve the mechanical properties because of which there is substantial saving in the material. High strength low alloy steels materials are utilized in offshore and onshore at critical services. However, such benefits can be exploited provided these steels can be welded with appropriate development of welding process such as cold wire addition® in multi wires with process controller using WINCC programmer, Z5 version to give better weldments, which will not compromise the integrity, and operating condition. To obtain higher productivity and quality, it is necessary to develop a welding procedure for butt joint of line pipe steels. This paper describes the recent work carried out by Welspun, in this regard to establish the welding procedure using GMAW and submerged arc welding process and evaluation of mechanical properties. Macro and micro structural analysis were also made to characterize the weld metal properties.

Analysis of Plastic Deformation in a Steel Cylinder Striking a Rigid Target

1954 ◽  
Vol 21 (1) ◽  
pp. 63-70
Author(s):  
E. H. Lee ◽  
S. J. Tupper
Keyword(s):  
Compression Test ◽  
Dynamic Compression ◽  
Strain Curve ◽  
High Strength ◽  
Stress Strain ◽  
Steel Cylinder ◽  
Theoretical Approaches ◽  
Stress Strain Relation ◽  
Strength Alloy ◽  
Dynamic Yield

Abstract The G. I. Taylor dynamic compression test consists of firing a cylinder of the material to be tested at a target of hardened armor plate, and deducing the dynamic yield stress from the resulting deformation. In the interpretation of the results, interest is concentrated on the wave front of initial plastic straining. The present paper attempts the theoretical determination of the entire strain distribution in such a test cylinder of nickel-chrome steel, this material being chosen since the dynamic influence on the stress-strain relation is likely to be small, thus permitting the static relation to be used in the theory. Strain distributions deduced by two theoretical approaches compare satisfactorily with the distribution of strain obtained in such a dynamic compression test, thus justifying the assumption for this material at the speed considered. The treatment of this problem requires a theory of the propagation of plastic waves, which is developed in this paper, for the particular type of stress-strain curve pertaining to the high-strength alloy steel tested.

Semi-Automatic Gas-Less Process for Girth Welding X-80 Line Pipe

2006 ◽  
Author(s):  
Badri K. Narayanan ◽  
Patrick Soltis ◽  
Marie Quintana
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Slag System ◽  
High Strength ◽  
Automatic Process ◽  
Line Pipe ◽  
High Toughness ◽  
New Process ◽  
Girth Welding ◽  
Acidic Components

A new process (M2M™) to girth weld API Grade X-80 line pipe with a gas-less technology is presented. This process combines innovations in controlling arc length and energy input with microstructure control of the weld metal deposited to achieve high strength (over matching 550 MPa yield strength) and Charpy V-Notch toughness of over 60 Joules at −20°C. This paper will concentrate on the metallurgical aspects of the weld metal and the systematic steps taken to achieve high strength weld metal without sacrificing toughness. The development of an appropriate slag system to achieve the best possible microstructure for high toughness weld metal is discussed. The indirect effects of the slag system on the weld metal composition, which in turn affects the microstructure and physical properties, are detailed. In order to achieve sound weld metal without gas protection using a semi-automatic process, a basic slag system with minimal acidic components is used to improve the cleanliness of the weld metal without sacrificing weldability. In addition, a complex combination of micro-alloying elements is used to achieve the optimum precipitation sequence of nitrides that is critical for high toughness. The final part of this paper gives details about the robustness of this process to weld high strength pipe. The results show that this is a practical and unique solution for girth welding of X-80 pipe to achieve acceptable toughness and over a 15% overmatch in yield strength of X-80 pipe without sacrificing productivity.

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.

Spatially Resolved Materials Property Data From a Uniaxial Cross-Weld Tensile Test

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
M. Turski ◽  
M. C. Smith ◽  
P. J. Bouchard ◽  
L. Edwards ◽  
P. J. Withers
Keyword(s):  
Plastic Strain ◽  
Weld Metal ◽  
Speckle Pattern ◽  
Welding Process ◽  
Parent Material ◽  
Image Correlation ◽  
Electronic Speckle Pattern Interferometry ◽  
Stress Strain ◽  
Spatially Resolved ◽  
Process Work

Application of electronic speckle pattern interferometry (ESPI) is described to measure the spatial variation in monotonic tensile stress-strain properties along “cross-weld” specimens machined from a stainless steel three-pass welded plate. The technique, which could also be done with digital image correlation, was applied to quantify how the material 0.2%, 1%, 2%, 5%, 10%, and 20% proof stress varied with distance from the center-line of the weldment for parent and weld material associated with the first and final passes. The stress-strain curves measured by the ESPI method correlated closely with stress-strain data measured using conventional test specimens. The measured results are consistent with the hypothesis that thermo-mechanical cycles associated with the welding process work harden previously deposited (single-pass) weld metal and the surrounding parent material. The stress-strain response of the heat affected zone adjacent to the first weld pass is consistent with an accumulated (equivalent monotonic) plastic strain of 6.5% and that of the first pass weld bead was consistent with an accumulated plastic strain of approximately 4% greater than the state of the final pass weld metal.

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