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Petroleum Origin and Generation
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
The marine water surface is in constant contact with the atmosphere. At the interface between the water surface and atmosphere, the gases from the air enter the marine water and gases from the water escape to the atmosphere. So the gases are in exchange constantly with the water and atmosphere. The dissolved gases found in marine water are nitrogen, oxygen, carbon dioxide, hydrogen sulfide, ammonia, methane, hydrogen and some noble gases. Nitrogen is inert and as such not used in any biological/chemical process, except for a small quantity of nitrogen that is used by nitrogen-fixing organisms. The noble gases are also inert. Oxygen and carbon dioxide are important gases for metabolism/conversion processes in marine water, including the important photosynthesis process. Hydrogen sulfide, methane, hydrogen and ammonia are produced by the decomposition of organic matter at various stages at different depths. In deeper waters, where anaerobic (absence of oxygen) conditions prevail, hydrogen sulfide is produced by a sulfate bacteria reduction process. In the absence of free oxygen, anaerobic bacteria take the oxygen from sulfate ions to oxidize the organic matter, releasing hydrogen sulfide as a by-product.
Common Sense Emergency Response
Published in Robert A. Burke, Common Sense Emergency Response, 2020
MC 338 tanks (Figure 4.16) are used for transporting cryogenic gases, sometimes referred to as refrigerated liquids. These materials are very cold with boiling points of −130°F for carbon dioxide to −452°F for liquid helium. Common cryogenics include oxygen, nitrogen, helium, argon, and others. Many of the materials carried in 338 tanks are considered inert gases. That is, they do not readily react chemically to other materials, are not flammable, and are not poisonous. They do, however, have significant hazards when released as liquids or gases. Liquids are extremely cold and can cause frostbite and solidification of anything they contact, including body parts. Liquids also have large expansion ratios, producing huge amounts of vapor from the small spill. In some cases, as little as 1 gallon of a cryogenic liquid can produce over 900 gallons of gas. While these gases are inert in many cases, they can still displace the oxygen in air and cause simple asphyxiation.
Methods of joining materials
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
Gases such as nitrogen and carbon dioxide, which are often referred to as being inert, will, in fact, react with some molten metals. Thus, nitrogen will combine with molten magnesium, whilst carbon dioxide will react with steel, oxidising it under some circumstances. The only true inert gases are those which are found in small quantities in the atmosphere, namely argon, helium, neon, krypton and xenon. Of these, argon is by far the most plentiful comprising 0.9%, by volume, of the atmosphere – and is used for filling incandescent light bulbs, and also as a protective atmosphere in inert-gas welding. In the United States, substantial amounts of helium are derived from natural gas deposits, so it is used there as a gas shield in welding. Since argon and helium are expensive to produce, carbon dioxide (CO2) is now used in those cases where it does not react appreciably with the metals being welded.
Development of activated tungsten inert gas welding and its current status: A review
Published in Materials and Manufacturing Processes, 2022
Ashish W. Fande, Ravindra V. Taiwade, Laukik Raut
The parameters used in the ATIG are identical to those used in the TIG. In ATIG, it has been stated that the thickness of the flux coating and the proper choice of flux is important. Multiple process parameters and fluxes were used to perform the ATIG process on various materials with varying plate thicknesses. Molybdenum oxide (MoO3), Titanium oxide (TiO2), and Silicon dioxide (SiO2) are commonly used fluxes for A-TIG welding. These fluxes are mixed with an appropriate solvent to create a semi-solid paste. Solvents like acetone, methanol, and water can all be used to make the paste. However, because methanol and water take a longer time to evaporate, acetone is commonly used as a solvent .[88,94,95] This paste is then applied to the plate surface that will be welded (Fig. 2). The entire welding operation is carried out in an inert welding atmosphere to avoid weld porosity and defects. Table 2 shows a tabulated summary of ATIG welding on ferrous and nonferrous alloys. Figure 3 shows an illustration of the ATIG procedure.