Criterion for corrosion protection Polarization potential for cathodic

Criterion for corrosion protection Polarization potential for cathodic protection of steel against corrosion in soil, ground water : Upp = – 0. 85… – 1. 1 Volt relative to copper-sulfate reference electrode

MEASUREMENT OF POLARIZATION POTENTIAL WITH THE EXTRACTION OF THE OMICH COMPONENT Measurement of polarization potential in the laboratory • • • Galvanostatic method (Luggin's capillary), Tuning fork method Potentiostatic method The measured potential difference consists of the sum : - potential drop on the insulating cover - falling potential in the soil - polarization potential Ohmic component of the protective potential • Compensation methods • Auxiliary electrode method • Relaxation methods 1 - metal; 2 - double electric layer; 3 - insulation; 4 - measuring point, 5– voltmeter; 6 - reference electrode

MEASUREMENT OF POLARIZATION POTENTIAL WITH THE EXTRACTION OF THE OMICH COMPONENT Patent 43130 А, ФМІ НАН України The device VPP Connecting input terminals VPP for measuring polarization potential: 1 - wire connected to the metal (M) OK, 2 – with reference electrode (EP), 3 - with auxiliary electrode (DE). Advantages: - ease of use, - does not require placement of stationary reference electrodes underground; - does not require switching off the source

JUSTIFICATION OF THE METHOD OF MEASUREMENT OF POLARIZATION POTENTIAL WITH THE EXTRACTION OF THE OMICH COMPONENT – the capacitive conductivity of the insulation is much less than its active conductivity - capacitive conductivity of the double layer (at the defect site) shunts its active polarization conductivity - the coefficient of harmonics of alternating current, determined by the ratio of alternating and constant stresses in the soil across the route Condition for alternating current frequency 1 2 Phenomenological electrical diagram of the metal boundary with an insulating coating in an electrically conductive medium: 1 - general; 2 - direct current; 3 - alternating current Gi, Gp, Gg – electrical conductivity of insulation, polarization, soil Сi, Сp, – capacity of insulation, polarization 3 For insulating cover of underground metal structures: Operating frequency range of alternating current, Hz : 0, 2< f <2000

Triune mathematical model of underground pipeline electromagnetic field dzhala@ipm. lviv. ua

Methods of non-contact measurements of currens: radial 1 -4, 16; azimuthal 6 -9, 17; invariant 10 -12, 15 dzhala@ipm. lviv. ua

INTEGRAL observation Current distribution in 3 pipe-lines. dzhala@ipm. lviv. ua

DIFFERENTIAL observation dzhala@ipm. lviv. ua Non-contact measurement of current by BIT-KVP. - Distribution of cathode protection current J, pipe depth h, - current consumption DJ, - relative leakage of current DJ/JDz - and transient resistance Rmg(n).

Measured values and underground pipelines corrosion protection parameters determination dzhala@ipm. lviv. ua

Non-contact current meter ВСM-2 + GPS Current distribution of corrosion protection, depth of occurrence, transient resistance pipe-ground, Insulation condition monitoring. Place on electronic maps.

Information and measuring systems (IMS) for underground pipelines testing