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Pipeline Integrity Studies





External Corrosion Direct Assessment (ECDA) is a NACE protocol recognized by the U.S. Department of Transportation and the Pipeline and Hazardous Material Safety Administration (PHMSA), for its applicability to pipelines that cannot accommodate in-line inspection (ILI) tools, nor can they be taken out of service to be pressure tested to find time dependent defects. ECDA provides a means for assessing the integrity of such lines.


Vecor has extensive and successful experience supporting pipeline operators implementing ECDA programs to comply with regulations and ensure the reliability of their operations.

Internal Corrosion Direct Assessment (ICDA) protocol was initially developed for natural gas transmission lines that normally carry dry gas (DG-ICDA), but may suffer from short-term upset of wet gas or water. In addition, a number of “direct assessment” methodologies have been developed over the last two decades including wet gas (WG-ICDA) and liquid petroleum (LP-ICDA).

The basis behind ICDA is that detailed examination of locations along a pipeline where an electrolyte such as water would first accumulate provides information about the remaining length of pipe. The primary goal of the approach is to determine if internal corrosion is likely or unlikely to exist in a chosen length of pipe. Locations most likely to accumulate electrolyte are predicted using the results of pipeline multi-phase flow modeling.

Why Vecor?

Vecor has highly qualified personnel, some with over 30 years of experience worldwide in the pipeline integrity and cathodic protection business. Vecor operates under a culture of Safety, Quality and Respect for all our clients and employees.


We have set Operator Qualification and Safety programs in Veriforce, Avetta and ISNetworld where we manage with transparency all the records of our certified staff.

Vecor has completed many ICDA projects and has extensive experience in the concept of applying flow and corrosion models to assess the potential for internal corrosion in a pipeline system as well as identifying potentially susceptible location through Internal Corrosion Direct Assessment on dry gas, wet gas and liquid petroleum pipelines according NACE Standards SP0206, SP0110 and SP0208 respectively.  Our highly qualified and certified staff of Internal Corrosion Engineers is ready to face any challenge and help you accomplish your regulatory and reliability goals.

How Vecor works.

ECDA is in itself a continuous improvement protocol, which allows locating and addressing external corrosion but also identifying sites of major likelihood, where corrosion may occur. The methodology is structured in four-steps: Pre-Assessment, Indirect Examination, Direct Examination and Post-Assessment.



During this phase, detailed information about the pipeline historical data is collected, as well as information about the right-of-way (ROW) conditions. Pre-assessment objectives are to evaluate  the  feasibility to conduct the ECDA protocol, define the regions of pipe  to be inspected and provide a selection of tools or methods  that  will  be  used  through the indirect inspection phase.

Indirect Inspection

The indirect inspection phase uses two or more complementary aboveground methods to identify any indication of external corrosion or coating damage on the pipeline which could have the potential to develop corrosion in the future. Most common methods are:

  • Close interval surveys (CIS)
  • Direct and alternating current voltage gradient surveys (DCVG/ACVG)
  • Pipeline current mapping (PCM)
  • Soil resistivity and soil analysis.


The data recollected on the field is processed in order to evaluate the general condition of the pipeline segment. The detailed study allows the classification and prioritization of the found defects if any. The action plan is discussed for the Direct Examination is discussed and approve by the customer.

Direct Examination

A direct examination of the pipeline is conducted after prioritizing the indications gathered from the indirect inspection phase. This phase allows confirming the condition of the pipe coating, mechanical defect, corrosion damage, and potential environmental threat from a series of data collected on the bell-hole such as soil resistivity, pH among others. All the parameters contribute to evaluate whether the cathodic protection system is working properly.

Post Assessment

Post-Assessment main objectives are to define reassessment intervals and to assess the overall effectiveness of the ECDA process. This phase offers a summary of the test conducted, overall results and recommendations for improving the pipeline protection. Where corrosion is found, remaining strength evaluation along with root cause analysis and remaining life determination, are also conducted during this phase in order to provide recommendations for pipe repair as required.

ICDA methodology is based on finding locations along a length of pipe or areas where electrolytes such as water are most likely to accumulate. These locations can be predicted through the analysis of multiphase flow modeling. The predicted corrosion locations are then inspected or examined using traditional inspection methods to validate the model. The ICDA protocol involves the following four phases:


In the course of this phase historical data is collected. The data includes information about the pipeline design, construction records, operational conditions, maintenance programs, corrosion survey records and gas & liquid analysis reports. The historical data helps to determine whether ICDA is feasible, and to define ICDA regions. The goal is gathering the necessary operational data to properly perform multiphase modeling.

Indirect Assessment

If the actual pipe condition at the inspection locations is consistent with the predicted damage, confidence in the predictions is increased and fewer locations needs to be inspected, as compared to simply inspecting the entire pipeline, which is particularly a benefit when a pipeline cannot be inspected using ILI.

During this phase, multiphase flow modeling is applied and a pipeline elevation profile is developed using sub-meter accuracy GPS and pipeline current mapping tool (PCM). Outcome from the model and elevation profile allow predict and rank susceptible locations of damage (i.e. identifying sites where internal corrosion may be present).





Direct Inspection

Directly examine locations predicted to have corrosion, validate the predictions, and determine the integrity of the pipeline relative to the internal corrosion threat. Multiple excavations can be performed for direct examination using ultrasonic thickness testing to evaluate whether metal loss from internal corrosion has occurred.


Post Assessment

Post assessment covers analysis of data collected from the previous three phases to assess the effectiveness of the ICDA process and determine reassessment intervals.


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26 November 2015


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