STANDARD. ISO. First edition. Petroleum and natural gas industries —. Cathodic protection of pipeline transportation systems —. Part 1. Purchase your copy of BS EN ISO as a PDF download or hard copy directly from the official BSI Shop. All BSI British Standards. STANDARD. ܚ. ISO. First edition. an Petroleum and natural gas industries -. Cathodic protection of pipeline transportation systems
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For buried pipelines, the potential measured against the reference electrode shall be measured, generally within 1 s after the protective current is switched off.
ISO – Standards Australia
NOTE 1 It can be assumed that the coupon metal will adopt a potential, with respect to the adjacent soil that is similar to the pipe-to-soil potential at a coating defect with isl same size on the pipe. Representative soil resistivity values should be obtained at pipeline depth along the route of the pipeline, and shall be obtained at various depths at prospective locations for anode groundbeds.
For high strength steels specified minimum yield strength greater than MPa and corrosion-resistant alloys such as martensitic and duplex stainless steels, the limiting critical potential shall be determined with respect ido the detrimental effects in the material due to hydrogen formation at the metal surface.
International Classification for Standards ICS is an international classification system for technical standards. The type and frequencies of further specialized surveys will depend on factors such as suspected coating deterioration, effects of elevated temperatures, construction activities, interference currents, etc.
Remedial actions shall be taken if periodic tests and inspections indicate that protection is no longer adequate.
If their use is unavoidable, the casing shall be designed to cause minimal interference with, or shielding of, the CP. The criterion for CP is therefore E u Ep The protection potential of a metal depends on the corrosive environment electrolyte and on the type of metal used. Current density requirements also depend upon the oxygen content and resistivity of the soil. The readings might not reflect the potential at the pipe-to-soil interface.
Welding of cable connections shall not be carried out on bends or within mm from pipeline welds. Monobloc isolating joints should be used wherever possible. Where some doubt exists, a combination of two or more of the methods described can provide more certainty. The basic design shall include a calculation of the groundbed resistance based upon the most accurate soil resistivity data available. CP potentials measured on thermally-insulated pipelines are usually not indicative of the potentials which exist at the metal-to-electrolyte interface beneath the coating.
Subscription pricing is determined by: This standard is also available to be included in Standards Subscriptions. The operator uses the electromagnetic induction to detect and measure the intensity of the signal using an array of sensing coils carried through the magnetic field to compute pipe current.
If permanent stabilization is required, non-metallic, perforated casings should be used. In the calculation of the groundbed resistance, the soil resistivity data corresponding to the centre-line horizontal groundbed or mid-point vertical groundbed of the anodes shall be used and the possibility of multi-layered soils with significantly different soil resistivities considered.
Generally, voltages higher than 50 V rectifier output should be avoided. For non-metallic casings and coated steel casings, if usedCP should be provided to the pipeline inside the casing by installing galvanic anodes or impressed-current polymer anodes along the bottom of the pipe, together with a reference electrode inside the casing.
This part of ISO is not intended to inhibit alternative equipment or engineering solutions to be used for the individual application.
BS EN ISO 15589-1:2017
Testing at the isolating joint should be done to assure that an interference condition has not then been introduced; NOTE While installing isolating joints will reduce the magnitude of the stray current, it also introduces another current pick-up and discharge location, hence the reason for testing at the isolating joint. By applying a direct current to the pipeline in the same manner as CP, a voltage gradient is established in the soil due to the passage of current to the bare steel at coating defects.
Measurements of corrosion potentials should be carried out at the monitoring stations prior to energizing the CP system. Buried cables should be of one continuous length ww w. If other pipeline materials are used, 155589-1 criteria to apply are defined under the responsibility of the pipeline operator.
It can also apply to landfalls of offshore pipeline sections protected by onshore-based cathodic protection installations. A further objective can be to collect data for optimization of future CP designs. As a general guide a potential difference of less than mV may be regarded as inconclusive. The monitoring plan shall include at least the following: Safety-earthing and instrument-earthing shall be mutually compatible with the CP system.
For multiple connections, the single cross-section of each conductor should be 2,5 mm2. In such cases, the pipelines shall be isolated from each other and provided with an individual negative connection to the current source.
Reference number ISO Key 1 IR Drop 2 polarization 3 rectifier on 4 corrosion potential 5 instant-on potential 6 depolarization 7 rectifier off 8 on potential 9 instant-off potential 10 depolarized potential corrosion potential X Time Y Structure-to-electrolyte potential, mV Figure A.
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