【国外标准】 Standard Practice for Measuring Static Sealing Pressure Using Pressure-Indicating Film (PIF) in Transportation Applications

5.1 This practice is a screening tool and should be used in conjunction with other more accurate real-time load-measuring techniques.5.2 This practice covers the use of PIF, which is available in several load ranges. This practice also covers the use of a manual or automatic scanning device to read indicated load.5.3 Limitations include those applications in which the PIF may be kinked, twisted, or buckled. PIF does not withstand elevated temperature, low temperature, or fluid aging and does not take into account any relaxation of bolts, gasket materials, or flange twisting, as it provides only the maximum attained pressure.1.1 This practice covers a standard means for measuring initial static sealing pressure in transportation applications.1.2 It uses a pressure-indicating film (PIF) that will record the maximum load imprint of the seal-to-flange interfaces. The imprints will vary in intensity based on load across and along the interface.1.3 These imprints can be used to determine if initial load on the gasket is adequate to attain a seal. These imprints may also indicate correct bolt torque sequence. These imprints may also be used to determine if the mating surface waviness or local flatness meets gasket requirements. Roughness is rarely found by PIFs because peak-to-peak wavelengths are too short. PIF is very good at finding waviness (peak to peak > 2.5 mm) and local flatness dips. PIFs provide an approximation of maximum pressures, and do not take into account relaxation of the joint after the torque sequence. Other methods involving dynamic measurement should be used if flange loading after relaxation is desired.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.