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.