API TR 17TR1:2003 pdf download

API TR 17TR1:2003 pdf download.Evaluation Standard for Internal Pressure Sheath Polymers for High Temperature Flexible Pipes.
6.5.2 It is imperative that the inlluence of temperature on mechanical property levels be established by approprtate testing. The temperature range covered should he defined by the extremes likely to be expenenced during service; these include the expected maximum. normal operating and shutdown temperature conditions for the pipe. The range of test temperatures used to develop this standard included —10. 4. 23. 120. 150. 175 and 21E’>C. There is little point in conducting tests on unaged testpieces above ROD MPT csee section 6.12). Tensile tests should be csrioi out on both unaged and aged testpieces: see section 6.13 for details of ageing conditions.
6.5.3 Reductions in ambient temperature modulus of up to 60% (hydrocarbon oib for equilibrium swollen candidate polymen have been measured during the associated UP. Values at high temperatures (above oil boiltng pointj have to he proportionated to overcome the problem of rapid liqttid evaporation during direct high temperature testing of swollen testpieces.
6.6 FRACTURE TOUGHNESS TESTING
The basis of this test (Annexe C) is given in a draft ESIS protocol 141. It provides a measure of fracture toughness (it by relating the tota] work done in separating a compact ;cnsjon testpicce by a pre-selected amount, to the depth of the crack which results, Other tests at the same temperature on replicate testpieces at different J values should follow. This procedure can be repeated at other temperatures: testing should cover the flexible pipe service temperature range, and include aged samples. Note that, according to the test standard, a slower loading rate (e.g.. 0.1 nins/mint ntust be used if a material exhibits unstable crack growth.
6.7 FATIGUE TESTING
6.7.1 This test extends the fracture toughness concept by providing stress/strain cycles on thc same testpiece type to illustrate the fatigue behaviour of thermoplastic materials in reasonably realistic strain modes. i’he purpose of fatigue measurements is to ascertain whether the crack growth rate of a candidate polynser lies above or below a critical value. With this test, a single testpiece can be used to cover a range of i values.
6.7.2 Video microscopy is used to determine crack growth rates at a series of J fracture toughness) values:
for testpieces machined from extruded pipe. a choice of initial notch orientation exists—axial or circumferential. (Circumferential cracking has been observed in current flexible pipe service). Plots of crack growth rate versus i are then developed for comparisons between ditterent materials. To aid comparisons, crack growth resistance has been defined enipirically) as the value of J at a trait growth rate of 10 nm/cycle.
6.11.2 The vanabk parameters for the HP gas permeation tests arc temperature and pressure. A typical test souence invohes making measurements at three (high I temperatures in order to develop Arrbenius plots for each pressure for the coeflicients of diffusion and permeation (Annexe E) extrapolation to sersice temperature shouW then be possible if tests can only be performed at lower temperatures (NB ii appropriate, care should be taken to ensure that Arrhenius-type linearity applies across the glass transition temperature (T1) of the polymer). HP permeation tests should be performed on both unaged and aged testpicces (see Section 6.13 for details of ageing conditions, Additional detail is proside*l in Annexe E.
6.11 .3 No pass fail criteria are specified fur this test. If the gas permeation rate is high for a particular candidate material, pipe design considerations will dictate whether the material is allowable as a pressure sheath. The barriers to gas permeation presented by the carcass and pressure armour layers of a typical unhonded pipe should he considered when assessing performance. In the absence of these barriers, or if a peaporlionation factor describing their influence is known. permeation rate through the pipe sheath can be estimated once Q is known (see Annexe E).
6.12 RGD TESTING
6.1 2.1 RGD resistance is a critical property for situations in which the flexible pipe transports.contains high pressure gas but one which, in screening tests., it may no be possible to simulate sers ice conditions. Since unconstrained tcstpieces are invariably more badly damaged by R(il) events than constrained samples. ii is crucial not to reject nsatetials out of hand based on apparently poor preliminary test results. The gas mixture employed should reflect service conditions as tar as possible, but the carbon dioxide (COy) content is of some importance; carbon dioxide provides a more searching test of RGD resistance then methane as it is invariably the more soluble of the two in polymeric materials. Hence it is accqtahk to use natural gas Iprimanly CH4 with about 1% C02) for preliminary RUt) tests.