Standard Practice for Compression versus Load Properties of Gasket Materials
5.1 The load versus thickness properties of a gasket material are an important factor with regard to the selection of a given material for use in a particular sealing application. Additionally, compression/load behavior data are a common request from users. The test allows comparison of materials at room temperature or elevated temperatures or both. Additionally, properties can be evaluated while loading and unloading the material at room temperature or elevated temperatures or both. The significance of the test method is based, in part, on the assumption that, if a material exhibits too much compression at either room temperatures or elevated temperatures, it will no longer function as effectively as a seal. The results may be used in certain flange design methods to characterize properties for design such as finite element analysis (FEA). The results may be used to confirm adequate assembly loading based on measured gasket compression in the field. Two or more materials can be compared to determine differences in their compression properties. A sample of material can be compared to an established standard or previously determined characteristics on original lots of the same material for quality assurance purposes.
5.2 If desired, samples may be tested with a raised profile flange, insert, or calibration ring described in 6.3 and Fig. 1 so that the area (2042 mm2 [3.18 in.2]) remains constant during the test.
FIG. 1 Test Assembly for Determining Load versus Compression
1.1 This practice measures the compression properties of a gasket material by measuring gasket deflection while it is subjected to an increasing compressive load until a target load is reached. The load and change in thickness are recorded at a defined loading rate as a function of time for the duration of the test.
1.2 Suggested loading rates are 0.5 MPa/s [72.52 psi/s] for all types of gaskets except for expanded polytetrafluoroethylene (PTFE), elastomer, and cork/elastomer gaskets when 0.1 MPa/s [14.5 psi/s] is used.
1.3 The Part A test is performed that measures the compression properties of a gasket material by measuring gasket thickness while it is subjected to an increasing compressive load until a target load is reached. This test is performed at room temperature but may be performed at an elevated temperature if desired or when agreed upon by producer and user.
1.4 The Part B test may be performed that measures the compression properties of a gasket material by measuring gasket thickness while it is subjected to increasing compressive loads that includes a sequence or sequences in which the gasket is unloaded followed by a resumption of the compressive load until a target load is reached. The unloading rate is the same as the loading rate unless different loading and unloading rates are desired or when agreed upon by producer and user. This test is performed at room temperature but may be performed at an elevated temperature if desired or when agreed upon by producer and user.
1.5 The testing parameters for both Parts A and B including the gasket material type, gasket dimensions, platen type (RF or FF), target load, loading time, recording interval used during the test, loading and unloading rates, and temperature are to be reported with the results.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.7 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.
1.8 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.
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