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HomeMy WebLinkAboutBLUE RHINO - PROPANE EXCHANGE SYS0 -~ -- ~; ~? '~ '~~ ~?~ ,3 i _' ~ ~~ i I F +~ ,. ~'' ~~~ ~Y~' `~1 ~r (BLUE RHINO -PROPANE EXCHANGE SYS) ~' HOWARD'S MI1vI MARKET - - i 3200 PANAMA LANE ~Steve4Underwood Howard's Mini-Mart.doc ~ ~.a~~~..~.~.~~..~,.~.~~w,,,x~dan.~.~. ~.~..m.~,..~~„~,~~~,.~._~_~.,-,_~~ Page 1,L CORROSION SPECIALISTS SINCE 1993 ~ r~-itech Corrosion Control October 22, 2005 Howard's Mini Mart 3200 Panama Lane Bakersfield, CA Attention Mr. Doug Young Subject: Cathodic Protection Survey Dear Sir: P.O B o x 1 1 6 5 8 B a k e r s f I @ I d, C A 9 3 3 8 9- 1 6 6 5 8 P H 1- 6 6 1- 3 1 9- 4 7 6 0 A cathodic Protection Survey was performed on Oct 22, 2005 bf the Howard's Mini Mart Facility located at 3200 Panama Lane Bakersfield, CA. The system layout is as follows: the rectifier is mounted on the rii7Yth wall of the store stockroom. The anode bed is located at an undetermined location on the west side of the store property. The tank structure leads come into the rectifier from a westerly direction; the tanks and pump units are Ir~cated just west of the store building. In order to obtain valid cathodic protection data the reference electrode (hal# cell) was placed inplanter at the south west corner of the property. The cathodic protection tests were performed with an interrupter placed in the DC circuit at intervals of 6 seconds on and 3 seconds off. The results are tabulated in the succeeding p'a~~es. The tank meets the requirements for cathodic Protection under the Code of Federal Regulations, 40 CFR Part ~$0. The cathodic protection levels of protection were taken with regards to the following NACE Standards: • RP0169-92 Standard recommended practice: Control of corrosion on Underground or Submerged Metallic Piping Systems. • RP 0285-85 Standard recommended practice: Control bf External Corrosion on Metallic Buried, Partially Buried, or Submerged Liquid Storage Systems. • STI R892-91 Recommended practice for Corrosion Protdction of Underground Piping Networks Associated with Liquid Storage and Dispensing Systems. • American Petroleum Institute (API) Recommended Practice 1632, Cathodic Protection of Underground Petroleum Storage Tanks and Piping Systems. While the Environmental Protection Agency (EPA) and local regfiations mandate testing to be conducted on three- year intervals to determine the effectiveness of the installed systefns, experience and good engineering practice dictate that an assessment on this type of system be made on an annual basis. This, coupled with the required bi- monthly inspections by the Howard's Mini Mart Facility personnel; Will assure the continued effective operation of the installed corrosion control systems. The annual inspection of the cathodic protection systems should consist of structure-to-soil potential measurements, current output of the anode bed, and a summary report to include field data and recommendations as required. 1 Steve Underwood- Howard's Mini Mart.doc~tlTM~Y~M~ µ- ~ ~~~ ~~ vw fM~mm~~~-~µ~ Page 2 Howard's Mini Mart Facility personnel are required to record the rectifier voltage and current meter outputs on a bi- monthly basis using the form presented herein. Notifying qualifi~3d personnel immediately should the readings vary +/- 20%frorn our initial test data noted in this report is highly recomi~nended. Altech appreciates the opportunity to have assisted you in this efftirt, please call us at 661-319-4760 with questions regarding any part of this report. Respectfully, AI Perez Project Manager/ Engineering N.AC.E. Cathodic Protection Tester #23 N.A.C.E. Cert"rficated Corrosion Technologist #3811 N.A.C.E. Intermediate Coating Inspector Training I, II, III, #2039 Steve Underwood -Howard's Mini Mart O & M.doc~y~~~~ ~~~~~~ ~~~~~ ~ ~ ~~~ ~ Page'1~~ ~~ ~:= ALTECH CORROSION C0~1'['ROL SERVICE OPERATING AND MAIN~'ENANCE MANUAL CATHODIC PROTEC`~ION SYSTEMS FOR FOUR UNDERGROUND STORAGE TANKS At HOWARD'S M11~1I MART PREPARED ~~R: Howard's Mini Mart 3200 Panamai Lane Bakersfield, Ca~~fornia PREPARED ~Y: ALTECH CORROSION C~1~ITROL SERVICE P.O.Boxl if 58 BAKERSFIELD; ~A, 93389 October 22; X005 *Steve Underwood Howard's Mni~~Mart O &~M.doc ~~M~ ~~~ ~ ~ ~ ~ ~ Page 2 TABLE OF CO1~T`~'ENTS Page 1.0 Monitoring and Maintenance Procedures 1.1 Monitoring 2 1.2 Maintenance 3 2.0 Trouble Shooting 2.1 System Operation 4 2.2 Rectifier Diagnostics 7 2.3 Safety Products 9 3.0 How Cathodic Protection Works 3.1 Basic Principles of Corrosion 10 3.2 Cathodic Protection Principles 11 3.3 What Can Cathodic Protection Do and IVrtt Do? 11 3.4 How Do You Tell If A Cathodic Protection System is Working? 12 3,5 Why and How Should Records Be Kept? 15 3.6 Inspections of Structure 15 4.0 Instructions, Potential Measurement 4.1 Instructions, Anode Output Measurement 16 4.2 Test Equipment 16 4.3 Commissioning Survey Operational Data 18 4.4 Potential.Survey Data Sheets 19 2 ~.,~ Steve Underwood Howard's Mini Mart O & M.doc Page 3 ff OPERATING AND MAINTEN.AJ~NCE MANUAL GALVANIC ANODE AND IMPRESSED CURRENT CATHODIC PROTECTIOI~T SYSTEMS The cathodic protection system for the four underground service tanks consists of an impressed current system. Maintenance of the impressed .current system consists mostly of rectifier monitoring, troubleshooting, and repair. The information cr~ntained in this manual concerns itself with impressed current systems. Proper maintenance is essential for the operation of the calthodic protection system. The complete or partial failure of a cathodic protection system is not usuellly accompanied by any visible signs. Very often the only means of detection is noting the change in structure-to-soil potential through the use of electrical instruments. If there is a failure on a cathodic protection system, the relatively slow process of corrosion. resumes, resulting in eventual large repair/replacement expense to the owner. Therefore, it is important to prt~perly maintain all cathodic protection systems. In addition to the change in structure-to-soil potentials as mentioned above, several other indications of failure may be detected. Changes in rectifier output in impressed current type systems may indicate problems. If the system is totally inoperative, a drop in power consumption will be indicated on the monthly power bill. Maintenance and operation of cathodic protection systems does not require a thorough knowledge of corrosion theory; however, knowledge of the basic principles of corrosion will be useful in understanding how cathodic protection works. 'pith this understanding, measurements made during field surveys will become meaningful and the measurement techniques can be more 3 Steve~Underwood Howard's Mini Mart O 8~ M.cloc .~~ ~~ ~ ~~ ~ w ~~~ Page 4~ readily adapted to unusual situations. An introduction to corrosion and cathodic protection theory, and the significance of structure potentials is provided in Section 3.0 of this manual. 1.0 Monitoring and Maintenance Procedures For the purpose of this Operating and Maintenance 11~anua1, monitoring refers to routine inspection on a monthly basis by Howard's Mini Mart personnel. Maintenance is the more detailed testing and adjustment of the system which shoti~d be performed by qualified Corrosion Control Personnel. 1.1 Monitoring The following procedure should be followed during riir5nthly monitoring of your impressed current cathodic protection systems: • Read the rectifier voltage and current output (see rectifier data sheet, section 4.3). Rectifier output and structure potential readings shall be considered acceptable when they are within +/- 20% as compared to the respective values recorded at the time of the last annual survey. The data for the System is listed in the post installation Survey report field data (Sec. 4.3 of this manual). Because normal system adjustments maybe made during annual maintenance surveys, the most recent survey data should be referenced when evaluating the monthly maintenance readings. If the readings are acceptable, then no further field wor1~ is required. If the readings are not acceptable, then the trouble shooting procedure outlined iri Section 2.0 should be followed. 1.2 Maintenance Steve Underwood -Howard's Mini Mart O 8~ IVl.doc~~ -~ ~,~..~~~~~~ ~~.~~m~w,~.~~rr .~,.~~..~„~,~..~w~_~. Page 5 z The following procedures should be followed during the annual cathodic protection resurveys of both types of cathodic protection systems: 1. Examine each rectifier for physical damage from: vandalism, wind, clogged ventilation, lightning, exposure or overheating. 2. Read and record DC voltage, DC ain~erage and tap setting on rectifier maintenance sheets. If there are significant changes in output when compared with records of previous visits, further investigation is warranted. 3. Turn the rectifier off. Feel the diodes for uneven heating. If all the diodes are not at the same temperature, employ the trot-Y)le shooting procedures described in Section 2.0 4. While rectifier is still off, check the bolted electrical connections for heat and looseness 5. Calculate rectifier efficiency: Percent Efficiency = DC Power/AC Powet x 100 DC Power = DC Volts x IBC Amperes AC Power = AC Volts x t~C Amperes Once the rectifier unit has been inspected and read; then proceed with the potential survey for both systems. Record structure-to-soil potentialm at the following locations: 1. At all test stations. 2. At vent and product piping to monitor electrical isolation status. Anode current should be measured at each wire shunt in each system type. Anode shunts are typically located at an anode junction box at-the rectifier and at the anode test station on the galvanic anode system. All ,data should 1~e recorded on a cathodic protection survey data sheet. If the test data does not conform to the established criteria for cathodic protection, institute the trouble shooting procedures: Typical survey data sheets are found in Section 4.4 of this manual. 5 Steve~Underwood -Howard's Mini~Mart O 8~ M doe ~~~'~~~~-~ ~~~~ ~ ~ ~ ~~ ~ ~ ~~ ~ Page 6 ~ 2.0 Trouble Shooting When impressed current systems are operating improperly, several considerations should be explored prior to testing rectifier components and circuits: 1. Past Data - DC output of rectifier Structure-to-soil potentials Electrical isolation checks 2. New Construction - Cable breaks Inadvertent electrical shorts to foreign structures 3. Installation of new foreign cathodic protection systems. 4. Extensive use of DC in area. 5. Recent storms. 2.1 System Operation Many rectifier problems are obvious to the experienced technician and do not require elaborate inspection procedures. The obvious should never be ignored. The majority of rectifier failures occur from: blown fuses, loose connections, defective teeters or open DC cables: These can generally be detected by a simple visual inspection of the tinit. 1. No DC voltage and/or current. A. Blown DC fuse: If this fuse fails, a DC voltage will be observed on the rectifier meter but no current. (1) If apparently due to steady overload; reduce the output slightly. (2) If the fuse blows repeatedly, even with the output reduced, a short circuit may exist, caused by a defective rectifier component or underground short. Determine whether the short is internal or external to the rectifier. With the rectifier off, disconnect the one of the DC output cables from the rectifier and re-energize the rectifier: If the fuse still blows, the short is Steve Underwood- Howard's Mini Mart O & M doc ~~~ ~ ~~~.~~~~~~~.~ ~~ ~an ~-~Page~ 7 u internal to the rectifier. In that case, isolate the component by the procedure outlined in the following section. (3) If the fuse blows occasionally for rio~ rapparent reason, the cause maybe: (a) Temporary overload due to seasonal changes in anode bed resistance. (b) Surges of AC voltage. (c) Intermittent shorts in rectifier components. (d) Intermittent shorts in ground bed circuit. B. Blown AC fuse: if this fuse fails, neither +~nltage nor current will be observed in the DC circuit. Check the fuse with a light or AC voltmeter. Replace if necessary. Do not overlook the possibility that service to the rectifier maybe interrupted. C. Loose connections: check all connectiots, fine and coarse transformer tap adjustments and diode connections. D. Defective meters: (1) DC voltmeter - if a current output is indicated on the DC ammeter, but no voltage is observed, place a portable voltmeter across the DC terminals. If no voltage is indicated on the portsble meter, check to be sure the ammeter is not frozen by turning the unit ot~ If a voltage is recorded, check for an open in the voltmeter circuit. This can usually be done by removing the voltmeter and visually inspecting the circuit. If no defect is observed, replace the voltmeter. (2) DC ammeter - if a voltage is indicted on the DC voltmeter, but no current is observed, insert an ammeter in the DC circuit. Turn the unit off and disconnect the positive DC cable: Connect the positive terminal of the ammeter to the rectifier lug and the negative terminal to the anode cable. Turn the unit on and observe the meter. If current flow is indicated, check the ammeter circuit for loose or t~pen connections. If no defects are Steve Underwood Howard's Mini Mart O $ M doc ~~~~-~~ ~~~~~ ~ ~~'~~~~f-~ ~ ~Page 8~p observed, replace the ammeter. E. Opens in ground bed cables: one of the rilvre common problems which. develop with impressed current systems is a brew in the anode circuit. Detection of an open in either the positive or negative leg is relatively simple. Monthly data on rectifier current and voltage outputs is usod to determine if the bed has slowly deteriorated or if the cables have been severed. In most cases where a faulty DC lead is encountered, the voltage output will be near the level last recorded, but the current output will be slight, if any. The steps taken to determine which lead is open and the method to locate the break aro ~ follows: (1) Open in negative cable - if the Break is suspected in the negative connection, attach a test lead frot~i the structure to the negative DC terminal of the rectifier. If the negative cable is in fact open, the test lead will complete the circuit and currant flow will be observed. Examine the route of the negative cable to c~~termine if any digging has recently occurred in the area. If the location of the break is not obvious, use a cable locator to locate the open. Do not discount a broken connection to the structure. (2) Open in positive cable - a break in the ground bed circuit most commonly occurs in the positive leg. This is due to the fact that any break in the insulation which exposes bare copier will result in current discharge to ground at that point. A completo severance of the cable will shortly follow. If the open occurs before tie first anode, the entire ground bed will be lost. It should be noted, however, that breaks may occur at any point within the circuit. If only a portion of the anode string is disconnected, the anode bed resistance will increase appreciably. To determine if the positive leg is in ~a~t open, install a temporary anode bed and connect to the positive termin~~ of the rectifier. If current flows in the .Steve-Underwood-Howard's Mini Mart O 8~ IVl.doc ~~~~~„£~~ ~rm. ~..,~.....~.a,=~~rryµ~~w~~~F4~~.-~~~~ ~~ Page 9 temporary circuit, disconnect and tise a cable locator to pinpoint the break. Disconnected anodes within a vertical column cannot normally be serviced. Therefore, identifying the exact location of such a failure is meaningless. It maybe feasible tc~ maintain effective corrosion mitigation despite one or more lost anodes liy increasing rectifier output voltage. However, several factors must be considered, and parameters of ground bed operation are beyond the scope cf this manual. A qualified consultant should be retained before modificatitms are implemented. 2. If the DC voltage is only about half what it should lie. (use circuit resistance as calculated from previous rectifier readings) when the current output is at the maximum, the trouble maybe: A. Open circuits in one or more of the diodem 'resulting in half-wave rather than full- wave rectification. This can be determined by using the diode troubleshooting techniques described in the next section. B. Rectifier connected for 240 VAC while l~t~~VAC is being supplied. 2.2 Rectifier Diagnostics When the rectifier unit is not functioning properly, systematically isolate the components until the defective part is located. The procedure to follow is: 1. Check the line voltage by placing the leads from an AC voltmeter or circuit tester across the line side of the circuit breaker. 2.. Check across the load side ~of the circuit breaker. The voltage should be the same as at the line side. 3. Check the rectifier input tap for loose connections and to verify adjustment for the proper AC voltage. 4. Check the secondary transformer winding$ with an AC voltmeter or circuit tester. If AC voltage is applied to primary windirig~, but none is present at the secondary, J 9~~ ,~~~. ~. ..-,.~..~.,_.~..,,~y.-.,~~~ ~.~..~m_~,~..~..~...~. ..~.~..,.~.~.~~,,. ~~,~~..~..~.:..~.r~r.:,~ ~ Steve Underwood -Howard's Mini Mart O & M doc a ~ a~. Page 10 listen for an audible hum from the transformer. A. If no tone is detected, measure the t~esistance of the primary winding with an ohm-meter (be sure to turn the unit off). The resistance should be within the range from one to ten ohms. B. If a tone is detected, the resistance of the secondary winding should be measured. If either resistance was quite high, the winding is essentially an open circuit and the transformer most be replaced. Make sure that the high resistance is in the winding and not a connection lug. The entire secondary winding mad be measured between highest coarse tap and the highest fine tap. If the Circuit breaker trips, indicating a short circuit, the transformer may be isal~ted from the DC circuit by removing the secondary tap adjustment termn~lls. If the circuit breaker continues to trip, inspect for visible shorts between the transformer leads. If it holds, the short is not in the transformer but in the DC circuit. 5. Check the AC voltage supplied to the rectilier diodes. This voltage should be the same as measured at the secondary transfc~t`tner winding. If AC is present at the secondary winding, but not at the diode terminals, check the leads from the transformer to the diodes. Replace any defective lead. 6. If AC is applied to the diodes, use an ohm-meter to determine the diode resistance. Disconnect each diode and measure both i'orward and reverse resistance with an ohm-meter. The forward resistance should tie negligible and the reverse resistance infinite. If either measurement does not concur, replace the diode. If the AC circuit breaker trips, isolate the diode from the DC circuit. If the breaker continues to trip, the diode is defective and trust be replaced. 7. If the circuit breaker does not trip when the diode is removed but does when the diode is connected, there is probably a sheet in the external DC circuit. This may i i~ Steve Underwood Howard's Mini Mart O & M doc ~~~ ~'~ ~~~~~~~~~~~~~~ ~Pa~ge 11 ~ be verified by removing the anode and stniCtiire leads, one at a time. 8. If DC is present at the diode, but not at the rectifier output terminals, check for loose connections or open leads between these points. This may be done by measuring the DC voltage between the divide output negative and each point in question on the positive circuit leg. The procedure is reversed to troubleshoot connections in the negative circuit leg. 9. If DC voltage is present at the rectifier output terminals, but no current is flowing, there is an open in one of the external DC leads. 10: Faulty meters may cause the rectifier t© appear .defective when it is actually functioning properly. The meters may be rltecked with portable meters known to be accurate. 11. A faulty lightning arrestor in this rectif er (AC or DC) may be isolated by removing it from the circuit. The rectifier will operate with either or both lighting arrestors removed. END OF TROUBLE SHOOTIl'~l0 SECTION 2.3 Safety Procedures Because cathodic protection systems operate at voltages well below the shock hazard level as defined by OSHA 2207 Subpart K 1926.405(K), no special precautions during monitoring or maintenance procedures are required. - If the unit has been installed correctly with regard for AC power grounding, then no significant risk of shock hazard resulting from unit damage or malfunction will be present. 11 Steve Underwood Howard's Mini Mart O &~M.doc ;~~ ~ ~ ~ ~~ Page 12 The AC adjustment taps should be considered hazardctis. Power should be shut off to the rectifier before adjusting or servicing. As with any electrical device, servicing should not be attempted by unqualified personnel. 3.0- How Cathodic Protection Works 3.1 Basic Principles of Corrosion When a metal corrodes, electrical current is generated. Tt~e area where corrosion occurs is called the anode. The current enters the soil or other conductive environment at the anode and flows to the non-corroding area, or cathode. At the same time, an equal quantity of electron current flows from the anode to the cathode through the metal. At the cathode the positive and negative current neutralize each other. For corrosion to occur, all ~at~r parts of this circuit must be present: a current generator or anode; a conductive environment such as soil or water; an electron path which must be a metal; and a cathode. There are many reasons why a certain area on a structure inay become an anode or a cathode. If two different metals are present one will become an anode and the other a cathode; this is called galvanic corrosion. Anodes and cathodes can form on ~ single metal if there is even a slight variation in the environment between different areas on the metal. These can be differences in the amount of air which can reach the metal surface, such as can occur in loosely and tightly packed soil, differences in soil or water properties such ~s dissolved salts or acids, or differences in the moisture content of the soil. Small differences in irietal condition between different areas on the metal can also cause anodes and cathodes to forlti: These can be differences in surface condition such as abraded and non-abraded, clean and rltsty, new and old, or differences in manufacturing conditions such as hot-rolled and cold-rolled or stressed (bent) and unstressed. Even threading of a pipe can cause the threaded areas to llecome anodic to the unthreaded area of the pipe. 1 Steve Underwood -Howard's Mini~Mart O &~M.doc ~~~ ~~~~Nfr~s~ f ~ ~~L~~~~µ Page 13 While these forms of attack have different causes, they all involve the same four parts of the corrosion circuit; an anode, a positive path, a negative path, and a cathode. 3.2 Cathodic Protection Principles Cathodic protection uses the principle of corrosion. The ft~ur components of the corrosion circuit are present except that instead of having an anode on the riietal we want to protect we connect a more active anode to the metal to supply excess negative current. This makes the entire surface of the metal we want to protect act like a cathode. Corrt~sion principles say that corrosion does not occur at a cathode and we can therefore protect a metal by electrically connecting to it a current source or anode. Cathodic protection is really a farm of corrosion but by understanding the corrosion circuit we can make corrosion an ally. The cathodic protection systems installed on the 4 underground service tanks is of the "impressed current" type, in which the current is not supplied by the anodes, but is supplied by an external direct current source, in this case, rectifiers. The anodes are, however, consumed at a slow rate. As far as the protected metal is concerned, the impressed current system is the same as a sacrificial anode system: However, the current is not beittg generated by corrosion of the anode, and an inactive material such as cast iron can be used. An anode is still required so that the current can enter the environment. 3.3 What Can Cathodic Protection Do and Not Do's A cathodic protection system can, in actual practice, protect a buried or submerged structure indefinitely, provided that the cathodic protection system is, properly designed, operated, and maintained. Maintenance of cathodic protection systems does not require access to the entire , structure, so cathodic protection systems on buried storage tanks can be practically maintained. Cathodic protection is also the only practical method of protecting large buried or submerged structures which were not originally protected or on whic~i the original paint or coating protection has failed. 1 ,Steve Underwood Howard's Mini Mart O & M doc ~ ~ ~ ~ ~.w.. ~ ~Pa . e 14 _ 9v.,..~.~.~ Cathodic protection does have certain limitations. First, the structure must be surrounded by an environment which can conduct the electrical current from the anodes to the structure. In soil the conductivity is primarily due to the presence of moisture: As the amount of moisture and the amount of dissolved salts increase, the soil becomes more conductive. Soil in a salt marsh is an excellent conductor, whereas moist soil such as loam is ~ ,food conductor, and dry sand is a poor conductor. Air cannot conduct electrical currents. Therefore, structures cannot be protected above ground or out of water using cathodic protection. It is not simply coincidence that highly conductive etivironments are also usually highly corrosive. This is because the corrosion cell can act more readily over a longer distance when the conductivity of the environment is high, allowing more current to flow. Another thing that cathodic protection cannot do is to improve the condition of any already corroded structure. Cathodic protection can stop further corrosion, but it cannot "plate back" corroded metal. 3.4 How Do You Tell If A Cathodic Protection Svst~tn Is Worlun~? Because a cathodic protection system is electrical in nature; it is possible to determine whether or not a cathodic protection system is working by taking electrical measurements. Because the soil in which the structure is buried or the water in whic~t it is submerged is conductive, these measurements are usually performed using the environment as a conductor. The single most important measurement made in cathodic protection field surveys is the potential of the structure. If it is more negative than the envirottinent, it attracts positive charges that cannot leave. If positive charges cannot leave, then corrosion cannot occur. 14 Steve Underwood -Howard's Mmi Mart O & M.doc ~~fMGw~~~~%~~~ ~ ~ Page 155 Measurements of single potentials cannot be made; all that can be measured are potential differences. The potential difference between the environment and the structure can be measured using a suitable meter. If a metallic probe is used to make contact with the enviroiinent, the potential of the probe would be unknown, so a measurement of the potential difference lyetween the probe and structure would depend on two variables and would not be meaningful. In order to provide a means of contacting the environment, reference electrodes have been develoled that have stable and reproducible potentials. By measuring the potential difference betweeti a standard reference electrode and a structure, a value is obtained for the potential of the structtit~e which is dependent only on the type of reference electrode and the structure's potential. A portable copper-copper sulfate reference electrode may be used for all routine potential monitoring. The test stations each contain PVC tubes which extend down closer to the tank surfaces, to measure a more local potential at the tank. Measuring Device: The meter used to measure the potential difference between the reference electrode and the structure is similar to an ordinary volt meter. However, an ordinary voltmeter cannot be used to measure these potentials because it has too low of an internal impedance. Low impedance allows enough current to flow in the meas~ririg circuit to affect the measurement. This is primarily because the reference electrode will change potential when appreciable current flows through it. A current of 1 mA in the measuring circuit will affect the potential of the reference electrode to the point that the readings obtained are unreliable. By correctly using a meter specifically designed (10 meg ohms per volt or gt°eater internal impedance) for use in making these potential measurements, the current flowing in the measuring circuit will be kept well below 1 mA. 15 ~.,~,~.~,,,.~,~.,~~, r ~ ~,e~.~._s~.~-wN~...~.,.~ . _ ~..~, .~ ~.., .~,~ ~ teve Underwood Howard's Mini Mart O 8~ M.doc Pa a 16 ~ Electrical Connections With Structures: In making field measurements of structure potentials, the only requirement is a good electrical connection with the structure. The potential being measured depends primarily on the location of the reference electrode (hence the PVC tube described earlier), not on the place where the connection is made to the structure. Each test station contains dual test leads to its corresponding tank, for the purpose a~ establishing the electrical connection. The rectifier negative terminal should not be used for this purpose with the cathodic protection system on due to measurement error introduced by the resistance of the lead cable. When the portable reference electrode is placed close to the structure, the potential measured is that of a local area of the structure near the reference electrode. When the reference electrode is placed far from the structure, the potential measured is close to an "average" potential of the structure. Since there will probably be a difference between the local and average potential readings, it is important that when the potentials are to be compared with potentials taken earlier or later, the portable reference electrode be placed at approximately the same location each time a potential is measured. Potential Measurements: It is usually desirable to mike potential measurements with the protective current turned "on" and "off'. Whenever the potential is read with the protective current off, this fact should be recorded. When making potential measurements there are several indications that the readings obtained are not accurate; e.g. if the meter always reads exactly the satire value with the reference electrode in different locations, or if the meter reading slowly fl~ictilates over a range in excess of 10 millivolts. Normal meter behavior is to slowly approach a Stable reading. Stable readings should be reached within 10 seconds. 15 -- iSteve Underwood Howard's Mini Mart O & M doc Page 17 ~KK Typical Potential Measurements: In most environments, steel structures which are being cathodically protected have typical potentials. Unprotected steel structures also have typical potentials, although the unprotected structure potentials vary much more than the protected structure potentials. A potential between -300 and -SC10 mV vs copper sulfate is typical of unprotected corroding steel structures. A potential between -800 and -850 mV vs copper sulfate is typical of a structure completely protected. If the potetrtial is more negative than -1100 mV then the structure may be overprotected. If the structure is overprotected, as much, or in some cases even more damage maybe occurring than if the stricture were unprotected. 3.5 Wh_y and How Should Records Be Kept? One of the first indicators of malfunction of a cathodic protection system is a sudden change in operating conditions such as structure potential or rectifier output. Only by keeping good records of operating conditions can these changes be discovered promptly. The date, location, and value of all structure potential readings should be recorded. Any maintenance performed, such as anode replacement or repair of faulty connections should be recorded to identify trouble spots where possible system modification maybe required. 3.6 Inspections of Structure If sections of the pipelines are removed during maintenance inspections or other repairs, then the effectiveness of the protection system can be determined by inspecting the structure. Gross corrosion is, of course, indicative of system failure. The presence of deposits on the structure should not be confused with corrosion. Calcareous deposits are formed on cathodically protected surfaces. These deposits are often significantly lighter in color than normal rust and may even be white. Only by removing the surface deposits and inspecting the underlying surface can a valid assessment of the cathodic protection of the pipelines be made. 1 ~' SteveAUndeiwood -Howard's Mini Mart O & M doc N~...~,~,~.,~~ ~'~ ~ ~ p~' .~,,. ~ ~~~ ~ Pa a 18 k 9~ 4.0 Instructions, Potential Measurement Using a suitable multimeter or voltmeter, select a scale fot' voltage measurements up to two volts. Connect the negative meter lead to a portable reference electrode. Connect the positive meter lead to a test lead in a test station. Ensure that ametal-to-metal connection is obtained. Read and record the meter display and date obtained as potential (voltage) with respect to the reference electrode location. Do not immerse the reference electrode terminal without the use of a special submersible adapter. On dry soil, the soil should be moist or moistened with tip water at the cell contact point. The meter should be a digital display type with input impedance of 10 meg ohms, minimum. If an analog multimeter is used, the test lead connections must be reversed from the description above. The reading obtained is then recorded as negative potential (-v) with respect to copper- copper sulfate. 4.1 Instructions, Anode Outaut Measurement Using a suitable multimeter or voltmeter, select a scale for voltage measurements up to 50 millivolts. Connect the meter leads across each anode shunt at the junction boxes. The reading in millivolts times 100 equals' milliamperes (.O1 ohm shunt). 4.2 Test Eauinment The following list of equipment is a minimum requirement for the maintenance and operation of the cathodic protection system. Many specialized instruments whose use is outside the scope of 1 'Steve Underwood Howard's Mmi Mart O & M doc ~~..~.~,a ~~~~~~~ ~ Page µ19 this manual but which are required for design, installation and troubleshooting of cathodic protection systems are not included in this list. A qualified corrosion engineer should be consulted regarding purchase of specific cathodic protection test and maintenance equipment. 1. Meter for Structure-to-Environment Potentials Meter Specifications: Input impedance......10 meg ohms/volt, minimum Range ................0 to 2 volt DC, minimum The functions of this meter are a minimum requirement. Many meters, cathodic protection instruments, and other high input impedance voltmeters may be used. . 2. Reference Electrodes a. CuCuSO4 electrode, stud type for buried or submerged structure use. b. Reagent grade copper sulfate crystals and deionized water for replenishing reference cell antimony (mix to obtain a saturated solution). A one-piece instrument which combines a potential meter and reference cell in one unit is also available. This can be used for portable cathodic protection potential measurements. 3. Lead Wires 6-foot test wires with clips - no. 16 or no. 18 stranded copper with rubber insulation. 500-foot test wires on suitable reels with clips - no. 16 or no. 18 stranded copper with rubber insulation. 15~ Steve Underwood -Howard's Mini Mart Rectffer month) Ins ~form:xls ~~~~~~f ~ ~~~ ~~~~~~~~~f~~~~~ ~~~~~~ ~~.~~~~Pa e 1 Howard's Mini Mart Monthly ~tectifier Data Sheet Altech Corrosion Control Service 1-661-319-4760 -:3~. Please keep sheet in rectl~er door panel READING DATE VOLTAGE CURRENT (AMPS) HOUR IVI~TER (IF INITIAL COMMENTS APPLICABLE) ............. Steve Underwood Howard's Mini Mart Rectifier monthly Insp. form xis Page 2 'Steve Underwood -Howard's Mmi Mart Site Photos.doc ~~~ ~ ~~ ~~ Page 1~ F `. ~S~ ~ r:r. ~ _,; J Steve Underwood -Howard's Mini Mart Site Photos.doc ~~ Page 2 Steve Underwood -Howard's Mini~Mart Survey Data Sketch.doc ~..n._,.~.„ .~ ._.y r.,.,.~ _~.~..... Page 1 _ ~:~ Alteo~ Corrosion Control ~~ ~~ :,101 Diamond Oaks Ave Bakersfield, CORROSION SPECIALISTS SINCE 1993 Ca. 93306 PH 1-661-319-4760 October 22, 2005 Howard's Mini Mart 3200 Panama Lane Bakersfield, CA Attention Mr. Doug Young Subject: Cathodic Protection Survey Dear Sir: A cathodic Protection Survey was performed on October 22, 2Ct05 on the Howard's Mini Mart Facility located at 3200 Panama lane in the City of Bakersfield, CA. The system layout is as follows: the rectifier is mounted on the north wall of the store stockroom. The anode bed is located at an undetermined location on the store property. The tank structure leads come into the rectifier from a southward direction; the tanks and pump units are located jUSt west of the store building. In order to obtain valid cathodic protection data the reference electrode (half cell) way placed in the planter located on the southwest corner of the property. The cathodic protection tests were performed with an interrupteP placed in the DC circuit at intervals of 6 seconds on and 3 seconds off. The results are tabulated in the succeeding pages. The tank meets the requirements for cathodic Protection under the Code of Federal Regulations, 4tl MFR Part 280. The cathodic protection levels of protection were taken with regards to the following NACE Standards: • RP0169-92 Standard recommended practice: Control t7f Corrosion on Underground or Submerged Metallic Piping Systems. • RP 0285-85 Standard recommended practice: Control of External Corrosion on Metallic Buried, Partially Buried, or Submerged Liquid Storage Systems. • STI R892-91 Recommended practice for Corrosion Prr~tection of Underground Piping Networks Associated with Liquid Storage and Dispensing Systerrt5. • American Petroleum Institute (API) Recommended Praitice 1632, Cathodic Protection of Underground Petroleum Storage Tanks and Piping Systems. Steve~Underwood - Howard's's Mirii~Mart Survey Data -Sketch doc ~~~ ~ ~~ Page 2 a While the Environmental Protection Agency (EPA) and local regulations mandate testing to be conducted on three-year intervals to determine the effectiveness of the installed systems, experience and good engineering practice dictate that an assessment on this type of system be mede on an annual basis. This, coupled with the required monthly inspections by the Howard's Mini Mart personnel, will assure the continued effective operation of the installed corrosion control systems. The annual inspection of the cathodic protection systems should consist of structure-to-soil potential measurements, current output of the anode bed, and a summery report to include field data and recommendations as required. Howard's Mini Mart personnel are required to record the rectifier voltage and current meter outputs on a bi- monthly basis using the form presented herein. Notifying qualified personnel immediately should the readings vary +/- 20% from our initial test data noted in this report is highly recommended. Altech appreciates the opportunity to have assisted you in this ef'#ort, please call us at 661-319-4760 with questions regarding any part of this report. Respectfully, AI Perez Project Manager/ Engineering N.A.C.E. Cathodic Protection Tester #23 N.A.C.E. Certificated Corrosion Technologist #3811 N.A.C.E. Intermediate Coating Inspector Training I, II, III, #2035 Steve Underwood Howard's Mmi Mart Survey Data - Sketch.doc ~ ~~ ~ ~~~~ ~m Page 3 CATHODIC PROTECTION ~~~STEM INSPECTION UNDERGROUND STORAGE TANKS CORROSION PROTECTION MONITORING FORM Altech Currosion Control Service 661-d19-4'60 ' Facility lnform~tion Print or T ~' Facility Name Howard's Mini Mart Facility ideritification Number = _ _ _ _ _ Street Address 3200 Panama L ne Number of Tanks 4 Four City Bakersfield. CA Tank type Steel State CA Zip Vent Material Steel Type et Corrosion Protection (Galvanic or Impressed Current) Name/Address of Testing Company For Impressed Current Systems Only Altech Corrosion Control Service Rectifier Serial Number 98059 P.O.Box 11658 Voltage 50V Current 12A Bakersfield. GA. 93389-1658 Conclusion Svstem functioning orooerly Phone Number 661-319-4760 Comments Person Conducting Test AI Perez .. Date of Test October 22.2005 teve Underwood -Howard's Mlni Mart Survey Data Sketch doc ~ ~ ~ ~ ~~ ~ ~ Page 4 ~ In the space below, sketch the important parts of the facility (tanks, tank mars way locations, vents, pump islands, buildings, etc.). Cgference cell locations where structure-to-soil potential or continuity measUremPnrc nave non made. N ~~__.. Rnrt~nr Reference d Cell ocation ~ a~ . ~ le Howard's Mini Mart 4 Chris's Liquors 3 2 1 Panama Lane ~, My signature below is affirrnation that I have sufficient education and/or experience to meet the definition of cathodic protection tester in [40 CFR 280.12], I am competent to perform the tests indicated above; that test results on this form are a complete and truthful record of all testing at this location on the date shown, and that I am responsible for all conclusions contained therein. AI Perez ., October 22.2005 Name Date Facility Name _Wholesale Fuels_ Facility I. D. Number = -_ _ -_ _ _ 100 MILLIVOLT POLARIZATION DECAY MEASUREM~hifiS (FOR IMPRESSED CURRENT SYSTEMS) (Not required if Instant Off Voltage reading exceeds 850 millivolts) Contact Points (Take readings wherever Access is available Location of Reference Cell Voltage (Current On) Instant C)ff Voltage Final Voltage Voltage Decay Comments (Pass, Fail, etc.) TANK 1 Planter s/w corner .,,, Unleaded Regular ... A. Fill Pipe 1050mv 1020mv 40~friv ...... 1020mv 614mv Pass B. Pump Disp. 1044mv 1020mv 405ttiv .... 1020mv 615mv Pass C. Vent 1043mv 1024mv 405ttiv ., 1024mv 619mv Pass ........ TANK 2 ............ Diesel A. Fill Pipe 1044mv 1019mv 407tnv 1019mv 612mv Pass B. Pump Disp. 1044mv 1020mv 405ttiv 1020mv 615mv Pass Steve Underwood -Howard's Mini Mart Survey Data -Sketch doc .~ ~ ~~ ~~ ~ ~~ ~ ~~~~ ~~~ ~~ Page 5 C. Vent 1043mv 1024mv 405thv 1024mv 619mv Pass TANK 3 ........ Unleaded .. A. Fill Pipe 1045mv 1019mv 405mv .............. 1019mv 614mv Pass B. Pump Disp. 1044mv 102Omv 405tnv 1020mv 615mv Pass C. Vent 1043mv 1024mv 405tnv .......... 1024mv 619mv Pass TANK 4 .... Unleaded Premium ... A. Fill Pipe 1048mv 1022mv 405ttty .............. 1022mv 617mv Pass B. Pump Disp. 1044mv 1020mv 405mv ...... 1020mv 615mv Pass C. Vent 1043mv 1024mv 405mv 1024mv 619mv Pass My signature below is affirmation that I have sufficient education and/or experience to meet the definition of cathodic protection tester in [40 CFR 280.12], I am competent to perform the. tests indicated tlbove, that test results on this form are a complete and truthful record of all testing at this location on the date shown, and that I ~iti responsible for all conclusions contained therein. Al Perez October 22, 2005