API TR 6J1:2000 pdf download

API TR 6J1:2000 pdf download.Elastomer Life Estimation Testing Procedures.
Life estimation testing may be considered a.s the best estimate of long term icsvce tile to evaluate the lung-term performance of an elastomer in a severe service emriroiunent. The basic technique involves collecting time to Iaihue data at elevated temperatures (higher than the maximum antic,ated servse temperature) and plotting the results on semi-log graph paper. The vertical scale is the log of time to bilute and the horizontal scale is the reciprocal ol the absolute tempera. tire. Figure I shows a typical life estimation piot. Alternately. the time to Failure at the service temperature also can be calcubied froni the apprvpnate mathematical formula.
4.4 Certain precautions should be exercised whcii perfoiming accelerated temperature and/or pressure tests. It should be venhed expenrnerttally that the failure mechanism (and activation energy) does not change with elevated temperatures or pressures. In addition, it must be recognized gas diffusion may occur through an elastomer seal an accelerated rate and this must be properly accounted for if this is used as failure criteria. ft also may be helpful to test an elastomer maleriai with known heki performance as a reterence for coinpanson. Stagnant fluids and gases may give better or worse life estimation than ii the fluids are periodically refresh
5 Procedure For Life Estimation Testing Of Elastomers
5.1 The proposed pnseedure requires the use of an auto- claw (a high temperature pressure vessel) to coLlect lime to failure data. Various autoclave arid llxture design-s can be used. Figure 2 illustrates one design for a life estimation auto- cLaw sealed with standard size 0-rings mide fl-urn the candidate elasiomer. The autoctavc should be capable of operation. with a proper safety factor, up to the maximum Ieniprraturc. pressure and test environment needed icr the accelerated lest. The internal volume should be appropriately sized to avoid depletion of the test environment during the test; the minimum internal volume should be equal to or exceed 100 cc. The main body and end closures contain 0-ring gland-s that are fabricated from an appropriate alloy. Typically. a corrosion resistant alloy is used to fabricate the test flxture. Since thenno-chemical degradation of the elasiosneric sealing element is of interest. thenno-mechanical effects should be minimized. Therefore, clearances between the end closure and the test vessel bore ire niininuized to eliminate extrusion thcrmo-,ncctianicaj type fai1ure of the candidate ebstomer.
If additional mechanical protection is required for the 0- ring scal. an anti-eismision ring (back-up nng) of suitable material can bc used. In life estimation testing, only the thenno-diernical effects of a severe environment on a candidate elastomer are evaluated. Actual geometry and thetmomechanical effects ate best-evaluated using lull scale testing.