Signature Сontrol & Ocean Physical Field Division

ELECTRIC SIGNATURE CONTROL AND CORROSION PROTECTION

The Krylov Institute provides electric signature control and corrosion protection solutions for naval & commercial ships, offshore structures, underground and underwater pipelines, as well as other metal structures operating in electroconductive media.

In the area of electric and corrosion protection the Krylov Institute offers:

• The "Kaskad"-type combined systems for electric signature control and corrosion protection of ship hull and propellers;
• Software package STAR3D-Electric for numerical simulation of corrosion protection tools for ships and other marine objects;
• A family of standard electric insulation assemblies for ship underwater structures made of dissimilar materials;
• Guidelines and instrumentation for corrosion protection quality control;
• Guidelines and software on ship electric field measurement and measurement result processing;
• Set of regulatory and technical documents on ship electric signature control and corrosion protection for design, construction and service applications;
• Development of special-purpose laboratory and sea test facilities;
• Expert evaluation of corrosion protection system designs and recommendations on rational application of protection tools.

To simulate static electric field (EF) the Krylov Institute has developed and manufactured a special-purpose facility - electrolytic basin for:

– finding surface and spatial distributions of electric potential and currents for galvanic corrosion and cathodic protection of metal structures in seawater;
– selecting the best suitable parameters for corrosion and electric signature control systems;
– validating software packages for mathematical simulation.

The facility consists of:

– dielectric basin of 2.7×1×1 m;
– fixtures for holding and positioning models in three dimensions;
– measuring probe displacement gear;
– model boundary condition setting system;
– special device for eliminating distorting effects of walls and bottom;
– measurement system for potentials and currents of model sources and electric field potential;
– computer-based data logging, processing and storage system.

Based on R & D studies the Krylov Institute has developed:

for ship design:

• rules for designing corrosion protection and electric signature control tools as well as recommendations regarding configurations of protection arrangements for various ship classes;
• guidelines and software to calculate electric field and corrosion protection parameters;
• methods for physical simulation of electric field;

for ship construction:

• combined systems of "Kaskad" type for electric signature control and corrosion protection of hull and propellers for ships of various purposes and classes;
• quality control methods for corrosion protection and electric signature control tools on building berth and during fitting-out;

for ship trials:

• guidelines on electric field measurements;
• guidelines and software for extrapolation of electric field measurements to different distances and computation of dipole moments;
• guidelines on checking out state of electric signature control and corrosion protection systems.

New generation of "Kaskad" type combined systems for electric signature control and corrosion protection

General layout of "Kaskad"type system

1 - active shaft grounding & system control unit; 2 - anode power source; 3 - slipring assembly; 4- anodes; 5 - reference electrodes (location and number of anodes and reference electrodes are shown conventionally)

Control unit and anode power source	Slipring assembly

Advantages of "Kaskad" type systems are:

– effective reduction of electric signature for "propeller - hull" galvanic couple;
– enhanced corrosion protection of propellers with provisions for protection level monitoring;
– reduction of extremely low frequency electromagnetic field related to galvanic current pulsations in the propeller shaft line;
– splash-proof slipring assembly with 28 brushes.

Main technical characteristics:

– rated output voltage 25 V;
– contact resistance between propeller and hull is not more than 10 ^-4 Ohm;
– hull protection potential control range: from minus 500 up to minus 1000 mV (relative to silver/silver chloride reference electrode) with accuracy ± 40 mV.

Distribution of electric potential U under ship hull

Guidelines on electric field measurement and measurement result processing

Guidelines determine approaches, means and procedures for measurement of electric field to be conducted for ensuring ship electric signature control and corrosion protection.

Measurements on stay	Electric field distribution under hull measured on stay

Measurements underway

Results are: – check of actual electric field levels against requirements; – detection of electric field sources; – monitoring of protection system condition; – estimation of protection system efficiency; – adjustment of "Kaskad" type system.
	Electric field distribution measured underway

	Software for extrapolation of electric field measurements provides the capability to determine electric field characteristics for conditions differing from the actual measurement conditions, e.g., for various water depth, and to recalculate field both to short and long distances from ship.
Software for extrapolation of electric field measurements