Quality control tests, metals processing

Adhesion tests can be broken into two categories qualitative and quantitative. They vary from a simple Scotch tape test to a complicated flyer tape test, which requires precision-machined specimens and a very expensive testing facility. Quantitative (such as peeling) tests have been developed for coatings on plastics (12), but not to the same extent for metal-to-metal systems. The quantitative testing systems in limited use, mainly in the electronics industry, are not commonly present in production plants but have been used to aid in process development. For quality control purposes, qualitative tests for metal-to-metal adhesion (13) are usually adequate. The adhesion of some plated metal parts is improved with baking for 1 to 4 h at relatively low (120 to 320°C) temperatures. 

Lot-to-lot differences in the purity of the therapeutic agent must be considered when evaluating in-process and finished-product test results. In addition to potency such qualities as particle size distribution, bulk density, and source of the material will be of interest. Such information should be available from the raw material test reports prepared by the quality control laboratory for each lot of material received. The physical characteristics of the excipients should not be overlooked, especially for those materials with inherent variability. Metallic stearates is a classic example. In such instances, the source of supply is desirable information to have available. 

The process for manufacturing seamless line pipe is shown schematically in Figure 5.8. In this process, a heated metal cylinder is pierced and then formed into the proper diameter and wall thickness. Seamless pipe is available through 26 in. (660 mm) diameter, but it is normally used only up to 16 in. (405 mmi diameter. Although seamless line pipe is the most expensive (15 to 25% above ERW), it is the most reiitable Even so, failures do occur. Hydrostatic test records reveal that about one failure occurs every 500 mu (800 km) of test. Some mills produce seamless pipe that has a significantly higher failure rate thus, it is important to ensure adequate quality control. 

A number of sensor arrays consisting of an assortment of commercial metal oxide gas sensors have been reported [45 7], For controlled tests, the sensors are mounted in an air-tight chamber fitted with gas inlets and outlets for controlled gas flow. Each sensor s heating element is controlled externally and resistance changes of the gas sensors are monitored by a computer data acquisition system. A significant effort in this area exists at the University of Warwick, Coventry, where for many years, sensor arrays, made from discrete Sn02 sensors or miniature integrated sensors, have been studied for ultimate application to food quality and food process control [47, 48]. 

Fabrication of an RPV requires many years to complete. The fabrication process is a series of carefully controlled operations with quality control checks after each step. The first of these controls starts with the steel supplier. The steel supplier must perform chemical analyses and destructive testing of the ingot material immediately after pouring the base metal. Each step in the procedure, from acceptance of raw materials at the shop to final shipment, is documented so that the complete history of the RPV is known. 

Several tests have been developed over the years to determine the crevice corrosion resistance of alloys. The objectives of these tests include comparison of alloys, qualification of alloys for a given service, evaluation of the effects of fabrication processes on crevice corrosion resistance, quality control, and life prediction. This chapter will briefly describe the types of tests, and their applicability and limitations, with a focus on tests that have been or are now being considered by ASTM Committee G-1 on Corrosion of Metals. While these test principles are applicable to a wide variety of alloys, the information presented is focused on stainless and nickel-base alloys. 

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