【国外标准】 Standard Test Method for Linear Dimensional Stability of a Gasket Material to Moisture

3.1 Gasket materials undergo several processing steps from point of manufacture to installation in a flange. Many applications require close control of dimensional change. An accurate test method for determining the relative stability of various materials is needed for design and quality assurance purposes. This test method is useful towards that end. It simulates the extreme storage conditions that a material may undergo prior to installation. Samples are allowed unrestricted expansion or contraction, and so this test method should not be used to predict behavior clamped in a flange or other applications, or during specific processing steps.3.2 This test method measures linear change, and may need to be modified if the test specimen is not flat, homogeneous, or free of voids.1.1 This test method covers a procedure to determine the stability of a gasket material to linear dimensional change due to hygroscopic expansion and contraction. It subjects a sample to extremes, that is, oven drying and complete immersion in water, that have shown good correlation to low and high relative humidities.21.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 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.1.4 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.