Direct Current Voltage Gradient Survey (DCVG)

What is DCVG?

Direct Current Voltage Gradient surveys are used to evaluate defects in pipeline coatings. Corrosion normally occurs where the bare metal surface of a pipeline comes in contact with its surrounding electrolyte (water and soil). The primary purpose of a DCVG survey is to find and size pipeline coating anomalies associated with corrosion. voltage gradient

DCVG equipment & procedures:

We use the PCS-2000 instrumentation when performing these surveys. This equipment uses time tested and field proven analog technology, enabling our crews to locate anomalies that other equipment uses time tested and field proven analog technology, enabling our crews to locate anomalies that other equipment may miss. All DCVG indications are electronically recorded with sub-meter accurate GPS location data using the Trimble GEO-HR GPS / Data Logger.

DCVG applications:

  • One of the indirect inspection tools approved in ANSI/NACE standard RPO502-2002, Pipeline External Corrosion Direct Assessment (ECDA) Methodology.
  • Verification of original coating condition on newly installed pipelines. The data collected can identify areas of potential coating concerns allowing the owner to make informed decisions on corrective actions.
  • One of the indirect inspection tools approved in ANSI/NACE standard RPO204-2004, Stress Corrosion Cracking (SCC)Direct Assessment Methodology.
Allied Corrosion provides a variety of field services and surveys.  These are an important component of a complete pipeline integrity program.
INTERESTED IN LEARNING MORE?

Find out about our other Field Services

Slider
Close Menu
×
×

Cart

Material
Voltage Range
Relative Position
Least Noble (More Anodic)
Magnesium
-1.60V to -1.67V
Zinc
-1.00V to -1.07V
Beryllium
-0.93V to -0.98V
Aluminum Alloys
-0.76V to -0.99V
Cadmium
-0.66V to -0.71V
Mild Steel
-0.58V to -0.71V
Cast Iron
-0.58V to -0.71
Low Alloy Steel
-0.56V to -0.64V
Austenitic Cast Iron
-0.41V to -0.54V
Aluminum Bronze
-0.31V to -0.42V
Brass (Naval, Yellow, Red)
-0.31V to -0.40V
Tin
-0.31V to -0.34V
Copper
-0.31V to -0.40V
50/50 Lead/Time Solder
-0.29V to -0.37V
Admiralty Brass
-0.24V to -0.37V
Aluminum Brass
-0.24V to -0.37V
Manganese Bronze
-0.24V to -0.34V
Silicon Bronze
-0.24V to -0.30V
Stainless Steel (410, 416)
-0.24V to -0.37V
(-0.45V to -0.57V)
Nickel Silver
-0.24V to -0.30V
90/10 Copper/Nickel
-0.19V to -0.27V
80/20 Copper/Nickel
-0.19V to -0.24V
Stainless Steel (430)
-0.20V to -0.30V
(-0.45V to -0.57V)
Lead
-0.17V to -0.27V
70/30 Copper Nickel
-0.14V to -0.25V
Nickel Aluminum Bronze
-0.12V to -0.25V
Nickel Chromium Alloy 600
-0.09V to -0.15V
(-0.35V to -0.48V)
Nickel 200
-0.09V to -0.20V
Silver
-0.09V to -0.15V
Stainless Steel (302, 304, 321, 347)
-0.05V to -0.13V
(-0.45V to -0.57V)
Nickel Copper Alloys (400, K500)
-0.02V to -0.13V
Stainless Steel (316, 317)
0.00V to -0.10V
(-0.35V to -0.45V)
Alloy 20 Stainless Steel
0.04V to -0.12V
Nickel Iron Chromium Alloy 825
0.04V to -0.10V
Titanium
0.04V to -0.12V
Gold
0.20V to 0.07V
Platinum
0.20V to 0.07V
Graphite
0.36V to 0.19V
Most Noble (More Cathodic)

Primary voltage range for material
Voltage range in crevices or stagnant and poorly aerated water