Materials Consideration

The probabilistic analysis presented in this chapter is not restricted to a specific fabrication approach but rather presents results as a function of the fiber volume fraction and can be applied to a wide range of pipe rehabilitation methods. The time-dependent failure probability analysis is illustrated for specific fiber volume fractions and can be repeated for any fiber volume fraction depending on the manufacturing process of interest. Typical fiber volume fractions of 30% and 40% are selected conservatively for example probability analysis conducted in the chapter. Recent efforts to measure fiber volume fractions used in composite pipe applications report fiber volume fraction values ranging from 47.6% to 54% for filament-wound composite pipes (Abdalla et al., 2008), and Chin and Lee (2005) measured volume fractions of 47% for unidirectional laminates manufactured via resin transfer molding in a trenchless rehabilitation scheme. 

Time-dependait and predictive component behavior is directly attributed to models based on durability tests at the material level. Bank et al. (1995) summarize predictive models for a particular material characteristic of FRP composites, including mechanics-based, chemical-based, accelerated-aging and long-term verification models. Of these, accelerated-aging models are the most commonly used for predictive modeling. 

Rehabilitation of Pipelines Using Fiber-reinforced Polymer (FRP) Composites 

While FRP composites are the primary focus in this durability discussion, it should be noted that degradation models for other materials within a component can be included in the framework for service life prediction (i.e., loss of area due to steel corrosion) in order to asses combined effects. The selection of material degradation models or inclusion of empirical data should reflect the environment where the rehabilitation is to take effeet. For instance, where combinations of high temperature and high humidity are antieipated, prediction models developed from moistore and elevated temperatures would be considered most appropriate for the constitoent materials selected in the rehabilitation. 

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Decision-making on the project involves a consideration by the relevant authority of the EIS (including consultation responses) together with any material considerations. 

Methanol is shipped overland by tank cars, tmcks, and dmms. The same safety and materials considerations apply to each of these types of... 

The selection of material to resist deterioration in seivdce is outside the scope of the B31.3 code (see Sec. 23). Experience has, however, resulted in the following material considerations extracted from the code with the permission of the pubhsher, the American Society of Mechanical Engineers, NewY ork. 

Fig. 25.5. Bar chart showing the coefficient of stali friction for various material considerations.

For compressors in general and for some types in particular, the cleanliness of the gas stream is the key factor in a reliable operation. Moisture or liquids in various forms may be the cause of an early failure or in some-cases a catastrophic failure. Corrosive gases require material considerations and yet even this may not entirely solve the loss of material issue that can certainly cause early shutdowns or failures and high maintenance cost. Fouling due to contaminants or reactions taking place internal to the ( i-pressor can cause capacity loss and the need for frequent shutdowns. 

Polyamides are the second largest group of synthetic fibers after polyesters. However, they were the first synthetic fibers that appeared in the market in 1940. This was the result of the work of W. H. Carothers in USA who developed nylon 66. At about the same time nylon 6 was also developed in Germany by I. G. Farben. Both of these nylons still dominate the market for polyamides. However, due to patent restrictions and raw materials considerations, nylon 66 is most extensively produced in USA and nylon 6 is most extensively produced in Europe. 

Fires do occur and accidents happen. In selecting the appropriate material, consideration should be given to its fire-safety properties and to methods of maintaining the integrity of the protective cladding in fire situations. 

Both physical and process-material considerations influence the choice and use of shaft seals in the industry. It is essential that the seal material is compatible with any process material and the operating variables. 

Flame resistance The underwriters ruling on the use of self-extinguishing plastics for contact-carrying members and many other components introduces critical material selection problems. All TSs are basically self-extinguishing. Nylon, polyphenylene oxide, polysulfone, polycarbonate, vinyl, chlorinated polyether, chlorotrifluoroethy-lene, vinylidene fluoride, and fluorocarbon are examples of TPs that may be suitable for applications requiring self-extinguishing properties. Cellulose acetate and ABS are also available with these properties. Glass reinforcement improves these materials considerably. 

Taksali, S., Grauer, J.N., and Vaccaro, A.R., Material considerations for intervertebral disc replacement implants. Spine J., 4, 231S-238S, 2004. 

The chemical compatibility of an FML with waste leachate is an important material consideration. 

Nature of the hazardous materials. Consideration of the nature of hazardous materials includes recognition of ... 

It is well known that phosphites or sulfides added to stabilizers of polymeric materials considerably enhance the stabilizing effects. Destruction of polymers is caused by the action of peroxides resulting from oxidation at the defects of polymeric chains. The additives decompose hydroperoxides according to the following equations ... 

Theoretical and material considerations for composites are dealt with in Chapter 8. Here we will focus more on processing considerations. 

Specific Material Considerations—Metals Following are some specific considerations which should be evaluated when applying certain metals in piping. 

Specific Material Considerations—Nonmetals Following are some considerations to be evaluated when applying nonmetals in piping. Refer to Tables 10-19,10-20, and 10-21 for typical temperature limits. 

Protein Concentration. For a given type of protein, a critical concentration Is required for the formation of a gel and the type of gel varies with the protein concentration. For example, gelatin and polysaccharide solutions will form gels at relatively low concentrations of the gelling material. Considerably higher protein concentration Is usually required for the gelation of globular proteins. 

When strength-of-materials considerations are not signilicant design features of an anticipated device, one can use strategies that seek to prevent the adsorption of proteins and cells. As Table 6.1 illustrated, a strategy to accomplish this would be to use hydrophilic polymers. The interaction of proteins and surfaces is a complex subject and depends on the nature of the protein, associations with other proteins, time, shear, and other factors including the chemistry of the surface. 

The off-gas must be cleaned for N2O down to a level below 100 ppm. Due to material considerations, the temperature in the reactor should not exceed 1500 K. For economic and/or safety reasons, it is preferable to keep the pressure at about one atmosphere. 

Nickel in Nanometer Materials. Coating a metal with an ultrathin layer of another metal creates properties not found separately in either of the materials. Considerable recent research has been directed toward improving the mechanical properties of bimetallic laminates, sometimes called composition modulatedfilms, which have interlayers only a few nanometers thick. Attractive properties also have been found for similar systems, called nanometer materials. Nickel has been used in combination with copper, ruthenium, and other metals for producing these new materials. 

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