Effect of pitting corrosion on local strength of hold frames of bulk carriers (2nd Report)—Lateral-distortional buckling and local face buckling

2004 ◽  
Vol 17 (8) ◽  
pp. 612-641 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto
Keyword(s):  
Pitting Corrosion ◽  
Distortional Buckling ◽  
Local Strength ◽  
Bulk Carriers

Pitting Corrosion and Its Influence on Local Strength of Hull Structural Members

2005 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto
Keyword(s):  
Tensile Strength ◽  
Pitting Corrosion ◽  
Structural Models ◽  
Distortional Buckling ◽  
Thickness Loss ◽  
Bulk Carriers ◽  
The Face ◽  
Face Plate ◽  
Corrosion Pits ◽  
The Web

The objective of this study is to obtain basic data for discussing the structural integrity of aged ships, especially hold frames of aged bulk carriers. Firstly, shapes of corrosion pits observed on hold frames of bulk carriers have been investigated. It was shown that the shape of the corrosion pits is a circular cone and the ratio of the diameter to the depth is in the range between 8 to 1 and 10 to 1. Secondly, a series of tensile tests has been conducted to investigate the effect of pitting corrosion on tensile strength. It was pointed out that the tensile strength decreases gradually and the total elongation decreases drastically with the increase of thickness loss due to pitting corrosion. Thirdly, a series of 4-point bend tests with structural models which consist of shell, web and face plates simulating hold frames of bulk carriers has been carried out to investigate the effect of pitting corrosion on collapse behavior and lateral-distortional buckling behavior. Following the experiment, a series of non-linear FE-analyses has been also made. In the case where tensile load acted on the face plate, cracks were initiated at the bottom of the pits when pitting concentrated on the web near the face plate. On the other hand in the case where compression load acted on the face plate, lateral-distortional buckling has been observed and the ultimate load of the structural models where pitting developed regularly on the web was found to be almost the same as that of the structural models where the web has uniform corrosion corresponding to the average thickness loss.

Effect of pitting corrosion on local strength of hold frames of bulk carriers (1st report)

2004 ◽  
Vol 17 (5) ◽  
pp. 403-432 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto ◽  
Hironori Arai
Keyword(s):  
Pitting Corrosion ◽  
Local Strength ◽  
Bulk Carriers

Effect of Pitting Corrosion on Ultimate Strength of Web Plates Subjected to Shear Loading

2007 ◽  
Vol 340-341 ◽  
pp. 489-494 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto
Keyword(s):  
Ultimate Strength ◽  
Pitting Corrosion ◽  
Shear Loading ◽  
Equivalent Thickness ◽  
Concentrated Load ◽  
Local Strength ◽  
Bulk Carriers ◽  
Shear Buckling ◽  
Corrosion Pits ◽  
Web Plates

Pitting corrosion is a great concern when the integrity of ship's hull structures is considered. Corrosion pits with a conical shape are typically observed on coated hold frames in way of cargo holds of bulk carriers which exclusively carry coal and iron ore. Therefore, it is important to investigate the effect of pitting corrosion on local strength of hold frames of bulk carriers. In the present study, a series of 3-point bend tests with structural models which consist of web, shell and face plates has been conducted. In these tests, a concentrated load has been vertically applied at the center of simply supported models so that shear load would act on the web plate with artificial pits. In this testing condition, load increased even after shear buckling occurred. When there is artificial pitting, fracture of web plates occurs due to strain concentration at the pits. It has been revealed that the empirical formula, which was developed based on non-linear FE-analyses, overestimates the equivalent thickness for the shear ultimate strength obtained in the present experiment, because the effect of web fracture is not taken into account in the analyses.

Probabilistic Model of Pitting Corrosion and the Simulation of Pitted Corroded Condition

2008 ◽  
Author(s):  
Norio Yamamoto
Keyword(s):  
Pitting Corrosion ◽  
Probabilistic Model ◽  
Surface Condition ◽  
Actual Condition ◽  
Strength Analysis ◽  
Good Representation ◽  
Statistical Nature ◽  
Corrosion Condition ◽  
Strength Evaluation ◽  
Bulk Carriers

Pitting corrosion is a great concern with respect to the integrity of ship hull structures such as the hold frames in way of the cargo holds of those bulk carriers which exclusively carry coal and/or iron ore. The actual strength of pitting corroded member depends on the pitting corroded surface condition; a condition which varies according to the generation and the progress of the corrosion pits. In order to investigate a practical strength evaluation method of the pitting corroded member, a serial strength evaluation for various pitting corroded conditions is necessary. However, because it was difficult to obtain actual pitting corroded members which satisfied the purpose of our analysis, we needed to use an alternative method of conducting this strength analysis; a method that used simulated pitting corroded members. In order to do this, the simulated pitting corrosion surface we used had to have been a good representation of the actual pitting corrosion condition. In this paper, we investigated the pitting corroded surface conditions of hold frames in way of cargo holds of bulk carriers in order to comprehend the statistical nature of such pitting corroded surface. We developed a simulation procedure based upon a probabilistic model and used it to generate an optional pitting corroded surface. Through our investigation, we were able to confirm that the simulated pitting corrosion condition is visually similar to the actual condition and has the same statistical nature.

Analysis of field uniformity and quantitative evaluation of subsurface pitting corrosion in conductors via GPEC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 19-29
Author(s):  
Shuting Ren ◽  
Yong Li ◽  
Bei Yan ◽  
Jinhua Hu ◽  
Ilham Mukriz Zainal Abidin ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Eddy Current ◽  
Pitting Corrosion ◽  
Gradient Field ◽  
Uniform Field ◽  
Eddy Current Method ◽  
Optimal Position ◽  
Pulsed Eddy Current ◽  
Field Uniformity ◽  
Processing Algorithms

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.

INCONEL ALLOY 22

Alloy Digest ◽  
2005 ◽  
Vol 54 (3) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Pitting Corrosion ◽  
Corrosion Resistant ◽  
Inconel Alloy ◽  
Resistant Alloy ◽  
Alloy 22 ◽  
Corrosion Resistant Alloy

Abstract Inconel alloy 22 is an advanced corrosion-resistant alloy with exceptional resistance to aqueous and pitting corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as joining. Filing Code: Ni-624. Producer or source: Special Metals Corporation.

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