Collaboration solves long standing corrosion problem

2020 ◽  
Vol 60 (2) ◽  
pp. 598
Author(s):  
M. Brameld ◽  
S. Thomas ◽  
G. S. Malab
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Ct Scanning ◽  
Test Program ◽  
Corrosion Reaction ◽  
Impervious Layer ◽  
Steel Equipment ◽  
Corrosion Problem ◽  
External Corrosion ◽  
Corrosion Pits

External pitting corrosion has been a long standing issue for stainless steel pressure equipment systems on Woodside offshore facilities. Experience has shown that this pitting cannot be effectively managed by inspection and, as a result, the current policy is that piping replacement should be planned once the presence of significant pitting corrosion has been identified. All Woodside offshore facilities have 316-grade stainless steel pressure equipment which is experiencing active external corrosion pitting to varying degrees. This represents the potential for hundreds of millions of dollars in piping replacement across the company. STOPAQ is an established product for the mitigation of external corrosion in carbon steel equipment however, it has not previously been used at Woodside on stainless steel equipment to address pitting corrosion. Through collaboration with the Woodside Future Laboratory at Monash University, Materials and Corrosion Engineering, Woodside Energy Limited has challenged the old established theory regarding the mechanism of pitting in stainless steel and a test program has been devised to validate the new way of thinking, which postulates that elimination of moisture and oxygen from the pits, by the application of an impervious layer like STOPAQ, will stifle the corrosion reaction and arrest the pitting. A recently completed test program at Monash which utilised computed tomography (CT) scanning, to very accurately determine the volume of corrosion pits, has confirmed that the application of STOPAQ to pitted stainless steel is very effective at mitigating this type of corrosion.

Modeling the Influence of Microstructure on Stress Distributions and Concentrations in Pitting Corrosion

2018 ◽  
Author(s):  
Patrick Brewick ◽  
Andrew Geltmacher ◽  
Siddiq M. Qidwai
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Mechanical Load ◽  
High Strength ◽  
Geometrical Shape ◽  
Stress Distributions ◽  
Concentration Factors ◽  
Corrosion Pit ◽  
Stress Concentration Factors ◽  
Corrosion Pits

Despite the many advances made in material science, stainless steel and aluminum remain the structural materials best-suited for the naval fleet. While these metallic materials offer many benefits, such as high strength and good toughness, their persistent exposure to the maritime environment inevitably leads to issues with corrosion. Among the various manifestations of corrosion, pitting corrosion is of particular concern because the transition of corrosion pits to stress-corrosion cracks can lead to catastrophic failures. Traditional pitting corrosion analyses treat the pit shape as a semi-circle or ellipse and typically assume a growth pattern that maintains the original geometrical shape. However, when the underlying microstructure is incorporated into the model, pit growth is related to the grains surrounding the pit perimeter and the growth rate is proportional to crystallographic orientation. Since each grain has a potentially different orientation, pit growth happens at non-uniform rates leading to irregular geometries, i.e., non-circular and non-elliptical. These irregular pit geometries can further lead to higher stresses. This work presents a detailed look at corrosion pit growth coupled with mechanical load through a numerical model of a two-dimensional stable corrosion pit. Real microstructural information from a sample of 316 stainless steel is incorporated into the model to analyze microstructural effects on pit growth. Through this work, stress distributions and stress concentration factors are examined for a variety of pit geometries, including comparisons of their range of values to a typical, semi-circular pit. The consequences of these stress distributions and concentration factors are discussed.

Effect of Pitting Corrosion on Strength of AISI 410 Stainless Steel Compressor Blades

2014 ◽  
Vol 606 ◽  
pp. 227-231 ◽  
Author(s):  
Mazmir Mat Noh ◽  
Farzin Mozafari ◽  
Muhammad Adil Khattak ◽  
Mohd Nasir Tamin
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Tensile Specimen ◽  
Maximum Diameter ◽  
Compressor Blades ◽  
Strength Tests ◽  
Corrosion Pits ◽  
Pit Depth ◽  
Geometry Analysis ◽  
Nucleation Phenomenon

In the present paper, effects of pitting corrosion on the strength of members made of AISI 410 Martensitic stainless steel were investigated. Stainless steel compressor blades in power generation industries commonly suffer from pitting corrosion. Pits geometry analysis and strength tests have been conducted. Pits geometry analysis established the maximum pit depth of 0.26 mm along with the maximum diameter of 1 mm. In addition, strength and elongation of the pitted tensile specimen gradually decrease with the increase of the area lost due to pitting corrosion. A damage nucleation phenomenon at the initial load values is also postulated.

On the Probabilistic Distribution of External Pitting Corrosion Rate in Buried Pipelines

2008 ◽  
Author(s):  
F. Caleyo ◽  
J. C. Vela´zquez ◽  
J. M. Hallen ◽  
J. E. Araujo ◽  
E. Perez-Baruch
Keyword(s):  
Corrosion Rate ◽  
Power Law ◽  
Pitting Corrosion ◽  
Oil And Gas ◽  
Degradation Mechanism ◽  
Clay Loam ◽  
Buried Pipelines ◽  
Southern Mexico ◽  
External Corrosion ◽  
Corrosion Pits

External pitting corrosion constitutes the degradation mechanism responsible for about 66% of the incidents reported in the last decade for oil and gas pipelines in Mexico. Thus, major efforts are underway to improve the characterization and modeling of pitting corrosion of buried pipelines. Special attention is devoted to estimate the average corrosion rate and corrosion rate variance because they are the key parameters in the estimation of the trend in pipeline reliability. This work presents the results of field and simulation studies in which soil and pipe data were gathered together with the maximum depth of external corrosion pits found at more than 250 excavation sites across southern Mexico. The distributions of parameters such as chloride, bicarbonate and sulfate levels, resistivity, pH, pipe/soil potential, humidity, redox potential, soil texture and coating type have been used to predict the distribution of pitting corrosion rate of pipelines in contact with clay, clay-loam and sandy-clay-loam soils. The time dependence of the pitting corrosion rate was fitted to a power law through a multivariate regression analysis with the maximum pit depth as the dependent variable and the pipeline age and the soil and coating properties as the independent variables. Monte Carlo simulations were conducted in which random values drawn from the distributions fitted to the field data were used to evaluate the power law model proposed for the corrosion rate. For each soil type, the distribution that best fitted the corrosion rate data was found. The results of this study will provide reliability analysts with a more accurate description of the growth rate of external corrosion pits. It is expected that this information will positively impact on integrity management plans addressing the threat posed by this damage mechanism.

Rapid Pitting Corrosion on Gas Scrubber

CORROSION ◽  
1960 ◽  
Vol 16 (12) ◽  
pp. 9-10
Author(s):  
J. T. Firestone
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Construction Materials ◽  
Salt Accumulation ◽  
Flow Process ◽  
Corrosive Attack ◽  
Corrosion Problem ◽  
Problem Lists ◽  
Design Factors

Abstract Rapid pitting attack on stainless steel gas scrubber is described. Attack was evident in only three weeks of operation from salt accumulation on areas not washed down by water showers. Describes internal equipment and flow process of gas through scrubber. Discusses investigation for cause of corrosion and exposure tests of materials to determine suitable construction materials to solve corrosion problem. Lists materials tested. Also describes corrosive attack on internal braces. Conclusion gives five design factors that should be realized for scrubber fabrication. 3.2.2

Precision and bias in quantitative EDS: ASTM results

1992 ◽  
Vol 50 (2) ◽  
pp. 1654-1655
Author(s):  
John J. Friel
Keyword(s):  
Stainless Steel ◽  
Quantitative Analysis ◽  
Mechanical Alloy ◽  
Dead Time ◽  
Test Program ◽  
Round Robin Test ◽  
Wide Range ◽  
American Society ◽  
Takeoff Angle ◽  
Standardless Analysis

Committee E-04 on Metallography of the American Society for Testing and Materials (ASTM) conducted an interlaboratory round robin test program on quantitative energy dispersive spectroscopy (EDS). The test program was designed to produce data on which to base a precision and bias statement for quantitative analysis by EDS. Nine laboratories were sent specimens of two well characterized materials, a type 308 stainless steel, and a complex mechanical alloy from Inco Alloys International, Inconel® MA 6000. The stainless steel was chosen as an example of a straightforward analysis with no special problems. The mechanical alloy was selected because elements were present in a wide range of concentrations; K, L, and M lines were involved; and Ta was severely overlapped with W. The test aimed to establish limits of precision that could be routinely achieved by capable laboratories operating under real world conditions. The participants were first allowed to use their own best procedures, but later were instructed to repeat the analysis using specified conditions: 20 kV accelerating voltage, 200s live time, ∼25% dead time and ∼40° takeoff angle. They were also asked to run a standardless analysis.

NIROSTA 4429

Alloy Digest ◽  
2000 ◽  
Vol 49 (5) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Pitting Corrosion ◽  
Intergranular Corrosion ◽  
Heat Treating ◽  
Low Carbon ◽  
High Nitrogen ◽  
Temperature Performance ◽  
Pitting Corrosion Resistance

Abstract Nirosta 4429 is a low-carbon, high-nitrogen version of type 316 stainless steel. The low carbon imparts intergranular corrosion resistance while the nitrogen imparts both higher strength and some increased pitting corrosion resistance. It is recommended for use as welded parts that need not or cannot be annealed after welding. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-787. Producer or source: ThyssenKrupp Nirosta.

Sign in / Sign up

Export Citation Format

Share Document