Surface Potential Surveys Training Manual
Contents
1. x O Decreasing Soil Resitivity Distance Units oer rst fe gt 00 A 12 08 Pm Rectifier Mode By tapping on the menu button in the Rect Mode field you can select either Always On if the rectifiers influencing the pipe are ON or Always Off if the pipe is unprotected or is temporarily depolarized Note The Cycle On Off option is not available for Surface Potential surveys as the process involves cell to cell potential difference single readings Survey Typically for Surface Potential surveys you would trigger readings using either the positive green handled data probe or the negative red handled data probe In the case where an in line survey is to be performed by two crew members one holding the positive data probe the other holding the negative data probe the choice of which push button switch to designate as the trigger for readings will depend on which data probe the crew member operating the Gx is holding Ifthe Gx operator holds the red handled negative data probe the selection should be read flag in the Survey category and if the Gx operator is holding the green handled positive data probe the selection should be flag read In either case the crew member who is not the Gx operator could use his push button switch to designate the location of survey flags D C P You can also use the push button switches when recording voltages at2. By tapping in the field labeled Valve Segment you can enter the name or number of the valve segment to be surveyed if known Starting Location very important Provide the Starting Location for the survey by tapping in the field labeled Starting Location and entering the location You can select to have location information displayed on the survey screen as station number feet or milepost station number meters or kilometer post for the metric case Whichever selection you make here will determine how you enter your starting location information For example if your pipeline locations are represented by station numbers you would select Station Number from the menu list and you would enter a starting location for the survey in the form of a station number If you do not know the station number associated with the beginning your survey enter 0 0 0 Step 8 Tap on the Next button on the above screen A version of the screen shown below will be displayed depending on the current Date amp Time and also the filename entered for your survey Set up 4 of 5 Work Order Technician Name Comments f Description Survey Date 7 12 2010 8 2 14 Survey Name fisystemCF Gx_Datalbedibed mem Previous Next Cancel Sancel Bot ee Ua omar Work Order optional By tapping in the field labeled Work Order you can enter the work order number associated with the survey if known 20 Te
3. Mark button on the Survey screen which would pull up the Side Drain screen By placing the negative data probe over the pipe at the epicenter spot and the positive data probe off to the left hand side of the pipe you can accept the Side Drain Left SDL reading by tapping on the Accept button The screen shown below will be displayed for an example value of 19 0 mV 39 Surface Potential Side Drain 15 8 w SDL 19 0 gt SDR Range 5 7 DC 400 MOhm Resistivity Kohm em Notes Bse A 1007m Next you would keep the negative data probe over the pipe and you would swing the positive data probe to the opposite side of the pipe the right hand side to take the Side Drain Right SDR reading The screen will be as displayed below after accepting the SDR reading for an example value of 17 0 mV 40 Surface Potential Side Drain Ba 16 5 SDL 1 9 0 SDR 1 Fao Range 5 7 DC 400 MOhm Resistivity KOhm em e Notes Bsn See H nom Note Alternatively to tapping on the Accept button on the screen you could press the push button switch on either data probe handle to accept the SDL and SDR readings Note The arrow direction on the Side Drain screen indicates the direction of current flow in the soil In the above case the direction of current flow is away from the pipe which is the case for an anodic area current
4. detailed in the ProActive Training Manual and is beyond the scope of this manual To examine the survey data in the Gx Driver you can click on the various page tabs now appearing on the Gx Driver Pipeline Survey window Survey Settings Readings Device Readings Graph By clicking on these page tabs you can view information on the Survey settings or you can view the actual survey and device data please see the ProActive Training Manual for details 48 APPENDIX 1 How to Delete Survey Files from the Gx Once you have copied your survey files to your PC see Section VI you can if you wish delete the files from your Gx s Flash memory card Since your survey files are stored on the Flash card you will have to access this memory SystemCF in order to delete selected survey files The procedure would be as follows Tap on the Start button on the Gx Tap on Programs Tap on Windows Explorer Double tap on SystemCF Double tap on Gx_ Data Tap and hold on the Survey File you wish to delete until a menu pops up e Tap on the Delete option This will delete the highlighted survey file 49
5. flags and the expected number of readings By tapping in the field labeled Flag Dist Error Limit you can type in the maximum permissible error For example the maximum permissible error is indicated as 20 on the above screen If the reading interval is expected to be 2 5 feet and the survey flag separation is 100 feet this means that 40 readings are expected If however only 30 readings are actually logged between survey flags an error window will appear on the screen since there is a 25 difference between the expected and actual number of reading in this example No error window will appear if the difference is less than 20 For this example you could have a minimum of 32 readings and a maximum of 48 readings between survey flags to stay within the 20 max error allowance Auto Pacing Mode optional Select whether or not you would like the readings to be uniformly spaced between any two survey flags regardless of the actual locations of the readings between the two flags By checking the box labeled Auto Pacing Mode you will enable the data logger to automatically adjust the reading locations in order to evenly space the readings between two survey flags Name of P L optional By tapping in the field labeled Name of P L you can enter the pipeline name Note This is not necessarily the same name as the filename for the SP survey that you used to setup the survey file Valve Segment optional
6. is leaving the pipe This is different from the arrow shown on a DCVG survey screen which always points back to the pipe Next you can manually enter a value for the soil resistivity measured in the vicinity of the anomaly As discussed in Section II the software will use this value in its calculation of the Corrosion Factor for the anomaly As indicated in the above screen you can select the units MQ m KQ m or Q m for your resistivity value or MQ cm KQ cm or Q cm if the cm length unit was selected during the survey setup process At this point you should tap on the Save button which will save all of the data associated with the anomaly 41 When the data are saved you will be given the opportunity to take a photograph at the Anomaly location as indicated by the question displayed on the screen shown below Single Test Station goat e DMM 729m Answering Yes on the above screen will take you to the Pictures screen as described in Appendix 3 of the Gx Data logger Pipeline Survey User s Manual Note Several seconds are required to open the picture program How to Position the Camera for a Picture Since the camera on the Gx is located on the underside of the handheld unit it is necessary to remove the unit from its mounting platform by grasping the unit around its mid section and pulling in an upward motion The unit should snap out of its retaining brackets You can now
7. pipe you are surveying could be part of the filename Surface Potential and the survey date do not have to be part of the filename as these tags are incorporated with the survey on the ProActive side assuming that you will be downloading the survey data to the ProActive application Note You will not be permitted to use invalid characters such as slashes or as part of a filename You will be alerted if you try to use any invalid characters Step 4 Once you have entered a filename tap the OK button on the above screen The screen shown below will be displayed The specific selections indicated on the screen will reflect the selections made for the previous survey Setup 1 0f 5 Survey Trigger CIS Rect Mode Cycle ON OFF Cane Button s Allowed To D C P Survey Save Survey Locations Increasing Decreasing Flag Read DCG Sidedrains in CIS Surveys _ Use Metric teal Ebie Step 5 Select the survey type by tapping on the menu button in the Survey Type field and highlighting the survey type of your choice 7stat fe Soe WB 1144 am By tapping on the Surface Potential option the screen shown below will be displayed depending on the previous survey selections Survey Surface Potential x Rect Mode Always ON Cane Button s Allowed To D C P Survey Survey Locations Left Right Increasing Flag Read
8. position the camera to take your photograph since the coiled cable connecting the Gx to the dual probe adapter provides a considerable degree of flexibility The unit can then be snapped back into position on the platform after picture taking by lining up the groove on the bottom orange bumper with the registration post on the platform and pressing in a downward motion Note By tapping on the X button on the Pictures screen top right hand corner after taking a photograph you will be returned to the Survey screen 42 Answering No on the above screen will return you directly to the Survey screen You would then pick up the survey where you left off and continue triggering readings until you encounter the voltage gradient field associated with another anomaly SECTION VI HOW TO COPY SURVEY FILES FROM THE Gx DATA LOGGER TO YOUR PC VI 1 Introduction Survey data are stored in independent files one file for each survey on the Flash memory card on the Gx data logger and you can copy survey files to your PC using one of two approaches manually or via the driver in the ProActive software program The ProActive software program represents MCM s CP data management system and this program allows integration of pipeline survey data in a database system and offers extensive reporting both textual and graphical capabilities on the survey data If you have the ProActive software program installed on your PC or
9. D C P s data collection points devices to save a device reading as opposed to tapping on the save button on the survey screen if you wish To do so you would select the Save radio button on the above screen If the None option is selected the push button switches will have no functionality at D C P s Note When Marking SP anomalies see the Surface Potential Training Manual Gx Data logger Version the push button switch functionality becomes accept regardless of whether save or none is selected here Survey Locations Once a value has been entered for the Distance between Readings see the Setup 3 of 5 screen that distance for example 5 0 feet can be added to each successive station number each time a reading is triggered or it can be subtracted from each successive station number each time a reading is triggered Your selection of Increasing or Decreasing will depend on your walking direction over the pipe with respect to the pipe s stationing You would select Increasing if the station number will be increasing as you perform the survey and you would select Decreasing if the station number will be decreasing as you perform the survey Use Metric By checking off the box labeled Use Metric the reading interval distance between triggered readings and the flag internal survey flag spacing will be displayed on the Setup 3 of 5 scree
10. ED handled data probe and a GREEN handled data probe These data probes which will be placed on the soil above the pipeline in either the Perpendicular or the In Line configuration see Section IJ have push button switches on top of the handles so that the operator can trigger readings at each of the survey measurement locations and can also be used to designate the locations of survey flags please see Section III 1 The reference electrode data probes are connected as shown to the input terminals of the dual probe adapter and the output terminal of the adapter is connected to the 5 pin socket on the top side of the Gx data logger 36 HOOK UPS FOR SURFACE POTENTIAL SURVEYS GPS Antenna Dual Probe Adapter Figure 3 E Left Hand Cane Use Black Band Cable Right Hand Cane Use Red Band Cable NOTE The red handled cane is connected to the dual probe adapter via a black band cable while the green handled cane is connected to the dual probe adapter via a red band cable This results in the reference electrode of the red handled data probe connecting to the negative side of the data logger s voltmeter and the reference electrode of the green handled data probe connecting to the positive side of the voltmeter Consequently the data logger s voltmeter will measure the soil potential at the location of the green handled positive data probe minus the soil potential a
11. Setup 2 0f 5 GPS Port Imcm External Auto Log GPS NMEA Manual MCM Internal Previous Only Log Corrected GPS Use GPS for Altitude Log GPS at Flags Log GPS at DCP Featur Log GPS at Side Drain Anomaly AC Cycle feo Hz Baj eiee As can be seen from the above screen there are 5 choices for GPS Type None This means that a GPS receiver is not being used MCM External This means that an external MCM GPS Accessory is being used currently not available NMEA This means that an external NMEA compatible GPS receiver is being used such as a Trimble unit Manual This means that location data will be entered manually when the GPS button is tapped on the survey screen during a CIS MCM Internal This means that the Gx s internal GPS unit will be used a u blox NEO WAAS enabled receiver Select the appropriate choice by tapping on your selection Com Ports When using an external GPS unit NMEA option connected via a serial cable select the COM 1 option which represents the built in serial port located under the flap on the bottom left hand side of the Gx data logger The COM 4 option will be automatically selected when the MCM Internal GPS receiver option is selected Only Log Corrected GPS This box should be checked if you only want differentially corrected GPS data to be logged by the Gx data logger on the survey Leaving this box un checked will result in standard GPS data being logged in
12. Surface Potential Surveys Training Manual Gx Data logger Version MIG MILLER co M C Miller Co Inc 11640 U S Highway 1 Sebastian FL 32958 CONTENTS Page E Introduction sis sass saae E EE Peg AEE serene teas 3 LE Physical Principles dieien E A a ieusiee 3 II How to Setup the Gx for Surface Potential Surveys Ill 1 Gx Data logger Setup Process cece eee 9 II 2 Survey Options Menu including Picture Taking Options and Editing Options 006 24 IV Equipment Hook ups lt 05 44314 0 vestemran tase eid Seen tener ars 36 V How to Locate and Mark Surface Potential Anomalies 38 VI How to Copy Survey Files from the Gx to your PC VET UM POCUCHONG migreni saet osi roe tiv ie a E 43 VI 2 The Manual Approach 2 ccicatscsparectenewtes coaoxamiense 43 VI 3 Using the Driver in the ProActive Program 45 APPENDIX 1 How to Delete Survey Files from the Gx 49 SECTION I INTRODUCTION The Surface Potential SP pipeline survey method is similar to the DCVG survey method at least in terms of how the reference electrodes are employed to measure the difference in potential between two points on the surface of the soil above a buried pipeline SP surveys however are typically performed on uncoated or poorly coated pipelines whereas DCVG surveys are usually performed on well coated pipe that has an impressed current source providing the signal str
13. ading or not at all never at SP readings Step 7 Tap on the Next button on the above screen which will result in the screen shown below being displayed depending on the settings used on the previous survey Name of P L Valve Segment Starting Location 0 7 5 Station Number Flag Dist Error Limit Dist Per Reading ks ft Distance Between Flags fico Ft Decenceencencecccccenccncccssccsccsensceseesed estat lf ST T 754m Dist Per Reading By tapping in the field on the above screen labeled Dist Per Reading you can type in the interval distance in feet or meters for the metric case expected between reading Typically in Surface Potential work this expected interval distance is 5 0 feet or 2 meter in the metric case Distance Between Flags By tapping in the field labeled Distance Between Flags you can type in the survey flag interval distance between survey flags for the section of pipeline being measured assuming that survey flags have been laid out Typically survey flags are located at 100 feet intervals In such a case you would have a new reference a stationing correction every 100 feet Note If survey flags are not in use enter zero in this field In this case tapping accidentally on the Flag button will not adversely impact your stationing Flag Dist Error Limit Select the maximum permissible error between the actual number of readings logged between 2 survey
14. ate readings with the actual time they were made When the Single Read GPS Timing mode is selected the screen shown below will be displayed Setup 5 of 5 Voltmeter Setting Read Mode Single Read GPS Timing Range 5 7 VDC 400 MOhm lt lt stat e SD 1052 am The only addition information that needs to be supplied here is the type of GPS receiver you will be using via the GPS Settings button Note Currently only the MCM Internal GPS Receiver can be selected for this voltmeter reading mode 22 Range By tapping on the menu button in the Range field you can select the voltmeter range and associated input impedance setting for your application from the full list of available options Note Use the scroll bar to view all options Note Since SP survey readings are typically small either tens of mV or hundreds of mV only with respect to sensitivity the most appropriate DC ranges are the 5 7V 400mV and 40mV ranges depending on the size of the gradient fields that you encounter Another issue is the signal to noise ratio with respect to being able to find and mark anomalies For small signals small gradient fields the voltmeter s noise level is the limiting factor The noise levels associated with the 5 7V the 400mV and the 40mV ranges are approximately as follows 5mV 1mV and 0 5mV respectively Step 10 Tap on the OK button on the Setup 5 of 5 scre
15. cases where differentially corrected data are not available Note If this boxed is checked and the unit is not receiving a differential correction message no GPS data will be logged Use GPS Altitude If this box is checked altitude data will be logged in addition to the Lat Long data whenever GPS data are logged Note Altitude data on some GPS units are not particularly accurate Log GPS at Flags If this box is checked GPS data will be logged automatically at survey flags when either the flag button is tapped directly on the Survey screen or when the push button switch on the designated flag cane is pressed Log GPS at DCP Features If this box is checked GPS data will be logged automatically at Devices or Geo Features when either the Device button is tapped on the Survey screen and a Device reading is logged or when the Geo Feat button is tapped on the Survey screen and a geo feature is registered Log GPS at Sidedrain Anomaly If this box is checked GPS data will be logged automatically when SP anomalies are marked as described in our DCVG Training Manual Gx Version Auto Log GPS By tapping on the menu button in the Auto Log GPS field the selections available will be displayed By selecting one of these options you can elect to have GPS data logged automatically at every SP reading at every second SP reading at every fifth SP reading at every tenth SP re
16. chnician Name optional By tapping in the field labeled Technician Name you can enter the name of the surveyor Comments Descriptions By tapping in the field labeled Comments Descriptions you can enter any general comments you might have regarding the survey perhaps weather conditions soil conditions etc Also shown on the above screen are the survey filename Survey Name field and the Start Date and Start Time for the survey Survey Date field Note The survey files are stored in the Gx_Data folder on the Gx data logger s CompactFlash memory SystemCF a non volatile memory Note These data cannot be changed manually Step 9 Tap on the Next button on the above screen A version of the screen shown below will be displayed depending on the settings selected for the previous survey Setup 5 of 5 Voltmeter Setting Read Mode Single Read Range 40 VAC 75 MOhm Bans Laien 21 Read Mode By tapping on the menu button in the Read Mode field you will see that there are two options available for selection as follows Single Read This voltmeter reading mode is appropriate for cell to cell potential difference single readings which are the basis of Surface Potential surveys Single Read GPS Timing This voltmeter reading mode is similar to the Single Read mode except that in this case the data logger uses the GPS clock signal to associ
17. data logger for a particular pipeline survey you can make changes to your setup selections with the exception of your Survey Type selection and the currently indicated Station If you have selected a Surface Potential survey for example you cannot change to a DCVG survey without setting up a new survey To change survey settings tap on Settings and tap on Change Global Settings View Settings To simply view your setup selections you can tap on View Settings on the above menu Alternatively you can use the Ctrl and S keys Voltmeter To run the stand alone voltmeter either tap on the Voltmeter option on the menu or use the Ctrl and M keys Please see section IV 6 below for more information on running the stand alone voltmeter Wave To run the stand alone waveprint generator either tap on the Wave option on the menu or use the Ctrl and W keys Take Pictures You can run the integrated camera program by either tapping on the Take Pictures option on the menu or by using the Ctrl and A keys Note Several seconds are required to open and close the camera program The Pictures screen shown below will be displayed 26 Pictures No Pictures H Take Pict settings Rename Delete start c ADE 141a To take a photograph tap on the Take Pict button The camera will go through a focusing process and you will see a Ready to Take indication at th
18. e of the potential gradient field Consequently in this case the polarity switch would be positive to negative as the anodic area is traversed The opposite polarity switch would be observed if the lead data probe was the red handled negative probe In order to make the process of determining polarity switches easier the survey screen displays the prior reading including its polarity in addition to displaying the current SP reading as shown in the screen below 38 Survey Survey Options Help vS vn We 55 a O Total Dist 50 0 O Last Ref Dit 50 0 N 295 0 w Geo Feat Device GPSData Log GPS Undo Flag Flag Mark GPS Status Standard GPS fale Baiba Note When readings are logged the latest logged reading the prior reading is displayed in the bottom mV field on the above screen and the current reading is displayed in the top mV field On the above example screen the prior reading was 25 6mV and the current reading is 18 5mV In this example a positive to negative polarity switch has been detected with the lead data probe being positive which means that an anodic area has been detected By fine tuning the location of the epicenter of the anomaly i e by straddling the epicenter with the data probes and reading close to zero mV the anomaly can then be marked by taking side drain readings on both sides of the pipe at the epicenter location To do so you would tap on the
19. e top of the screen when you can take a picture as indicated below Ready to Take Auto Day E3 Start k e E ge Y TE 12 47 PM ej 27 At this point press and release the camera button located at the top right hand corner of the keypad You will have the choice of saving the picture or deleting it as indicated by the 4 to Save 1 to Delete indication on the screen below To save the picture press and release the 4 key An example of a saved image is shown below on the Picture screen 28 Pictures 07_13_201008_27_01 Beale oenas As indicated in the above screen the image is given a filename by default which represents the date time stamp for the image The above image for example was recorded on July 13 2010 at 8 27am You can rename the image if you prefer by highlighting the image tapping on the image and tapping on the Rename button You can then enter a new name for the image For example the image above has been renamed Office Desk on the screen shown below 29 Pictures e You can view a larger version of the image by highlighting the image tapping on the image and tapping on the View button You can take multiple photographs at a test site by repeating the process outlined above For example the Picture screen shown below shows two renamed images 30 Pictures Gx Data logger So gt fe D 12 53 Pm If you would like to adju
20. en A version of the screen shown below will be displayed depending on the start location entered previously and the location type entered previously station number feet or milepost or station number meters or kilometer post for the metric option vs vie station Q 7 5 om Bl Total Dist seen Last Ref Dist eae Geo Feat Device GPS Data Log GPS Undo Flag Flag Mark GPS Status Standard GPS asta fe BADA eam 23 Note When readings are logged the latest logged reading the prior reading is displayed in the bottom mV field on the above screen and the current reading is displayed in the top mV field see the screen below for an example station 7 5 Total Dist ara Last Ref si cla 25 6 w Geo Feat Device GPS Data Log GPS Undo Flag Flag Mark GPS Status Standard GPS Ba Se a owar On the above example screen the prior reading was 25 6mV and the current reading is 18 5mV In this example a polarity switch has been detected which means that a gradient field has been detected HI 2 Survey Options Menu including Picture Taking Option and Editing Option By tapping on the Survey Options button on the Survey screen the Survey Options menu will be displayed as indicated below 24 Tapping on the down arrow on the above menu will reveal additional options as illustrated in the screen shown below 25 Settings Once you ve set up the Gx
21. ength Localized current flow can gives rise to potential gradients on the surface of the soil above a buried pipe due for example to the presence of corrosion cells combinations of anodic and cathodic areas on the pipe and the goal of an SP survey is to locate such potential gradient fields In the case of bare pipe typically only about 10 15 of the pipe will be subject to galvanic corrosion and in addition typically this small percentage is made up of small highly localized corrosion areas anodic areas that are randomly distributed along the length of the pipe Thus an above the ground survey technique that can accurately locate these isolated areas is invaluable The objective of SP surveys is to locate anodic areas existing along a segment of pipeline as evidenced by potential gradient fields having a particular polarity presenting themselves on the surface of the soil directly above the anodic areas Once any anodic areas have been located remedial action can be taken such as the installation of sacrificial anodes to suppress current flow from the corroding area with a view to preventing further external corrosion in that particular area SECTION 2 PHYSICAL PRINCIPLES When current flows onto or away from a localized area on a buried pipeline a voltage gradient field presents itself on the surface of the soil directly above the localized area In the case where current is flowing onto a pipeline at
22. h both data probes positioned outside the gradient field The potential difference measured between the probes will continue to increase as the data probes advance into the gradient field and will go through a maximum value before dropping through zero as the data probes straddle the epicenter of the anodic area and becoming negative After going through a maximum negative value the potential difference measured between the probes will decrease staying negative and eventually become zero again with both data probes positioned on the far side of the potential gradient field This type of longitudinal voltage profile is illustrated in Figure 1 It should be noted that the nuances of the profile shown in Figure 1 will only be observed if the survey is close interval in nature relative to the size of the potential gradient field 4 _ Survey Direction Potential Difference Increasing and POSITIVE i a ee ee eS Se Potential Difference ZERO when Straddling Anodic Area Potential Difference Decreasing and NEGATIVE ial lines K Figure 2 In Line SP Survey Method Illustration is for the case of transiting a localized ANODIC area with the lead data probe being the positive probe in which case the polarity of the longitudinal voltage switches from positive to negative as the operator walks through the voltage gradient field Anodic Area Severity Factor In addition to locating anodic areas there is interest in dete
23. he PC Case 1 Windows XP or earlier PC Operating System The Microsoft ActiveSync communication program is required on the PC If not currently installed the application can be installed from the CD provided with the Gx Data logger Once installed make sure that the 45 Allow USB Connections option is selected in the Connection Settings window of the ActiveSync application Next connect the USB cable from the Gx Data logger to the PC and switch ON the Gx via the RED power button The connection should be automatic and you will be asked if you d like to set up a partnership or not between the Gx and the PC Answer NO to this question as the ability to transfer file data is all that is required as opposed to a synchronized partnership You can then exit the Activesync application If the connection is not established automatically make sure that the connection option on the Gx is USB _ Serial which it should be by default To do so tap on the Start button on the Gx screen tap on Settings tap on Control Panel and double tap on PC Connection If USB Serial is not indicated tap on the Change Connection button and select USB _ Serial from the drop down menu Repeat the connection process Case 2 Windows Vista or Newer such as Windows 7 PC Operating System The Gx Data logger connects to these systems via the Mobile Device Center which replaces the Acti
24. ist and make the appropriate Survey Type selection CIS in this case Next click on the Go button This will open up a window labeled Gx Driver Pipeline Survey Note It may take a few seconds for the Driver Window to appear Step 6 Identify the Survey File to be Copied The Get Pipeline Survey from Gx field on the Gx Driver window will list all of the survey files currently stored on your Gx s Flash memory card Highlight the survey file that you would like to be copied to your PC Also check off the box labeled Copy to Local Folder and identify the target folder s location on your hard drive in the field underneath using the browse button This is the folder that you set up previously Step 1 above in which to save all of your survey files copied from your Gx Also if you used the metric system on the data logger check off the box labeled Use Metric Finally click on the Go button on the Gx Driver window 47 Step 7 Examine the Survey Data Prior to Posting the Data to the ProActive Database You will have actually completed the process of copying a survey file to a local folder on your PC by this point using the Driver in ProActive However before exiting the Driver it is recommended that you examine your survey data prior to posting the data to the ProActive database The process of posting the pipeline survey data to the ProActive database is
25. istivity in the area is relatively large Another approach regarding Corrosion Factor determination would be to use the sidedrain readings which are a direct measure of the gradient field magnitude as the numerator in the Corrosion Factor calculation as opposed to the maximum longitudinal voltage whose value is subject to data probe placement relative to the potential gradient field SECTION III HOW TO SET UP THE Gx DATA LOGGER FOR SURFACE POTENTIAL SURVEYS III 1 Gx Data logger Setup for Surface Potential Surveys Step 1 Double tap on the Gx_PLS icon on the Gx desktop The screen shown below will be displayed BPs Station y Total Dist p Last Ref Dist V Geo Feat GPS Data Log GPS Undo Flag estat Jfa gt 226 Pm Step 2 Tap on the Survey button located on the menu bar The screen shown below will be displayed STAA Survey Options Help New Survey Ctri N Continue Previous Survey Ctrl C Finish Survey Ctrl F GUAR Exit Ctr x Beate STW EH zam Under Survey there are several options If this is a new survey not a continuation of a previous survey tap on New Survey The screen shown below will be displayed Enter New Survey Filename 0 500 0 000 Lx J start fe 2 A 251P Step 3 Enter a filename for the Survey This should be a descriptive name that will help you identify the survey at a later stage Perhaps the name of the section of
26. n in meters as opposed to feet Soil Resistivity Distance Units As indicated in the Surface Potential Survey Training Manual Gx version you have the option to manually enter a value for soil resistivity measured at the location of a marked SP anomaly which will allow the ProActive software to calculate a Corrosion Factor value The units Q cm or Q m for soil resistivity that will appear on the SP anomaly marking screen for your manual data entry will depend on your selection here in the Soil Resistivity Distance Units field cm or m Step 6 Tap on the Next button on the above screen which will result in the screen shown below being displayed depending on the settings used on the previous survey 14 Setup 2 0f 5 GPS Type mcm Intern M V Only Log Corrected GPS V Use GPS for Altitude Ps Port Eom4 7 V Log GPS at Flags Auto Log GPS Never Auto 7 V Log GPS at DCP Featun v v Log GPS at Side Drain Anomaly AC Cycle 60 He ro aT oo AC Cycle By tapping on the menu button in the AC Cycle field on the screen shown above you will have the choice of 60Hz or 50Hz AC Select 60Hz for all U S applications This is an important select with regard to the AC filtering system that s applied to all of the DC voltage channels GPS Type By tapping on the menu button in the GPS Type field on the above screen the screen shown below will be displayed
27. on PC Connection If USB _ Serial is 44 not indicated tap on the Change Connection button and select USB Serial from the drop down menu Repeat the connection process Step 2 Follow the procedures detailed below Double click on My Computer on your PC Double click on Mobile Device Double click on SystemCF Double click on Gx_ Data Right click on the survey file you wish to copy amp select Copy Paste the file into a local folder on your hard drive Create a compressed zipped version of the file You would now be in a position to send the compressed file via email for example to a recipient who has access to the ProActive software program Note Do not rename the survey file prior to sending the file to the recipient as the survey file must have the same name as the survey itself VI 3 Using the Driver in the ProActive Software Program Step 1 Create a folder on your PC s hard drive perhaps in your My Documents folder that will be used to permanently save files copied from your data logger You might choose to name this folder something like Surveys Step 2 Establish a connection between the Gx and your PC Gx Data loggers can be connected to a PC using the USB cable supplied with the unit Connection via the USB Cable The requirements and procedures with regard to Gx Data logger PC connectivity depend on the operating system of t
28. onnection should be automatic and you will be asked if you d like to set up a partnership or not between the Gx and the PC Answer NO to this question as the ability to transfer file data is all that is required as opposed to a synchronized partnership You can then exit the Activesync application If the connection is not established automatically make sure that the connection option on the Gx is USB_ Serial which it should be by default To do so tap on the Start button on the Gx screen tap on Settings tap on Control Panel and double tap on PC Connection If USB _ Serial is not indicated tap on the Change Connection button and select USB _ Serial from the drop down menu Repeat the connection process Case 2 Windows Vista or Newer such as Windows 7 PC Operating System The Gx Data logger connects to these systems via the Mobile Device Center which replaces the Activesync program on the PC side Make sure that the USB connection option is set up via the Mobile Device Center Connect the USB cable between the Gx Data logger and the PC and switch ON the Gx The connection should be established automatically If the connection is not established automatically make sure that the connection option on the Gx is USB_ Serial which it should be by default To do so tap on the Start button on the Gx screen tap on Settings tap on Control Panel and double tap
29. otential difference readings are plotted in the bottom diagram against the position along the pipeline of the center point between the reference electrodes In Line SP Survey Method One way to perform a SP pipeline survey is to use the so called In Line method In this case the reference electrodes are both positioned over the pipe and their separation is kept fixed as the operator or operators in the case of large electrode spacings for example a 20 feet spacing walks down the length of the pipeline section With a view to detecting localized anodic areas and accurately measuring the longitudinal voltage profile the survey needs to be close interval in nature With the electrodes positioned as illustrated in Figure 1 1 e with the positive data probe leading when cathodic and anodic areas are encountered the polarity of the longitudinal voltage V minus V switches from negative to positive in the case of isolated cathodic areas while in the case of isolated anodic areas the polarity switches from positive to negative as the voltage gradient fields are traversed The longitudinal voltage polarity switching phenomenon is explained with reference to Figure 2 below For the case of a localized anodic area the potential gradient on the surface is positive and so when the positive data probe enters the gradient field a positive potential difference will be measured relative to the zero potential difference measured wit
30. rmining some sort of severity factor for each location However unlike in the case of DCVG surveys which utilize a known signal strength i e the IR drop in the soil in the vicinity of the anomaly there is no directly measurable signal strength in the case of Surface Potential surveys Consequently some other approach is required to come up with a severity factor At the present time the specification upon which our software is currently based calls for the generation of a Corrosion Factor value for each marked anodic location The calculation is as follows Corrosion Factor Maximum longitudinal voltage reading logged on either side of the SP anomaly within 2 reading intervals of the marking location Soil resistivity in the vicinity of the SP anomaly Since the magnitude of the current flowing away from an anodic area correlates with the rate of corrosion in that area factoring in soil resistivity makes sense if we re trying to get a handle on the rate of corrosion for a given magnitude of voltage gradient For instance for a given magnitude of voltage gradient on the surface the corrosion rate will be higher current flow away from the pipe will be larger if the soil resistivity in the area is relatively small Conversely for the same magnitude of voltage gradient on the surface the corrosion rate will be lower current flowing away from the pipe will be smaller if the soil res
31. some localized area that localized area is considered a cathodic area and the voltage gradient field on the soil above the pipe will have a negative polarity The largest negative potential will exist directly above the anomaly and the negative potential will decrease in magnitude to remote earth potential with distance away from the pipe The opposite is true in the case where current is flowing away from an isolated localized area on a buried pipeline In this case the area is considered an anodic area and the voltage gradient field presenting itself on the surface of the soil above the pipe will have a positive polarity The largest positive potential will exist directly above the anodic area and the positive potential will decrease in magnitude to remote earth potential with distance away from the pipe Since corrosion occurs on an uncoated buried pipeline via the development of corrosion cells both anodic and cathodic areas must exist simultaneously The current flowing away from the anodic area will be collected by the cathodic area and the return path for the current will be the pipeline itself This situation is illustrated schematically in Figure 1 below top diagram Direction of Current Flow in Soil i Cathodic Area Anodic Area l Positive Electrode Buried Pipeline Plan View Negative Electrode Survey Direction gt Figure 1 In Line method of conducting SP surveys Soil to soil p
32. st the camera settings from their default settings you can do so via the Settings button on the Pictures screen For example you can change the size and resolution of the image to be captured the lighting conditions under which the image will be captured and the focusing method to be used for example By tapping on the settings button the screen shown below will be displayed 31 eyeSEEsetup gx_ss_image File Options Help Save File Viewfinda 4f gt Image Format Lighting ISxGA 1280x960 Daylight Focus Mode a Ej Near Limit Auto v so En Far Limit POE As indicated on the above screen there are a number of page tabs labeled Camera Accessories Save etc For information on the selections available via the various tabs please see Appendix 3 Camera Settings in the Gx Pipeline Survey User s Manual Note For the default picture size SXGA 1280x960 the Flash light is not available However you can turn on the LED Lamp which is turned OFF by default if direct light is required You can do so via the Accessories tab on the above screen Also please note that the Flash light is available for the largest picture size highest resolution setting QSXGA 2048x1944 You can return to the Survey screen after the picture taking process by tapping on the X button on the Picture screen Edit Survey Data Collected survey data can be edited by tapping on the Edi
33. t Survey Data button or by using the Ctrl and E keys The screen shown below will be displayed depending on the readings values and reading interval etc 32 Edit Survey Data Data Dist 0 00 2 50 1 2 5 00 tone Location On Max Y 0 011 0 012 0 012 0 0 013 0 00 2 50 3 00 7 90 ere bone J toe PET 10 47 am 2 The data to be viewed can be selected by entering values in the From and To fields and tapping on the Retrieve button Using the horizontal and vertical scroll bars you can scroll through the collected data A row of data can be deleted by highlighting the row and tapping on the Delete button Multiple rows can also be deleted at the same time Pictures can be viewed and or deleted by first highlighting the location see screen below and tapping on the Pictures button 33 Edit Survey Data Data Alt Quality Ce a Once highlighted the picture can be deleted by tapping on the Delete button or viewed by tapping on the Pictures button Delete Last Readin By selecting the Delete Last Reading option from the menu you can have your last reading deleted without having to go through the Edit Survey Data option Alternatively you can use the Ctrl and D keys to access the function Add Comments You can add remarks comments at anytime on your survey by selecting the Add Comments option and manually en
34. t the location of the red handled negative data probe 37 SECTION V HOW TO LOCATE AND MARK SP ANOMALIES The objective in SP surveys is to locate anodic areas i e areas on the buried pipe where current is leaving the pipe As discussed in Section II such areas can be located by observing a polarity switch in the recorded in line or longitudinal voltage As also discussed in Section II the nature of the polarity switch 1 e positive to negative or negative to positive depends on whether the lead data probe is the positive or the negative probe For the case where the positive data probe is leading 1 e leading with the green handled data probe since the potential gradient on the surface 1s positive over an anodic area a positive potential difference will be measured as a gradient field is entered relative to the zero potential difference measured with both data probes positioned outside the gradient field The potential difference measured between the probes will continue to increase as the data probes advance into the gradient field and will go through a maximum value before dropping through zero as the data probes straddle the epicenter of the anodic area and becoming negative After going through a maximum negative value the potential difference measured between the probes will decrease staying negative and eventually become zero again with both data probes positioned on the far sid
35. tering data on the screen shown below 34 Add Coments f Note asta fe SoA 11 59 4m Alternatively you can use the Ctrl and O keys to access the function Tap on the OK button on the above screen to return to the Survey screen after entering your comments Restart Flags You can reset survey flags by selecting the Restart Flags option from the menu This action will establish your current location as the new zero reference as far as flagging is concerned and zero should be entered automatically in the Last Reference Distance field on the Survey screen Set Graph Scale Rather than having the software auto scale the graph on the Survey screen to accommodate the actual data values logged you can establish the maximum and minimum values for the graph scale in order to restrict the data values to be displayed on the graph To do so you would un check the box labeled Auto Scale on the window shown below and enter specific values for maximum and minimum 35 Maximum fosoo OOOO Minimum ear GPS Status Standard GPS tsa SoSeiasa Tapping on the OK button will return you to the Survey screen SECTION IV EQUIPMENT HOOK UPS The Gx data logger data probe and data probe cable hook ups for Surface Potential surveys using M C Miller equipment are illustrated in Figure 3 below As can be seen from Figure 3 two reference electrode data probes are illustrated a R
36. vesync program on the PC side Make sure that the USB connection option is set up via the Mobile Device Center Connect the USB cable between the Gx Data logger and the PC and switch ON the Gx The connection should be established automatically If the connection is not established automatically make sure that the connection option on the Gx is USB_ Serial which it should be by default To do so tap on the Start button on the Gx screen tap on Settings tap on Control Panel and double tap on PC Connection If USB _ Serial is not indicated tap on the Change Connection button and select USB _ Serial from the drop down menu Repeat the connection process Step 3 Double click on the ProActive icon on your PC s desktop screen This will open up ProActive s main menu window A window labeled Entire Database will also be seen here The suggested organization of your database is discussed in the ProActive Training Manual 46 Step 4 Click on the Surveys speed button on the main menu bar This will open a window labeled Data Logger Get Pipeline Survey By clicking on the menu button in the Data Logger field you can select the data logger from which you are copying the survey file The various data loggers currently supported by ProActive are offered as choices in the menu list Step 5 Select the Gx Data logger Option Highlight GX in the menu l
37. you can bring your Gx to a PC that has ProActive installed on it you can use the ProActive program to automatically access survey files on the Gx If either of these situations applies you would proceed to Section VI 3 Note The ProActive program is required to actually view the survey data If you do not have ProActive installed on your PC and you cannot bring your Gx to a PC that has ProActive installed on it you can copy survey files manually from your Gx to your PC and you can subsequently send the copied files to a recipient who is a ProActive user If this situation applies you would proceed to Section VI 2 VI 2 The Manual Approach Step 1 Establish a connection between the Gx and your PC 43 Gx Data loggers can be connected to a PC using the USB cable supplied with the unit Connection via the USB Cable The requirements and procedures with regard to Gx Data logger PC connectivity depend on the operating system of the PC Case 1 Windows XP or earlier PC Operating System The Microsoft ActiveSync communication program is required on the PC If not currently installed the application can be installed from the CD provided with the Gx Data logger Once installed make sure that the Allow USB Connections option is selected in the Connection Settings window of the ActiveSync application Next connect the USB cable from the Gx Data logger to the PC and switch ON the Gx via the RED power button The c
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