EPRG Tier 2 Guidelines for the Assessment of Defects in Transmission Pipeline Girth Welds

2010 ◽  
Author(s):  
Rudi Denys ◽  
Robert Bob Andrews ◽  
Mures Zarea ◽  
Gerhard Knauf
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Pipe Material ◽  
Tier 2 ◽  
Planar Defects ◽  
Transmission Pipeline ◽  
Metal Yield ◽  
Girth Welds

This paper presents the proposed revisions of the EPRG guidelines for the assessment of defects in transmission pipeline girth welds. The revisions cover Tier 2 of the guidelines, in particular (a) the extension of the guidelines to include Grade L555 (X80) material, (b) the assessment of surface-breaking defects with heights up to 5mm and (c) the assessment of multiple co-planar defects. Since the welds should be, at least, matching the pipe material in yield strength, the paper also defines the required levels of weld metal yield strength for the safe application of the guidelines.

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.

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.

Structure and Properties of X80 and X100 Pipeline Girth Welds

2004 ◽  
Author(s):  
J. A. Gianetto ◽  
J. T. Bowker ◽  
D. V. Dorling ◽  
D. Horsley
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Tensile Properties ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Narrow Gap ◽  
Line Pipe ◽  
Metal Arc Welding ◽  
Girth Welds ◽  
Strength And Toughness

This study aims to provide an understanding of the factors that control weld metal strength and toughness of mechanized field girth welds produced in X80 and X100 line pipe steels using a range of pipeline gas metal arc welding procedures. In the investigation of X80 welds, a series of experimental single and dual torch gas metal arc welds were prepared with three C-Mn-Si wires, which contained additions of Ti, Ni-Ti and Ni-Mo-Ti. The weld metal microstructures, tensile properties, notch toughness, and fracture resistance were evaluated. The results indicate that high weld metal yield strength and good toughness can be achieved. The X80 single torch welds exhibited higher yield strength but lower toughness compared to the corresponding dual torch welds. For the development and evaluation of welding procedures for mainline girth welding of X100 pipe, two narrow gap mechanized gas metal arc welding procedures were evaluated with emphasis placed on measurement of the tensile properties. The results show that dramatically different properties (strength and toughness) can be found as a result of differences in energy input, interpass temperature and weld width or offset distance. Additionally, the preliminary tensile testing, which utilized both standard round bar and modified strip tensile specimens, illustrates the potential variation that can occur when assessing all-weld-metal tensile properties of narrow gap pipeline girth welds.

Welding of Internally Clad X65 Pipes With Precipitation Strengthened Ni-Based Filler Metals

2017 ◽  
Author(s):  
Graciela C. Penso ◽  
Boian T. Alexandrov
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Parameter Optimization ◽  
Filler Metal ◽  
Gas Metal Arc Welding ◽  
Welding Parameter ◽  
Cold Metal Transfer ◽  
Alloy 625 ◽  
Metal Yield ◽  
Cold Metal

X65 steel pipes internally clad with Alloy 625 used in subsea oil extraction are normally welded together with Alloy 625 filler metal. For pipe reeling applications, DNV-OS-F101 requires pipe girth welds to overmatch base metal yield strength with 100 MPa. Since Alloy 625 filler metal does not meet this requirement, Ni-base super alloys 718 and 282 were considered as potential welding consumables for reeling applications. The solidification behavior in weld metal of these alloys diluted with Alloy 625 pipe ID cladding was evaluated using thermodynamic simulations. The response to precipitation hardening by multiple reheat cycles was studied by producing multilayer buildups with cold metal transfer (CMT) and pulsed gas metal arc welding (GMAWp) processes. Weld buildup of Alloy 718 exhibited insufficient hardening response and yield strength, while Alloy 282 met the DNV overmatch requirement. Successful narrow groove welding of X65 pipes with Alloy 282 was performed using CMT process. Welding parameter optimization allowed resolving centerline solidification cracking and lack of fusion defects. The weld metal yield strength was lower than in the multipass buildup, which was attributed to lower number of reheats in groove welding. Meeting the overmatch requirement for yield strength in Alloy 282 groove welds requires further parameter optimization.

Evaluation of Weld Metal Strength Mismatch in X100 Pipeline Girth Welds

2004 ◽  
Author(s):  
Henryk G. Pisarski ◽  
Yuri Tkach ◽  
Marie Quintana
Keyword(s):  
Fracture Toughness ◽  
Adverse Effects ◽  
Weld Metal ◽  
Axial Stress ◽  
Limit Load ◽  
Allowable Stress ◽  
Simple Method ◽  
Weld Width ◽  
Girth Welds ◽  
Assessment Procedures

A relatively simple method based on standard fracture mechanics flaw assessment procedures, such as BS 7910, but modified using published mismatch limit load solutions is described. It is used to illustrate the effects of weld width and strength mismatch on CTOD requirements for girth welds in Grade X100 strength pipeline material subjected to axial stress. It is shown that fracture toughness requirements based on standard analyses not allowing for mismatch effects can be unnecessarily conservative when either undermatched or overmatched welds are present. Adverse effects of undermatching, in reducing the allowable stress, can be mitigated by reducing weld width. It is shown that even small amounts of overmatching (e.g. 10%) can be beneficial by allowing axial stress to exceed the SMYS of the parent pipe and reducing CTOD requirements.

A Justification for Designing and Operating Pipelines Up to Stresses of 80% SMYS

2002 ◽  
Author(s):  
Martin McLamb ◽  
Phil Hopkins ◽  
Mark Marley ◽  
Maher Nessim
Keyword(s):  
Yield Strength ◽  
Oil And Gas ◽  
Large Diameter ◽  
Pipe Material ◽  
Gas Pipelines ◽  
Long Distance ◽  
Remote Locations ◽  
Pass Through ◽  
The Impact ◽  
Minimum Yield

Oil and gas majors are interested in several projects worldwide involving large diameter, long distance gas pipelines that pass through remote locations. Consequently, the majors are investigating the feasibility of operating pipelines of this type at stress levels up to and including 80% of the specified minimum yield strength (SMYS) of the pipe material. This paper summarises a study to investigate the impact upon safety, reliability and integrity of designing and operating pipelines to stresses up to 80% SMYS.

Study of the Sensitivity of the Guanabara Bay PE-3 Pipeline to Geometric Imperfections

2004 ◽  
Author(s):  
Adilson Carvalho Benjamin ◽  
Joa˜o Nisan Correia Guerreiro ◽  
Rita de Ca´ssia Carvalho Silva ◽  
Abimael Fernando Dourado Loula
Keyword(s):  
Yield Strength ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Pipe Material ◽  
Guanabara Bay ◽  
Pressure Loading ◽  
Geometric Imperfections ◽  
Von Mises ◽  
Von Mises Stresses

This paper describes the study performed to investigate the sensitivity of the Guanabara Bay PE-3 pipeline to geometric imperfections. The main results of several FE analyses are presented. It is concluded that the PE-3 zigzag pipeline is geometrically stable when submitted to the maximum pressure loading and maximum temperature loading established in the design. Also it is shown that the von Mises stresses calculated in the analyses were below the yield strength of the pipe material.

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.

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.

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