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API TR 6J1:2000 pdf download

API TR 6J1:2000 pdf download.Elastomer Life Estimation Testing Procedures.
5.2 The severe service environment is introduced into the test chamber tonned by the iwo end closures. The test vessel is pressurized and heated to a predetermined temperature during each lest cycle. The length of the test cycle is established by the testing protocol. i.e.. steady state temperature for downliole components or alternating low and high temperature cycles for surface welihead equipmcnL In this example for a surface welihead application, a 72-hour (3-day) test cycle is used. Figure 3 shows how the 3-day test cycle is conducted. The objective of the test sequence is to establish the rate of chemical degradation as a function of temperature.
5.3 The selection of a starting temperature for a life estimation experiment is somewhat arbitrary. A good starting point is an elevated temperature that will consistently give a failure in one or two lest cycles. Some experimentation may be required to establish this maximum test temperature. Once the maximum test temperature is determined, lower test temperatures can he selected, usually in 1O°C(18°F) increments. For example, if 450°F is determined to be the maximum test temperature where only one test cycle can be consistently completed, the next lower lest temperature would be 432°F If the experiment follows the Anhenius relation. two or more test cycles should be completed at 432°F. If two or more test cycles are not achieved at 432°F. the test temperature would be lowered by another 18°F until at least two or more test cycles are achieved consistently. At each subsequent lest termperature, sufficient test runs should be done to obtain test datathat are statistically significant. A minimum of three differenttest temperatures should be used, but preferably, five tests ormore should be done with some replicates.
5.4Use of the Arrhenius principle in estimating the life ofan elastomeric component requires that the chemical processthat controls degradation remains constant. If test tempera-tures are excessive,other reactions may occur and dataobtained may lead to erroneous life estimation.Once suffi-
cient data have been accumulatea,a tealook for any non-lin-
reaction occurred during testing,the best-nit line shouldapproximate a straight line.ror an the test data should indi-
service temperature.An estimate of service life can be readfrom the vertical scale of the life estimation plot or it can be
calculated from the appropriate mathematical formula.
5.5 Proper simulation of the chemical reactions that occurbetween candidate elastomers and the severe service envi-ronment requires a sufficient volume of chemicals must bepresent to prevent depletion of the reactants.A three (3) day test cycle is used so that the candidate elastomeric material isregularly exposed to fresh chemicals. In service,the elas-tomer may be constantly exposed to a steady stream of freshchemicals and/or produced fluids/gases or it may only beexposed to stagnant conditions.At the end of the 3-day testcycle,the test vessel is typically rapidly depressurized andpurged of the liquid and gas phases.Other decompressioncycles can be used with agreement of all concerned parties.Fresh liquid and gas are added and the candidate sealing ele-ments are pressure tested at ambient temperature. For spe-cific applications,other temperatures below anbient can beused. If the seals hold pressure for one hour without leakage,the test vessel is heated up to the test temperature for another3-day test cycle.This is repeated until failure is observed.


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