Criticality, materials

National Defense Stockpile Goal for tin at 42,700 metric tons. On January 2, 1980, the Strategic and Critical Materials Transaction Authorization Act became effective. This authorizes the President to dispose of materials determined to be excessive to the current needs of the stockpile. This act provides for the sale of up to 35,600 metric tons of tin, including a contribution of up to 5100 metric tons of tin to the International Tin Council (ITC) buffer stock (see below). The GSA set up a schedule to offer about 500 metric tons of Grade A tin, for domestic sales and consumption only, every other Tuesday beginning July 1, 1980. On December 14, 1981, the restrictions on exporting the GSA tin sold were lifted sales increased immediately. Thus, from July 1, 1980, through December 11, 1981, the total GSA sales were 3170 metric tons. An additional 1815 metric tons were sold soon thereafter, mostiy to traders (10). 

Radiographic tests are made on pipeline welds, pressure vessels, nuclear fuel rods, and other critical materials and components that may contain three-dimensional voids, inclusions, gaps or cracks that are aligned so that the critical areas are parallel to the x-ray beam. Since penetrating radiation tests depend upon the absorption properties of materials on x-ray photons, the tests can reveal changes in thickness and density and the presence of inclusions in the material. 

External seals (Fig. 10-115) are installed with all seal components protected from the process fluid. The advantages of this arrangement are that (1) fewer critical materials of construction are required, (2) installation and setting are somewhat simpler because of the exposed position of the parts, and (3) stuffing-box size is not a hmiting factor. Hydraulic balancing is accomphshed by proper proportioning of the seal face and secondary seal diameters. 

Match batch size to container size of critical components, using an integral number of whole containers, where possible Double check materials being added to reactor Complete batch loading sheets for each batch run Use of operator sign-off sheets Preweigh reactants before transferring to reactor Verify raw materials (certificate of analysis for critical materials)... 

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. 

M2 Thickener It is pulverized Ml thickener with an antimoisture substance (attasorb clay) added in the ratio of lp attasorb clay to 19p Ml thickener. It readily absorbs moisture from the air, but not to the extent of M1 thickener, because less air circulates thru the pulverized particles the attasorb clay further lowers moisture absorption. A container may be resealed after part of the M2 thickener has been used provided it has had minimum exposure to air. Since M2 thickener is composed mainly of Ml thickener, it retains most of the characteristics of Ml, including the disadvantages of being manufd from critical material, absorption of water from the air, and sensitivity to moisture. 

The last, but by no means the least, important of the military characteristics is availability under wartime conditions. Materials are classified as strategic, critical, and non-critical in this respect A strategic material is one that must be imported into the United States a critical material is one that is available in the United States but, because of either limited plant facilities or excessive demands, becomes nonavailable a noncritical material is one that is readily available in. sufficient amounts under wartime conditions. An insecticide to be of value to the military forces must be readily available under wartime conditions, must not be dependent upon the importation of certain essential materials, and must not impose a burden upon plant facilities in the United States. 

Hot Extrusion of Shells. A modification of the Ugine-Sejournet hot extrusion process (using glass as lubricant) is used by Scaife Company of Oakmont, Pennsylvania. In this process a complete shell (such as 4.2 inch) can be produced in one piece from a simple billet. Important features of the development are in the substitution of readily available billet stock for seamless steel tubing, a critical material in times of war. Another feature of this process is that it requires about 25% less steel Refs Ordnance, 38, 753 (1954) 2) Iron Age... 

Critical materials register requires all businesses discharging waste products into the water or any sewer system to report the annual amount... 

Libowitz, G. G., Metal Hydrides for Energy Storage, Critical Materials Problems... 

As brass was a critical material during WWII, in Europe, the Germans started to use steel an d many cases were manufd from this material(Ref 28a,p Ger 27). As steel proved to be a satisfactory material, steel cases are now made in other countries including US(Refs 8,9,10,11,13, 15,17,21,24a 28). Other metals such as Al and its alloys(Refs 2,3,4 7) or Zn-Cu alloys(Ref 6) have also been tried. The possibility of using sintered iron Cartridges has been investigated at Frankford Arsn, Philadelphia(Ref 20), but further work is required. Plastic cartridge cases are described in Refs 12 27... 

In additic-, to using these materials for construction of various bldgs for Ordnance plants or for construction of fortifications(pill boxes, etc ), cement and concrete(except the reinforced) (Refs 8 9) were used for manuf of ammo, such as landmines, bombs, mortar shells and hand grenades. This was done in order to save iron, which was a critical material in some countries during WWI WWII, but it seems that items which were required to produce blast effect rather than fragmentation could conveniently be made of concrete... 

An important question for any modeling effort, especially one aimed at a quantitative description of complex transport processes, is the level of accuracy of the model. As will become evident in the discussion of transport models and specific calculations, the values for thermophysical properties and transport coefficients must be known, as well as the dependence of these coefficients on temperature and pressure. Information is lacking for this data base. Critical material properties for semiconductor materials are not known... 

Cleaning validation protocols should describe the equipment to be cleaned, procedures, materials, acceptance criteria, parameters to be monitored and controlled, and the analytical methods to be employed for testing. Validation of cleaning procedures should reflect equipment to be used for key and final intermediates and APIs. The selection of cleaning procedures to be employed should be based on material solubility and cleaning difficulty. The calculation of residue limits should consider the potency, toxicity, and stability of critical materials. 

Behrisch, R. In Critical Materials Problems in Energy Production, Stein, C. (ed.), p. 91. New York Academic Press 1976... 

Hlinak AJ, Kuriyan K, Morris KR, Reklaitis GV, Basu PK. 2006. Understanding critical material properties for solid dosage form design. J. Pharm. Innov. 1(1) 12-17. 

However, some excipients have multiple functions. For example, microcrystalline cellulose can function as a filler, a binder, and a disintegrant. As seen in Table 7.3, a typical low-dose formulation could include more than 85% filler—binders. Thus, physical and chemical properties for these specialty excipients are extremely important in a low-dose formulation for manufacturability, product performance, and longterm stability. Because the poor physicomechanical properties of components are not altered during manufacture as they are in the wet or dry granulation process, critical material properties and their impact on product quality attributes should be well characterized and understood.23 Discussion in this section will focus on fillers-binders. For those requiring more information on excipients, several excellent books and review articles are available in the literature.24-27... 

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