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AS 2832.1-2015 pdf free download
AS 2832.1-2015 pdf free download.Cathodic protection of metals Part 1 : Pipes and cables.
The response of a structure to stray current excursions is dependent upon many factors. including soil resistivity, degree of soil aeration, moisture content and the structure coating quality. The magnitude of the stray current excursions may also be dependent on the proximity of the traction systems or in the case of telluric effects the orientation of the pipeline (see Paragraph A4). The extent of depolarization is determined by the frequency. magnitude and the duration of anodic excursions. The measured potential is the sum of the polarized structure potential and the potential from the voltage gradient in the electrolyte. When potentials are affected by stray current it may not be possible to determine the magnitude of the voltage gradients along the pipeline and to compare the measured potential with the protection criterion. In such cases, an estimation of the electrolyte voltage gradient will suffice to determine the protection criterion. This measured potential is used to determine the magnitude and duration of anodic excursions.
NOTE: Infrequent excursions lcss ihan 500 mc in duration may he excluded from the evaluation if they arc not concidered to be a corrocion rick.
Requirements for the protection of buried structures subject to traction and telluric current effects are specified in Clauses 220.127.116.11.2 and 18.104.22.168.3.
22.214.171.124.2 Truc lion current effecis
Where structures are required to be evaluated for traction stray current effects in accordance with this Clause, it is necessary to record the potential during a sufficient period of time to ensure that the maximum exposure to the stray current effects is encompassed. This period shall include the quiescent traction period, the morning and evening usage peaks and is nominally twenty four hours with a minimum of not less than twenty hours. If a data logger is used for the monitoring of potential, its frequency of sampling shall be not less than four samples per minute.
The protection criteria for structures subject to traction current effects varies with the structure polarization time as follows:
(a) Structures with short polar! ration times
Structures with sound coating characteristics, or have otherwise been proven to polarize and depolarize rapidly in response to stray current, shall comply with the following criteria:
(i) The potential shall not be more positive than the protection criterion for more than 5% of the test period.
(ii) The potential shall not be more positive than the protection criterion plus 50 mV (i.e. —800 niV for ferrous structures for more than 2% of the test period.AS 2832.1-2015 pdf free download.
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