API TR 6J1:2000 pdf download

API TR 6J1:2000 pdf download.Elastomer Life Estimation Testing Procedures.
Uk estinwion testuig may be considered as the best estimale of long term service life to evaluate the long-tcrni perfoi e of an ebsiomer in a severe service environment. The basic technique involves collecting time to failure data at elevated temperatures (higher than the maximum anticipated servce teniperatuit) and plotting the results on scmi-log graph paper. The vcital scale is the log of time to failure and the horizontal scale is the reciprocal of the absolute emperalure. Figure I shows a typical life catimatioriplol. Alternately. the time to failure at the service temperature also can be calcubted from the appropriate maihcmaticai formuLa.
4.4 Ceitain precautions should be esercised when performing accelerated temperature andlor pressure tests. It should be verified experimentally that the failure mechanism (and activanan energy) does not change with elevated temperatures or pressures. In addition, it must be recognized gas diffusion may occur through an ebstomer seal an accelerated rate and this must be property accounted for if this is used as failure criteria. It also may be helpful to lest an ebstomer material with known held performance as a reference for comparison, Stagnant fluids and gases may give better or worse life estinsation than if the Ituids are periodically refreshed
5 Procedure For Life Estimation Testing
01 Elastomers
5.1 The proposed procedure requires the use of an mutodave (a high temperature pressure vessel) to collect time to failure data Various autoclave and fixture designs can be used. figure 2 illustrates one design for a life estimithon autoclave sealed with standard sizc 0-rings made from the candidate elastomer. The antoclave should be capable of operation, with a proper safety factor, up to die maximum temperature. pressure and test enviroiwnerd needed for the accelerated lest. The internal volume should be appropriately sized to avoid depletion of the test environment during the teat the minimum internal volume should be equal to or exceed 101) cc. The main body and end closures contain 0-ring glands that are fabricated front an appropriate alloy. Typically, a corrosion resistant alloy is used to fabricate the test fixture. Since thenno-chemical degradation of the elasiorneric sealing element is o1 interest. themie-mechanical effects should be mmmired. Therefore, clcarances between the end closure and the lest vessel bore are minimized to eliminate extrusion (thermo-rncchanical type failure) of the candidate eb.stcwner.
If additional mechanical protection is required for the 0. ring seal, an anli-extausion ring (back-up ring) of suitable material can be used. In life estimation testing, only the thcrrno-chemical effes-ts of a severe environment on a candidate ebstomer are evaluateit Actual geometry and themiomechanical effects are best-evaluated using full scale testing.
5.2 The severe service environment is introduced into the test chamber formed by the two end closures. The test vessel is pressurized and heated to a predetermined temperature during each test cycle. The length of the test cycle is established by the testing protocol. i.e., steady state emperature for downhole components or alternating low and high temperature cycles for surface wellhcad equipment. 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 test cycles. Some experimentation may be required to establish this maximum lest temperature. Once the maximum test temperature is determined, lower test temperatures can be selected, usually in 10°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 test temperature would be 432°F. If the experiment follows the Arrhenius 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 lest cycles are achieved consistently.