# Presentation: 497901

## Direct Assessment Basics

**Richard Lopez**
**Office of Pipeline Safety**
**Southwest Region**

## Why Direct Assessment?

**Alternative to ILI or Hydro Test When Not Feasible or Practical**
**Many Gas Transmission Pipelines are “Not Piggable”**
**The Cost to Make Them Piggable can be Prohibitive (from $1M to $8M per mile)**

**Notes:**

Industry has estimated that to make lines piggable would cost somewhere between $90 to 700 Billion.

## Why Direct Assessment?

**ILI or Hydro-testing Could Cause Customer Supply Interruptions **
**LDC Laterals Often Sole Source Supply**
**Pipeline Safety Improvement Act 2002 – Section 23**
**TPSSC Equivalency Recommendation**

**Notes:**

Industry has estimated that to make lines piggable would cost somewhere between $90 to 700 Billion.

## Factors Impeding Piggability

**Telescopic Connections**
**Small Diameter Pipelines**
**Short Pipelines**
**Sharp Radius Bends**

**Notes:**
Not “piggable” involves pipe with varying diameters, short radius bends, reduced opening and pipe restrictions, as well as operating pressures too low to move pigs in a pipeline at controlled speeds, without exceeding MAOP if pigs get stuck and increased pressure is needed to dislodge them. 

## Factors Impeding Piggability

**Less than Full Opening Valves**
**No Alternate Supply if Pig is “Hung Up”**
**Low Pressure & Low Flow Conditions**
**Scheduling and Coordination is an Anti-trust Issue**

**Notes:**
Not “piggable” involves pipe with varying diameters, short radius bends, reduced opening and pipe restrictions, as well as operating pressures too low to move pigs in a pipeline at controlled speeds, without exceeding MAOP if pigs get stuck and increased pressure is needed to dislodge them. 

## Features in Common with ILI

**Indirect Examinations**
**Validation/Excavation/Direct Exam**
**Integrate & Analyze Data**
**Identify & Address Data Gaps**
**Identify Remediation Needs**
**Determine Re-assessment Intervals**

**Notes:**
Obtaining as much Information about a pipeline is a key ingredient to the IMP processes.  To refine and define the threats to the pipeline, possibly reduce the threat and the uncertainty, often it is desirable and economical to obtain more data about pipeline conditions and characteristics.  Operators search their records for all available information and data about a pipeline’s physical characteristics, construction conditions, and its operating history, (corrosion locations, when CP was fists applied, lost, etc, and where any leaks occurred.

Indirect tools use aboveground diagnostic tools to locate and help prioritize indications.
Direct tools excavate at indications and examine pipe to better understand what is happening to the pipeline.
Methods use the results of examinations for total pipeline assessment.

Remediation Needs may involve pipe replacements, pipe repairs, coating reconditioning, etc.

Evaluating and confirming a pipeline’s integrity involves assessing the remaining risks, reordering anomaly and excavation priorities, and implementing preventive and mitigation programs to reduce or eliminate continued threats to the P/L.

Re-inspection intervals involves applying defect growth models to determine safe operating conditions and to determine intervals for inspection and when the pipe must be re-evaluated.

## Factors Impeding Hydro-Test

**Service Interruptions **
**Sole Source Supplies**
**Concerns of Causing Pipeline Damage**
**Dewatering Concerns/Difficult to Dry**

**Notes:**
Concerns have been stated that hydro testing grows pipe imperfections and cracks, may do more harm to the pipeline than verify a lines’ integrity,  and may result in supply interruptions if water is not completely removed after testing, and may even foster internal corrosion.

## Factors Impeding Hydro-Test

**Dewatering Concerns/Difficult to Dry**
**Growth of Sub-critical Defects**
**Water Availability & Disposal**
**No Characterization of Future Risk**

**Notes:**
Concerns have been stated that hydro testing grows pipe imperfections and cracks, may do more harm to the pipeline than verify a lines’ integrity,  and may result in supply interruptions if water is not completely removed after testing, and may even foster internal corrosion.

## DA Basics - Overview

**Distinct Assessment Process for each Applicable Threat (i.e., EC, IC, & SCC)**
**Scope of DA as an IM Assessment is more Limited than either ILI or Hydro**

**Notes:**
What is critical for success in using the Direct assessment process is:
Expertise, skill, and experience in understanding and implementing the NACE ECDA, ICDA and SCC Standards. 
Processes of gathering, integration and analysis of data both historical to the pipeline and newly obtained data.
Mechanical Damage detection (or third party damage (TPD)) by ECDA will be limited by presence of coating holidays.  It is important to understand the limits of any IMP approach, what threats can be expected and what tools are capable of addressing that threat.  If a pipeline is expected to contain failure threats other than those that may be discovered by DA tools, such as material defects, cracks at welds, design or construction defects, low toughness levels, gouges covered over, etc, other tools must supplement DA tools to address these.
Stress that assessment and integration and analysis of data during all steps of the DA process is very important.
There are some advantages compared with Hydro and ILI as we’ll see a bit later.

## DA Basics - Overview

**May be the Assessment Method of Choice (esp. for Non-piggable Lines and Low-Stress Gas Lines that cannot be Hydro Tested)**
**Involves Integration of Risk Factor Data to Identify Potential Threats**

**Notes:**
What is critical for success in using the Direct assessment process is:
Expertise, skill, and experience in understanding and implementing the NACE ECDA, ICDA and SCC Standards. 
Processes of gathering, integration and analysis of data both historical to the pipeline and newly obtained data.
Mechanical Damage detection (or third party damage (TPD)) by ECDA will be limited by presence of coating holidays.  It is important to understand the limits of any IMP approach, what threats can be expected and what tools are capable of addressing that threat.  If a pipeline is expected to contain failure threats other than those that may be discovered by DA tools, such as material defects, cracks at welds, design or construction defects, low toughness levels, gouges covered over, etc, other tools must supplement DA tools to address these.
Stress that assessment and integration and analysis of data during all steps of the DA process is very important.
There are some advantages compared with Hydro and ILI as we’ll see a bit later.

## Keys to Successful DA

**Expertise, Skill, Experience**
**Follow NACE Standards**
**Document Justifications for Not Implementing “Should” and “May” Recommendations in the Standards **
**Documents Reasons for Program Decisions and Options Selected**

**Notes:**
Take some time here to explain some keys to successfully implementing a DA approach.
What is critical for success in using the Direct assessment process is:
Expertise, skill, and experience in understanding and implementing the NACE ECDA, ICDA and SCC Standards. 
Processes of gathering, integration and analysis of data both historical to the pipeline and newly obtained data. 
Stress that assessment and integration and analysis of data during all steps of the DA process is very important. The amount of data and the quality of data will be a key to successful application of DA.
Examples of the Types of Data that will be required: 
Design and pipe characteristics
Materials of construction
Construction practices
Cathodic protection application history
CP survey data
Repair and maintenance history (including pipe inspection reports)
Locations of 3rd party construction
Locations of components and appurtenances (valves, taps, supports, clamps, sleeves, casings, etc.)
Soil characteristics
Other integrity surveys or tests (ILI runs)

## Keys to Successful DA (cont.)

**Data Management**
**Collection, Integration, Analysis**
**Data Quality**
**Understand Limitations of DA**
**Provide Detailed Procedures for All Process Steps**

**Notes:**
Take some time here to explain some keys to successfully implementing a DA approach.
What is critical for success in using the Direct assessment process is:
Expertise, skill, and experience in understanding and implementing the NACE ECDA, ICDA and SCC Standards. 
Processes of gathering, integration and analysis of data both historical to the pipeline and newly obtained data. 
Stress that assessment and integration and analysis of data during all steps of the DA process is very important. The amount of data and the quality of data will be a key to successful application of DA.
Examples of the Types of Data that will be required: 
Design and pipe characteristics
Materials of construction
Construction practices
Cathodic protection application history
CP survey data
Repair and maintenance history (including pipe inspection reports)
Locations of 3rd party construction
Locations of components and appurtenances (valves, taps, supports, clamps, sleeves, casings, etc.)
Soil characteristics
Other integrity surveys or tests (ILI runs)

## Today’s Discussion will Focus on ECDA

**NACE RP0502 has been Issued**
**ECDA Process is More Mature than ICDA or SCCDA**
**Overview of NACE RP0502 Process for ECDA**

**Notes:**
PSIA of 2002 requires OPS to address DA, this OPS NPRM or one in future will reference the standard, and TPSSC recommended that OPS consider DA equivalent to ILI and Hydro.
The NACE Std on ECDA has been issued.  So today we will focus on ECDA.  It is a more mature and better understood technique.  NACE will brief you later today on the status of development of standards for ICDA and SCCDA.

ECDA is a process to find Holidays, breaks in a pipeline’s coating,  where corrosion can attack the pipe wall and reduce its safety margin of operation. Mechanical Damage detection (or third party damage (TPD)) by ECDA will be limited by presence of coating holidays.  It is important to understand the limits of any IMP approach, what threats can be expected and what tools are capable of addressing that threat.  If a pipeline is expected to contain failure threats other than those that may be discovered by DA tools, such as material defects, cracks at welds, design or construction defects, low toughness levels, gouges covered over, etc, other tools must supplement DA tools to address these.

## Limitations of ECDA

**ECDA Can Not Deal With:**
**Lines Susceptible to Seam Failure**
**Near-neutral pH SCC**
**Fatigue Failures in Liquid Lines**
**Internal Corrosion**
**Plastic Pipe**
**Pipe in Shielded Areas**

**Notes:**
The NACE Std on ECDA has been issued.  So today we will focus on ECDA.  It is a more mature and better understood technique.  NACE will brief you later today on the status of development of standards for ICDA and SCCDA.

ECDA is a process to find Holidays, breaks in a pipeline’s coating,  where corrosion can attack the pipe wall and reduce its safety margin of operation. Mechanical Damage detection (or third party damage (TPD)) by ECDA will be limited by presence of coating holidays.  It is important to understand the limits of any IMP approach, what threats can be expected and what tools are capable of addressing that threat.  If a pipeline is expected to contain failure threats other than those that may be discovered by DA tools, such as material defects, cracks at welds, design or construction defects, low toughness levels, gouges covered over, etc, other tools must supplement DA tools to address these.

## Limitations of ECDA

**ECDA has Limited Applicability to:**
**Mechanical Damage (Only to the Degree that Coating is also Damaged)**

**Notes:**
The NACE Std on ECDA has been issued.  So today we will focus on ECDA.  It is a more mature and better understood technique.  NACE will brief you later today on the status of development of standards for ICDA and SCCDA.

ECDA is a process to find Holidays, breaks in a pipeline’s coating,  where corrosion can attack the pipe wall and reduce its safety margin of operation. Mechanical Damage detection (or third party damage (TPD)) by ECDA will be limited by presence of coating holidays.  It is important to understand the limits of any IMP approach, what threats can be expected and what tools are capable of addressing that threat.  If a pipeline is expected to contain failure threats other than those that may be discovered by DA tools, such as material defects, cracks at welds, design or construction defects, low toughness levels, gouges covered over, etc, other tools must supplement DA tools to address these.

## 4 Step ECDA Process of NACE RP0502

**Pre-assessment **
**Indirect Assessment **
**Direct Physical Examination**
**Post-assessment**

**Notes:**
Basic concept is similar to ILI (pigging).  Technologies can be used as a diagnostic tool to assess pipeline integrity.  Defect growth models can be used to determine “safe” operating conditions and to determine re-assessment or inspection frequencies.  Direct Assessment diagnostic techniques generate data concerning integrity characteristics. 
Throughout each of the process steps, integration of data from inspection tools and historical data and operational data leads to assessments of the overall health of the pipeline system.

## Pre-assessment

**Process Similar to Risk Assessment**
**Assemble and Analyze Risk Factor Data**

**Notes:**
Pre-Assessment
Data collection
Threat Analysis
ECDA feasibility for pipeline
Indirect inspection tool selection
ECDA region identification

## Pre-assessment

**Purpose:**
**Determine Whether ECDA Process is Appropriate and Define “ECDA Regions”**
**Select Appropriate Indirect Inspection Tools (e.g., CIS, DCVG, PCM, C-SCAN)**
**Complementary Primary and Secondary Tools are Required**
**Identify Inspection Expectations**

**Notes:**
Pre-Assessment
Data collection
Threat Analysis
ECDA feasibility for pipeline
Indirect inspection tool selection
ECDA region identification

## Pre-assessment

**Data Collection (Table 1 of NACE Standard)**
**Pipe Related**
**Construction Related**
**Soils/Environmental**
**Corrosion Protection**
**Pipeline Operations**

## Pre-assessment

**ECDA Indirect Insp. Tool Feasibility**
**Complementary Tools – Evaluate pipe with different technologies (see table 2 of NACE RP0502)**

## Pre-assessment

**Feasibility Influenced by:**
**Degree of Shielding (Coating type, Terrain)**
**Accessibility (Pavement, Water Crossings, Casings)**

## Pre-assessment

**Establish ECDA feasibility regions**
**Determine which indirect methods are applicable to each region**
**Tools may vary from region to region**

## Pre-assessment

**What is a Region?**
**Segment is a Continuous Length of Pipe**
**Regions are Subsets of One Segment**
**Characterized by Common Attributes**
**Pipe with Similar Construction and Environmental Characteristics**
**Use of Same Indirect Inspection Tools Throughout the Region is Appropriate**

## Indirect Inspection 

**Close Interval Survey (CIS)**
**Direct Current Voltage Gradient (DCVG)**
**C-Scan**
**Pipeline Current Mapper (PCM)**
**Alternating Current Voltage Gradient (ACVG) (PCM with A-Frame)**

**Notes:**
Examples of the kinds of tools that may be used in ECDA.

## Indirect Inspection 

**Pearson**
**Ultrasonic**
**Waveform**
**Soil Resistivity, Pipe Depth**

**Notes:**
Examples of the kinds of tools that may be used in ECDA.

## Indirect Inspection 

**Direct Current**
**Measure Structure Potential**
**Identify Locations of High CP Demand to Small Area**

## Indirect Inspection 

**Alternating Current**
**Apply AC signal**
**Determine Amount of Current Drain (i.e., Grounding) and Location**
**Identify Locations of High AC Current**

## Indirect Inspection 

**Types of Direct Current Tools**
**Close Interval Survey (CIS or CIPS)**
**Direct Current Voltage Gradient (DCVG)**
**Types of Alternating Current Tools**
**Alternating Current Voltage Gradient (ACVG)**
**Pearson Survey**
**AC Attenuation (PCM, EM, C-Scan)**

## Indirect Inspection 

**Purpose:**
**Locate Areas Where Coating Damage May Exist**
**Evaluate Whether Corrosion Activity is Present**
**Apply Primary and Secondary Tools**

**Notes:**
Indirect Examination Objective:   Identify coating faults and areas where corrosion activity may have or may be occurring. 
The step utilizes a minimum of two complementary indirect techniques or tools.

Also, extremely important to correlate geospatial tool data – locations where readings are being taken, along with documenting surface conditions, other utility facilities at the location of the readings, trench indications, etc, along with operating history data 

## Indirect Inspection 

**Timing Such That Conditions are Same**
**Overlay and Evaluate Data for Clarity, Quality, and Consistency**
**Distance Correlation Should be Good**

**Notes:**
Indirect Examination Objective:   Identify coating faults and areas where corrosion activity may have or may be occurring. 
The step utilizes a minimum of two complementary indirect techniques or tools.

Also, extremely important to correlate geospatial tool data – locations where readings are being taken, along with documenting surface conditions, other utility facilities at the location of the readings, trench indications, etc, along with operating history data 

## Indirect Inspection via CIS

**May Detect Large Coating Holidays**
**Measure Pipe to Soil Potential at Regular Intervals (2.5 – 5 ft. Desirable)**
**Protection criteria**
**-850mV polarized potential**
**100mV polarization**

## Indirect Inspection via CIS

**Secondary Interpretation**
**Change in potential profile**
**Amount of IR drop (Low or High)**
**ON and OFF Readings are Desirable**

## Indirect Inspection via DCVG

**Measures Voltage Gradient in Soil**
**CP Current Greatest Where Coating is Damaged**

**Notes:**
V = I*R
V = I*R

## Indirect Inspection via DCVG

**Interrupt Rectifier to Determine ****∆****V**
**One Electrode**
**Two Electrodes **
**Parallel or perpendicular to ROW**
**Coating Holiday Size Indicated by % ****∆****V**
**Triangulation Used to Locate Holiday**

**Notes:**
V = I*R
V = I*R

## Indirect Inspection via ACVG

**Impose AC current**
**Measure Gradient Between 2 Electrodes Spaced ~1m Apart**
**Gradient Corresponds to Current Flow**

## Direct Physical Examination

**Establish “Priority Categories” from Indirect Inspection**
**Excavations for Direct Examination**

## Direct Physical Examination

**Purpose:**
**Confirm Presence of Corrosion Activity**
**Determine Need for Repair or Mitigation**
**Evaluate Likely Corrosion Growth Rate**
**Support Adjustments to Excavation Scope**
**Evaluate Need for Other Technology**

## Direct Physical Examination

**Categorize Indications**
**Immediate Action Required**
**Schedule for Action Required**
**Suitable for Monitoring**
**Excavate and Collect Data Where Corrosion is Most Likely**

## Direct Physical Examination

**Characterize Coating and Corrosion ****Anomalies**
**Establish Corrosion Severity for Remaining Strength Analysis**
**Determine Root Cause**

## Direct Physical Examination

**In-process Evaluation, Re-categorization, Guidelines on Number of Direct Examinations**
**All “Immediate” Must be Excavated**
**Prioritize “Scheduled” & “Monitored”**
**If >20% Wall Loss Found, Examine at Least 1 More (2 More for 1****st**** ECDA)**

## Direct Physical Examination

**If No Indications**
**At Least 1, and 2 for 1****st**** ECDA**
**Choose More Corrosive Region**

## Direct Physical Examination

**Dig a Bell Hole**
**Visual Inspection**
**Coating Condition**
**Ultrasonic Testing**
**Radiography**
**Soil Chemistry and Resistivity**

## Direct Physical Examination

**Collect Data at Dig Site**
**Pipe to Soil Potentials**
**Soil Resistivity**
**Soil and Water Sampling**
**Under-film pH**
**Bacteria & SCC Related Data**
**Photographic Documentation**

## Direct Physical Examination

**Characterize Coating and Corrosion Anomalies**
**Coating Condition**
**Adhesion, Under Film Liquid, % Bare**
**Corrosion Analysis**
**Corrosion Morphology Classification**
**Damage Mapping**
**MPI Analysis for SCC**

## Direct Physical Examination

**Remaining Strength Analysis**
**ASME B31G**
**RSTRENG**

## Direct Physical Examination

**Determine ****Root**** Cause**
**For Example**
**Low CP**
**Interference**
**MIC**
**Disbonded Coatings**
**Construction Practices**
**3****rd**** Party Damage**

## Post-Assessment

**Evaluates Composite Set of Data and Assessment Results**
**Sets Re-inspection Intervals**
**Validates ECDA Process**

**Notes:**

This step may result in reordering priorities of anomalous conditions, 
It may identify continuing excavation needs for further evaluations and more data upon which to base a decision and eliminate uncertainty of as to whether further work is required.
It may identify the need for other assessment technologies I.e. ILI especially if numerous conditions are identified with ECDA tools, too numerous to dig all of them and analyze the pipe at each location. 

## Post-Assessment

**Remaining Life - Maximum Flaw**
**Maximum Remaining Flaw Size Taken Same as Most Severe that was Found**
**Second Maximum if Unique**
**If No Corrosion Defects, Same as New**
**Other (e.g., Statistical)**

## Post-Assessment

**Remaining Life Growth Rate**
**Measured Corrosion Rate**
**Maximum Depth / Burial Time**
**16mpy (80% C.I. for Corrosion Tests)**
**0.3mm/y if at Least 40mV CP Demonstrated**

## Post-Assessment

**Linear Polarization Resistance (LPR)**
**Probe or Existing Buried Coupon**
**Coupon Retrieval**
**Assess ECDA Effectiveness**

## Post-Assessment

**Perform at Least 1 Extra Dig at Random Location**
**Pipe Condition Should be Better than at Indications**
**For 1****st**** ECDA**
**Additional Dig at Low Priority Indication**
**Company-specific Performance Metrics**

## ECDA Summary

**There is No Panacea for Pipe Integrity Verification**
**All Tools Have Limitations**
**External Corrosion Direct Assessment is Based on the Use and Integration of Existing and Emerging Technologies**

## ECDA Summary

**External Corrosion Direct Assessment can be Effective if Properly Applied **
**Requires Effective Data Collection and Management as well as a Commitment to Validation**
**Operators Choose Best Tools to Achieve Pipeline Reliability, Safety, and Asset Preservation**