Innovative Methodology to Monitor the Condition Of Aged Pipelines in Petrochemical Plants
Alberto L. Geraci and Antonino Risitano Dipartimento di Ingegneria Industriale e Meccanica Facoltà di Ingegneria, Università di Catania, Italy
Massimo Dicembre Responsabile di Ispezione e Collaudi Raffineria di ERG Raffinerie Mediterranee S.p.A., Priolo, Italy
ABSTRACT
One of the major problems in older petrochemical plants is the condition of aged pipelines. A project is under development to use thermal infrared imagery, combined with eddy current methods and integrated with risk analysis procedures, to monitor such condition. The project has a tremendous potential for defining the innovative methodology the authors are proposing. They expect, if the project is successful, that the methodology, once fully developed and brought into operation, will become a significant part of maintenance programs in petrochemical plants. This will fill a gap in the existing rules for aged pipelines.
INTRODUCTION
Many old petrochemical plants are at risk because of aged pipelines. Even if the maintenance procedures are fully compliant with the required rules (ASME, API, ASTM codes) as well as with company standards and rules enforced by local Governments, there is still the risk of a defect. For instance, a crack caused by corrosion may generate a leakage of an oil product, which is extremely dangerous in terms of fire and explosion. A methodology, still under development, will help crews face this problem efficiently.
MATERIALS AND METHODS
For a number of aged lines in the Refinery of “ERG Raffinerie Mediterranee S.p.A.” at Priolo in Syracuse, Italy, sections of pipes were selected as “critical points.” These critical points included features like road crossing, flanged joints, welded areas, tees, direction changing, etc. At such points, the presence of defects is highly likely, and traditional techniques are not sufficient.
The condition of the line (“zero point”) will be defined and the evolution of the possible defect will be evaluated, in order to create a data base prototype. This also will be used to monitor the pipes using thickness measurements, thermography, and eddy current methods at regular intervals over an extended period. The proposed methodology, still under development, includes:
- Survey (on the drawings and the field) of pipes considered.
- Location of critical components according to operating conditions, construction characteristics, layout, and history (if available).
- Ranking of such components in relation to the associated risks, with definition of risk parameters.
- Organizing a survey program to fix the frequency of inspections.
- Creation of an archive of aged pipelines surveys and risk parameters evolution.
The study area is located on the ground at the base of a pier. Pipelines investigated were selected among those listed in Table 1, which shows their size and characteristics. They were selected to meet our criterion of having represented all major features of a refinery piping system. Line Number 13 (gasoline), Line Number 26 (gas oil), and Line Number 30 (fuel oil) were selected. Sections of lines selected are shown Figure 1, Figure 2, and Figure 3. Subsequently, Line Number 3 (crude oil) was included in the selection, because crude oil usually contains impurities, increasing the chance of corrosion.
| Pipeline (No.) | Product | Nominal Diameter (in) | Design Temperature (°C) | Design Pressure (kg/cm2) | Operating Pressure (kg/cm2) |
|---|---|---|---|---|---|
| 3 | Crude Oil | 34 | 85 | 17.10 | 12.80 |
| 13 | Gasoline | 12 | 7 | 13.40 | 10.00 |
| 23 | Gas Oil | 22 | 70 | 13.70 | 10.27 |
| 26 | Gas Oil | 6 | 70 | 13.70 | 10.27 |
| 30 | Fuel Oil | 20 | 85 | 17.10 | 12.80 |
Table 1. List of pipelines under investigation.
Figure 1. Sections of Line Number 13 (gasoline).
Figure 2. Sections of Line Number 26 (gas oil).
Figure 3. Sections of Line Number 30 (fuel oil).
EXPECTED RESULTS
A FLIR Systems ThermaCAM SC 3000 infrared camera helps acquire data. Different methods and times for data acquisition are being experimented, include:
- Before the sunrise.
- After the sunset.
- In the dark.
- Using a shield to avoid glare over the pipe.
- Painting the section of pipe under investigation black to improve the emissivity.
Even as the project is at an early stage, the acquisition of infrared data without sun seems to be the most promising method. A number of images are under acquisition, and many more will be taken in the next year and a half (the duration of the project). Images will be linked with data from eddy current instruments. Major features of the piping system, history of maintenance, operating and environment conditions, and associated risks are also taken into account.
Expected results using thermal infrared imagery and eddy current methods, integrated with risk analysis procedures, shows great promise. There is the general expectation this innovative methodology, once fully developed and brought into operation with the aid of computer techniques, will become a significant part of the maintenance programs at the “ERG Raffinerie Mediterranee S.p.A.” Refinery. Because such innovative methodology fills a gap in the existing rules for aged pipelines, similar petrochemical plants all over the world may find a use for it as well.
SUMMARY
For a number of aged lines at the ERG Refinery of Priolo in Syracuse, Italy, sections of pipes were selected as “critical points”, containing features like road crossing, flanged joints, welded areas, tees, direction changing, etc. The project is at an early stage. The condition of the line (“zero point”) will be defined, and the evolution of the possible defect will be determined. This will help to create a database prototype, and to monitor the pipes using thickness measurements, thermography, and eddy current methods at regular time intervals. The proposed methodology, still under development, includes the survey of at-risk pipes, the location of critical components, ranking them in relation to the risk with defining risk parameters, organizing a survey program, and the creation of an archive.
REFERENCES
Geraci, A.L., G. La Rosa, and A. Risitano, “Applications of Remote Sensing Techniques to Industrial Plants”, International Conference on Monitoring, Surveillance, and Predictive Maintenance of Plants Structures, Associazione Italiana Prove non Distruttive, Taormina - Giardini Naxos, Italy, 1989.
Geraci, A.L., G. La Rosa, and A. Risitano, “A Thermographic Method for the Localization of Leaks in In-Service Buried Piping Systems”, Second International Congress on Water Ecology and Technology, International Water Supply Association, Moscow, Russia, 1996.
ACKNOWLEDGEMENTS
The authors wish to thank the “ERG Raffinerie Mediterranee S.p.A.” for allowing inspection of pipelines to make this work possible. They are also grateful for the support of “Ispezione e Collaudi” personnel who provided additional data and information for this paper.
ABOUT THE AUTHORS
Alberto Geraci and Antonino Risitano are Professors at the University of Catania, Italy, and have been using thermal infrared imagery for more than 25 years.
Massimo Dicembre is Responsible for Inspection & Testing at ERG Refinery in Priolo, Italy.