Material selection chemicals

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

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... 

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

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. 

Uniform corrosion is the deterioration of a metal surface that occurs uniformly across the material. It occurs primarily when the surface is in contact with an aqueous environment, which results in a chemical reaction between the metal and the service environment. Since this form of corrosion results in a relatively uniform degradation of apparatus material, it can be accounted for most readily at the time the equipment is designed, either by proper material selection, special coatings or linings, or increased wall thicknesses. 

Proper material selection for chemical and process equipment is one of the first important problems encountered by the designer. Among the many parameters that must be considered are structural strength specifications, heat resistance, corrosion resistance, physical properties, fabrication characteristics, composition and structure of material and cost. 

One of the most effective methods of preventing corrosion is the selection of the proper metal or alloy for a particular corrosive service. Once the conditions of service and environment have been determined that the equipment must withstand, there are several materials available commercially that can be selected to perform an effective service in a compatible environment. Some of the major problems arise from popular misconceptions for example, the use of stainless steel. Stainless steel is not stainless and is not the most corrosion-resistant material. Compatibility of material with service environment is therefore essential. For example, in a hydrogen sulfide environment, high-strength alloys (i.e., yield strength above 90,000 psi or Rc 20 to 22) should be avoided. In material selection some factors that are important to consider are material s physical and chemical properties, economics and availability. 

The materials selection procedure should take into account the commissioning requirements of all parts of the plant in order not to include any materials that cannot safely be degreased or chemically cleaned. 

The first interactive electronic encyclopedia for users of plastics, materials selection is carried out using 3 search routines. The Chemical Resistance Search eliminates materials that cannot meet user specified chemical resistance requirements. The other search routines ( Elimination and Combined Weighting ) eliminate candidate materials based on 72 properties, falling within one of the following groups General and Electrical, Mechanical, Cost Factors, Production Methods and Post Processing. All data is evaluated and based on independent tests conducted in RAPRA s laboratories. 

Rubacams is a computer aided materials selection routine for elastomeric materials. Covering 99 generic types of rubber, each material is cross referenced with over 190 chemical agents and materials property data including physical, chemical mechanical and process related properties. Search results... 

Zeolite chemistry is an excellent example of how a three-dimensional surface can alter the course of chemical reactions, selecting for one product out of a host of potential candidates. In addition to the many commercial applications that they have found, shape-selective zeolites have provided the basis for a rich new area of catalytic science and technology, one expected to spawn yet more materials, knowledge, and applications. 

Chemical class searches can be helpful when making selections of materials for use with chemicals which have not been tested for permeation. By extrapolating the information provided by the program for a chemical class, one can (with caution) often select materials that will have better protective qualities than those material selected without this information. However, the uncertainties illustrated from the data in Table I are inherent in any polymer selections made this way. 

Hyperpolarized 129Xe not only allows for sufficient signal intensity for chemical shift selective gas phase MRI, it also provides the means for a unique type of contrast. The imaging contrast derived from the transport of hyperpolarized gases into the material can be utilized to obtain snapshots of the gas flow and diffusion into porous samples. In this context, it is important to appreciate that Figures... 

A portion of material selected from a larger quantity of material. Typically a chemical compound or mixture of compounds submitted to an assay or a screen. 

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