Cathodic Protection Training Course


Module 15

Computerisation of cathodic protection and corrosion control



The 'DYNAMIC' project.

This project was born of discussions with computer software engineers and the need to present an overall 'picture' of a complete network of pipelines, rather than dealing with each individual pipeline as if it were an independant unit. As detailed in the previous pages, the electrical balance of a cathodic protection system can be modeled to give an idea of the electrical current flow. In reality, there is never a single cathodic protection system which is the sole influence on a pipeline, and this presents difficulty when trying to visualise the effects of all systems on one another.

The DYNAMIC project was a proposal to make an active computer map of the pipeline network which would calculate the effect of all the electrical influences, that could be detected. Discussions were held with a computer 'software house' that had produced the control system for the national electricity grid of the UK, and they conducted a feasibility study on the technical aspect of the project.

A broad specification was written and a paper published, internationally, to establish a priority date and copyright on the concept. A team was gathered, to handle the project and they are available when a client is identified.

In the mean time, work has progressed at the 'bottom end' of the project with the working models of corrosion cells, groundbed current distribution, 'junction box' circuit analysis model, interference simulation, schematic mapping, and modelling of the various monitoring and measuring techniques.

It has become apparent that the use of a computer worksheet (such as Excell) allows the use of the schmatic to extend to a convenient method of storing and accessing all information relating to a pipeline network.

The concept can now be applied to a pipeline system and a specimen can now be examined.



The operator can first view the whole schematic of the pipeline network to establish an image of the relative position of the location to be examined.



This small image can be enlarged when the location has been identified and the operator can go to the larger schematic, which has notes built under the features.



In this example, the green lines represent pipelines, the green 'cells' represent manifolds, and the blue cells represent oilfield gathering centres.



The notes contain a broad description of the item, such as pipeline specifications, date of construction and leak details.



Using the 'Formula' menu, the user can then 'go to' the individual field schematic which shows the layout of the pipelines in this particular area.



This schematic also shows the latest cathodic protection, voltage readings, at the positions that they were taken.



The computer transfers this information from the data entry form which can be adopted to accept readings direct from a compatible data-logger.



Eriemu Input Form

WH no CP WH CP FS CP FS noCPEriemu Grid ref. Eg316 fl 1s 2.6 360 1090 1200 50410 fl 1l 2.6 360 1090 1200 506 fl 2l 1.8 390 1110 1202 490 fl 2s/3s 1.8 390 1110 1202 488 fl 4s 1.7 370 1080 1204 468 fl 4l 1.7 370 1080 1204 466 fl 5s 2.1 370 1080 1206 464 fl 5l 2.1 370 1080 1206 462 fl 6s 2.8 410 1180 1208 472 fl 6l 2.8 410 1180 1208 470 fl 7s 2.6 400 1180 1210 498 fl 7l 2.6 400 1180 1210 496 fl 8l 4.8 410 1180 1212 478 fl 8s 4.8 410 1180 1212 480 fl 9s 2.9 410 1180 1214 476 fl 9l 2.9 410 1180 1214 474 fl 10s 3 380 1170 1216 502 fl 10l 3 380 1170 1216 500 fl 11s 0.8 360 1200 1218 458 fl 11l 0.8 360 1200 1218 456 fl 12s 1.8 390 1110 1220 494 fl 12l 1.8 390 1110 1220 492 fl 14s 0.7 380 1120 1222 460 fl 14l 0.7 380 1120 1222 458 fl 16s 0.8 380 1210 1224 452 fl 16l 0.8 380 1210 1224 450 fl 17s 2.2 450 1200 1226 484 fl 17l 2.2 450 1200 1226 486

Features, such as leak locations, can be added to the schematic to aid analysis. In the example, below, it can now be seen that these two leak sites are associated with a pipeline crossing and there could have been stray current interference.



A small section of this package has already been applied in the field with notable effect. This element is designed to examine the curent readings submitted by technicians who obtain the measurements from junction boxes and pipeline connections on site.

The spread sheet is simply used to calculate the total current into a node and the total current out. If these are not equal, then it is reported as an IMBALANCE which the technician must investigate. If the reading into a conductor is not equal to the reading out of the other end of that conductor, then it is reported as a READING ERROR.

This may seem to be a very simple task, which could have been performed manually, but applying this element to records of current readings, gathered over a ten year period, showed that less than 50% could have been correct. This work had been carried out by a variety of contractors who can now be required to submit measurements which will be more meaningful.

Of course, this does not prevent the unscrupulous contractor from simply calculating the required readings himself, but that could be overcome by engaging more than one contractor (rivals). The spread sheet would show an imbalance if the results from different areas did not balance when integrated.



BENEFITS

The immediate benefit of installing the DYNAMIC package, is that it requires accurate circuit diagrams and information to model the schematic diagrams. The gathering of this information is the equivalent of a detailed audit of the operators assetts, records and staff efficiency. The effect of this can be extremely disturbing to those who have anything to hide, and this matter should not be taken lightly. It can be the most devastating form of inspection ever undertaken, as the DYNAMIC package requires all information to agree.

As a management tool, it allows any operator, access to an overview of the corrosion control situation, presented in a user friendly format that requires no specialised interpretation.

It is envisaged that the DYNAMIC package will be produced by professional computer software engineers who will create a detailed map which the operator can use to zoom into any subject area for examination. The user will be able to access all relevant information and display it in graffic format during analysis or discussion. It is possible that such a tool will reveal areas of concern before the contingency arises and assist in designing remedial measures.