Chemical environment test standards

ASTM Chemical Environment Test Standards. Since intergranular corrosion is one of the most serious problems in the satisfactory application of stainless steels, several procedures are available for the measurement of the susceptibility of these steels to this type of corrosion. The procedures have been formalized as standardized tests, designated as ASTM A 262 (Ref 102), and are widely accepted as a basis for certifying that a specific stainless steel meets specifications. A limitation of these tests is that they specify specific environments rather than the environment of the actual application. In many applications, however, reasonable correlations have been established between acceptable response to the tests and successful service performance. 

Standard fatigue tests normally require extended periods of time to complete regardless of the type of stress/strain used. Accelerated fatigue tests change some conditions of the test in the hope of reaching the same end point in less time. Potential means of accelerating the tests include changing factors such as the temperature, frequency, chemical environment, levels of stress or strain, or the addition of stress concentrators. 

In applications where possible degrading elements exist, candidate adhesives must be tested under simulated service conditions. Standard lap shear tests, such as ASTM D1002, which use a single rate of loading and a standard laboratory environment, do not yield optimal information on the service life of the joint. Important information such as the maximum load that the adhesive joint will withstand for extended periods and the degrading effects of various chemical environments are addressed by several test methods. Table 15.2 lists common ASTM environmental tests that are often reported in the literature. 

Today, five main aspects must be taken into account machines, chemicals, environment, farmer, and agricultural products. These five aspects must be considered as a unique system or a dynamic system with close interaction (Fig. 3). Future standards should take these into consideration in the development of better quality in agriculture and environment. Standards should clearly define test procedures to ensure uniformity within all institutions carrying out tests. 

Although published tests such as ASTM C-279 may be used to determine an acid brick s chemical resistance, no standard test exists to predict silica brick behavior. It is necessary to rely on personal experience or to evaluate a brick s performance in a simulated test environment. 

Standard Specification for Reinforced Plastic Laminates for Self-Supporting Structures for Use in a Chemical Environment, Standard C-582, American Society for Testing and Materials, Philadelphia, PA (1984). 

In each testing mode the same basic procedure is followed. A load is applied to the specimen under the appropriate conditions of temperature and chemical environment, and its deformational response is followed over a prolonged period of time. The applied load is much less than that required to induce yielding of the sample during standard mechanical property testing. The selection of appropriate experimental parameters requires a knowledge of how the creep data will be used. As creep data are principally used to predict reliability in end use... 

Also, the electronic control-valve device s level of immunity to, and emission of, electromagnetic interference (EMI) can be an issue in the chemical-valve environment. EMI requirements for the control-valve devices are presently mandatory in the European Community but voluntary in the United States, Japan, and the rest of the world. International Electrotechnical Commission (lEC) SOI, Parts I through 4, Electromagnetic Compatibihty for Industrial Process Measurement and Control Equipment, defines tests and requirements for control-device immunity. Immunity and emission standards are addressed in CENELEC (European Committee for Electrotechnical Standardization) EN 50 081-1 1992, EN 50 081-2 1993, EN 50 082-1 1992, and prEN 50 082-2 1994. 

These test procedures and standards are subject to change, so it is essential to keep up to date if one has to comply with them. It may be possible to obtain the latest issue on a specific test (such as a simple tensile test or a molecular weight test) by contacting the organization that issued it. For example, the ASTM issues new annual standards that include all changes. Their Annual Books of ASTM Standards contain more than seven thousand standards published in sixty-six volumes that include different materials and products. There are four volumes specifically on plastics 08.01-Plastics 1 08.02-Plastics 11 08.03-Plastics III, and 08.04-Plastic Pipe and Building Products. Other volumes include information on plastics and RPs. The complete ASTM index are listed under different categories for the different products, types of tests (by environment, chemical resistance, etc.), statistical analyses of different test data, and so on (56,128,129). 

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