scholarly journals Corrosion Behavior and Failure Mechanism of Prestressed Rock Bolts (Cables) in the Underground Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Qiong Wang ◽  
Fengnian Wang ◽  
Aiwu Ren ◽  
Rui Peng ◽  
Jian Li
Keyword(s):  
Failure Mechanism ◽  
Corrosion Behavior ◽  
Coal Mine ◽  
Pitting Corrosion ◽  
Service Time ◽  
Outer Diameter ◽  
Uniform Corrosion ◽  
Rock Bolts ◽  
Premature Failure ◽  
Underground Coal Mine

Premature failure of rock bolts (cables) due to stress corrosion cracking (SCC) is a phenomenon that has been reported to occur in the underground environment. In the 1990s, many failure accidents of bolts which occurred in the United Kingdom were caused by SCC [1]. In this study, the corrosion behavior and failure mechanism of rock bolt (cable) samples obtained from the underground coal mine were examined and discussed. Macroscopic observation and weight loss tests were carried out for the bolts’ corrosion characteristics without failure. The results show that the bolts with short service time (1.5–2 yrs) underwent uniform corrosion. However, bolts with longer service time (3–8 yrs) experienced different pitting corrosion degrees. The corroding degree of different parts of bolt samples shows the following decreasing trend: bolt head > bolt end > free section. The absolute corrosion degree increased with the service time, while the corrosion rate was the highest in the early stage and dropped down in the later stage. At the same time, the macro- and micromethods were used to analyse the failure mechanism in the broken cable sample. Failure of one cable sample with a medium service life (6 yrs) was found to be controlled by the SCC. It was induced by long-term action of O, Cl, and S in the surrounding rock environment and resulted in pitting corrosion. The pitting corrosion reduced the outer diameter of the rock cable and its bearing capacity, leading to the final fracture.

scholarly journals Corrosion Behavior and Failure Mechanism of Rock Bolt(Cable) in Underground Coal Mine

2020 ◽  
Author(s):  
Qiong Wang ◽  
Aiwu Ren ◽  
Songyang Yin ◽  
Mengyi Li
Keyword(s):  
Failure Mechanism ◽  
Corrosion Behavior ◽  
Coal Mine ◽  
Pitting Corrosion ◽  
Service Time ◽  
Rock Bolt ◽  
Outer Diameter ◽  
Uniform Corrosion ◽  
Premature Failure ◽  
Underground Coal Mine

Abstract Premature failure of rock bolt (cable) due to stress corrosion cracking (SCC) is a phenomenon that has reported to occur in underground environments. In this study, the corrosion behavior and failure mechanism of rock bolt (cable) samples obtained from underground coal mine were examined and discussed. Macroscopic observation and weight loss test were carried out for the corrosion characteristics of the bolts without failure. It is found the corrosion form is uniform corrosion for the bolts with short service time (S-1, S-2). But for the bolts with longer service time (S-3, S-4 and S-5), experience different degrees of pitting corrosion and the number of corrosion spots on the surface of the sample increases with increase of the service time. The corrosion amount of different parts of the bolts shows the rule of bolt head > bolt end > free section, and the corrosion amount increases year by year with the service time, but the corrosion growth rate is fast in the early stage and slows down in the later stage. At the same time, the failure mechanism of the failure sample S-6, which has been in service for 6 years, was analyzed with macro and micro methods. The results show that S-6 have been in O, Cl and S surrounding rock environment for a long time, resulting serious pitting corrosion and spalling of the surface material of the steel strand, which reduces the outer diameter of the rock cable and its bearing capacity, finally leads to the instantaneous SCC fracture of the sample S-6.

scholarly journals A REVIEW: BEHAVIOR OF PITTING CORROSION IN MANUFACTURING FOOD EQUIPMENT

2019 ◽  
Vol 50 (4) ◽  
Author(s):  
Alwan & et al.
Keyword(s):  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Corrosion Damage ◽  
Metals And Alloys ◽  
Corrosion Products ◽  
Corrosion Mechanism ◽  
Uniform Corrosion ◽  
Layer Surface ◽  
Material Layer ◽  
Localized Form

Corrosion is the deterioration or destruction of metals and alloys in the presence of an environment by chemical or electrochemical means. The phenomenon of corrosion behavior studies is three elements include economic, safety and maintenance. Pitting corrosion is a localized form of corrosion by which cavities or "holes" are produced interring the material layer surface. It's considered to be more dangerous than uniform corrosion damage because it is more difficult to detect, predict and design against. Pitting corrosion can produce pits with open holes or covered with a semi-permeable capsule of corrosion products. In this review, we study about the pitting corrosion mechanism and stages in the manufacture food equipment metals in different conditions and environment.

scholarly journals A Study of the Pitting and Uniform Corrosion Characteristics of X65 Carbon Steel in Different H2S-CO2-Containing Environments

CORROSION ◽  
10.5006/2537 ◽  
2018 ◽  
Vol 74 (8) ◽  
pp. 886-902 ◽  
Author(s):  
Frederick Pessu ◽  
Yong Hua ◽  
Richard Barker ◽  
Anne Neville
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Critical Concentration ◽  
Small Diameter ◽  
Gas Content ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Attack ◽  
The Impact

There have been increasing concerns related to the challenges posed by hydrogen sulfide (H2S) corrosion to the integrity of oilfield pipeline steels. In environments containing variable quantities of both carbon dioxide (CO2) and H2S gas, the corrosion behavior of carbon steel can be particularly complex. There is still no universal understanding of the changes in the mechanisms, sequence of electrochemical reactions and impact on the integrity of carbon steel materials as a result of changes in H2S-CO2 gas ratio. The film formation process, film characteristics, and morphology in CO2- and H2S-containing systems are also known to be different depending upon the environmental and physical conditions and this influences the rates of both general and pitting corrosion. Questions still remain as to how the combined presence of CO2 and H2S gases at different partial pressure ratios influence the corrosion mechanisms, as well as initiation and propagation of surface pits. This paper presents an investigation into the overall (i.e., general and pitting) corrosion behavior of carbon steel in CO2-H2S-containing environments. The work explores the impact of changes in ratios of CO2 and H2S partial pressures at both 30°C and 80°C in a 3.5 wt% NaCl solution. All experiments are performed at atmospheric pressure, while H2S gas content is varied at 0 ppm (0 mol%), 100 ppm (0.01 mol%), 1,000 ppm (0.1 mol%), 10,000 ppm (1 mol%), and 100,000 ppm (10 mol%) in H2S-CO2 corrosion environments. Corrosion film properties and morphology are studied through a combination of scanning electron microscopy and x-ray diffraction. The results show that the morphology and composition of iron sulfide formed changes with H2S gas concentration because of the continuous interaction of the corrosion interface with the corrosion media even in the presence of initially formed FeS (mainly mackinawite). This often leads to the formation of a different morphology of mackinawite as well as different polymorphs of FeS. This also has the impact of either increasing or decreasing the uniform corrosion rate at low and higher concentration of H2S gas depending on the temperature. Pitting corrosion is also evaluated after 168 h to determine the impact of increasing H2S content on the extent and morphology of pitting corrosion attack. The results from the pitting corrosion investigation show that increased and severe pitting corrosion attack occurs at higher H2S concentration and temperature. The morphology of pitting corrosion attack is also linked to the changes in the H2S content with an indication of a critical concentration range at which the nature of attack changes from narrow and small diameter pits to severe localized attack. The critical concentration threshold for such transition is shown in this study to reduce with increasing temperature.

Investigations into the corrosive environments contributing to premature failure of Australian coal mine rock bolts

2016 ◽  
Vol 26 (1) ◽  
pp. 59-64 ◽  
Author(s):  
P. Craig ◽  
S. Serkan ◽  
P. Hagan ◽  
B. Hebblewhite ◽  
D. Vandermaat ◽  
...  
Keyword(s):  
Coal Mine ◽  
Rock Bolts ◽  
Premature Failure ◽  
Australian Coal ◽  
Corrosive Environments
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