Australian New Zealand Standard AS / NZS Pipelines – Gas and Liquid Petroleum – Field Pressure Testing – Western Australia. AS – , Field Pressure Testing, Revision committed formed, Expected AS – , Safety Management Studies, With. AS/NZS Accessed by CITIC PACIFIC MINING PTY LTD on 03 Dec AS/NZS Australian/New Zealand Standard?.
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An ice-point verification is sufficient. Some pipelines initially operate at pressures below design pressure for long periods, decreasing the initial leak sensitivity in service.
AS Pipelines-Gas and liquid petroleum – Field pressure testing_图文_百度文库
288.55 Where this has been done in practice, the occurrence of ruptures during field tests from manufacturing defects has almost disappeared. Surge and similar conditions may result in pressures that are higher than MAOP, particularly in liquid petroleum pipelines. The end-points that have been used in the Australian industry for testing under this Standard were verified against actual strain measurements on pipes in test sections.
Leak testing may only be performed on a section that has previously been subjected to a satisfactory strength test. Description of the weather and weather changes 288.55 the test. Experience indicates that exposed pipe temperatures tend to follow ambient rather than direct exposed sun temperatures due to shading, heat exchange and time lag effects.
The formulae assume no change in the shape of the leaking orifice. It is important that the other potential causes be either eliminated or quantified before it is determined that an investigation of a premature end-point for yielding in the test section is required. Figures G1, G2, G3, G4 and G5 relate the theoretical volume of water loss which can be determined from the lost pressure multiplied by the slope to the equivalent circular smooth hole diameter to achieve the same leak rate in pipes of different thickness and subject to different test pressures.
The water in the test section at the commencement of the leak test will have experienced a resultant temperature change of 0. The standard allowable test fluid 288.5 rate see Table 5.
The following conditions apply: It was published on 4 April The test liquid shall be selected after consideration of the consequences of a rupture of the test section 285.5 escape of the liquid during the test, with regard to the effects such an incident would have on the general public, operating and testing personnel, testing and operating equipment, and the environment. Uncertainty is determined according to Clause I4.
Unrestrained pipeline with end caps Restrained pipeline Ring expansion test on line pipe? Calculations made to determine the flow of fluid through a defect in a pipeline are complex. This edition of the Standard provides a procedure for the evaluation of indication of leakages that are very small.
SCOPE OF ACCREDITATION
Verification determines that the instrument satisfies grading requirements. Temperature-measurement points shall be carefully selected to ensure that the measurement is relevant to the relationship being measured.
Similarly, oxy-cutting may cause either an underestimation or an overestimation. The objective of this Standard is zs set out methods for the determination of the strength and the leak-tightness of a pipeline test section. The maximum practicable length may also be limited by considerations of placement of and access to temperature probes, the collection of data by manual, remote or automated means, and travel times within the specified measurement time intervals.
An end-point known as halfslope is recommended for cold-expanded pipe which has a characteristically rapid change in stress strain slope introduced by the cold expansion.
An understanding of the uncertainty of the assessment of whether the test section is leaking or not is an integral element of the assessment of the test.
The fixed sensitivity of the pressure instrument during testing even if no pressure change is noted ensures that the certainty with which a given leak rate can be determined decreases as the volume of the test section increases, and this imposes a limit on the size of pipe section that can be tested.
Computer routines spreadsheets have been developed for each of the hydrocarbon density groups, enabling a tester to precalculate the variables for the range of temperatures expected to prevail. Falling pressure readings are reliable and convenient, and the calculations are simplified if readings are taken in pressure decrements of kPa each.
The pipeline industry has, however, traditionally carried out leak tests 2885. a higher pressure for a number of reasons, including the following: In the absence of reliable estimates, a ratio of may be used. Few other situations offer sufficient resistance to the very high axial force that may occur in a fully restrained pipe.
Table J1 illustrates the magnitude of the temperature changes that can be expected. Other methods may be used. Standardized spreadsheet routines could be supplied to testers undertaking such work, requiring insertion of density and pipe details to derive the variables.
The data from Table F2, when plotted as in 2885.5 F2, indicate 0.
Pressures in Column 2 are absolute and the unit is kPa. The simple relationship is affected by the relative amounts of water added to expand the steel of the pipes and to compress the test liquid.
Zero added volume at kPa arises from the calculations in Paragraph F3. Figure D2 is typical of a welded pipe before a mill pressure test. High performance pressure calibrators may provide equivalent performance. A lower straining rate reduces the stress at which yielding occurs.
Such pipe wall temperature-measuring devices for leak test evaluation are used to determine temperature changes on pipe walls where in ground temperatures may show diurnal changes of approximately 0. The report shall include all necessary calculations.
The maximum hold period is set at 8 288.55 because research suggests that no useful purpose can be served by continuing any longer; on the contrary, if time-dependent strain were still occurring, continuation is more likely to be harmful than beneficial. These entries are for information only. As this amount of air dissolves, the pressure in the test section would fall by more than 30 kPa, significantly affecting the interpretation of the test results.
Higher pressures can be used and would be applicable where combined strength and leak tests are carried out at the same pressure. Both the equipment and the technique of assessing leaks from pressure change present a number of problems. Permanent strain of 0. Where the section is small, so that the sensitivity of leak detection substantially overrides the uncertainty due to temperature changes or temperature sa, high sensitivity is attained even without full thermal stability, the hold period is 3 hours and temperature measurements and correlation of temperature changes with pressure changes are not necessary.