Surveys

From surveys and asset management, Allied Corrosion Industries’ field-proven specialists are fully trained and operator qualified in the technology of taking and efficiently recording a full suite of surveys and testing.

Interference Testing

Interference current comes in two basic categories: AC interference sources and DC interference sources. Both categories of interference current damage the pipeline. Allied Corrosion’s field specialists have extensive experience in identifying interference problems, along with providing the correct mitigation solution. Identifying stray currents, whether static or dynamic, is a key step in preventing stray current corrosion and extending the life of your asset.

Potential Surveys

Potential Surveys are used to predict corrosion, especially when used in conjunction with other surveys, such as soil resistivity. Potential surveys record pipe-to-soil potentials across the pipeline at regular intervals. Those potentials that are less negative than the negative potential of 850 mV as measured with an copper-copper sulfate reference electrode, the greater the possibility of corrosion. Allied Corrosion Industries, Inc., routinely performs a full suite of potential surveys, and are the first choice for pipeline owners/operators.

Close Interval Survey/Close Interval Potential Survey
Interrupted Potential Survey – IR Drop Free Survey
Test Station Potential Survey

Gradient Surveys

Gradient Surveys are used primarily to assess the integrity of the pipelines’ coating. Corrosion can only occur where bare metal is in direct contact with the electrolyte (soil, water, etc). A coating defect is referred to as a “holiday”. Hence, all pipeline corrosion only occur only where coating holidays exist. The gradient survey allows the technician to locate holiday locations to include a relative size of the holiday. Using the gradient survey data along with the corresponding potential survey pipeline, allows the technician to classify the severity of the corrosion activity at each holiday location. This allows the pipeline owner the ability to prioritize and categorize the order in which holiday areas should be inspected.

DCVG – Direct Current Variation Gradient Survey
ACVG – Alternating Current Gradient Surveys

Pipeline Asset Surveys

Interrupted Potential Survey
Interval Potential Survey
Surface Potential Survey

Direct Current Voltage Gradient Survey (DCVG)
Alternating Current Voltage Gradient Survey (ACVG)

ECDA
ICDA
SCCDA

Direct Assessment Field Services

When you partner with Allied Corrosion, you improve operational certainty by mitigating risks through our full suite of inspection and assessment services. Our Integrity Management Team is ready to provide turn-key assessment and inspection services or we can perform any single or multiple step(s) that you, the owner/operator require. Over the course of its lifetime, a pipeline may face many threats to its integrity. Allied’s Direct Assessments are key to staying ahead of potential corrosion risks, ensuring that your pipeline assets run reliably for the duration of their lifetime.

Alternating Current (AC) Attenuation Survey

The use of an attenuation survey helps pipeline owners and operators understand coating defects on assets protected via cathodic protection. AC Attenuation Surveys can be conducted on long-distance pipeline.

Depth of Cover Survey

Because different states have different requirements and regulations as it relates to the depth of cover of buried pipeline assets, depth-of-cover surveys are required to ensure that the pipeline is at the proper depth which meets and complies with both local and federal regulations. This will assist in limiting pipeline damage associated with environmental events and/or third-party excavation damage.

Soil Resistivity and Acidity pH Survey

Soil Resistivity is the measure of the soil’s capacity to resist or reduce the flow of electric current through it. Varying levels of resistivity can affect the stability of power systems, as well as the level of corrosion-inducing currents leaving the surface of the pipeline or protected asset. Acidity pH levels in the surrounding soil around the pipeline can be collected at the same time as measuring soil resistivities. This allows the pipeline technician the ability to better assess the comprehensive corrosion risks surrounding the asset at each test site location.

Class Location/HCA ID/HCA Change

All pipelines are segmented into classification areas referred to High Consequence Areas-HCA. HCA’s are primarily defined by the population density near the pipeline route. Allied Corrosion offers HCA Identification/Class Location Surveys that meets Federal and State Department of Transportation Regulations, to include following NACE recommendations dealing with HCA’s. This is a vital part of any pipeline integrity management plan. Pipeline owner operators must dedicate corrosion mitigation efforts in High Consequence Areas to ensure the integrity of pipelines and the safety of the surrounding areas. Should the population density or dwelling density along your pipeline assets change in the course of your operations, Allied Corrosion will partner with the owners/operators in complying with class location change regulations.

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)

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