Material selection based

Another serious problem in heat exchangers is corrosion. Severe corrosion can and does occur in tubing and very often with common fluids such as water. Proper material selection based on a full analysis of the operating fluids, velocities and temperatures is mandatory. Very often, heavier gauge tubing is specified to offset the effects of corrosion, but this is only a partial solution. This should be followed by proper start-up, operating and shut-down procedures. 

This standard was and still is widely used by operators, either in the oil and gas production fields or refineries. Most SRV manufacturers have established a standard Bill of Materials that complies with the minimum requirements of NACE MR0175, taking into account certain specific valve material selections based on their hardness and under the condition of the following operating conditions ... 

It is therefore of great importance to understand and agree upon a material selection based on additional and very detailed end-user process data. The minimum additional required data to make a reasonable material selection is ... 

Summary of Physicochemical Parameters. In the previous section steric parameters 4 . and were introduced to describe the effective size of solution components and the average size of the transport corridor, respectively. A variety of quantities that could be used to represent

dense membranes and the skin layer of reverse osmosis membranes in which the transport corridors are beyond the resolution capabilities of modern instruments and may be dynamic in nature. Therefore, any discussion of membrane material selection based on steric considerations must be qualitative. 

In pervaporatlon, reverse osmosis, ultrafiltration and to a lesser extent microfiltration, both steric and chemical factors Influence permeation and separation. Thus, proper membrane material selection la Important. While the physical structure of the membrane is in large part a function of membrane preparation procedures, the chemical nature and, to some degree, the physical properties of the membrane are dependent upon the chemical nature of the membrane material. Thus, membrane material selection based on the chemical nature of the polymer and the solution components to be separated is feasible. 

The outputs from finite element analysis will tell the chemist many of the important predictive characteristics of the part. The effects of load (stress, strain, and deflection) are measured. Material selection based on strength and part dimensions and tolerances are determined and easily adjusted. The effects of heat (heat transfer and thermal stresses) are determined as well as material selection based on conduction and insulation. Special applications such as bending and vibration characteristics, crashworthiness, fatigue, and noise can be determined. The design requirements, such as expected loads, load cycle cost, mass targets, and budget targets, can be predicted and met with proper application of the FEA tool. 

This table should be used as a guideline for material selection based on temperature only. No consideration for various services has been made in the assembly of this table. 

Detailed reviews of oil refining corrosion problems and control methods are given in a book by White and Ehmke [78]. Oil refining corrosion problems are generally solved by making appropriate materials selection based on accumulated industry experience as reflected in published papers plus API and NACE committee reports. Neutralization and inhibition are used in some cases. Monitoring is generally by inspection supplemented by analysis of process streams (e.g., acidity) and by special probes. 

Material selection based on functional requirements of the part, plus structural requirements. 

In addition some samples were reformed by pressing into sheets small samples were then cut for ageing in air drculated ovens at various temperatures, between 120 and 150°C, both in and out of contact with copper. These oven ageing trials were conducted in order to validate the extrapolation to higher temperatures so that future material selection based solely on DSC measurement of OIT could be vahdated. The time to failure in the oven ageing trials was assessed by a simple three-point bending test, since it was found that the polypropylene lost aU mechanical integrity rather rapidly once the oxidation process was under way. The time to failure was reported as OIT at the lower temperatures and these results incorporated into the Arrhenius plots. 

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