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T ERN A T I O N A L
CORROSION 2011 CO~'~FEREI\JCE & EXPO
DEVELOPMENT OF DEVICES TO PREVENT VANDALlSM OVER CATHODIC PROTECTlON COMPONENTS IN SOCIAL CONFLlCTED REGIONS Jorge Canto Corros ion y Proteccion Ingeneria, S.C. Rio Nazas 6. Cuernavaca , Morelos. Mexico. 62290.
Corrosion y Proteccion Ingeneria , S.C.
Rio Nazas 6. Cuernavaca , Morelos.
Lorenzo M. Martinez-dela-Escalera Corros ion y Proteccion Ingeneria, S.C . Rio Nazas 6. Cuernavaca , Morelos . Mexico.62290 .
Jorge A. Ascencio(1) Instituto de Ciencias Físicas , Universidad Nacional Autonoma de Mexico, Ave Universidad 1001 , Col. Chamilpa , Cuernavaca , Morelos. CP 62210 .
Arturo Godoy Corrosion y Proteccion Ingeneria , S.C . Rio Nazas 6. Cuernavaca , Morelos. Mexico. 62290. Fernando Rubi Corrosion y Proteccion Ingeneria, S.C. Rio Nazas 6. Cuernavaca , Morelos. Mexico. 62290 .
Lorenzo Martínez Corrosion y Proteccion Ingeneria, S.C. Rio Nazas 6. Cuernavaca , Morelos. Mexico. 62290 . Leonardo De Silva-Munoz, Instituto de Investigaciones Eléctricas Reforma 113, Cuernavaca , Morelos, Mexico 62490 .
ABSTRACT Vandalized rectifiers , anode beds, wirings, and power transformers are common causes of cathodic protection (CP) fa ilure and corrosion problems for Mexican pipelines. The cost of replacing vandalized rectifiers , ground beds , cables and transformers , and the resulting corrosion damage to pipelines has a serious economic impact. In recent years, vanda lism has increased being hammer and chisel the main tools employed by vandals. In order to deter this kind of actions, a novel approach is needed for the protection against vandalism for CP systems. Concealing , dissuading , alerting , and strengthening are the key conceptual basis of a set of devices and strategies that were developed to protect CP components in socially hostile environments. We present the design of a double layer reinforced concrete bunker for the protection of deep anode bed top sections providing mu ltiple vents for anodicreaction products, alarm wiring, and a cavity for manual measuring of the anode current. For rectifier protection , a system was developed in order to conceal and protect a rectifier under the floor level , where it can only be drawn out employing a magnetic handle. Finally, the use of plastic instead of concrete for pipeline CP system test stations was proposed along with high impact signs that better communicate the dangers of excavating on pipeline right of ways. Keywords: Cathodic protection systems , vandalism, anode beds , hydrocarbon pipelines
Consultant at Corrosion Corrosion y Proteccion Ingeneria, SC .
© 2011 by NAC E Intem ational. Requests fo r pcrmi ssion to pub lis h thi s ma nu scrípt In an y form oin part or in w hol e . mu st be in writ ing to NACE Intem ationa l , Publicatio ns Oi v ision, 1440 Sou th Creek Orive. HOll5to n , Texas 77084 . The materia l presente d an d th e views ex pressed in th is pape r are so le ly those of the author(s) and a re not necessari ly en dorsed by the As sociati on.
The use of pipelines for transporting hydrocarbons through different regions of Mexico involve performing different prevention , maintenance, inspection and corrective tasks in order to ensure the integrity of the pipeline networks. Corrosion risks are one of the highest concerns of pipeline network managers . They can have a serious impact on pipeline integrity that can derive into catastrophic events . Pipeline corros ion is controlled through induced current cathodic protection (CP) systems ; however, CP system failures are often encountered (1),(2) This is illustrated in figure 1, where results of a survey of 483 rectifiers of CP systems localized on the north and west of Mexico showed that around 15% of the rectifiers were not operating. Considering that a rectifier normally protects kilometers of pipelines, one damaged rectifier can considerably increase corrosion risks and thus augment the probability of catastrophic pipeline failures. During the survey , it was found that the main reason behind rectifier malfunction was vandalism and theft of cables, structures and electrical equipment. Increasing security and social education campaigns implemented by pipeline owners has had a limited success , thus, a new approach is needed in arder to stop CP systems destruction by thieves and vandals .
Figure 1. From a universe of 483 rectifiers inspected, over 15% of all rectifiers were found not working (red dots) due mainly to vandalism. Considering the special requirements of cathodic protection system elements and installations in arder to fulfill their purpose, and after analyzing the methods used by thieves when stealing and destroying CP system hardware , three solutions are presented for the protection of three vital CP system elements: rectifiers, deep anode beds and test stations . The proposed systems have been implemented in the field in order to test their performance under real conditions and to detect possible design flaws . AII systems and components presented are under an intellectual property protection process . VANOALlSM ON CP SYSTEMS ANO COMMON PREVENTIVE ACTIONS
Most vandal acts on CP systems throughout the country share four common characteristics : 1) Attacked sites are usually remote; 2) Stolen components are easy to sell or are useful as improvised construction elements or electrical installations; 3) Minimal effort is required for extracting components of interest. 4) Attacked sites are usually quite visible.
Although extraction methods and damage extent vary considerably between attacked sites, common stolen components are rectifiers, cables, concrete structures, and either parts or whole concrete test stations (figure 2).
Figure 2. Vandals can target almost every component of a CP system such as a) rectifiers, b) ground beds, and c) test stations and grounding copper rods. d) From a sample of over 483 rectifiers, over 80% have a 1OOVolts / 1OOAmps capacity, however less than 75% are operated over 50 amps. One particular issue that considerably increases the economic impact of CP system vandalism is the fact that most of the rectifiers installed along the studied pipelines are over dimensioned. While the majority of the rectifiers have capacities of 100 volts and 100 amperes, most of them operate under 50 amps (figure 2d). Rectifiers of 100V/1 OOAmps have a lot of copper, the principal material searched by the vandals. This means a high profit for a little effort for the thieves and very high cost for pipeline owners. Several attempts have been made in order to hinder vandal acts on hydrocarbon pipeline CP installations. One example is installing rectifiers at an elevated position on posts (figure 3a). This makes rectifiers less accessible to thieves; nevertheless cables can still be stolen. Another approach has been to enclose rectifiers inside concrete and metal cages (figure 3b). Such structures make thieves work harder in order to steal CP components but also increases their visibility and gives to the locals the impression that there are valuable items inside that are worth the effort. Collaboration with locals has been one of the most effective options by installing rectifiers inside buildings located on properties of local families. The family looks after the installation while they receive free electricity from the pipeline owner (figure 3c). An additional strategy that has hindered rectifier theft is to submerge rectifiers inside oil filled tanks. The rectifiers can operate normally while thieves are discouraged to tamper with an unknown substance.
Figure 3. Several approaches have been unsuccessfully attempted, including a) elevated rectifiers , b) triple housings , c) relocating rectifiers inside houses allowing owners to use electricity, and d) oil submerged rectifiers among others . PROPOSED SOLUTIONS By identifying the most common forms of vandalism on CP elements and by taking into account the requirements for CP installations, the following strategies were proposed: • Substitute over dimensioned rectifiers by smaller and more adequate units. As mentioned above, most of the 483 examined rectifiers had a capacity of 100 Volts and 100 Amps while most of them operated under 50 Amps. Installing 50V/50A rectifiers will lower damage repair costs in case of vandalism; in addition , having less copper than the 100V/100A rectifiers , thieves will find them less attractive. • Concealing rectifiers underground . Installing rectifiers and transformers inside underground enclosures with special locking mechanisms will allow rectifiers operate without being detected by thieves. In case of being found, the enclosures should be strong enough to stop or discourage any vandal actions . • Protecting deep anode surface installations inside concrete bunkers. Deep anode bed cables are normally accessible to ma intenance personnel in order to measure the current drained by the anodes . This means that cables are also accessible to vandals who usually steal cables and anode bed components. By constructing concrete bunkers above deep anode installations with a cavity that allows manual current monitoring upon protected cables, the anode beds would remain accessible to maintenance personnel but practically impossible to steal. • Embedding cables in concrete . Sometimes thieves need to access only two points along buried cables in order to steal them by cutting them and then' pulling them out. By embedding in concrete all cables, pulling out the cables becomes impossible .
â€˘ Polymer test station structures. Concrete test stations can be used as construction elements for improvised housing. They are also vulnerable to the elements and easily damaged by vehide impacts . Using plastics instead of concrete for test station structures reduces their attractiveness for thieves, and improves their resistance to impacts and to the elements .
Concealed Rectifier As mentioned aboye, the proposed approach in order to protect rectifiers from vandalism is to install the rectifier inside underground enclosures . In this design , the rectifier in installed inside a removable box that resides inside an underground cavity. With the rectifier in place, the only thing visible is a metallic rectangle on a concrete floor . The box can be removed from the cavity by using a magnetic handle that attaches magnetically to the smooth surface of the box. The enclosure is equipped with an air based cooling system, a vibration sensor, and a bolt lock (figure 4ab).
20 21 Figure 4. Invisible rectifier system, a) design scheme , b) actual working prototype and c) temperature variation at the center of the rectifier , during operation with the cooling system on (red bars) and off (blue bars). A working prototype was constructed and tested. The tests confirmed that the use of a cooling system was necessary in order to keep the rectifier temperature at an acceptable level (45Â°C instead of 75Â°C) and that the use of air as cooling media was enough for an adequate temperature control (figure 4c).
Concrete Bunkers for Protection of Rectifier and Anode Bed Installations. To complete the protection scheme for the rectifiers , a concrete bunker is propo sed with a double layer of steel reinforced concrete . The concept is described in figure 5. In the case of anode beds, in order to avoid theft of anode bed components and cables , a smaller enclosing steel and concrete structure is proposed. The structure consists of two steel cages embedded in concrete that endose the upper part of an anode bed installation (figure 5) . The concrete bunker can effectively protect the anode bed installations from vandal attacks. This has been proven on the field even in high vandalism risk areas. Inside the bunker, an alarm system alerts maintenance personnel in case of
security breach. The bunker also features gas vents for releasing the gases produced by the anodes , and a small cavity that allows maintenance personnel to perform manual measurements and diagnosis upon the anode bed components without compromising components safety.
Figure 5. Diagrams (a ,b) and component list (e) of a bunker for an invisible underground rectifier. Construction steps of a deep anode bed bunker in a high conflict region at Rosarito B. C. Mexico (d足 f) . Polymer test station
Vandals usually use cathodic protection system test stations beca use of their structural rigidity that is useful for improvised housing construction . Plastic test stations were designed and tested as
substitutes to traditional concrete test stations. Plastic is cheap , easier to transport and to install and is more resistant to the elements. Among the common problems encountered that compromised the integrity of test stations are accidental impacts from vehicles; using plastic instead of concrete can make test stations more resistant to this kind of events . One of the main reasons cathodic protection systems are vandalized is the lack of information about the hazards associated to the excavation on pipeline right of ways and of the importance of cathodic protection systems to their safety. With this on mind, the new test stations were designed with brighter colors and with more dramatic signs indicating the nature of the buried pipelines and cables, their function and the risk of tampering with them. Local dialects and languages of pre-Hispanic origin were also used along with Spanish in arder to better send the desired message. This strategy along with the use of plastic has demonstrated to be effective against vandal attacks upon test stations.
Figure 6. Polymer test station, using high impact communication signs, including pre-Hispanic languages still widely used among some regions of Mexico. The combination of the proposed solutions has proven to be effective against vandalism . It has been considered to implement these solutions in other regions with high vandal activity upon cathodic protection system installations.
CONCLUSIONS In arder to protect hydrocarbon pipeline cathodic protection system installations from vandalism and deft, one of the main reasons behind pipeline CP system malfunction in Mexico, a number of strategies were proposed and implemented on the field. The proposed solutions effectively stopped intentional and unintentional damage to CP system components even in high vandalism risk areas . Implemented on a major scale, these strategies can have an important impact on pipeline integrity management, as properly working cathodic protection systems are extremely necessary for pipeline networks, and can also dramatically reduce maintenance costs associated to frequent CP system failures and to stolen equipment replacement. Finally, stopping vandal actions upon CP systems increases safety and reliability of pipeline networks.
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ACKNOWLEDGEMENTS This work was supported by CONACYT INNOVAPYME C0003-2010-01 Jorge Cantó, Lorenzo M. Martínez de la Escalera Hernán Rivera and Arturo Godoy al50 recognize the help of a doctoral scholarship of CONACYT. We also thank the support of the Secretaria de development of this of research.
Economico de Morelos to the
This work was also by the technical support of Francisco J. Arturo España, Roberto Ramirez, Miguel Camacho, Fernando Benitez, José Luis Bernal and Cesar Carvajal.