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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Temporary and permanent connections between the test section and all associated test equipment shall be adequately ws and supported. The freedom from ruptures has been maintained even where a large number of ruptures occurred during the testing. The half-slope end-point is characterized by a rate of addition of test fluid per unit pressure 2885.5, which is excessive. During the test for air content, the pro forma of Table F1 is completed to become Table F2 by the entry in Column 3 of the total volume bled from the test section for each observed pressure.
Appendices D and E give a simple explanation of how the ae processes and testing practices at the mill affect the way the pipe will behave in the field tests.
Note the extended linear portion and elevation of the ad end-point compared with Figure D2 and Figure D3. Consideration is to be given to the effect of pressure on all components in the test section, e. Care should be exercised when pressurizing to 0.
Notwithstanding all such precautions, diurnal temperature variations may produce significant pressure variations. Dissolution takes place slowly, however, resulting in a slow pressure decline.
For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards New Zealand offer a number of update options. Where it is necessary to use more than one pig, a slug of liquid of adequate volume shall separate the pigs, to ensure that air is not entrained in the test liquid behind the last pig. Continuing solution of residual air.
SCOPE OF ACCREDITATION
In the pressure testing of pipe, the three stresses are hoop stress, longitudinal stress, and radial stress. As these procedures commonly take place over a short time interval, particularly in the case of depressurization, and backfill materials and the surrounding soil are generally of poor conductors of heat, temperature changes in the test section are to be expected. Consider the restrained test section, the details of which are given in Paragraph C. For higher test pressures, a larger volume is acceptable and the limit should be calculated and included in the test program see Appendix F.
If there are no observed leaks and the leak test is to be carried out at the same pressure, the test is simply continued with the strength-test hold period counting as part of the leak test period.
The following conditions 2885.5 The test program shall demonstrate the relative sensitivities in the rate of pressure change in the test section to test aw loss and temperature.
Where the test pressure is greater than either the mill test pressure or a previous test pressure, Paragraph A6. Units shall be converted to SI units before any rounding. The Standard provides a table of allowable unaccountable test fluid leakage rates for each of the four Location Classes defined by AS V2 0 0.
It is also assumed that the test sections are in Class R2 locations. Description of the weather and weather changes during the test.
Unless significant lengths of the test section have been pressured well above the SMYS qs see Paragraph E5a premature end-point is likely to indicate substantial quantities of under-strength pipe in the test section. The von Mises hypothesis relates the effects of three principal stresses acting at right angles to product yielding.
It is rare for a leak test to be conducted in conditions that are fully stabilized, so a very careful examination of temperature trends at each measuring point is essential. During the hold period of the leak test, changes of temperature that would result in volume changes in a free state will result in pressure changes in the constrained state of a leak test. Some researchers have suggested that a short hold period is preferable to limit the growth of defects.
No allowance is made for changes in hole size due to elasticity of the steel at different pressures. Pressures in Column 2 are absolute and the unit is kPa. 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 22885.5 during the test.
Strength test pressure at the highest point Assessment of thermal stability may be by a number of means, and these are discussed in Paragraph A4. G-frame, captive end caps, on line pipe? Strength tests may be carried out by raising the pressure to a predetermined level and holding for a fixed time.
This will remove any error resulting from the use of simple elastic strain in the higher stress ranges. Equivalent graphs may be generated electronically. This exponential-like fall in pressure is mostly due to dissipation of the heat produced during pressurization. Copies of the verification or calibration records for the — i ii primary pressure measurement instrument; device used for measurement of added volume in volume-strain tests; and iii devices used 28885.5 measurement of temperature in temperature-correlated leak tests.
A reason for the variation has to be sought and an understanding of the situation developed. The result can be compared with the actual onset of yield observed in the field pressure test.
AS Pipelines-Gas and liquid petroleum – Field pressure testing_图文_百度文库
Subject to their length, road, rail and river crossings are generally pre-tested to their appropriate maximum test pressure before being included in a test section that may have different wall thickness or steel properties. There may be temperature gradients within the water from the pipeline centre and the pipeline inner surface, and there will be temperature variation in the water and the steel along a long section of pipeline and in a pipeline with varying depths of cover.
These equations, which differ from those used in earlier editions of this Ad, take account of the fact that the compressibility and the temperature coefficient of expansion of test media vary with both temperature and pressure.
It should be possible to read reliably pressure and volume to the same sensitivity as one unit on the graph, that is, one-thousandth of the pressure equivalent to SMYS and one-thousandth of the volume equivalent to SMYS. The limit of residual air. Aw maximum hold period is set at 8 h because research suggests that no useful purpose can be served by continuing any longer; on the ass, if time-dependent strain were still occurring, continuation is more likely to be harmful than beneficial.
During pressurization, besides the heating of the water due to adiabatic compression there will be a small drop in temperature of the steel due to. Pressure change is usually measured by a deadweight tester, which is a very accurate, reliable, stable, and sensitive item of equipment. The statement shall be signed by the supervising test engineer.
Where the assessment in Clause 4. For semi-conductor probes as commonly used, a sensitivity of 0. The assessment of the unaccountable pressure change is dependent upon the pipe size, test section length, and the test pressure. The volume of air that can dissolve is approximately 20 ppm at the relevant conditions.