RU2808042C1 - Protector with replaceable active element - Google Patents

Abstract

FIELD: offshore protection.

SUBSTANCE: invention relates to a system of electrochemical protection against corrosion of offshore structures using sacrificial protection. A protector with a replaceable active element for electrochemical protection of marine structures comprises at least one active element, a protector base and a cable outlet through which the protector base is connected to the protected structure. The base is made in the form of cells, inside which a reinforcing cage passes, and grippers are located at the ends of the active elements to replace these elements in case of depletion during the operation of the structure.

EFFECT: repairing a worn protective alloy on an underwater protected object without the need to replace the entire protector.

5 cl, 3 dwg

Description

The invention relates to a system for electrochemical protection against corrosion of offshore structures using sacrificial protection. The main distinctive feature of the method is the possibility of repairing the tread by replacing spent cells of the tread alloy (active element) on a working tread protection system. A protector with a replaceable active element can be used for long-term protection of underwater marine structures, both for objects already in operation with failed protector protection, and for those newly commissioned, with the possibility of extending the residual life of the protector protection.

A “Device for protecting the underwater part of metal structures against corrosion” is known (see patent RU No. 124263, IPC C23F 13/06 dated 01/20/2013) containing an anode with a place for connecting an electrical conductor, which is made in the form of a plate of sacrificial alloy attached to the bottom of the reservoir using a base placed on piles, while the length and width of the anode exceed its height.

The disadvantages of this technical solution are:

- the difficulty of replacing the tread during operation without carrying out a large amount of expensive diving construction and installation work, including due to the large weight of the tread;

- only one version of the device with the possibility of installation on the seabed and only on piles.

There is a well-known utility model “Bracelet made of protectors for corrosion protection of the underwater part of metal structures of a structure” (see patent RU No. 2270277, IPC C23F 13/06 dated 02/20/2006) which is similar to the claimed technical solution. It describes a bracelet that consists of protectors with supporting elements rigidly connected to the supporting reinforcement, made in the form of two half-cylinders interconnected. The protectors are made in the form of plates located evenly on the load-bearing reinforcement with a gap relative to each other, and the plates are rigidly connected to each other through the corresponding supporting elements of the load-bearing reinforcement.

The disadvantages of this technical solution are:

- the impossibility of replacing active tread elements during operation without carrying out a large amount of expensive diving welding and installation work;

- lack of possibility of remote execution of this design. “Protector for protection against corrosion” (see patent RU No. 85161, IPC C23F 13/08, F16B 35/00 dated July 27, 2009) is similar to the claimed technical solution. It consists of a destructible electrode and a threaded fastener. The electrode to be destroyed is made in the form of a prismatic part made of a tread alloy, and the head of the threaded fastening element is located in the body of the prismatic part with the top and side surfaces offset from the outer surface of the prismatic part. The utility model relates to mechanical engineering, to devices for the cathodic protection of metal structures from corrosion, in particular for the protection of car bodies and underbody.

The disadvantages of this technical solution are:

- the device is not intended for use in marine conditions;

- small protector sizes, which do not allow the device to be used at most oil and gas facilities.

The objective of the proposed invention is to increase the reliability of underwater marine objects by creating protective protection with the possibility of maintainability of equipment in marine conditions. The main criterion for determining the mass of the tread alloy when designing marine tread protection systems is the required total protective current flowing from the tread, which must be equal to the product of the standardized protective current density and the area of the protected structure.

When designing sacrificial protection, the design service life of systems is usually 30 years, but often, already at the beginning of operation of the sacrificial protection system, the total protection current exceeds the calculated values and does not decrease over time. This can lead to increased consumption of the active element of the protector and, as a consequence, to a decrease in the service life of the protector with the risk of emergency situations at an underwater structure due to corrosion destruction. Until now, repair or restoration of the active tread element on an underwater object was practically impossible, but the claimed technical solution can solve this problem.

This problem is solved by the fact that to implement electrochemical protection, rods are used as an active element of the protector, inside which there is a reinforcing cage with grippers at the ends of the active elements; with the help of these grips, the remote-controlled device can replace the depleted (spent) rod with a new one. The rods are installed in the base of the tread (base). For each rod in the base there is a connecting connector, which is connected to a corrosion monitoring system installed inside the base or to a common cable outlet connected to the protected structure. The number and geometric parameters of cells (rods) are calculated in accordance with the area of the protected structure. When installing the protector on the seabed (remote version), the base of the protector is connected to the protected structure via a cable (cable outlet).

The technical result provided by the above set of features is the ability to repair a worn tread alloy of the protector on an underwater protected object without the need to replace the entire protector, which reduces the cost of repairing the ECP system.

In fig. Figure 1 shows a protector that is installed on the seabed: 1 - replaceable active elements of the protector, 2 - base of the protector, 3 - cable outlet, 4 - protected structure (pipe), 6 - grips for replacing a depleted element.

In fig. Figure 2 shows a cross-section of a protector with replaceable active elements installed on a pipe: 1 - active elements of the protector, 2 - base of the protector, 3 - cable outlet, 4 - protected structure (pipe), 5 - contact connectors, 6 - grips for replacing active ones elements, 7 - casing or other mounting element on the pipe. In fig. Figure 3 shows a top view of the protector installed on the pipe.

A protector with a replaceable active element consists of replaceable active elements 1, the current from which, due to the potential difference created between the steel of the protected structure 4 and the alloy of the active elements of the protector 1, flows to the surface of the protected steel underwater structure 4, protecting it from corrosion. Replaceable active elements 1 dissolve in this case.

An electrical circuit is created: protected structure 4 - cable outlet 3 - base 2 - active protector elements 1 - protected structure 4. In the section “protected structure 4 - cable outlet 3 - base 2 - active protector elements 1”, current flows through conductors of the first type ( with electronic conductivity - metal), and in the section “active elements of the protector 1 - protected structure 4” the current flows through a conductor of the second type (with ionic conductivity - sea).

Replaceable active elements 1 installed in the base 2 are connected by cable 3 through contact connectors 5 to the protected structure 4.

When one or more active elements 1 are completely dissolved, they are replaced. To do this, a remote-controlled uninhabited underwater vehicle (ROV) swims up to the protector and uses a manipulator to grab the grip 6 of the active element 1. Next, the ROV disconnects the rod 1 from the contact connector 5 of the base of the protector 2 and performs the current operation with all dissolved active elements 1. Installation of a new active element 1 happens in reverse order. A remote-controlled underwater vehicle with a gripper 6 captured in the manipulator with a new active element 1 installed, floats up to the protector and inserts the rod 1 into the contact connector 5.

In the particular case of a protector with replaceable active elements 1, the contact connectors 5 can be made with either a threaded or another fastening unit, incl. without threaded connection.

Claims (5)

1. A protector with a replaceable active element for electrochemical protection of offshore structures, characterized in that it contains at least one active element, a protector base and a cable outlet through which the protector base is connected to the protected structure, wherein the base is made in the form of cells, inside which a reinforcement frame passes through, and at the ends of the active elements there are grippers for replacing these elements when they are depleted during the operation of the structure. 2. A protector with a replaceable active element according to claim 1, characterized in that the base of the protector is installed on the structure being protected. 3. A protector with a replaceable active element according to claim 1, characterized in that the base of the protector is placed so that it can be installed on the seabed. 4. Protector with a replaceable active element according to claims. 1, 2, 3, characterized in that the contact connectors on the base are made with a threaded connection. 5. Protector with a replaceable active element according to claims. 1, 2, 3, characterized in that the contact connectors on the base are made without a threaded connection.