Susceptibility to Preferential Corrosion of Pipeline Welded Joints in Condensed and Dragged Water Droplet - Part 1

2021 ◽  
Author(s):  
Petrônio Zumpano ◽  
Juliana L. Cardoso ◽  
Zehbour Panossian ◽  
Ilson P. Baptista ◽  
Helio Miranda ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Welded Joints ◽  
Copper Content ◽  
Corrosion Inhibitors ◽  
Test Procedure ◽  
Optimal Dosage ◽  
Parent Metal ◽  
Water Droplets ◽  
Longitudinal Joints ◽  
Welding Processes

Abstract Preferential weld corrosion (PWC) is due to the formation of galvanic cells between the weld metal (WM), the parent metal (PM) and the heat affected zone (HAZ). This work has studied PWC susceptibility in longitudinal and circumferential welded joints of submarine systems and the applicability of corrosion inhibitors to mitigate the corrosive process. DNVGL SAW 450, DNVGL SMLS 450 and low alloy forged, with different nickel, copper and silicon content were tested. Several factors influence PWC susceptibility in welded structures and those selected to be studied were weld joint geometry, PM fabrication process, welding process and welding consumable chemical content. For each welding processes, welded coupons were made with similar heat input. Pipe SAW seam welds of two different plate suppliers and different nickel and copper content were tested. Tests in circumferential weld joints were predicted for 79 different combination of chemical composition: PM chemical composition and manufacturing process; welding processes; chemical composition of welding consumables. Selected welding processes are the most used by offshore industry (SAW, mechanized GMAW and manual GTAW). The root configuration of respective welding procedure specifications produce a desired variation in width geometry. The corrosion tests started with the longitudinal joints and will be further reproduced for circumferential joints. A test procedure has been developed for corrosion evaluation through immersion test, galvanic current measurement (GCM) through zero resistance ammeter (ZRA) and localized electrochemical test through SVET. Two test solutions were considered, simulating condensed and dragged water droplets in order to verify the susceptibility or occurrence of the preferential welding corrosion in the welded joints. The results for longitudinal joints indicated a greater susceptibility to PWC in dragged water than in condensed water droplets and a greater susceptibility of joints with greater anodic potential due to a higher nickel and copper content in the parent metal. A correlation between the corrosion rates obtained in both medium and the moisture contents of gas pipelines will be performed to determine the need for the addition of corrosion inhibitors and to establish the minimum required dosage. A future work will involve circumferential joints and the evaluation of the optimal dosage of corrosion inhibitors.

scholarly journals Monitoring of the process of Flash-Butt Welding

2013 ◽  
Vol 18 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Yevgenia Chvertko ◽  
Mykola Shevchenko ◽  
Andriy Pirumov
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
Statistical Methods ◽  
Welded Joints ◽  
Welding Parameter ◽  
Monitoring Systems ◽  
Butt Welding ◽  
On Line ◽  
Welding Processes

Statistical methods of analysis are currently widely used to develop control and monitoring systems for different welding processes. These methods allow to obtain information about the process including effect of all factors on its results, which is often difficult to evaluate due to the complexity of the process. The authors made efforts to apply these methods to develop the system for monitoring the parameters of flash-butt welding in real-time mode. The paper gives brief information about the features of flash-butt welding of reinforcement bars and some basic limitation of this process application. The main reasons of formation of defects in welded joints are given as well as analysis of possibility of application of monitoring systems for their determination. The on-line monitoring system based on neural networks was developed for evaluation of process deviations. This system is believed to be adequate for determination of process violations resulting in disturbances of welding parameter and can be used for prediction of possible defects in the welded joints.

Characterization of Local Deformation in Welded Joints Using a Combined Experimental and Numerical Approach

2014 ◽  
Vol 627 ◽  
pp. 241-244 ◽  
Author(s):  
Pawel Kucharczyk ◽  
Sebastian Münstermann
Keyword(s):  
Chemical Composition ◽  
Weld Metal ◽  
Welded Joints ◽  
Base Material ◽  
Welding Process ◽  
Numerical Approach ◽  
Geometrical Model ◽  
Local Deformation ◽  
Heat Treated ◽  
Welded Structure

The microstructure of welded joints differs significantly from that of the base material, what changes their mechanical properties and influences fatigue life. The aim of this work was the investigation of the local deformation field within a butt joint made of 10 mm thick structural steel S355. However, a direct sampling even of the weld metal was impossible due to small dimensions of butt joints. Therefore, the following procedure was utilized in order to manufacture big samples of the microstructure identical to that of the local weldment areas.A geometrical model of the welded structure describing the relevant areas e.g. weld metal, heat-affected zone was established. It was based on the results of the metallographic investigations, hardness mapping and electron-probe-micro-analysis of the local chemical composition. The welding process was numerically simulated using SYSWELD program to estimate the time-temperature-transition (TTT) curves for each identified area. The parameters of the heat input source were calibrated. Afterwards, the material of the defined chemical composition was heat-treated according to the TTT curves. For the validation purpose the heat-treated work pieces were evaluated in terms of microstructure and hardness distribution. Finally, the up-scaled samples of the respective bulk microstructure were manufactured and investigated in monotonic tests.

scholarly journals Strain Capacity of Girth Welded Joints in HSAW Pipes

2017 ◽  
Author(s):  
Koen Van Minnebruggen ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Welded Joints ◽  
Structural Integrity ◽  
Tensile Load ◽  
Tensile Loading ◽  
Experimental Result ◽  
Large Strains ◽  
Automatic Welding ◽  
Strain Capacity ◽  
Axial Tensile ◽  
Welding Processes

The general aim of a recently finalized European project, i.e. EU RFCS SBD-Spipe, is to generate specific know-how concerning the development and possible use of spirally welded pipes for demanding applications. The demanding applications relate especially to structural integrity issues, both onshore and offshore, requiring good performance under application of large strains resulting in buckling, collapse and/or tensile loading. The outcome of this project can also be used as technical basis for improving standards and guidelines, that address design and safety of spirally welded pipelines. The contribution of Ghent University to this project focusses on the aspects of tearing resistance, defect tolerance and strain capacity of girth welded joints subjected to remote axial tensile load. A numerical and experimental approach is used for the assessment of flaw tolerability and strain development upon tensile loading. Spiral pipes of steel grade API-5L X70 with 36” and 48” diameters have been girth welded using both a manual and semi-automatic welding processes. Curved wide plate specimens have been extracted from the pipes and artificial weld defects have been introduced. The specimens have been loaded in tension up to failure at a temperature of −10°C. This paper reports on the experimental result of a series of curved wide plate tests.

Characterization of Dissimilar Welded Joints Between Austenitic and Duplex Stainless Steel Grades for Liquid Tank Applications

2018 ◽  
Author(s):  
G. Ubertalli ◽  
M. Ferraris ◽  
P. Matteis ◽  
D. Di Saverio
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
Welded Joints ◽  
Industrial Applications ◽  
Duplex Stainless Steels ◽  
Steel Pipes ◽  
Steel Grades ◽  
Welding Processes

Lean duplex stainless steels have similar corrosion and better mechanical properties than the austenitic grades, which ensure their extensive spreading in industrial applications as a substitute of austenitic grades. In the construction of liquid tanks, however, it is often necessary to weld such steels with a range of fittings which are commonly fabricated with austenitic stainless steel grades. Therefore, this paper examines dissimilar welded joints between LDX 2101 (or X2CrMnNiN22-5-2) lean duplex stainless steels plates and austenitic stainless steel pipes, carried out by different arc welding processes. The investigation focuses on the correlation between the welding procedures and the microstructural and mechanical properties of the welded joints.

scholarly journals Application of Dynamic Beam Positioning for Creating Specified Structures and Properties of Welded Joints in Electron-Beam Welding

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2233
Author(s):  
Tatyana Olshanskaya ◽  
Vladimir Belenkiy ◽  
Elena Fedoseeva ◽  
Elena Koleva ◽  
Dmitriy Trushnikov
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Weld Metal ◽  
Thermal Effect ◽  
Welded Joints ◽  
Electron Beam Welding ◽  
Welded Joint ◽  
Parent Metal ◽  
Cooling Rates ◽  
Structures And Properties

The application of electron beam sweep makes it possible to carry out multifocal and multi-beam welding, as well as combine the welding process with local heating or subsequent heat treatment, which is important when preparing products from thermally-hardened materials. This paper presents a method of electron beam welding (EBW) with dynamic beam positioning and its experimental-calculation results regarding the formation of structures and properties of heat-resistant steel welded joints (grade of steel 20Cr3MoWV). The application of electron beam oscillations in welding makes it possible to change the shape and dimensions of welding pool. It also affects the crystallization and formation of a primary structure. It has been established that EBW with dynamic beam positioning increases the weld metal residence time and the thermal effect zone above the critical A3 point, increases cooling time and considerably reduces instantaneous cooling rates as compared to welding without beam sweep. Also, the difference between cooling rates in the depth of a welded joint considerably reduces the degree of structural non-uniformity. A bainitic–martensitic structure is formed in the weld metal and the thermal effect zone throughout the whole depth of fusion. As a result of this structure, the level of mechanical properties of a welded joint produced from EBW with dynamic electron beam positioning approaches that of parent metal to a greater extent than in the case of welding by a static beam. As a consequence, welding of heat-resistant steels reduces the degree of non-uniformity of mechanical properties in the depth of welded joints, as well as decreases the level of hardening of a welded joint in relation to parent metal.

About weldability and welding of Al alloys: case study and problem solving

2017 ◽  
Vol 2 (85) ◽  
pp. 67-74 ◽  
Author(s):  
E. Fracchia ◽  
F. Gobber ◽  
M. Rosso
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
Optical Microscope ◽  
Sem Analysis ◽  
Al Alloys ◽  
Hot Tearing ◽  
Parent Metal ◽  
Oxide Inclusions ◽  
Welding Processes

Purpose: Among many disciplines within engineering, welding is probably one of the most inexact – rather more of an art than a science. As weldment is meant the complete joint comprising the weld metal, heat affected zones (HAZ) and the adjacent parent metal and should have the same properties as the parent metal. This paper aims provides a basic understanding of the metallurgical principles involved in how aluminium alloys achieve their strength and how welding can affect these properties. The most important and applied welding processes to Al alloys are here shortly introduced, as well as the preparation of parent metals prior to welding and good welding practice to avoid and/or keep under control defects and failures. Some case studies with possible failures will be introduced together with actions and suggestions to solve the observed problems. Design/methodology/approach: Two sheets of the EN AW 5454 (AlMg3Mn) alloy were weld with resistance welding process and after a mechanical processing of lamination was observed the presence of the defect. The microstructure of the defect as well as the welded part were evaluated with stereomicroscope (LEICA MS5), optical microscope (LEICA MEF4M), and with SEM analysis (LEO 1540 VP equipped with an energy dispersive X-ray spectroscope Oxford Link Pentafet). Findings: The well welded part was analysed with optical microscopy and electronic microscopy resulting with the attended mechanical properties. Micro-hardness indentations on the joint demonstrated the good mechanical properties of the joint while with the microscopic observations were identified the orientation and presence of precipitates typical of this alloy. In the defect, microscopically observations showed the presence of oxide inclusions. Research limitations/implications: There are a number of problems associated with the welding of aluminium and its alloys that make it difficult to achieve this ideal. The features and defects that may contribute to the loss of properties comprise the following: gas porosity, oxide inclusions and oxide filming, solidification (hot) cracking or hot tearing, reduced strength in the weld and HAZ, lack of fusion, reduced corrosion resistance and reduced electrical resistance. Originality/value: This case study illustrated clearly the importance of the cleaning on the surfaces to obtain a well welded joint ensuring the desired mechanical properties.

Study on the Effect of Weld Speed and Tool Rotation Speed on the Quality of Friction Stir Welded Joints by Using XRD and EBSD

2016 ◽  
Author(s):  
Jaishree Sanjeevi Maran ◽  
Pratyush Kumar Patro ◽  
Ilangovan Murugesan ◽  
Sai Krishna Sekar ◽  
Sidhaarth Bamarani Thangaswamy
Keyword(s):  
Welded Joints ◽  
Rotation Speed ◽  
Welding Process ◽  
X Ray Diffraction ◽  
Friction Stir ◽  
Tool Rotation Speed ◽  
Dissimilar Alloys ◽  
Two Parameters ◽  
Welding Processes ◽  
Tool Rotation

Friction Stir processing, a novel welding process which weld similar and dissimilar metals and alloys in solid state for joining metallic alloys and it has replaced conventional welding processes and have become an alternative welding technique. The commonly used aluminum alloys AA6061 and AA5086 were joined together using FSW. In this study, two parameters such as weld speed and tool rotation speed are taken into account. By varying these parameters the dissimilar alloys were welded together. The welded joints were analyzed for its chemical composition and phases formed due to heat produced by friction. The composition is characterized by Electron Back Scattered Diffraction technique (EBSD) and X-ray Diffraction technique (XRD). The influence of tool rotation speed and weld speed on texture has been studied.

Long Term Creep Rupture Strength of 9Cr1MoNbV Narrow Gap Welded Joints Improved by Normalizing and Tempering After Welding

2007 ◽  
Author(s):  
Takashi Sato ◽  
Kohji Tamura ◽  
Koichi Mitsuhata ◽  
Ryuichi Ikura
Keyword(s):  
Welded Joints ◽  
Power Plants ◽  
Rupture Strength ◽  
Thermal Power ◽  
High Strength ◽  
Creep Rupture ◽  
Narrow Gap ◽  
Parent Metal ◽  
Welding Procedure

With the increase of steam parameters of coal-fired thermal power plants, high strength 9%Cr steel containing niobium and vanadium became major material in high temperature boiler components. As the microstructure of these steels is tempered martensite, it is known that the softening occurs in HAZ of the weldment. In the creep rupture test of these welded joints the rupture strength is lower than that of the parent metal, and sometimes this reduction of strength is caused by Type IV cracking. To develop an effective method to improve the rupture strength of welded joints, a normalizing-tempering heat treatment after weld was proposed. 9Cr1MoNbV plates with a thickness of 40–50 mm were welded by 10 mm width automatic narrow gap MAG welding procedure using specially modified welding material. After normalizing at 1050C and tempering at 780C, material properties of the welded joints were examined. Microstructure of the HAZ was improved as before weld, and rupture strength of the welded joints was equal to that of the parent metal. The long term rupture strength of the welded joints as confirmed in the test exceeded 30,000 hours. This welding procedure has been applied to the seam weld of boiler hot reheat piping in USC plants successfully.

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