Pipeline Surveys with G1 Data Logger

• Trigger-mode CIS (both manual & automatic triggering).

• Timer-mode CIS.

• DCVG surveys.

• Combined DCVG/CIS surveys(single-pass).

• Time-based data-logging in stationary mode (GPS time stamping for accurate data compensation when telluric and/or stray currents are picked-up / discharged randomly during a CIS).

Survey screens show a graphical representation of the data as they're being recorded, including registered survey flags (F) and test stations (D), for convenient real-time monitoring of collected survey data.

Graphical reports, including pipelines overlaid on a topographical map, can readily be produced by uploading the data collected on the G1 to ProActive, McMiller's advanced, easy to use, software program.

G1 Data-Logger Hardware

Given the nature of the environments in which pipeline surveys are typically conducted and the nature of the actual voltages that are logged by data-loggers on these types of surveys, the voltmeter component of the data-logger has to satisfy a number of important performance criteria. The performance criteria that are particularly significant for a voltmeter employed in pipeline survey work are as follows:

High Voltage Isolation

Since pipeline surveys are typically conducted in the vicinity of electrical devices (such as rectifiers) and power line systems, and since transient over-voltages can occur frequently and at high levels in today’s electrical systems, it is imperative that a high degree of voltage isolation be provided to ensure operator safety.

The IEC (International Electrotechnical Commission) has specified that voltmeters employed in Category IV environments, which are environments typically encountered during pipeline survey work (outside areas in the vicinity of electrical devices and power lines), must provide at least 1kV isolation (steady-state voltage) and at least 12kV transient (momentary) overload protection.  It is critical that purchasers of data-loggers that are intended for use in such environments be aware of these (minimum) requirements.

The M. C. Miller Co. (MCM) voltmeter (PCMCIA SIN110), which is used in all MCM data-loggers including the G1, is designed for 3kV (steady-state) isolation (tested to 1kV) and 50kV transient voltage isolation (tested to 15kV), and thus is designed to exceed the IEC Standard for Category IV environments.  On the other hand, the National Instruments voltmeter models (PCMCIA NI4050 and NI4060) provide no high voltage isolation, while model NI4070 only provides up to 300V (steady-state) isolation.  [NI voltmeter cards are used, for example, in Allegro data-loggers].  Consequently, it is imperative, from an operator’s safety standpoint, to be aware of the specific voltmeter PCMCIA card that is employed in any data-logger you might be considering for pipeline survey work and to be aware of any associated liability issues.

Voltmeter Response Time & Resolution

In cases where fast rectifier current interruption cycles are in-effect during surveys [on the order of 1Hz, for example (perhaps 0.7 sec. On/0.3 sec. Off cycles)], it is imperative that the voltmeter response time be fast in order that true On/Off voltages can be measured.

It is particularly important that the response time be fast even when the input impedance of the voltmeter is on a high setting.  A high input impedance setting is required for a voltmeter when the source resistance associated with a measurement is high, for example, in a high soil resistivity situation, in order that a voltage measurement is not affected by the source resistance and a true reading is presented.

Consequently, in pipeline survey work (CIS and DCVG surveys) where poor contacts (of data-probes with the soil) can occur and high soil resistances can be encountered (both of which impact the “source resistance”), it is important to employ a voltmeter that has a high input impedance setting option.  In addition, it is critical, in the case of fast interruption cycling, that the high input impedance setting also be a fast response setting.

Furthermore, the voltmeter setting should provide high resolution and high accuracy.

The MCM voltmeter (PCMCIA SIN110) has a setting which satisfies all three of these criteria simultaneously, which is the 5.7 Volt, 400 MΩ setting. This setting provides a response time of 80 ms and a resolution of 0.17 mV, while presenting an input impedance of 400 MΩ.   

Noise & AC Interference Filtering on Fast Cycle Setting

Since AC interference and noise can be encountered on buried pipelines, it is imperative that the voltmeter does not saturate at the voltage levels that might typically be induced which would lead to erroneous On/Off pipe-to-soil voltage readings.  It is also imperative that the fast cycling On/Off potentials can be “extracted” from the background noise. 

The MCM voltmeter (PCMCIA SIN110) will not saturate even with an AC signal as large as 120V appearing at the input and will maintain sufficient speed to process the fast cycle waveform data.  The MCM voltmeter accomplishes this feat by using a sophisticated combination of analog pre-processing and digital signal processing (DSP).  The sampling rate for the DSP is 3600 times per second. 

The M.C. Miller Company, which has been serving the needs of the Cathodic Protection industry for over 60 years, represents a single source for the hardware, software and training needed to carry out CIS and DCVG surveys for ECDA evaluations.

With regard to satisfying the “Indirect Inspections” step of the ECDA methodology, M.C. Miller provides a one-stop-shop for the hardware requirements of both CIS and DCVG surveys, including portable reference electrode data-probes, data-loggers (rugged, handheld PC’s with MCM’s digital voltmeter and state-of-the-art survey application programs), current interrupters with GPS clock synchronization and soil resistivity measurement equipment. In addition, MCM’s data-loggers are fully-supported by a database management software program, known as ProActive, which allows pipeline survey data to be uploaded from our data-loggers and to be associated with the relevant line segments in your pipeline system. The ProActive program allows permanent storage of your pipeline survey data in a database system and provides you with a multitude of reporting options, including extensive graphical reporting. 

In addition to providing integrated hardware & software packages for  CIS and DCVG surveys, the M.C. Miller Company also offers in-depth training courses to technicians and managers covering the physical principles of the CIS and DCVG survey techniques, the use of MCM hardware (including our data-loggers) to conduct pipeline surveys and the functionality of the ProActive software program, with emphasis on managing pipeline survey data (please see the Training section). It should be noted that other survey data, such as SmartPig data, for example, that may be acquired as part of an ECDA evaluation, can be easily imported to ProActive, and the data can be integrated with any other pipeline survey data to provide a complete picture of the status of a pipeline or of a line segment.