ASTM F 38-00
These test methods are designed to compare related materials under controlled conditions and their ability to maintain a given compressive stress as a function of time. A portion of the torque loss on the bolted flange is a result of creep relaxation. Torque loss can also be caused by elongation of the bolts, distortion of the flanges, and vibration; therefore, the results obtained should be correlated with field results. These test methods may be used as a routine test when agreed upon between the consumer and the producer. To measure the amount of creep relaxation of a gasket material at a predetermined time after a compressive stress has been applied there are 2 methods used: - Test Method A - Creep relaxation measured by means of a calibrated strain gauge on a bolt. - Test Method B - Creep relaxation measured by means of a calibrated bolt with dial indicator.