No pipe material is perfect, even steel. Protective coatings and cathodic protection provide significant added protection. But even with these valuable design enhancements, buried pipes are not 100 percent fail-safe.

Soil stress and excessive operating temperatures can damage pipe coating and expose pipe to external corrosion. Water and corrosive contaminants in the product stream can cause internal corrosion damage. High operating stress levels in conjunction with environments conducive for stress corrosion cracking can cause cracking failures.

Regular pipeline assessment is critical in order to mitigate these issues. Direct assessment is a cost-effective preventative inspection method that enables you to identify and act upon issues before they cause a costly leak or rupture.

Of the approved techniques for validating and assessing pipeline integrity, direct assessment is often the preferred technique to identify external corrosion, internal corrosion and stress corrosion cracking in shorter pipe segments – generally from 0.5 to 2 miles – or in pipelines that cannot easily accommodate in-line inspection tools.

The effectiveness of a direct assessment rests largely on the provider’s expertise in locating past or currently active corrosion along with accurately predicting future problem areas. This process is enhanced when the assessment is conducted using “smart” tools that collect and store data in a format that can be accessed and updated electronically, and then layered onto a GIS map for an instant snapshot of a pipeline’s condition.

The Four-Step Direct Assessment Process

Whether we are conducting an ECDA, ICDA or SCCDA, Aegion follows the same four-step process to evaluate and mitigate the impact of corrosion on pipeline integrity.

Pre-assessment begins with collecting historic information about a pipeline, including pipe and construction data, corrosion protection data, historical operating parameters and information on soil and other environmental conditions. If the appropriate direct assessment is feasible, the pipeline is divided into regions and the appropriate inspection and complementary evaluation techniques are selected based on conditions.

The purpose of this step depends on the type of direct assessment undertaken:

ECDA -- Indirect inspection is used to identify the locations of coating faults, insufficient cathodic protection, electrical shorts, electrical interference, geologic current shielding and other pipeline anomalies.

ICDA -- Indirection inspection is used to identify locations at risk for internal corrosion, with consideration of the gases, liquids and solids passing through the pipeline.

SCCDA – Indirect inspection is used to identify the corrosive agents and tensile stresses at work on a pipeline.

Data from these inspections is consolidated and compared. Specialists then analyze the results to identify indications of corrosive activity.

The pipe is examined to assess the degree of corrosion damage. Direct examination requires excavation so physical inspections and nondestructive tests can be conducted on pipe surfaces and, in some cases, the surrounding soil and water.

Finally, we work with you to assess the overall effectiveness of the direct assessment and determine a timeframe for reassessment. Because ECDA, ICDA and SCCDA are continuous improvement processes, it helps to streamline future assessments. With an assessment plan in place, over time accumulated data makes it easier to identify locations where corrosion has occurred, is occurring or may occur in the future.   

Corrpro

7000 A Hollister, Suite 300
Houston, TX 77040