Corrosive gases: effect

Environmental hazards such as corrosive gases effects on system, peripherals, I/O racks, cabling... 

Environmental and Corrosion Control Effects of Hydrogen Sulfide Scavengers in Oil and Gas Exploration... 

Whether these corrosive gas tests are reaUstic for materials other than those used for connectors or for operating electronic equipment is not clear. The test should be carried out, but the observation of no failures should not be taken to mean there will be no field failures in typical urban environments. Similarly, any failures that are observed should be carefully evaluated to ensure that the same mechanism would he operative in field situations. Connectors tire a somewhat unique part of an electronic assembly in that the active part is frequently a noble mettil and the sensitivity of the mated surfaces to failure may be lower thtin many other parts of electronic assemblies. Most failures in electronic assemblies attributable to the environment are due to ionic particle contamination in conjunction with atmospheric moisture. In 20 years of evaluating field failures in the United States, the author has never seen a failure that could be attributed to the effects of SOj, has seen a few caused by H2S or HCl, has heard of a few caused by NOx, and has seen several hundred that were caused by ionic contamination. Clearly, valid accelerated testing of electronic components, circuit boards, and assemblies must include ionic contamination. Emerging methods are discussed in the Fine Particle Testing section in this chapter. 

Direct exhaust-gas impingement (erosion corrosion) can occur due to the high-velocity exhaust gas stream on the internal surfaces of the exhaust system. This effect is important at sharp bends and surfaces normal to the gas flow. The combination of particulate matter with hot corrosive gas produces this type of attack. 

These fillers are of great industrial importance, and are the main subject of this chapter. They owe their fire retardant effectiveness to their ability to decompose endothermically at polymer pyrolysis temperatures, with the release of inert gases such as water. Thus, unlike some other flame retardants, they are able to combine a high level of flame retardancy, with low smoke and low toxic and corrosive gas emissions, and are thus becoming of increasing importance. One of the simplest such materials is aluminium hydroxide (also known as alumina trihydrate, ATH). 

In addition to their use in non-halogenated systems, fillers, especially of the hydrate type, have been extensively studied for use in halogenated polymers such as polyvinyl chloride, or in conjunction with halogenated flame retardants. The aim is to combine their effects and produce a composite with high flame retardancy, low smoke and low corrosive gas emission. 

In both its liquid and gaseous form, chlorine is neither flammable nor explosive. It currently is classified as a poison or toxic gas, class 2.3, which requires a subsidiary corrosive label. In Canada, it is classified as a corrosive gas, class 2.3. Its principal hazard arises from inhalation. The Chlorine Institute s Chlorine Manual describes chlorine s physiological effects, chemical characteristics, and physical properties. It also includes information on employee training for proper handling and protection when using chlorine [11]. Additional information on chlorine, including exposure limits, can be found in the monograph in Part II. 

Such gas effects have to be considered in the electric lamp industry and in the case of semiconductors which are now used in numerous devices susceptible to corrosion. Sparney and Ruler of the Philips laboratories in Eindhoven recently published a paper on this subject, describing a new method of studying the surface electrical properties of semiconductors. The method depends on conducting resistivity measurements for pressures of... 

One of the maj or ways of protecting oil and gas production and operating systems against corrosion is by applying corrosion inhibitors. The corrosion inhibitors are evaluated in order to determine if the corrosion preventive measures applied are necessary, and if the required lifetime can be achieved with a particular inhibitor, as the effective life of corrosion inhibitors varies with the quantity of water intrusion. The purpose of this chapter is to evaluate the on-line monitoring of corrosion and corrosion inhibitor effectiveness under different conditions. 

Erosion is the deterioration of a surface by the abrasive action of solid particles in a liquid or gas, gas bubbles in a liquid, liquid droplets in a gas or due to (local) high-flow velocities. This type of attack is often accompanied by corrosion (erosion-corrosion). The most significant effect of a joint action of erosion and corrosion is the constant removal of protective films from a metal s surface. This can also be caused by liquid movement at high velocities, and will be particularly prone to occur if the solution contains solid particles that have an abrasive action. 

Surface Fluorination of Polymers. Fluorocarbon-coated objects have many practical appHcations because the chemically adherent surface provides increased thermal stabiHty, resistance to oxidation and corrosive chemicals and solvents, decreased coefficient of friction and thus decreased wear, and decreased permeabiHty to gas flow. Unusual surface effects can be obtained by fluorinating the polymer surfaces only partially (74). 

Final Purification. Oxygen containing compounds (CO, CO2, H2O) poison the ammonia synthesis catalyst and must be effectively removed or converted to inert species before entering the synthesis loop. Additionally, the presence of carbon dioxide in the synthesis gas can lead to the formation of ammonium carbamate, which can cause fouHng and stress-corrosion cracking in the compressor. Most plants use methanation to convert carbon oxides to methane. Cryogenic processes that are suitable for purification of synthesis gas have also been developed. 

---