scholarly journals Weld corrosion of GH3535 in molten (Li,Na,K)F

2018 ◽  
pp. 2577-2584
Author(s):  
Yanli Wang ◽  
Keyword(s):  
Weld Corrosion

Development of Selective Seam Weld Corrosion Test Method

2014 ◽  
Author(s):  
J. A. Beavers ◽  
C. S. Brossia ◽  
R. A. Denzine
Keyword(s):  
Base Metal ◽  
Field Testing ◽  
Test Method ◽  
Transportation Safety ◽  
Seam Weld ◽  
Corrosion Kinetics ◽  
Pipeline Failures ◽  
Weld Corrosion ◽  
Pipeline Safety ◽  
Non Destructive

Selective seam weld corrosion (SSWC) of electric resistance welded (ERW) pipelines has been identified as a potential risk to pipeline safety. Due to recent pipeline failures, where seam weld defects may have played a significant role, the National Transportation Safety Board called upon the Pipeline and Hazardous Materials Safety Administration (PHMSA) to conduct a comprehensive study to identify actions that can be used by operators to eliminate catastrophic longitudinal seam failures in pipelines. Battelle contracted Kiefner and Associates, Inc. and Det Norse Veritas (U.S.A.) Inc. (DNV GL) with the objective to assist PHMSA in addressing this issue. The objective of one of the tasks performed by DNV GL was to develop a reliable, rapid, non-destructive, field-deployable test method that can quantify SSWC susceptibility on operating pipelines containing ERW seams. For this effort, two different, field deployable, non-destructive methods were evaluated in laboratory testing. The methods were validated using a standard destructive test for assessing SSWC susceptibility. One method was based on measurement of the local potential difference between the seam weld and the adjacent base metal while the second was based on differences in the corrosion kinetics between the seam weld and the base metal. The method that is based on corrosion kinetics was found to be most effective in identifying SSWC susceptible pipe steels. It utilizes a barnacle cell to conduct linear polarization resistance measurements on small, selected areas of the pipe (e.g., the weldment or base metal). Additional laboratory as well as field-testing is planned to further validate the test method.

New Classification Approach for Dents With Metal Loss and Corrosion Along the Seam Weld

2016 ◽  
Author(s):  
J. Bruce Nestleroth ◽  
James Simek ◽  
Jed Ludlow
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Metal Loss ◽  
Integrity Assessment ◽  
Seam Weld ◽  
Low Field ◽  
Electric Resistance Welding ◽  
Weld Corrosion ◽  
Pipeline Safety

The ability to characterize metal loss and gouging associated with dents and the identification of corrosion type near the longitudinal seam are two of the remaining obstacles with in-line inspection (ILI) integrity assessment of metal loss defects. The difficulty with denting is that secondary features of corrosion and gouging present very different safety and serviceability scenarios; corrosion in a dent is often not very severe while metal loss caused by gouging can be quite severe. Selective seam weld corrosion (SSWC) along older low frequency electric resistance welding (ERW) seams also presents two different integrity scenarios; the ILI tool must differentiate the more serious SSWC condition from the less severe conventional corrosion which just happens to be near a low frequency ERW seam. Both of these cases involve identification difficulties that require improved classification of the anomalies by ILI to enhance pipeline safety. In this paper, two new classifiers are presented for magnetic flux leakage (MFL) tools since this rugged technology is commonly used by pipeline operators for integrity assessments. The new classifier that distinguishes dents with gouges from dents with corrosion or smooth dents uses a high and low magnetization level approach combined with a new method for analyzing the signals. In this classifier, detection of any gouge signal is paramount; the conservatism of the classifier ensures reliable identification of gouges can be achieved. In addition to the high and low field data, the classifier uses the number of distinct metal loss signatures at the dent, the estimated maximum metal loss depth, and the location of metal loss signatures relative to dent profile (e.g. Apex, Shoulder). The new classifier that distinguishes SSWC from corrosion near the longitudinal weld uses two orientations of the magnetic field, the traditional axial field and a helical magnetic field. In this classifier, detection of any long narrow metal loss is paramount; the conservatism of the classifier ensures that high identification of SSWC can be achieved. The relative amplitude of the corrosion signal for the two magnetization directions is an important characteristic, along with length and width measures of the corrosion features. These models were developed using ILI data from pipeline anomalies identified during actual inspections. Inspection measurements from excavations as well as pipe removed from service for lab analysis and pressure testing were used to confirm the results.

The influence of electrolyte reduction potential on weld corrosion

2002 ◽  
Vol 47 (24) ◽  
pp. 3949-3955 ◽  
Author(s):  
T Hemmingsen ◽  
H Hovdan ◽  
P Sanni ◽  
N.O Aagotnes
Keyword(s):  
Reduction Potential ◽  
Weld Corrosion

scholarly journals THE PREFERENTIAL WELD CORROSION OF X65 CARBON STEEL PIPELINE UNDER CO2 ENVIRONMENT

2020 ◽  
Vol 42 (1) ◽  
pp. 15-28
Author(s):  
Nofrizal Nofrizal
Keyword(s):  
Weld Metal ◽  
Flow Rate ◽  
Heat Affected Zone ◽  
Pipeline Steel ◽  
Jet Impingement ◽  
Corrosion Process ◽  
Corrosion Mechanism ◽  
Submerged Jet ◽  
Corrosion Rates ◽  
Weld Corrosion

Preferential weld corrosion (PWC) is a severe corrosion form of attack found in pipeline weldments in oil and gas industries. PWC occurs when the corrosion rate of the weld metal (WM) and heat affected zone (HAZ) is higher than the parent metal (PM). PWC was generated by galvanic corrosion mechanism due to dissimilarities in the composition and microstructure of the metal in the three weld regions.The aim of this research is to study the effect of flow rate on preferential weld corrosion (PWC) in X65 high strength pipeline steel using submerged jet impingement by investigating the mechanism of PWC on a weldment in artificial seawater saturated with carbon dioxide at 1 bar. A novel submerged jet impingement apparatus that consist of 3 rings (outer, inner and centre) was designed so that the parent material, heat affected zone and weld metal could be analysed in a high shear stress environment. Corrosion experiments were performed with X65 pipeline steel under no flow and flowing condition at 10 m/s at 30oC and pH4. The galvanic current characteristic between the weldment regions was recorded using a zero-resistance ammeter, and the self-corrosion was analysed by using linear polarisation resistance measurements. Total corrosion rates were calculated from the sum of the galvanic and self-corrosion contributions. The morphology, structure, chemical on the surface of X65 after corrosion process was investigated by means of scanning electron microscopy (SEM) and focus ion beam (FIB) to examine the corrosion product that form in brine containing dissolved carbon dioxide.In a no-flow condition, the result shows that the galvanic characteristics on all weldments were similar and the WM is cathodic and protected in comparison with the HAZ and PM. In flowing condition, the estimated flow rates associated with the different positions on the target vary depending on either (a) PM and HAZ or (b) the WM. The effects of target flow rate on WM have a similar trend, but the overall corrosion rates are greater due to PWC. The result of surface analysis after corrosion process showing that removal of hardened layer and subsurface cracking were causes of enhanced degradation.

Study on Welding Techniques of 316L Lined Bimetallic Pipe

2019 ◽  
Vol 944 ◽  
pp. 944-949
Author(s):  
Fa Gen Li ◽  
Xun Ji Li ◽  
Wei Wei Li ◽  
Xian Ming Li ◽  
Ze Liang Chang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Failure Analysis ◽  
Research Work ◽  
Welding Process ◽  
High Hardness ◽  
Gas Production ◽  
Structure Design ◽  
Cored Wire ◽  
Welding Defects ◽  
Weld Corrosion

It is well known that welding technique was often a knotty problem for bimetallic lined steel pipes to use widely. A number of failures in secession of weld cracking and weld corrosion had been observed in oil fields in recent years, which seriously disrupted the order of oil and gas production. To solve welding problems of 316L bimetallic lined pipes, works outcome about failure analysis and welding process research were presented in this paper. Failure analysis results confirmed that Welding defects, high hardness regions was the main reasons about failure problems of weld crack while structure design defects of seal weld and bad back-protection effects of flux-cored wire resulted in weld corrosion. Welding defects in the regions of seal weld became the failure source while the high hardness both in the region of seal weld and weld joint formed the crack propagation channel, and therefore both initially contributed to weld cracking. Additionally owing to the structure design of seal weld, liner layer would be heated over and over again during the period of seal weld and then it was not enough to protect CRA layers from being damaged during the period of girth weld. As a result the corrosion resistance in the welding area was reduced to become a weak area. On the basis of failure analysis, further research work was carried out to improve welding performance. Seal weld structure and girth weld process was improved. The difference of welding wires and welding process was analyzed, and their defects were described separately. Results showed that the welding performance welding by ERNiCrMo-3 and supporting technology was more reliable than ATS-F309L and supporting technology, whether seal weld or butt welding. The distribution and value of the hardness could be effectively controlled; Moreover, corrosion resistance performance was also better. Therefore, the seal weld and girth weld conducted by ERNiCrMo-3 and supporting technology was feasible.

Basic Understanding of Weld Corrosion

2006 ◽  
pp. 1-12
Keyword(s):  
Base Metal ◽  
Filler Metal ◽  
Weld Penetration ◽  
Factors Influencing ◽  
Basic Understanding ◽  
Weld Corrosion

Abstract Corrosion failures of welds can occur even when the proper base metal and filler metal have been selected, industry codes and standards have been followed, and welds have been deposited that possess full weld penetration and have proper shape and contour. This chapter describes some of the general characteristics associated with the corrosion of weldments. The role of macro- and microcompositional variations, a feature common to weldments, is emphasized in this chapter to bring out differences that need to be realized in comparing the corrosion of weldments to that of wrought materials. The discussion covers the factors influencing corrosion of weldments, microstructural features of weld microstructures, various forms of weld corrosion, and welding practice to minimize corrosion.

Sign in / Sign up

Export Citation Format

Share Document