【国外标准】 Standard Practice for Measuring Intergranular Attack or End Grain Pitting on Metals Caused by Aircraft Chemical Processes

4.1 If not properly qualified, chemicals and chemical processes can attack metals used during aircraft maintenance and production. It is important to qualify only processes and chemical formulas that do not have any deleterious effects on aircraft metallic skins, fittings, components, and structures. This test procedure is used to detect and measure intergranular attack or pitting depth caused by aircraft maintenance chemical processes, hence, this test procedure is useful in selecting a process that will not cause intergranular attack or end grain pitting on aircraft alloys.4.2 The purpose of this practice is to aid in the qualification or process conformance testing or production of maintenance chemicals for use on aircraft.4.2.1 Actual aircraft processes in the production environment shall give the most representative results; however, the test results cannot be completely evaluated with respect to ambient conditions which normally vary from day to day. Additionally, when testing chemicals requiring dilutions, water quality and composition can play a role in the corrosion rates and mechanism affecting the results.4.2.2 Some examples of maintenance and production chemicals include: organic solvents, paint strippers, cleaners, deoxidizers, water-based or semi-aqueous cleaners, or etching solutions and chemical milling solutions.1.1 This practice covers the procedures for testing and measuring intergranular attack (IGA) and end grain pitting on aircraft metals and alloys caused by maintenance or production chemicals.1.2 The standard does not purport to address all qualification testing parameters, methods, critical testing, or criteria for aircraft production or maintenance chemical qualifications. Specific requirements and acceptance testing along with associated acceptance criteria shall be found where applicable in procurement specifications, materials specifications, appropriate process specifications, or previously agreed upon specifications.1.3 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.