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ABSTRACT: This paper presents the results from a 5 year laboratory and in situ investigation into the cause of corrosivity of rock support systems in underground hard rock mines. Long term in situ monitoring of corrosion was complemented by controlled investigations in corrosion chambers. During site visits, samples of corroded support units were collected from several mines and subsequently analyzed using S.E.M. and photomicrography. A series of controlled experiments in the corrosion chambers qualified and quantified the influence of minerals and rock deposits on the corrosion rate of steel and rock support. 1. INTRODUCTION Despite great strides in the design and implementation of ground control systems, it has been difficult to eliminate ground falls. One quality control issue related to support is related to a reduction in support capacity over time due to corrosion of the reinforcement and surface support units. This is illustrated in Figure 1. A corroded wire mesh failed and therefore, it no longer provided the support for which it was designed for. The reduction in support capacity due to corrosion may not be explicitly considered in the selection and design of an underground support system, as demonstrated by Figure 1. Quite often, corrosivity is found to be the issue during an investigation in the mechanisms and cause of failure that may have resulted in a fall of ground. Usually the investigation puts an emphasis on fracture analysis, and in doing so, this may identify the contribution of corrosion to a unit or system failure, [1]. Fracture analysis focuses on the separation of a solid body into two or more parts under the action of stress. The stress would have initiated and propagated the formation of cracks. A ductile fracture mechanism is characterized by considerable plastic deformation prior to and during propagation of the crack.
- Research Report > Strength High (0.54)
- Research Report > Experimental Study (0.54)
Life Time Assessment of Offshore Water Injection Pipelines As a Function of Microbiologically Influenced Corrosion
Comanescu, Iulian (Corrosion in aggressive environments, Swerea KIMAB AB) | Melchers, Robert E. (Centre for Infrastructure Performance and Reliability, The University of Newcastle) | Taxen, Claes (Corrosion in aggressive environments, Swerea KIMAB AB)
Corrosion of water injection pipelines (WIP) in the oil and gas industry is a major issue involving potential premature life time predictions and unpredicted costs like periodic biocide treatment and pipeline pigging. This paper presents a part of a larger project concerned with improving understanding of the influence of bacterial activity on corrosion, as distinct from abiotic corrosion, in oil and gas transport systems for better management of pipeline systems. Observations are made concerning life time as a function of microbiologically influenced corrosion (MIC) risk and relationships between MIC, bacterial numbers and types, and water quality INTRODUCTION Accurate prediction of pipeline lifetime is of major importance for operators and owners. To obtain adequate prediction of the expected lifetime for a line it is necessary to know the root causes of possible failures and how often failures occur. The main root causes how to be measured in place to mitigate problems as they arise. In order to achieve this "Classification Societies" and "Oil Companies" have invested and continue to invest a lot of time and money to obtain the necessary knowledge for preventing future failures. Reports and recommendations such as PARLOC (2001) and DNV (2006) now are available to help identifying the most common failure causes, and how to prevent future accidents. In DNV's (2009) "Recommended Practice" document they concluded that in Gulf of Mexico corrosion represents about 40% of the total numbers of failures resulting in leakages. Internal corrosion represents 81% of the corrosion failures. For the North Sea pipelines corrosion failures represented 27% of the total number of failures and internal corrosion was the major cause. It is evident that the main problem for pipelines both in the North Sea and in the Gulf of Mexico is the result of internal corrosion (DNV 2009).
- Europe > United Kingdom > North Sea (0.45)
- Europe > Norway > North Sea (0.45)
- Europe > North Sea (0.45)
- (4 more...)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Oil & Gas > Midstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.77)
Abstract The present study compares corrosion mass loss and pit depth measurements on carbon steel corrosion coupons exposed under similar operating parameters, but with different biological consortia. One set of data were obtained from standard flush disc corrosion coupons used to monitor corrosion rates in a water injection pipeline on the North Sea continental shelf. The coupons were exposed on average for 6 months over 6 years operational time. These data are compared with published corrosion data of coupons exposed in abiotic district hot water systems from several power plants situated in Europe. The exposure time for these coupons was 9 months. Both systems were anoxic and in the same temperature range and are comparable. Observations regarding relationship between MIC and bacterial consortia, bacterial numbers and type, water quality and corrosion products are also made. The corrosion rate of the water injection pipeline is approximately 10 times higher compared with the corrosion rate in the abiotic district hot water system. It is concluded that the increased corrosion on the carbon steel coupons in the early stage is caused by MIC. This is also supported by the chemical and biological information available for the pipelines. The results reported here constitute the first step of an overall study to improve the level of understanding of the bacterial contribution to the total corrosion rates of carbon steel in water injection flowlines. Such understanding is expected to improve management and operational decision-making for practical control of corrosion in the field, by providing predictions of expected life time as a function of control of biotic consortia (e.g. through pigging, and biocide treatments). Further, it will facilitate decisions concerning choice of pipeline construction materials for future design.
- North America > United States > Texas (0.28)
- Europe > United Kingdom > North Sea (0.25)
- Europe > Norway > North Sea (0.25)
- (2 more...)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
ABSTRACT: The Mauritian textile industry is, nowadays, facing serious competition on the international market. With the aim of improving its productivity, corrosion has been identified as a major cost for the industry due to the huge amount of chemicals used in the dyehouses. The present study was therefore performed at one of the major dyehouses in Mauritius so as to identify the different types of corrosion occurring, the effect of the chemicals employed on the common metals used in the dyehouse and the cost of corrosion in the plant. The different types of corrosion occurring were assessed through visual inspection on the pipes, accessories and machines in the dyehouse. The effect of the chemicals on the common types of metals used was investigated through electrochemical tests using the Tafel technique. Three different types of metal and seven different types of chemicals were tested. It was found that low carbon steel had the highest corrosion rate among the metals tested and stainless steel UNS 31603 was the more corrosion resistant. Hydrochloric acid was the most corrosive fluid. The cost of corrosion over a yearly period was estimated to be $450,000 and this was 75% of the maintenance cost. INTRODUCTION The textile industry in Mauritius is a major pillar for the Mauritian economy and has been an engine of the economic growth over the past three decades. It started in the 1970s and it was meant to diversify the largely agro-based economy by encouraging the establishment of export-oriented textile companies. The Mauritian textile industry therefore has to improve its productivity so as to face the fierce competition on the international market. Corrosion presently costs much to the textile factories and, therefore, it has become important to analyse this problem so as to decrease its related costs.
- Africa > Mauritius (0.72)
- North America > United States > Texas (0.19)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)