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36 for the project cannot provide the required current. To reduce had been installed on top of the existing jacket and therefore the resistance of the circuit and keep the system partially oper- the cathodic protection system was unable to function. ating, the owner has to regularly spray water on the underside of the approach slabs to reduce system resistance. INSTALLATION AND QUALITY CONTROL Design could also include the impact of other systems Proper installation is necessary for the success of any system. present on the structure. For example, the cathodic protection Therefore, qualified individuals must be used to install cathodic system on the bridge carrying I-64 in Norfolk, Virginia, can- protection systems. If qualified installers are not available, not be operated owing to supposed interference between the then the installers might be required to obtain assistance from rectifiers and other electrical systems on the bridge. This sys- qualified consultants who can provide guidance and quality tem was installed to protect approximately 400,000 square control. feet of the deck surface area. Upon energization of the sys- tem, it was observed that the rectifier cards were failing with- A qualified quality control and quality assurance provider in weeks. When operational, the system was providing ade- must be included in the installation process. There are several quate protection. The cause of the burnout of the rectifier examples of systems that are nonoperational from the time of cards was not confirmed; however, several theories were put installation. On the underside of the roadway of the Brooklyn forth by the involved parties including short circuits, ground- Battery Tunnel, a mixed metal oxide mesh anode was installed ing problems, interference from alternating current on the and encapsulated with shotcrete. Improper installation resulted bridge for lighting, etc. (34). A review of the impact of the in the shotcrete disbonding from the underside of the roadway cathodic protection system into the bridge electrical grid was at many locations. The problems were not identified during never conducted. In another example, an impressed current installation. This multimillion dollar system had to be dis- cathodic protection system on a bridge deck or decks in New carded as it was not fully functional (50). A similar problem Jersey failed to provide corrosion control because the design- was encountered on the Queen Isabella Causeway in Texas; ers had not included the impact of corrugated metallic forms however, owing to good quality control, the encapsulation was present at the bottom of the bridge deck(s). Owing to its large properly installed after three attempts and the system func- surface area, a majority of the cathodic protection current tioned as expected. Similarly, during installation of a mixed was received by the corrugated forms and an insufficient metal oxide mesh system on the top and the bottom surface of amount was received by the reinforcement. The failure of the the historic arches of the Jefferson Street Memorial Bridge in zinc foil with adhesive anodes on the hammer heads of the Fairmont, West Virginia, a trained and experienced inspector James River Bridge and the Route 58 eastbound lane over was able to detect the slight variation in the color of the anode, Leatherwood Creek (both in Virginia), was attributed to the which implied that the mixed metal oxide had not been sin- orientation of the panels of zinc in the vertical direction, tered to the titanium expanded mesh. The supplier denied it at which allowed water to flow along the joints and enter the first and had the contractor install the defective material. Test- space between the anode and the adhesive resulting in dis- ing of the suspect mesh verified the lack of mixed metal oxide bondment (34). on the mesh and it cost the contractor $500,000 to correct the problem. The last reported inspection, after 5 years of opera- Placement of rectifiers on bridge decks where they are tion, indicated that the system is functioning as designed. susceptible to lightning strikes required the Virginia DOT to keep replacing several control cards every year on the James Electrical shorts between the anode and the reinforcing River Bridge when the conductive paint system was installed steel are the most common problems encountered in the instal- on the hammerheads. The rectifiers had alternating current lation of these systems. A rigorous testing schedule must be and direct current lightning arrestors; however, these arrestors maintained to ensure that there are no shorts, especially in were destroyed after the first lightning strike and the control impressed current systems. Many systems have failed as a cards were damaged during subsequent strikes. The project result of the presence of shorts. manager for DP-84 indicated that in several projects in which DP-84 was involved, rectifiers suffered damage from light- ning strikes. Thus, design could also include a careful selec- MONITORING AND MAINTENANCE tion of the placement of the rectifiers and protection against lightning and vandalism. The respondents in the survey have made it clear that monitor- ing and maintenance of the cathodic protection system is too In addition to good design, a detailed set of specifications burdensome and that most agencies are finding it difficult to is required for installation. The specifications would take into cope with this process. Initial cost and monitoring are the fac- account the actual condition of the structure. In one project in tors that discourage the application of cathodic protection sys- Florida, the zinc expanded mesh system in a jacket failed to tems. Of the twenty-four respondents who have at least one provide adequate cathodic protection. Analysis of the failure cathodic protection system, only 10 monitor them as summa- indicated that the project specifications did not provide any rized in Table 17 in chapter four. Therefore, 14 agencies do not instructions to remove the existing jacket and the new jacket monitor their cathodic protection systems. Among the respon-
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37 dent states, only five monitored all of the systems, with TABLE 22 another four monitoring only some. The province of Ontario STATUS AND OPERATION OF CATHODIC PROTECTION SYSTEMS indicated that owing to downsizing of the government and the outsourcing of maintenance, it is concerned about its ability to Question Yes No monitor and maintain impressed current systems and are more Is the current status of operation of all or some of 11 11 inclined to use galvanic systems in the future. Texas does not the cathodic protection systems available to the agency? believe it can monitor and maintain the systems and therefore While they were operational, did the cathodic 15 2 does not use them. Utah had a total of seven systems, all of protection systems stop corrosion and extend which failed because they were not able to monitor and main- the remaining service life of the reinforced tain them and also because personnel involved with those pro- concrete component? jects are no longer with the department and very little if any If not, has a cause been determined? 4 2 information is now available. Only nine agencies indicated Note: Table based on results of Questions 41, 44, and 45 of the survey. that they have at least one person to monitor their cathodic protection systems and five believed that they had sufficient Site visits by the SHRP team before 1992 uncovered staff to monitor all of their systems. Monitoring and mainte- some systems that were believed by the agencies to be oper- nance being a significant burden was selected by the most ational, but had either failed or were powered off (51). The respondents (12) as a reason for not selecting cathodic protec- owners did not have the correct information on the systems tion systems in the future as noted in Table 21. Ohio, which in their jurisdiction. Under FHWA Demonstration Proj- had started to use cathodic protection systems in the 1980s, ect 84, similar experiences were discovered in several has lost all personnel who were familiar with the systems and states. Agencies believed that their systems were opera- at present even status information on these systems is not tional when, in actuality, they were not. In one instance, the available to the agency. present staff of the agency did not even know that they had a cathodic protection system in their jurisdiction. Table 22 summarizes the responses to the question that asked if the TABLE 21 agency was aware of the status of the cathodic protection NOT INCLINED TO USE CATHODIC PROTECTION systems they have. IN THE FUTURE No. of Seven of the 22 respondents to Question 42 (Table 23) Reason Respondents indicated that they had less than 5% of their cathodic protec- Cathodic protection system did not work at all 3 tion systems operational. In Question 47 (Table 24), most Cathodic protection did not stop corrosion and 0 respondents believed that the failure of their cathodic protec- concrete repairs were required after cathodic tion systems could be attributed to insufficient current output protection installation within the by the system owing to improper settings. Improper current first 5 years settings are a symptom of inadequate monitoring and main- Cathodic protection components failed and could 7 tenance and can be easily rectified and not be a reason for the not be maintained inadequate performance. Monitoring and maintenance was a significant 13 burden Many of the disappointing experiences have resulted The agency does not have the resources to 7 from failure of systems as a result of insufficient monitor- monitor and maintain the cathodic protection ing and maintenance; many agencies simply do not have the system resources. Some agencies installed systems for non-technical The technology is not well understood by the 3 agency reasons. As their understanding of the technology and their confidence in its ability to provide protection were inadequate, The consultants are not well versed in the 1 technology to recommend it to the agency sufficient motivation did not exist to allocate the necessary resources. In some instances, the agencies did not appreciate Applicators and contractors that do business with 2 the agency do not have any experience with the technology TABLE 23 PERCENT OF SYSTEMS OPERATIONAL Experience of other agencies suggest cathodic 1 % Cathodic protection is too complicated, does not work, is Protection too expensive, and requires significant Systems No. of Responses monitoring and maintenance Agency staff with experience in cathodic 2 5 7 protection has retired or have been promoted 20 0 and new staff have no experience with cathodic 40 2 protection 60 2 Cost of cathodic protection was relatively higher 10 80 4 then other options 100 7 Other 3 Note: Table based on results of Question 42 Note: Table based on results of Question 31 of the survey. of the survey.