April 2011 

Industry Guidance for the Development of Inspection Plans 

for Buried Piping

 

Prepared by: Buried Pipe Integrity Task Force 

Final Draft 

April, 2011 

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TABLE OF CONTENTS 

1.0 Preface ................................................................................................................. 4

2.0 Purpose ................................................................................................................ 4

3.0 Background ......................................................................................................... 4

4.0 Terms and Definitions ......................................................................................... 6

5.0 Buried Piping Reasonable Assurance Flow Chart-Description .................... 10

6.0 References ......................................................................................................... 21
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1.0 Preface 

This document provides industry guidance for the determination of reasonable 

assurance for structural and/or leakage integrity for buried piping. The criteria and 

guidelines presented in this document were developed as a consistent basis for 

establishment of what is necessary to provide “reasonable assurance of integrity”. 

2.0 Purpose 

The purpose of this document is to provide a technically based approach for 

development of inspection plans that establish reasonable assurance of structural 

and/or leakage integrity of buried piping through the application of the results of both 

indirect inspections and direct examinations. The approach is programmatically founded 

in the precepts established in the “Recommendations for an Effective Program to 

Control the Degradation of Buried and Underground Piping and Tanks (EPRI 1016456, 

Revision 1) and utility site specific program documents. This document is intended to 

establish reasonable assurance for scoped buried piping systems; optimizing the 

inspection scope, while not requiring 100% inspection. 

3.0 Background 

Reasonable assurance is an industry methodology used to achieve increased 

confidence in the capability of a structure, system or component (SSC) to perform its 

intended function. Reasonable assurance does not equate to absolute assurance or 

confidence. Rather, reasonable assurance collects appropriate 

data/insights/information to support the establishment of increased confidence. 

Situations may occur where sufficient data cannot be easily collected; in these cases, 

the available data may be supplemented with additional insights to bolster a technical 

foundation of reasonable assurance. If available information (even with supplemental 

insights) is insufficient to support a conclusion of reasonable assurance, then additional 

actions must be taken to achieve reasonable assurance. Ultimately, the establishment 

of reasonable assurance is the obligation of the owner. This guideline provides insights 

to achieve consistency among industry users to identify what actions are generally 

necessary to establish reasonable assurance for structural and/or leakage integrity for 

buried piping. 

Reasonable assurance of integrity in buried piping systems containing licensed material 

or non-licensed material is obtained when activities such as an engineering evaluation 

(including a Fitness-for-Service assessment), indirect inspections of underground 

components, direct examination and remediation (if necessary), are performed. Such a 

combination of activities will provide a high level of confidence that the structural and 

leak integrity of the buried piping systems, will be managed and effectively maintained. 
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A reasonable assurance of integrity process is based on defining systems that are in 

scope, risk ranking these systems, and then identifying a sample of locations in these 

systems for inspections. It relies on engineering analyses, expert judgment, operating 

experience, and groundwater protection program data to determine what regions of the 

buried pipes are vulnerable to degradation and adequately characterizing the 

vulnerability so that, if necessary, appropriate corrective actions may be taken. This 

process is based on risk identification and inspection sampling intended to greatly 

reduce the potential for unacceptable leakage or failures in the most susceptible 

systems. 

Engineering evaluation is an important part of the “reasonable assurance of integrity” 

process. The engineering evaluation will consider but not limited to items such as high 

consequence and/or likelihood areas, previous inspection results, fabrication practices, 

material type, backfill, coating, soil condition, water levels, water and soil chemistry, 

cathodic protection, operational history, industry operating experience, site operating 

experience and groundwater protection program data. This engineering evaluation will 

identify the risk of potential leakage, the most probable locations, and/or areas of likely 

susceptibility. The evaluation will also identify the potential consequences that could 

result if a leak occurred. With this information, an inspection plan can be developed and 

implemented that provides information regarding the condition of the structure, system 

or component. The inspections can be indirect in that they will provide information on 

the condition of the pipe remotely – from ground level or from an exposed section of 

pipe that is distant or remote from the pipe location of interest. Inspections include a 

direct examination of the pipe wall and a visual inspection of the outer surface coating to 

determine coating integrity. Direct examination can also be achieved using an in-line 

vehicle (or Pipeline Inspection Gauge “PIG”) deployed with demonstrated direct 

examination equipment that is capable of detecting degradation that is possible at the 

location of interest and that is large enough to challenge structural or leakage integrity if 

present.

The specific inspections and examinations that are performed will be based on the type 

of degradation observed or expected, the susceptibility of the pipe to leakage, the 

consequences of a leak, and the location of the pipe. The scheduling of re-inspection 

and re-examination is also dependent on the engineering determination of susceptibility, 

consequences, and the results of the initial inspection or examination. 
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4.0 Terms and Definitions 

4.1. Adverse Inspection Findings – Indications from inspections that require 

immediate repairs or repairs within one cycle. 

4.2. Baseline Inspections - Inspection of new or replaced pipe or components 

that have not previously been involved in plant operations. 

4.3. Corrosion Rate (CR) is the rate of corrosion occurring over a defined period 

of time.

4.4. Direct Examination - A Nondestructive Evaluation (NDE) examination where 

the NDE sensor(s) is in immediate contact with or in close proximity to the 

section of the component being examined. Results provide some degree of 

quantitative measurement of wall thickness or discontinuity size. Direct 

examinations can be performed from the interior or exterior surface. 

Detection and characterization capabilities vary by NDE method as well as by 

specific NDE technique. Examples of NDE methods include ultrasonics, eddy 

current, radiography, visual and various electromagnetic techniques. Visual 

examinations need to be supplemented with NDE or engineering judgment 

that addresses the condition of the pipe wall. 

 

4.5. Fitness-for-Service (FFS) - is a technical evaluation of direct examination 

data to determine acceptable flaw size, degradation rate, remaining life, and 

the time to the next inspection or repair/replacement/mitigation. 

4.6. Highest Susceptible Locations are the highest likelihood and consequence 

risk ranked lines, segments or zones as defined in the buried piping 

susceptibility analysis and risk ranking database. 

4.7. Indirect Inspection – Survey techniques used to assess the likelihood of 

degradation without having direct access to the section of the component 

being examined. These inspections typically measure surrounding conditions 

that may be indicative of corrosion or damage. Results are typically qualitative 

and less accurate than direct examinations. Examples of indirect inspection 

methods include over-the-line surveys and for the purpose of this document, 

long range guided wave.

4.8. Initial Inspection - The inspection of pipe or components that have been in 

service but have not been previously inspected. 
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4.9. Inspection Program - A systematic evaluation of in-scope components using 

various techniques (e.g., ultrasonic testing (UT), radiographic testing (RT), 

visual testing (VT), leak testing (LT), eddy current testing (ET)). 

4.10. Lg – is the total length of piping associated with a group of lines.

4.11. L indirect – is the total length of pipe associated with a group of pipe lines 

that have been indirectly inspected.

4.12. Line Grouping - is a process that may be used to optimize inspection scope 

and schedule duration. Lines/segments/zones are grouped based on various 

attributes, such as but not limited to process fluid, pipe material, coatings, 

depth, age, soil/backfill, etc.

4.13. Next Scheduled Inspection (NSI) - is the time duration until another 

inspection of the pipe line group is required. 

4.14. Opportunistic Inspection – An inspection performed when buried or 

underground components are exposed or excavated due to another activity 

providing an opportunity to inspect and document the results for a program 

component. 

4.15. Piping Segment - Portions of buried piping systems that are grouped 

together for risk ranking purposes based on similarities such as installation, 

manufacture, or environmental conditions. Some risk ranking methods may 

use other terms to refer to piping segments, such as zones. 

4.16. Post Assessment is an assessment of all indirect and direct examination 

results including a FFS evaluation that will determine the projected structural 

and leakage integrity of a pipe. 

4.17. Remaining Life (RL) is defined as the time period until the pipe wall 

thickness is no longer acceptable. 

4.18. Visual Inspections involve direct observation by inspectors or by the use of 

remote visual inspection devices.
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Figure 5-1 Buried Piping Inspection Reasonable Assurance (RA) Flow Chart 
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Figure 5-2 Buried Piping Inspection Reasonable Assurance (RA) Flow Chart 
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5.0 Buried Piping Inspection RA Flow Chart-Description

5.1 Buried Piping Program Susceptibility Analysis and Risk Ranking 

1. Susceptibility Analysis and Risk Ranking are used to determine the overall 

likelihood and consequence of a line, segment or zone failure. 

2. This evaluation is based on detailed site specific information and provides 

a risk assessment of all piping within the program scope. 

3. The following potential exclusions from the program scope may be 

considered in the susceptibility and risk ranking process. The basis for the 

exclusion should be documented: 

a. Segments or zones constructed of materials not susceptible to the 

associated ID and OD degradation mechanisms like titanium and 

super austenitic stainless (e.g., AL6XN or 254 SMO). 

b. Segments or zones of materials fully backfilled using controlled low 

strength material (flowable backfill) in accordance with NACE SP0169-

2007, unless the pipe is susceptible to ID degradation. 

c. Piping sections that are hydrostatically tested in accordance with 49 

CFR 195 subpart E on an interval not to exceed 5 years. 

5.2 Create Line Groupings 

1. The purpose for the grouping of lines is to be able to extrapolate inspection 

results from one or more examinations to the rest of the group, optimizing the 

number of excavations. 

2. Separate segments or zones by process fluid (e.g., Tritiated, Service Water, 

& Oil lines would be grouped separately; Corrosive vs. non-corrosive fluid, for 

instance chemical feed would be grouped separately from condensate and 

separately from tritiated circulating water piping) 

3. Further separate or create groups of lines with similar physical attributes by 

the following order of importance : 

a. Material (e.g., Carbon Steel, Stainless Steel, Plastic, Fiberglass, 

and Aluminum would be grouped separately) 

b. Coating type/age 

i. ID coating, type/age 

ii. OD coating, type/age 

c. Line depth (the basis for this grouping is the effect of live loads, and 

overburden): 

i. < 10ft below grade -- Can see the effects of live loads 
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ii. > 10ft below grade 

d. Pipe Age (e.g., Inspections on newer lines should not be used to 

justify reasonable assurance on older lines). 

e. Location in similar soil conditions (e.g., Lines in close proximity to 

one another in the same underground path/fill trench, backfill) 

f. Cathodic protection availability and operating history 

g. Operating Conditions 

i. Temperature (e.g., lines that undergo cyclic temperature 

changes and/or are >100F would not be grouped with 

ambient temperature lines). 

ii. Operating frequency, and durations (e.g., continuous vs. 

infrequent/outage only) 

h. Pipe joining methods (e.g., socket vs butt welds or threaded 

connections & could be a consideration for the adequacy of the 

external coating application) 

4. It is not required to separate or create new groups for each category listed in 

5.2.3 above. 

5. Each segment or zone should be included in a Line Group. 

6. Documentation is required to support the basis for each line grouping. 

7. Inspections would be performed on the highest susceptible locations in each 

group. 

5.3 Indirect Inspection 

1. Indirect inspections, when feasible, are the best approach for determining 

the number and location of direct examinations that are required. 

2. Indirect inspections are not required and the owner can go straight to 

direct examinations. 

 

3. Indirect Inspection Selection is based on the highest susceptible locations 

in a line group. 

4. Review each of the Indirect Inspection techniques per station or industry 

examination guidelines for determining applicable or optimum methods for 

each grouping or individual segments/zones. 
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5. Review historical cathodic protection survey data and segment or zone 

location accessibility in order to refine the inspection selection areas. 

6. Review the Groundwater Protection Program data. 

7. Indirect inspection measurements should be referenced to precise 

geographic locations and documented so that inspection results can be 

used for excavation and direct examinations. Indications from inspections 

should be aligned with other results, drawings and structures. 

 

8. Verification of the indirect inspections should be done using the direct 

examination results. At least one direct examination will be performed in 

each high risk line grouping. 

5.4 Classify Indirect Inspection Results 

1. Criteria for classifying indirect inspection results must be established. 

2. The criteria for classifying the severity of indications should take into 

account the indirect inspection techniques used and the conditions 

surrounding the pipe segment. The following general classifications may 

be used: 

• Severe – indications having the highest likelihood of active corrosion 

activity; 

• Moderate – possible pipeline corrosion activity; or 

• Minor – the lowest likelihood of active corrosion activity. 

3. The capability and accuracy of the inspection method used must be 

considered as part of the engineering evaluation. 

5.5 Direct Examination Initial Sample Size 

1. When indirect inspections (for example a combination of Guided Wave 

and Above Ground Coating Surveys), covered greater than 50% of total 

(group) length including the highest susceptibility locations and where no 

severe indication (Section 5.4) is identified; one direct examination of the 

highest susceptible location to confirm the indirect inspection results would 

be required for each high risk line grouping, irrespective of the total line 

length. If an acceptable direct examination was achieved (i.e., Post 

Examination Assessment), then reasonable assurance could be 

demonstrated. 
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2. When indirect inspections covered less than 50% of total length of a pipe 

group and where no severe indication is identified: 

a. For those High Risk Ranked lines that are safety related or contain 

Licensed Material or are known to be contaminated, that have pipe 

groups with total lengths of piping less than approximately 500’ (ft), 

then one direct examination of the highest susceptible location, with 

acceptable results, may be sufficient to demonstrate reasonable 

assurance. In selecting the location of the direct examination, 

consideration can be given to the accessibility of examination 

locations. 

b. For those High Risk Ranked lines that are safety related or contain 

Licensed Material or are known to be contaminated, that have pipe 

groups with total lengths of piping greater than approximately 500’ 

(ft), but less than 2500’ (ft), two direct examinations of the highest 

susceptible locations, with acceptable results, may be sufficient to 

demonstrate reasonable assurance. In selecting the location of the 

direct examination, consideration can be given to the accessibility 

of examination locations. 

c. For those High Risk Ranked lines that are safety related or contain 

Licensed Material or are known to be contaminated, that have pipe 

groups with total lengths of piping greater than approximately 2500’ 

(ft), three direct examinations of the highest susceptible locations, 

with acceptable results, may be sufficient to demonstrate 

reasonable assurance. In selecting the location of the direct 

examination, consideration can be given to the accessibility of 

examination locations. 

d. For those lines that are High Risk Ranked and are not safety 

related, do not contain Licensed Material or are not known to be 

contaminated that have pipe groups with total lengths less than 

approximately 500 ft, one direct examination of the highest 

susceptible location, with acceptable results, may be sufficient to 

demonstrate reasonable assurance. In selecting the location of the 

direct examination, consideration can be given to the accessibility 

of examination locations. 

 

e. For those lines that are High Risk Ranked and are not safety 

related, do not contain Licensed Material or are not known to be 

contaminated that have pipe groups with total lengths greater than 
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approximately 500 ft, two direct examinations of the highest 

susceptible locations, with acceptable results, may be sufficient to 

demonstrate reasonable assurance. In selecting the location of the 

direct examination, consideration can be given to the accessibility 

of examination locations. . 

 

f. For those lines that are Medium and Low Risk Ranked, a 

monitoring plan should be established and direct examinations 

performed on an opportunistic basis to determine reasonable 

assurance. 

3. For indirect inspections that indicate severe levels of corrosion activity, 

categorize locations for direct examination and proceed to section 5.6. 

4. For indirect inspections that indicate moderate and minor levels of 

corrosion activity the direct examination or examinations in section 5.5.2 

would be focused on the highest area of indicated degradation. 

5. Where indirect inspections that evaluate wall thickness are performed at 

the most susceptible locations in a group, and the results of such 

inspections indicate NO or MINOR likelihood of corrosion activity, then 

confirmation of the indirect inspection results may be obtained from a 

direct examination of another indirect inspection location in the same 

group (where the same inspection technique was used). This can be 

allowed when accessibility issues exist for conducting a direct 

examination. 

Using the figure below to illustrate this concept; a guided wave shot is 

taken in Excavation 1 showing only “minor” indications at “B” and “D”. 

A direct exam is performed that validates these results, and the remaining 

life is acceptable. A second set of guided wave shots is taken through a 

wall penetration (highest susceptible location), showing minor indications 

at “A” and “C”. The pipe condition and indications at “A” and “C” would be 

considered validated by the direct examination completed in Excavation 1 

with an acceptable remaining life. A second excavation would not be 

required to validate indications “A” and “C”. To provide additional 

assurance of pipe integrity for all of these indications; one or more of the 

monitoring activities listed in section 5.8-3 should be periodically 

performed. 
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5.6 Direct Examination Selection 

The objective of direct examination is to assess the extent of corrosion activity 

for line segments selected for examination based on the risk assessment and 

indirect inspections, when performed. When no significant degradation is 

found from a direct examination the remaining service life and next scheduled 

inspection should be calculated using the guidance in the following sections. 

1. Indirect inspections results should be used in determining the priority of 

direct examinations. Below is an example of criteria used for prioritizing 

direct examinations based on the severity of indications from the indirect 

inspections: 

a. Severe Indications – Initiate Direct Examination Plan with 

Contingencies for Mitigating Action for: 

i. Severe indications in close proximity 

ii. Severe indications in a region with multiple moderate indications 

iii. Isolated severe indications in a high risk region or area 

iv. Indications known to be actively corroding 

v. Moderate indications in a region of high risk, prior leaks or severe 

corrosion 

b. Moderate Indications – Scheduled Action Required 

i. Isolated severe indication in a low risk region 

ii. Groups of moderate indications 

iii. Groups of minor indications in a medium risk region 

iv. Groups of minor indications in close proximity 
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c. Minor Indications – Monitor 

i. All remaining indication scenarios 

2. If no Indirect Inspections were performed for a group, then selection of the 

direct examination locations is based on the highest susceptible location 

of each line group considering location accessibility. Review historical 

cathodic protection survey data or other relevant parameters to refine the 

direct examination area. 

3. Direct examinations resulting from excavations should include coatings 

inspections by a person trained and experienced in coating condition 

assessment. 

4. At least one Direct Examination is required for each High Risk Line Group 

in order to establish reasonable assurance for the Group. 

5. A Direct Examination at an individual excavation will assess a minimum 10 

feet length of pipe, if feasible. When there is more than 1 pipeline in an 

excavation, each pipeline that receives an examination accounts for a 

separate direct examination. 

5.7 Inspection Sample Expansion Considerations 

When a pipe segment or zone has degradation detected by direct 

examination that exceeds the acceptance criteria in section 5.8 and 5.9: 

1. Determine the extent of the corrosion by mapping the axial and transverse 

lengths and depths of the corroded area. 

2. Review the indirect inspection results for the affected segment or zone 

and determine if additional excavation is required to perform direct 

examination of other areas with severe or moderate indications. 

3. Determine any segments or zones that share the same corrosion 

susceptibility characteristics and schedule additional direct examinations. 

The timing of the additional examinations should be based on the severity 

of the degradation identified and should be commensurate with the 

consequence of a leak or loss of function. 

4. Scope expansion must be sufficient to provide confidence that the extent 

of condition reasonably bounds the degradation. 

5. Document the findings and actions in the appropriate corrective action 

program. 
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5.8 Post Examination Assessment

The purpose of the post assessment process is to define the inspection 

interval (time to Next Scheduled Inspection or NSI), assess the effectiveness 

of the program, and then feed the results back to the pre-assessment step to 

revise the risk ranking of buried pipe segments or zones as a continuous 

improvement process. The cumulative goal of the evaluations for a piping 

group is to complete a post assessment; including a fitness for service 

evaluation, that determines the remaining life and next scheduled inspection 

interval to provide quantitative reasonable assurance for that group.

1. The assessment of the examination results should be made using a 

Fitness-for-Service (FFS) assessment. Any degradation found during a 

direct examination should be appropriately documented. 

2. The FFS evaluation performed will apply to all lines, segments, or zones in 

the group. 

a. When direct wall thickness measurement meets tmin & tmeas is >87.5% 

of tnom no FFS evaluation is required, unless active degradation is 

identified. 

b. When direct wall thickness measurement meets tmin & tmeas is <87.5% 

of tnom:

i. Perform an FFS 

ii. Evaluate cause of degradation (consider all variables-backfill, 

coatings, installation, etc.) 

iii. Evaluate the extent of degradation (localized verses global) 

iv. Evaluate the need for scope expansion 

 

c. When direct wall thickness measurement does NOT meet tmin: 

i. Evaluate cause and extent of degradation 

• Inspection scope expansion (See section 5.7) 

• Determine the Extent of Condition 

• Repair degraded areas 

• Evaluate potential mitigation strategies 

• Enter into the corrective action program 

3. Monitoring activities should be considered as part of the reasonable 

assurance programmatic or compensatory actions. Examples for the 
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justification of the scheduling/deferral of reasonable assurance direct 

examinations are: 

• Increased Ground Water Initiative related well monitoring frequency 

• Enhanced Cathodic Protection and/or Area Potential Earth Current 

(APEC) Surveys 

• Soil Analysis 

• Coating Scans 

• Flow/pressure testing 

• Guided Wave inspections 

• Corrosion Probes 

• Leak Testing (Acoustic monitoring, etc.) 

5.9 Fitness for Service (FFS) Evaluation 

The purpose of the FFS evaluation process is to provide guidelines for 

evaluating wall thickness degradation in safety and non-safety related 

components. Engineering should use these guidelines, or other applicable 

methodologies, when establishing the acceptance criteria or refining the 

acceptance criteria when warranted. The projected life of the component, 

based on these calculations, is to be used to establish the interval between 

examinations. An engineering technical evaluation is required for any deferral 

of the next scheduled examination past the remaining life date. 

a) Corrosion Rate 

It is recognized that for buried piping, most degradation mechanisms 

are not linear with time. Any corrosion rate calculated from one 

inspection is likely to have a large inaccuracy and could be either 

conservative (for inactive degradation mechanisms) or nonconservative (for recently activated mechanisms). Whenever possible, 

external corrosion rates should be determined by directly comparing 

measured wall thickness changes over a known time interval. 

Therefore, it is recommended to perform at least two inspections 

before a more accurate corrosion rate can be established. 

When previous pipe wall thickness measurements or other data are 

not available, default corrosion or pitting rate may be used to 

determine re-inspection intervals. NACE recommends a default pitting 

rate of 16 mils/year. NACE further indicates that the default corrosion 

rate may be reduced by 24% (from the default 16 mils/year), provided 

that the Cathodic Protection (CP) levels of the pipeline segments being 
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evaluated have had at least 40 mV of polarization, considering the 

voltage drop, for a significant fraction of the time since installation. If 

the evaluated line can potentially be subjected to an internal corrosion 

process, such as Flow Accelerated Corrosion (FAC), 

Erosion/Corrosion (E/C) or Microbiologic Influenced Corrosion (MIC), 

effects of internal wall loss should also be considered. 

For components with multiple examinations the corrosion rate may be 

more refined, as outlined in equation 1 below: 

 CR = (timemeas1 – timemeas2 ) x SF / time.......................Equation 1 

Where: 

 CR = Corrosion rate, also referred to as Rml in Ref. 14 

 timemeas1 = tmeas at 1st examination 

 timemeas2 = tmeas at 2nd or subsequent examination at 

same location 

 tmeas = The minimum measured value 

 SF = Safety Factor (recommend at least 10%) = 1.10 

 time = The length of time between the (timemeas1 and 

timemeas2) examinations (years) 

b) Remaining Life (RL) Calculation 

For the examination of a buried pipe component, the remaining life 

(RL) may be calculated as per Equation 2 below: 

 RL = (tmeas – tmin) / CR...........................................Equation 2 

Where: 

 tmeas = The minimum measured value from the 1st examination 

 tmin = The minimum acceptable wall thickness for the current 

inspection required to meet Code requirements. 

 CR = Corrosion Rate (mils/year). Whenever possible external 

corrosion rates should be calculated from direct comparison of 

changes in wall thickness over time. However, for the initial 

examination the time period of active corrosion is unknown. In the 

absence of a known period of time from the initiation of corrosion, a 

default corrosion rate (CR) of 16 mils/year may be used. 
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If the evaluated line can be subjected to FAC, E/C, and/or MIC, then 

the effects of internal wall loss should be considered. 

3. Time to Next Scheduled Inspection (NSI) 

When tmeas is found to be less than or equal to 50% of tnom, the reexamination interval should be taken as one-half the remaining life (RL) 

calculated in Equation 2. The examination interval may be increased if it 

can be determined that the corrosion mechanism is inactive, for example a 

coating repair has been applied. When corrosion is less than 50% of tnom 

(i.e. tmeas is greater than 0.5 tnom), the re-inspection interval may be taken 

as 75% of RL, as summarized below: 

 tmeas </= 0.5 x tnom: NSI = 0.5 x RL.............................Equation 3

 tmeas > 0.5 x tnom: NSI = 0.75 x RL...........................Equation 4 

4. Mitigation or Engineering Technical Evaluation 

a) A determination should be made to either mitigate directly or to 

perform additional engineering technical evaluation/analysis if the 

remaining life does not support the period of time until the pipe will 

be available for the next examination (e.g., refueling outage). 

b) If more than a single line is in the group, the lines with no 

examination data need to be evaluated based on the examinations 

performed for determination of condition. Additional examination 

may be required based on this evaluation. 

c) A determination should be made to repair, replace or implement 

compensatory actions. 

d) All engineering evaluations should be performed and documented 

as required by station procedures. 
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6.0 References 

1. “Recommendations for an Effective Program to Control the Degradation of 

Buried and Underground Piping and Tanks 1021175 (EPRI 1016456, Revision 1) 

2. Radiological SSC Groundwater Initiative Risk Evaluation Criteria 

3. A.P. Moser "Buried Pipe Design”, McGraw Hill, 2nd Edition (Table 2.7 “Live 

Loads”). 

4. Section XI, Div. 1 Class 2 and 3 Metallic Piping Buried in a Back-Filled Trench, 

Inquiry, Draft “What Rules may be used to evaluate Class 2 and Class 3 metallic 

piping buried in a back-filled trench subjected to metal loss on the internal and 

external surfaces of the pipe or fitting” 

5. ASME B&PV Code, Section XI 

6. ASME B&PC Code, Section III 

7. ASME B31.1, “Power Piping” 

8. ASME Standard B31.3, “Process Piping” 

9. ASME B31-G, “Manual for Determining the Remaining Strength of Corroded 

Pipelines” 

10. American Petroleum Institute (API) Standard 510 Pressure Vessel Inspection 

Code: “Maintenance Inspection, Rating, Repair, and Alteration” 

11. API Standard 570 Piping Inspection Code: “In-service Inspection, Rating, Repair, 

and Alteration of Piping Systems” 

12. API Standard 653, “Tank Inspection, Repair, and Reconstruction” 

13. ASME Code Case N-597-1, “Requirements for Analytical Evaluation of Pipe Wall 

Thinning”, Section XI Div. 1. 

14. ASME Code Case N-513, “Evaluation Criteria for temporary Acceptance of Flaws 

in Moderate Energy Class 2 or 3 Piping”, Section XI, Div. 1. 

15. API 579-2/ASME FFS-2, “Fitness-For-Service” 

16. NACE Standard Practice SP0169-2007, Control of External Corrosion on 

Underground or Submerged Metallic Piping Systems, 2007. 

17. NACE International Standard Recommended Practice, RP0502, Item No. 21097, 

“Pipeline External Corrosion Direct Assessment Methodology”. 

18. NUREG -1801, Rev. 2, Generic Aging Lessons Learned