Material selection diagrams

Once the PFD and matenal balaiK e is developed, process engineer should pirovide necessary process infomiation (such as process conditions, coirosive component concentration, line velocity, etc.) for each process stream on a metaHurgical selection table for metallurgist to decide what material of construction (MOC) should be used for each process line and equipment. Usually, PFD and material balance table are also provided to metallurgist for his/her evaluation. When metallurgist finished his/her work, he/she can mark on the PFD at each line and equipment to indicate what material to be used. This marked PFD is the material selection diagram. 

Some companies have their standard metallutgical selection table for process engineer and metallurgist to fill out. Sometimes metallurgist has to modify this table for a specific project, tf this table is not available, consult the metallurgist for this project about what process information are required for him/her to evaluate MOC of line and equipm t. 

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A component is presently made of brass. Use a modulus-density materials selection diagram, or look up the appropriate data, to suggest two metals which, in the same shape, would be stiffer. 

This section will discuss problems that can complicate the selection procedure. Such problems include the variability of materials selection criteria, conflicting project objectives such as minimizing capital cost, and mandatory criteria such as those in governing engineering codes. Other topics discussed include organization of the information needed for the materials selection process, a procedure for materials selection, and the use of a materials selection diagram. 

For small or uncomplicated jobs, a simple template may be preferred. A customized template is not usually needed for replacing or revamping a couple of vessels or a small piping system, or for a unit involving only a few, if any, corrodents. A rubber stamp template, with a process flow diagram, may be used to quickly create a materials selection diagram, as illustrated in Example 21.1. 

Preliminary project Summary of equipment Material selection diagrams Operations and... 

Equipment List Material selection diagrams Mechanical data sheets for the equipment Equipment mechanical design calculations Equipment inspection reports Insulation, fireproofing and painting specifications... 

Materials fundamentals atomic bonding, crystalline structure, imperfection, phase diagrams and kinetics. Materials metals, ceramics, plastics and composites Materials selection for the chemical process industries... 

Figure 8.13 shows a material selection chart of the wear rate constant for dry sliding friction in Eq. (8.21) plotted as a function of hardness, FI, in MPa. The most favorable materials will have a high hardness and a low wear rate constant. Diamond would be the best choice from this diagram, but may be prohibitive from a cost standpoint, even when used only as a liner, if it is even possible to produce such components. 

The process of granulation was carried out batch-wise in a drum of diameter 0.5 and 0.4 m long at a constant rotational speed n = 20 rpm and constant drum filling (cp = 10%), for a range of moisture contents w [kg of water/kg of dry material] selected for each raw material separately. A schematic diagram of the experimental set-up is shown in Fig. 2. 

Phase diagrams can also be used as an aid for material selection of oxide compounds that can be used at high temperature. Examination of diagrams (summarized in Tables 2-5) reveals that oxide compounds with melting temperatures above 1800°C are predominantly single metal oxides (e.g., A1203 or Ti02) or binary oxides... 

In the second stage, the materials selection information on the varions templates is entered on a simplified process flow diagram (PFD), creating a MSD. The MSD is then reviewed for consistency. A checklist determines if factors snch as excessive pressnre drop mnst be addressed. 

Based on these maximum permissible strain values, permissible stress can be determined using isochronous stress-strains diagrams or time-temperature superposition curves (Figure 5.5). With the permissible stress value, an approximate dimensioning of the component can be performed, followed by the next step in the material selection process. The required safety factors are referred to in Table 1.35. 

This competition between mechanisms is conveniently summarised on Deformation Mechanism Diagrams (Figs. 19.5 and 19.6). They show the range of stress and temperature (Fig. 19.5) or of strain-rate and stress (Fig. 19.6) in which we expect to find each sort of creep (they also show where plastic yielding occurs, and where deformation is simply elastic). Diagrams like these are available for many metals and ceramics, and are a useful summary of creep behaviour, helpful in selecting a material for high-temperature applications. 

The problem must be simplified considerably to permit solution in the context of this book. Suppose an equilateral triangle is subjected to some loads in the vertical direction as in Figure 7-22. A load P of 100 lb (445 N) is applied to the top joint, and that load can go in either the downward or upward direction (in the diagram, not in space ). This truss must take its reversible load with, say, a factor of safety of two against whatever event would cause it to fail. What material, size, and weight of truss element would you select to satisfy the design requirements that include building the structure for the lowest cost ... 

Fig. 4.1 Diagram of the method for selective vapor detection that includes fabrication of core (1) and core shell (2) materials, their assembly into a colloidal crystal film (3), exposure of the film to different vapors (4), measurements of the spectral response of the film (5), and multivariate analysis of the spectra (6) to obtain a vapor selective response of the colloidal crystal film...

Figure 23-1 shows the hazards identification and risk assessment procedure. The procedure begins with a complete description of the process. This includes detailed PFD and P I diagrams, complete specifications on all equipment, maintenance records, operating procedures, and so forth. A hazard identification procedure is then selected (see Haz-ard Analysis subsection) to identify the hazards and their nature. This is followed by identification of all potential event sequences and potential incidents (scenarios) that can result in loss of control of energy or material. Next is an evaluation of both the consequences and the probability. The consequences are estimated by using source models (to describe the... 

Assessment ofphase diagrams. Selection, designing and planning of materials are relevant subjects from a fundamental point of view but, of course, are also interrelated basic topics in material science and engineering. Study and classification of preparation methods and of constitutional and fundamental properties followed by an investigation of application and performance characteristics are essential aspects of such topics and procedures. 

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