Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
ABSTRACT Sulfide stress cracking (SSC) and hydrogen induced cracking environments. Metallic thermal protect carbon steel from the (HIC) can cause severe damage in spray coatings based on aluminum corrosive media, when wet H2S program, a series of electrochemical tests were conducted. These tests involved exposure of coated samples to various environments containing .HJ3, ammonia~ chloride and cyanide to study the behavior of the aluminum coating associated with a stainless steel interlayer both applied by thermal spray. Results showed that the aluminum layer was corroded rapidly in solutions with pH higher than 11. In alkaline solutions with pH lower than 9 a protective aluminum layer and the corrosion rate was very low. INTRODUCTION The high corrosion resistance of aluminum makes metallic thermal spray coatings based on aluminum alloys a natural choice to protect steel equipment from exposure to many corrosive environments, However, the performance of these coatings in wet HzS environments found in the petroleum industry has not been examined to a great extent in the published literature. It is already known that, in water at 25 C, aluminum has a good corrosion resistance in the pH interval of 4.0 to 8.5(1) because it is protected by a passive, aluminum oxide layer. Outside of this pH range, the. corrosion rate of aluminum depends on the nature of the individual ions in the solution. The corrosion rate is extremely high in hydrofluoric acid, sodium carbonate and sodium hydroxide, but very low in acetic acid and sodium disilicate. Konstantinova etalz~2)measured the corrosion rate of aluminum tubes in seawater at 90 C in the pH range of 6 to 9 as a function of time. Results showed that corrosion decreased considerably at lower pH values in this range, whereas, in other media aluminum had a tendency to form pits. This pitting tendency increased in the presence of CaCO~, CU2+and Cl- and decreased at temperatures higher than 60 C. The addition of Cl- to water, ethanol and water-ethanol solutions at ?(3)Results showed an increase in the corrosion different temperatures were studied by Persiantseva etah rate with chloride addition along with a sharp increase in hydrogen evolution. A ten fold increase in hydrogen evolution tier Cl- addition to a 0.5 M H2SOdsolution was similarly detected by Zartsyn et t#ii(4).
- 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)
- Health, Safety, Environment & Sustainability > Health > Noise, chemicals, and other workplace hazards (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
INTRODUCTION ABSTRACT Low aluminum Fe-Al alloys are being investigated for use as protective coatings in reducing environments. Intermetallic compositions have already demonstrated excellent high temperature corrosion resistance in both oxidation and Striatum edronm ents, however, they are limited in use due to low room temperature ductility and poor weld ability arising from hydrogen embrittlement. Using Gas Tungsten Arc and Gas Metal Arc Welding process without the use overheat and post weld heat treatments, a weld ability regime below approximately 10wf% Al in the overlay has been found. The high temperature sulfidation behavior of alloys located near this crack boundary (5 to 12.5wt% Al) was examined using a thermo gravimetric balance in a reducing gas mixture of O.l% H2-1.0% H-h-Balance Ar gas at 700C. Light optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy were used to analyze the cross- section almorphologiea. It was seen that the FeAl alloys exhibited lower weight gains than bare water wall tubes (carbon steel) and 309 stainless steel. Aluminum additions to the iron were found to extrinsically affect the iron sulfide reaction product morphology. Low carbon steel with no aluminum, formed a continuous, and somewhat dense, iron sulfide scale that provided some protection. Small additions of aluminum (5-7.5 wt Yowl) resulted in the growth of iron sulfide as nodules or a porous surthcescale. Larger additions (above10 w 0/0)were to limit the growth of iron sulfide and significantly reduce corrosion rates. These results indicate that Fe-Alcl@lings containing 5to 10wt?% Al show potential promise for applications requiring a combination of weld ability and sulfidation resistance in moderately reducing environments. Weld overlay coatings are being used to protect low alloy steel water-wall panels of coal-fired boilers with low NOX burners. By depositing an alloy that offers better sulfidatiort resistance than the underlying tubes, the accelerated wastage ?4 that is presently experienced can be decreased. A material system presently under consideration fm use as a cladding is iron-aluminum. While data are indicating the excellent corrosion resistance of iron aluminizes in reducing environments 2,thesealloy aren?t readily weld able. The intermetallic compositions have been shown to be susceptible to hydrogen (cold) ?*?5 This problem has been observed to be more prevalent as the aluminum content of the cracking subsequent to deposition . demit is increased 18. Recentwork?9has shown that when depositing under the conditions normally used to produce overlay - in a M= (no PXKJIa or post-weld ha torment), a maim of 10wt???Al can be tolerated in the cladding before cracking occurs (Figure 1). Other investigations ?4mhave shown that by using pre-heat and post weld heat treatment$ the severity of the hydrogen cracking problem can be reduce@ thus allowing for higher aluminum content overlays to be produced crack &e. However, the use of such extensive treatments is usually not possible when coating large scale structures. Therefore, alloys with lower aluminum contents are being investigated fm weld overlay coatings. Studies conducted on time alloys have shown that even small additions of aluminum to iron can decrease suffixation rates by an order of magnitude 21-X.However,the conditions used in these studies (temperatures above 700Cand PHz>107 atm) we resume what more aggressive than environments bind in fossil-fired boilers with low NOX burners =7. Recent work x has shown that weldable compositions of Fe-Al alloys performed reasonably well in moderately reducing environments (temperatures below700C, P~,<10?atm and Pm> 10-~atm). Compositions with 5-10 wt% Al were s
- 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)
ABSTRACT Electrochemical polarization data for the individual thin film electrodes Al and Zn as well as in galvanic couple connecting the two together have been generated using atmospheric corrosion sensors developed recently. Thin films of these metals were subjected to cyclic fog testing and to continuous immersion in selected electrolytes corresponding to atmospheric condensates and were tested also in actual atmospheric exposure under bold (totally open and subject to direct hit by rain and sun light) and sheltered (not hit by rain and sun light) conditions. Results generally indicate that zinc corrodes by very large amount tending to protect aluminum in the process. Aluminum corrodes by the least and remains passivated under test conditions involving only plain water. In the presence of chloride ion~ pitting is activated, though zinc provides initial protection and tends to stabilize passivation. Under open bold conditions, zinc electrode experiences the largest corrosion current densities and passivates itself and Al remains also in the passive state. The potentials of both electrodes converge to nearly the same value around +100 mV measured against an open silver film. Under the sheltered locations, both the corrosion potentials and current densities oscillate, possibly due to repeated tendencies of passivation and depassivation and attainment of a totally protected state for Al may require secondary protection measures along with the use of zinc. INTRODUCTION Can articles and structures made out of aluminum alloys be protected efficiently in the open atmosphere by the application of the cathodic protection principle, particularly by coupling to zinc or to the common zinc anodes? An answer to this question would certainly require that the electrochemical behavior of the aluminum - zinc galvanic couple be known precisely as a function of exterior atmospheric variables, such as temperature, humidity and chemistry of the condensed layer of water. Atmospheric corrosion sensors that have been developed recently at LSU/SU [1-3] enable electrochemical characterization of such couples not only in the open atmosphere, but under accelerated laboratory test conditions as well. Through these tests the kinetics of corrosion processes in galvanic couples can be followed as a function of time in the presence of corrosion products on the corroding metals. Using such a sensor, electrochemical polarization tests have been undertaken on aluminum ? zinc couples in the open~ natural atmosphere, as well as in two kinds of laboratory tests, cyclic fog (plain and salt-laden) test and continuous immersion. The results obtained from the polarization of electrodes, Al and Zn separately and the A1-Zngalvanic couple, are presented, discussed and interpreted in this paper to answer the question posed at the beginning of this section. Aluminum articles that are prone to corrosion are generally protected by the application of coatings and/or corrosion inhibitors. Cladding corrosion resistant aluminum layers on corrosion prone aluminum alloys (alcladding) is a well developed practice. Some of the alloys are anodized and colored or impregnated with a corrosion inhibitor in the oxide layer for protection. Alternatively, corrosion inhibitors are added to the corrosive to form corrosion protective films on the surface of alloys. Commonly used coatings are of two kinds: organic (polymeric) and chemical conversion-type. In the former category the fluoro-polymers are dominant, while chromate conversion coatings are the most effective ones for the aluminum alloys. The chromate coatings used on aluminum articles, such as solar collectors and solar heat exchangers, etc. have since been discontinued owing to their carcinogen
- 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)
ABSTRACT It is people that are involved in the process of designing, building, and maintaining equipment and structures. People who are not familiar with good corrosion design and practices end up compromising system performance. Examples of the way people can affect these compromises using the eight forms of corrosion are discussed in the paper. INTRODUCTION In the process of developing and fielding equipment, a number of things need to be accomplished. A need or requirement for the equipment must exist for now or in the Mure. Once the need is identified, a program can be founded to look at various alternatives to meet the need. Once an approach is established, a prototype can be built. Testing of the prototype to see if it fulfills the need is eventually accomplished Sometimes the need gets changed as the prototype is built and tested. The prototype may meet most of the identified needs, but does not necessarily meet them all. However, the prototype may have other properties that are beneficial so the needs maybe altered to fit new scenarios. After the prototype is built and successfully tested, consideration must be given to producibility and production. Is the prototype capable of being manufactured and fielded in a cost effective manner? Will the item be a low cost (cheap) model that requires significant maintenance and/or spare parts? Will the design be a more expensive model up front, but be capable of providing service for a number of years with little or no maintenance? In the past, the Army basically had three sources of funds for hardware: (1) Research and Development funds were used to build prototypes and test the alternatives. (2) Procurement funds were used to buy the equipment. (3) Maintenance dollars were used to keep equipment running in the field. An economic analysis was required prior to production of new equipment. This ensured the lowest cost item would be procured. The equipment was continuously maintained with low cost spare parts that required significant down time for repair and significant logistics support for procurement. The Army is currently experiencing that the low cost concept is not viable in today?s environment. Downsizing troops has reduced the number of people available to perform field maintenance. Reducing procurement budgets do not allow for replacement of old interns with new as often as in the past. Sophistication of the hardware has resulted in a higher dollar value for the items. All these situations are happening at the same time, making it necessary to buy hardware that is producible, reliable, and requires little or no maintenance. To accomplish all these goals requires people. People to do the planning, the designing, the manufacturing, the fielding, etc. This paper identifies the people required in the development, manufacturing and fielding equipment and shows how some of their efforts affect the overall corrosion resistance of a piece of equipment. Good design today has to include considerations for corrosion resistance because lack of it becomes a very expensive proposition. A recent vehicle corrosion problem in Hawaii determined that 15 percent of the soldier?s maintenance dollar went toward fixing corrosion problems. Corpus Christi Army Depot determined some time ago that 25 percent of their annual payroll went to fixing corrosion problems. These costs become a significant part of the life cycle cost and must be considered if any reduction in the cost of ownership is to be realized by item/program managers. People in the system include the performance/contract writers, purchasing /procuring agents, metallurgists, specification tiprocess writer, materials engineers, quality a
- North America > United States > Hawaii (0.24)
- North America > United States > Gulf of Mexico > Western GOM (0.24)
- Materials > Metals & Mining (1.00)
- Government > Military > Army (1.00)
- 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)