Assemblies and methods for monitoring cathodic protection of structures

Patent metadata

Field	Value
Publication number	US-11807945-B2
Application number	US-202217886178-A
Country	US
Kind code	B2
Filing date	Aug 11, 2022
Priority date	Aug 26, 2021
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

Assemblies and methods for monitoring the cathodic protection of underground or submerged structures may include a coupon assembly including a conductive test coupon and a reference electrode for determining the voltage potential difference of the protected structure without substantially interrupting surrounding current sources. The reference electrode may be at least partially covered with an electrolytic material in electrical contact with the surrounding environment via a plug including a porous material. A method of installation of the assembly may allow a single technician to install the coupon assembly using a probe rod without extensive on-site excavation. The coupon assembly may be configured to seat securely with the probe rod for stability during installation, and release from the probe rob when the probe rod is separated from the coupon assembly and withdrawn from the ground, leaving the coupon assembly at a preselected depth or preselected distance from the protected structure.

First claim

What is claimed is:

1. A method for installing a cathodic protection coupon monitoring assembly to monitor cathodic protection of an at least partially buried structure or an at least partially submerged structure, the method comprising:
passing lead wires from a coupon assembly through a probe rod, the coupon assembly including an electrically conductive test coupon and a reference electrode, the probe rod comprising an elongated rod member extending between a proximal rod end provided with a grasping portion and a distal rod end at least partially including a rod cavity;
engaging the coupon assembly with the rod cavity at the distal rod end of the probe rod;
tensioning the lead wires, thereby to stabilize the coupon assembly at the distal rod end of the probe rod;
while tensioning the lead wires, inserting the probe rod and the coupon assembly to one or more of a preselected depth or a preselected distance relative to the structure;
releasing tension on the lead wires;
withdrawing the probe rod from the preselected depth, leaving the coupon assembly at the one or more of the preselected depth or the preselected distance; and
connecting the lead wires to an electrical junction in communication with a testing device configured to facilitate measurement of potential differences detected by the coupon assembly.

2. The method of claim 1 , wherein inserting the probe rod and the coupon assembly to the one or more of the preselected depth or the preselected distance comprises forming a pilot hole at a preselected distance from the at least partially buried structure or the at least partially submerged structure, and then inserting the probe rod and the coupon assembly into the pilot hole.

3. The method of claim 1 , wherein the electrically conductive test coupon includes a hollow interior at least a partially filled with a hardenable filler configured to protect the interior of the electrically conductive test coupon from corrosion.

4. The method of claim 1 , further comprising obtaining a calibration measurement to measure a potential difference between a reference electrode and the at least partially buried structure or the at least partially submerged structure without interrupting one or more surrounding current sources.

5. The method of claim 1 , further comprising:
obtaining a polarized measurement of the potential difference between a reference electrode and the electrically conductive test coupon without interrupting one or more surrounding current sources, and wherein obtaining the polarized measurement comprises averaging a plurality of potential difference measurements over a selected time interval;
comparing the potential difference between the reference electrode and the electrically conductive test coupon to known cathodic protection criteria; and
determining, based at least in part on the comparing, whether the at least partially buried structure or the at least partially submerged structure has corrosion associated therewith.

6. The method of claim 1 , further comprising:
removing a cap from a distal end of the coupon assembly;
filling at least a portion of the coupon assembly with an electrolyte; and
replacing the cap so as substantially to seal the electrolyte within the coupon assembly.

7. The method of claim 1 , wherein the structure is at least partially buried in soil, the soil having one or more soil characteristics, and wherein the step of inserting the probe rod and the coupon assembly to the one or more of the preselected depth or the preselected distance relative to the structure comprises inserting the probe rod and the coupon assembly to one or more of a representative preselected depth or a representative preselected distance, such that soil at the representative preselected depth or the representative preselected distance has representative soil characteristics consistent with the one or more soil characteristics, the one or more soil characteristics comprising one or more of temperature, pressure, moisture content, chemistry, chemical additives, or solids loading.

8. A method to install a cathodic protection coupon monitoring assembly, the method comprising:
passing lead wires from a coupon assembly through a rod cavity of a probe rod, the probe rod including a rod member extending between a proximal rod end and a distal rod end, the distal rod end at least partially including the rod cavity, and the coupon assembly including:
a first fitting,
an electrically conductive test coupon adjacent the first fitting,
a reference electrode, and
a second fitting positioned between a distal end of the coupon assembly and the electrically conductive test coupon, the second fitting including a fitting chamber configured to be at least partially filled within electrolyte, and the reference electrode at least partially inserted within the fitting chamber;

engaging the coupon assembly with the probe rod;
inserting the probe rod and the coupon assembly to a preselected depth;
withdrawing the probe rod from the preselected depth so that the coupon assembly remains at the preselected depth; and
connecting the lead wires to an electrical junction in communication with a testing device configured to facilitate measurement of potential differences detected by the coupon assembly.

9. The method of claim 8 , wherein inserting the probe rod and the coupon assembly to the preselected depth comprises forming a pilot hole, and then inserting the probe rod and the coupon assembly into the pilot hole.

10. The method claim 9 , further comprising:
forming the pilot hole in soil with the probe rod; and
injecting water through one or more perforations in the probe rod, thereby to stabilize the soil surrounding the pilot hole.

11. The method of claim 8 , wherein the electrically conductive test coupon includes a hollow interior at least partially filled with a hardenable filler configured to protect the hollow interior of the electrically conductive test coupon from corrosion.

12. The method of claim 8 , further comprising: tensioning the lead wires to stabilize the coupon assembly at the distal rod end of the probe rod; releasing tension on the lead wires; and
obtaining a calibration measurement to measure a potential difference between the reference electrode and one or more of: (a) an at least partially buried structure, or (b) an at least partially submerged structure without interrupting one or more surrounding current sources.

13. The method of claim 12 , further comprising:
obtaining a polarized measurement of the potential difference between the reference electrode and the electrically conductive test coupon without interrupting the one or more surrounding current sources;
comparing the potential difference between the reference electrode and the electrically conductive test coupon to known cathodic protection criteria; and
determining, based at least in part on the comparing, whether the at least partially buried structure or the at least partially submerged structure has corrosion associated therewith.

14. The method of claim 8 , further comprising:
removing a cap from the distal end of the coupon assembly;
filling at least a portion of the fitting chamber with an electrolyte; and
replacing the cap so as substantially to seal the electrolyte within the coupon fitting chamber.

15. The method of claim 8 , wherein the structure is at least partially buried in soil, the soil having one or more soil characteristics, and wherein the step of inserting the probe rod and the coupon assembly to the preselected depth comprises inserting the probe rod and the coupon assembly to a represe

Assignees

• Marathon Petroleum Co Lp

Inventors

• Ell Ryan Grant

Classifications

• C23F13/22 Primary

  Monitoring arrangements therefor · CPC title

• G01N17/046

  Means for supporting or introducing coupons · CPC title

• C23F13/04 Primary

  Controlling or regulating desired parameters · CPC title

• C23F2213/32

  Pipes · CPC title

• C23F2213/31

  Immersed structures, e.g. submarine structures · CPC title