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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Appendices D and E give a simple explanation of how the manufacturing processes aas testing practices at the mill affect the way the pipe will behave in the field tests.
It may also aw applicable to high pressure steel pipelines designed and constructed to national Standards of other countries. Where leak detection is by correlation of pressure with temperature, the hold period shall be not less than 24 h.
Unlike the hold pressure for the pressurecontrolled test, the hold 285.5 for the yield test is not known in advance of the test but is determined during the test from the actual behaviour of the test section in situ. This is evidenced by a drop in the rate of pressure loss. Falling pressure readings are reliable and convenient, and the calculations are simplified if readings are taken in pressure decrements of kPa each.
The Standard recommends that the air content should be shown to be insignificant or should be measured, and provides a simple field method in Appendix F.
Standards may also be withdrawn.
SCOPE OF ACCREDITATION
The sensing element and, where necessary, the instrument shall be protected against the effects of ambient and extraneous temperature sources and electrical interference. 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 highest degree of certainty approaching absolute certainty is achieved when the factor is at least 1. The format of the records should be consistent with the requirements of the operating authority. Tests for which the maximum pressure has the potential to result in yielding of any pipe under test are required to be conducted in a manner that monitors the amount of straining during the test.
The testing liquid is normally water, but provision is made for the use of certain hydrocarbon liquids that do not vaporize rapidly. The Standard provides a table of allowable unaccountable test fluid leakage rates for each of the four Location Classes defined by AS This level will commonly be at least 0. The maximum hold period is set at 8 h 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.
It will 28885.5 noted that cold expansion has introduced a linear portion and a relatively high half-slope end-point. This Standard also provides additional information on a number of subjects, which would assist the experienced and competent person in the preparation of the test program and the assessment of the test, and would contribute to the understanding of the testing of pipelines by approving authorities, owners, designers, and contractors.
Strength tests may be carried out by raising the pressure to a predetermined level and holding for a fixed time. If the pressure is below kPa, air in the test section may mask the ability to detect leaks. The minimum strength test pressure and leak test pressure at the highest and lowest points of the test section, and their relationship to the pressure at the measuring 28855. It should be realized that ae the dissolution rate is very low, the relevant amount of air is expelled immediately when the pressure is reduced.
This effect of temperature rise due to adiabatic compression of the water is more noticeable at higher ground temperatures, typical of desert regions in summer and the tropics. V2 0 0.
AS Pipelines-Gas and liquid petroleum – Field pressure testing_图文_百度文库
A detailed plot of pressure in the test section against volume added to the test section is made. 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 data in Table F2 reflect the appropriate accuracy of the equipment and calculations. The straining rate may be considered to approach zero during any hold period.
Temperature-to-pressure gradients ax pressure-to-time gradients should be compared between the test sections. However, a clear definition of what constitutes a successful test is required.
If the elevation difference is ignored and the biaxial 285.5 is considered, the minimum pressure p min. Hydrostatic testing is used to establish— a b the strength and leak tightness of a test section; and the pressure strength of a pipeline for the purposes of determining or confirming the maximum allowable operating pressure of the pipeline.
Equation F1 indicates that as q increases, the curvature 285.5 the plot caused by the term V a 1? An assessment of the possibility of longitudinal or circumferential expansion due to pressure causing damage to the pipe coating.
The pressure strength is measured or calculated at the highest point in the test section. Petroleum products experience much greater temperature changes during adiabatic aa of the order of 2 to 3 times that of water.
The rate of change may be calculated over any convenient time interval for which reliable values of pressure changes are obtained.