Material selection selecting

Carbon and low-alloy steels are probably the most commonly used materials for pipes handling water, petroleum products, and some chemicals. Reference 1 provides a summaiy of the different specifications used for pipelines. Steel tends to corrode by both pitting and uniform surface deterioration [2]. Steel must usually be protected from corrosion both on the inside from the material being carried and on the outside from corrosion by the atmosphere, soil, or water that surrounds the pipe. External corrosion protection is provided by material selection, selective backfill, barrier coatings, stray current control, and cathodic protection. Internal corrosion protection can be provided by inhibitors, coatings, design process control, and materials selection. 

DILLON Materials Selection for the Chemical Process Industries freeman Hazardous Waste Minimization... 

Table 2. Summary of Criteria for Material Selection and Performance Evaluation ...

Other above-ground continuous flow systems have been designed and operated for SCWO processes. A system developed by ModeU Development Corp. (Modec) uses a tubular reactor and can be operated at temperatures above 500°C. It employs a pressure letdown system in which soHd, Hquids, and gases are separated prior to pressure release. This simplifies valve design and material selection on the Hquid leg. 

Plaspec Material Selection Database Data Resources, Inc. Dialog, STN detailed engineering and design data, chemical descriptions, and trade names for over 11,500 grades of plastics materials... 

The American Society of Mechanical Engineers (ASME) United Engineering Center 345 East 47th Street New York, NY 10017 The ASME Boiler and Pressure Vessel Code, under the cognisance of the ASME PoHcy Board, Codes, and Standards, considers the interdependence of design procedures, material selection, fabrication procedures, inspection, and test methods that affect the safety of boilers, pressure vessels, and nuclear-plant components, whose failures could endanger the operators or the pubHc (see Nuclearreactors). It does not cover other aspects of these topics that affect operation, maintenance, or nonha2ardous deterioration. 

The fifth component is the stmcture, a material selected for weak absorption for neutrons, and having adequate strength and resistance to corrosion. In thermal reactors, uranium oxide pellets are held and supported by metal tubes, called the cladding. The cladding is composed of zirconium, in the form of an alloy called Zircaloy. Some early reactors used aluminum fast reactors use stainless steel. Additional hardware is required to hold the bundles of fuel rods within a fuel assembly and to support the assembhes that are inserted and removed from the reactor core. Stainless steel is commonly used for such hardware. If the reactor is operated at high temperature and pressure, a thick-walled steel reactor vessel is needed. 

Ways to Succeed, 1993—1994 Materials Selection Guide, Eorm No. 304-00286-1292X SMG, The Dow Chemical Co., Midland, Mich., 1993. 

J. R. Hague, J. F. Lynch, A. Rudnick, F. C. Holden, and W. H. Duckworth, eds., Eefractory CeramicsforMerospace A. Materials Selection Handbook, The American Ceramic Society, Inc., Columbus, Ohio, 1964. 

At very high and very low temperatures, material selection becomes an important design issue. At low temperatures, the material must have sufficient toughness to preclude transition of the tank material to a brittle state. At high temperatures, corrosion is accelerated, and thermal expansion and thermal stresses of the material occur. 

Careflil material selection is required to prevent brittle failure of tanks at low temperatures. In addition, for tanks where the service temperatures are reduced, it is essential that an engineering analysis be performed to ensure that the tanks are not subject to brittle failure at the house temperature. The tank and vessel codes usually specify allowable materials based on design temperature. Further information about selection of metals for low temperature is available (8). 

The case is the largest portion of the container. The case is divided into compartments which hold the cell elements. The cores normally have a mud-rest area used to collect shed soHds from the battery plates and supply support to the element. Typical materials of constmction for the battery container are polypropylene, polycarbonate, SAN, ABS, and to a much lesser extent, hard mbber. The material used in fabrication depends on the battery s appHcation. Typical material selections include a polypropylene—ethylene copolymer for SLI batteries polystyrene for stationary batteries polycarbonate for large, single ceU standby power batteries and ABS for certain sealed lead—acid batteries. 

Other Types of Portland Cements. White Portland cementis standard Type I or III Pordand cement with raw materials selected and controUed to have negligible amounts of Hon and manganese oxides, which impart the gray color. The white Pordand cement is used in decorative and architectural appHcations like precast curtain waUs, terra22o surfaces, stucco, tile grout, and decorative concrete. 

The final product has a low ash and/or low iron content achieved by raw material selection or special processiag. 

Processing is key to the reproducible manufacture of ceramics. The tolerance of a finished ceramic to defects determines the raw materials selected, and the control that must be exercised during processing. More expensive advanced ceramics require higher quaUty, more expensive raw materials coupled with more carefully controlled manufacturing processes. 

These standards specify design, construction, and testing details such as material selection, shop inspection and tests, drawings and other uses required, clearances, construction procedures, and so on. 

Temperature. The temperature of the liquid being pumped is important because it affects the seal face material selection as well as the wear life of the seal face. 

The hydrostatic test is, in one sense, a method of examination of a vessel. It can reveal gross flaws, inadequate design, and flange leaks. Many beheve that a hydrostatic test guarantees the safety of a vessel. This is not necessarily so. A vessel that has passed a hydrostatic test is probably safer than one that has not been tested. It can, however, stiU fail in service, even on the next appheation of pressure. Care in material selection, examination, and fabrication do more to guarantee vessel integrity than the hydrostatic test. 

The tubeside fluid must be clean or at least chemically cleanable. With a large number of tubes in the coil, cleaning of inside surfaces is not totally rehable. Fluids that attack stressed materials such as chlorides should be reviewed as to proper coil-material selection. Fluids that contain sohds can be a problem due to erosion of relatively thin coil materials unlike the thick plates in spiral-plate units and multiple, parallel, fluid passages compared to a single passage in spiral-plate units. 

Tube to tubesheet joints, a weakness of most nonmetallic units, are fused by special techniques that do not severely affect the chemical suitabihty of the unit. Some nonmetallics use Teflon or O rings that add an extra consideration to material selection. 

Membrane manufacturers require a standard test to maintain batch-to-batch quality. Few use proteins. Materials selected are ones for which the complications are minimized, the probe is simple, fast, and cheap to detecl , does not readily biodegrade, and gives results, whatever they are, which are reproducible. There is no standardization of these tests within the industry. 

In the absence of factual corrosion information for a particular set of fluid conditions, a reasonably good selection would be possible from data based on the resistance of materials to a very simifar environment. These data, however, should be used with some reservations. Good practice calls for applying such data for preliminary screening. Materials selected thereby would reqmre further study in the fluid system under consideration. 

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