Internal Corrosion Integrity Assessment
Qualifying the Internal Corrosion Threat & Executing the
ICDA Plan
PROBLEM Pipeline Integrity Management regulations require
the evaluation of all potential threats within a High Consequence
Area (HCA). Unlike multi-threat integrity assessment methodologies
such as inline inspection or hydrostatic testing, Operators
who elect to use Direct Assessment (DA) can be faced with
performing both ECDA and ICDA in order to satisfy the regulations.
The use of two DA methods has the potential to extend the
overall inspection duration, in addition to significantly
increasing the cost as a result of the additional excavations
required.
 SOLUTION SI has developed a written procedure (ICDA Plan)
to address the potential for internal corrosion within a covered
pipeline segment. Our integrated engineering-based approach
considers all necessary information to determine the likelihood
for Internal Corrosion activity through a structured, formal
evaluation process. Enhanced Pre-Assessment activities establish
whether liquids exist in the system and then progressively
escalate the investigation to determine whether the physical
pipeline design and operating conditions would support the
collection of water – a necessary criteria for internal corrosion.
Increased understanding of the operating parameters can be
used to supplement the risk threat assessment for a given
pipeline, indicating that ICDA is not required, possibly opportunity
monitoring might be a more effective option. Conversely, the
results may indicate a greater threat than previously anticipated.
SI has both the engineering and field inspection services
to perform all activities outlined in Figure 1. Projects typically
follow 2 major emphasis areas: (1) Develop a practical and
compliant operating procedure to conduct DG-ICDA on identified
pipeline segments; and (2) Utilizing the new procedure, initiate
the ICDA investigation and perform the Pre-Assessment and
ICDA Region Identification activities on there covered segments
previously inspected via ECDA.
ICDA Threat Qualification
 ICDA Threat Qualification includes the review of existing
Internal Corrosion risk model information, in addition to
integrating specific internal corrosion data as defined in
the ICDA procedure. At the conclusion of this step, a formal
report is prepared, accompanied by the Data Element checklists,
maps and feasibility analysis.
The ICDA Threat Qualification
activity includes:
- Pre-Assessment to determine ICDA
Feasibility and supplemental data needs
- Establish
ICDA Regions based on defined criteria in the ICDA Plan
-
Calculate critical inclination angle constraints where/if
liquid holdup would be likely
- Develop a representative
elevation profile along the pipe segment, adjusting for known
depth of cover variations (i.e., directionally drilled crossings,
drips, bridges)
- Locate Internal Corrosion suspect
areas on a map & recommend excavation sites
One of the greatest barriers to implementing an ICDA methodology
is knowledge of the pipeline profile so an Inclination Assessment
can be performed. SI has developed, in cooperation with a
premier PODS™ data model provider, a rapid, low cost inclination
assessment tool. The tool utilizes readily available USGS
digital elevation model datasets to build a 3-D profile of
the pipeline. Aligning the pre-assessment information with
this virtual pipeline elevation model, a reasonable inclination
assessment can be achieved yielding effective Internal Corrosion
conclusions.
 The final results from the Region Identification activity
will be summarized and presented in both a graphical and tabular
form. A license-free ArcGIS viewing tool, ArcReader™ (similar
to Acrobat Reader for PDF files), is provided to review the
inclination calculations and critical site predictions.
Published
Map Files (PMF) are provided with every project and include:
pipeline centerline; local roads, RR, water features; and
aerial imagery (when available). The added benefits of the
PMF reporting format are:
- Allows for visual confirmation
of pipeline centerline to minimize errors introduced by data
misalignment
- Comprehensive database of aligned and
calculated IC data types
- Facilitates site selection
and excavation planning
- Provides easy of data analysis
- Data can be easily returned to a company’s GIS or
enterprise database
The time required to complete the internal corrosion threat
qualifications is relatively short and can be performed without
the time or expense associated with field-based methods. This
method is best suited for pipelines with no prior history
of corrosion and transports normally dry gas. For pipelines
with a stronger potential for internal corrosion, or those
in which a liquid sampling program (i.e., from drips, taps,
etc.) indicates the presence of water or bacteria, more precise
inclination methods are encouraged. Cost Avoidance of unnecessary
excavations can be significant.
IMG
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