NACE TEG292X: 3/16/08

ICDA – Improving Detection SuccessUnderstanding the limitations…

Steve Biagiotti, MSc, PESr. Associate

Structural Integrity Associatessbiagiotti@structint.com

NACE TEG292X: 3/16/08

Objective:

Share issues discovered while implementing ICDA to improve your success of good results

• Issues we will cover: Inclination modeling Site selection Locating the greatest area of corrosion Corrosion Decision Criteria 1st Time Assessment activities

NACE TEG292X: 3/16/08

Where can ICDA be used? • Single HCA’s• Individual Pipelines• Entire piping Networks… also w/Threat Verification

Feasibility: There are limitations to the approach, so not suitable for all applications

NACE TEG292X: 3/16/08

NACE R0206This is a “Guide”, you still need a written plan to answer the Who, What, Why, Where, and When’s –but most importantly, you need the Decision Criteria

NACE TEG292X: 3/16/08

ICDA Process1.Pre-Assessment:

• Data Analysis• Feasibility

2.ICDA Regions ID• Inclination Assessment• Flow Conditions

3.Direct Examination • Select & Excavate • G-Scan & B-Scan• Evaluate

4.Post-Assessment• Remaining Life• Reinspection• Effectiveness

NACE TEG292X: 3/16/08

STEP 1: Pre-Assessment DataThe data sources included:

Exported information from the corporate databases Subject Matter Expert (SME) testimonials Review of alignment sheets

NACE TEG292X: 3/16/08

ICDA Process1.Pre-Assessment:

• Data Analysis• Feasibility

2.ICDA Regions ID• Inclination Assessment• Flow Conditions

3.Direct Examination • Select & Excavate • G-Scan & B-Scan• Evaluate

4.Post-Assessment• Remaining Life• Reinspection• Effectiveness

NACE TEG292X: 3/16/08

ICDA Premises1. Any water present in the line, from upsets or

condensation, will continue to move through the system or become reabsorbed.

2. Water is moving in a laminar flow regime. 3. Water is always on the bottom of pipe. 4. Water will stop moving in

the line where the gravitation forces equal the forces associated with fluid velocity.

5. Corrosion occurs at static water location.

NACE TEG292X: 3/16/08

What’s needed to calculate Inclinations?

• Elevation data along the pipeline … GPS survey (recreational, sub-meter or sub-cm) GPS Survey adjusted w/ Depth of cover Centerline Overlays on Digital Elevation Models

• Method depends on Error Sources Centerline ± 50ft (what’s reported to NPMS?) Elevation spacing interval Selected Gas Velocity

– Min, Max, Avg., Historical, Most Typical, Single value…

“40.12345N”: ±2.8ft 10-6: ±3.4”=8.6cm 10-8: ± 0.034”=0.01cm

Pressure: 50-1100 psiTemp: 60º-130ºFSuperficial Gas Velocity: <70fpsDiameter: 4” to 48”

NACE TEG292X: 3/16/08

Errors• Data errors due to the age of data, incomplete density of

observations or results of spatial sampling • Measurement errors such as positional inaccuracy, data

entry faults, or observer bias .• Processing errors such as numerical errors in the

computer, interpolation. "In science, the word error does not carry the usual

connotations of the term mistake or blunder. Error in a scientific measurement means the inevitable uncertainty that attends all measurements. As such, errors are not mistakes; you cannot eliminate them by being very careful. The best you can hope to do is ensure that errors are as small as reasonably possible and to have a reliable estimate of how large they are"

(Taylor, 1997, p. 3)

NACE TEG292X: 3/16/08

Inclination Angle Sensitivity-Profiles

5 10 20 30 40 50 60 70 80 90 100 2001 11.3 5.7 2.9 2.9 1.4 1.1 1.0 0.8 0.7 0.6 0.6 0.32 21.8 11.3 5.7 3.8 2.9 2.3 1.9 1.6 1.4 1.3 1.1 0.65 45.0 26.6 14.0 9.5 7.1 5.7 4.8 4.1 3.6 3.2 2.9 1.410 63.4 45.0 26.6 18.4 14.0 11.3 9.5 8.1 7.1 6.3 5.7 2.915 71.6 56.3 36.9 26.6 20.6 16.7 14.0 12.1 10.6 9.5 8.5 4.320 76.0 63.4 45.0 33.7 26.6 21.8 18.4 15.9 14.0 12.5 11.3 5.725 78.7 68.2 51.3 39.8 32.0 26.6 22.6 19.7 17.4 15.5 14.0 7.130 80.5 71.6 56.3 45.0 36.9 31.0 26.6 23.2 20.6 18.4 16.7 8.535 81.9 74.1 60.3 49.4 41.2 35.0 30.3 26.6 23.6 21.3 19.3 9.940 82.9 76.0 63.4 53.1 45.0 38.7 33.7 29.7 26.6 24.0 21.8 11.345 83.7 77.5 66.0 56.3 48.4 42.0 36.9 32.7 29.4 26.6 24.2 12.750 84.3 78.7 68.2 59.0 51.3 45.0 39.8 35.5 32.0 29.1 26.6 14.055 84.8 79.7 70.0 61.4 54.0 47.7 42.5 38.2 34.5 31.4 28.8 15.460 85.2 80.5 71.6 63.4 56.3 50.2 45.0 40.6 36.9 33.7 31.0 16.765 85.6 81.3 72.9 65.2 58.4 52.4 47.3 42.9 39.1 35.8 33.0 18.070 85.9 81.9 74.1 66.8 60.3 54.5 49.4 45.0 41.2 37.9 35.0 19.375 86.2 82.4 75.1 68.2 61.9 56.3 51.3 47.0 43.2 39.8 36.9 20.680 86.4 82.9 76.0 69.4 63.4 58.0 53.1 48.8 45.0 41.6 38.7 21.885 86.6 83.3 76.8 70.6 64.8 59.5 54.8 50.5 46.7 43.4 40.4 23.090 86.8 83.7 77.5 71.6 66.0 60.9 56.3 52.1 48.4 45.0 42.0 24.295 87.0 84.0 78.1 72.5 67.2 62.2 57.7 53.6 49.9 46.5 43.5 25.4100 87.1 84.3 78.7 73.3 68.2 63.4 59.0 55.0 51.3 48.0 45.0 26.6

Vert

ical

Dro

p (ft

)

Horizontal Run (ft)

• Reduce spacing to improve resolution sensitivity

• 10m (30ft) DEM data available in many areas

NACE TEG292X: 3/16/08

Inclination Angle Sensitivity (f [P,V])10” Dia, 800 psi, 60°F 10” Dia, 900 psi, 60°F∆ Pressure

∆ flow

NACE TEG292X: 3/16/08

Using DEM data30 Meter DEM

10 Meter DEM

• DEM (Digital Elevation Model) represents the earths surface in a regularly space grid of elevation points.

• Data sets are based on a 10 or 30 meter grid.

• Data is represented as a regular grid cell which is a 30 meter by 30 meter or 10 meter by 10 meter square with elevation values for each cell, given in feet above mean sea level.

10m DEM has 9 times more points than the 30 Meter DEM.

NACE TEG292X: 3/16/08

DEM Calculations

NACE TEG292X: 3/16/08

ImageryDigital Ortho Quarter Quad (DOQQ)

National Agriculture Imagery Program (NAIP)

Aerial Photography (flown) 1 Foot Resolution

DOQQ 1 – 4 meter resolution and meets National Mapping Accuracy Standards

NAIP 1 meter ground sampling

w/1 foot Resolution ------------------------------------------1 ft or ~ 1/3 meter resolution

NACE TEG292X: 3/16/08

Imagery informationDOQQ NAIP

NACE TEG292X: 3/16/08

Reconnaissance – entire Region

• Necessary to supplement data gathering

• Integrated Data maps are helpful

ABC

NACE TEG292X: 3/16/08

• Above Grd?• Are terrain

features within DEM resolution?

Benefits of ReconUnplanned Angles

NACE TEG292X: 3/16/08

Benefits of ReconVerification of Digital Information

NACE TEG292X: 3/16/08

Benefits of ReconVerification of Slope Information

NACE TEG292X: 3/16/08

Benefits of ReconRoad – Slope Locations

False elevation reading - to close to

road

Characteristic “Saw Tooth” Inclination pattern -- Red area indicates same region as photo above.

NACE TEG292X: 3/16/08

Benefits of ReconAbove Ground Facilities

NACE TEG292X: 3/16/08

Benefits of ReconTree Cover and Land Changes

lake not tree cover

False elevation because of tree cover

NACE TEG292X: 3/16/08

Confirmation Surveys

Point s

eque

ntial

order

Distan

ce fro

m Start

Elevati

on Valu

e (ft)

Angle

(°)

from cu

rren

ORDER DESCRIPTION LATITUDE LONGITUDE DIST_START DEPTH / INCHESELEVATION ANGLEcp1 NAIL 40°59'28.99108" 111°55'24.95059" 0 0 4252.28

50 FL 40°59'29.64791" 111°55'21.76772" 0 0 4236.58 #DIV/0!

51 NG 40°59'29.62447" 111°55'21.75734" 2.500602551 0 4236.42 #NUM!

52 NG 40°59'29.54800" 111°55'21.70272" 11.29709443 0 4237.22 -5.2

53 NG 40°59'29.47235" 111°55'21.64432" 20.16491611 0 4241.41 -28.2

54 NG 40°59'29.43907" 111°55'21.60980" 24.44760254 0 4242.17 -10.2

55 BOA 40°59'29.41615" 111°55'21.58094" 27.65281087 0 4242.11 1.1

56 BOA 40°59'29.20438" 111°55'21.37029" 54.48229769 0 4241.12 2.1

58 HP 55" 40°59'29.04160" 111°55'21.17213" 76.46201965 55 4238.3 -4.6

59 HP 103" 40°59'28.44043" 111°55'20.62033" 150.54904573 103 4239.77 -4.2

60 HP 65" 40°59'28.01370" 111°55'20.21916" 203.55626652 65 4237.88 5.5

61 HP 60" 40°59'27.67071" 111°55'19.90150" 245.95112063 60 4237.07 1.7

62 HP 52" 40°59'27.43688" 111°55'19.67374" 275.35401440 52 4237.51 0.4

63 HP 48" 40°59'27.07359" 111°55'19.33240" 320.47304550 48 4239.09 -1.6

82 HP 60" 40°59'26.98341" 111°55'19.24343" 331.86527950 60 4239.33 -6.2

81 HP 49" 40°59'26.76846" 111°55'19.03226" 358.97515350 49 4239.33 1.9

80 HP 45" 40°59'26.57262" 111°55'18.84693" 383.35676179 52 4238.22 2.0

79 HP 48" 40°59'26.24549" 111°55'18.54154" 423.89777723 48 4238.18 0.5

78 HP 49" 40°59'25.97332" 111°55'18.28263" 457.84152304 49 4238.7 -1.0

77 HP 65" 40°59'25.68982" 111°55'18.01474" 493.11976266 65 4239.65 -3.7

76 HP 60" 40°59'25.41428" 111°55'17.74587" 527.79005743 60 4239.39 1.1

75 HP 59" 40°59'25.16165" 111°55'17.50943' 559.12404605 59 4238.86 1.1

74 HP 58" 40°59'24.98638" 111°55'17.34794" 580.75072175 58 4238.4 1.4

73 HP 67" 40°59'24.48959" 111°55'16.87207" 642.85777981 67 4237.9 -0.2

72 HP 80" 40°59'24.20067" 111°55'16.59089" 679.17736888 80 4236.31 0.8

• Always confirm suspect pipe elevation behavior• A local survey is cheaper than digging in the wrong place

NACE TEG292X: 3/16/08

ICDA Process1.Pre-Assessment:

• Data Analysis• Feasibility

2.ICDA Regions ID• Inclination Assessment• Flow Conditions

3.Direct Examination • Select & Excavate • G-Scan & B-Scan• Evaluate

4.Post-Assessment• Remaining Life• Reinspection• Effectiveness

NACE TEG292X: 3/16/08

• Site Selection Considerations• Inspection Strategy• Acceptance criteria• 1st Time Assessment

additional analysis techniques

Direct Examination: Where should we dig?

NACE TEG292X: 3/16/08

ICDA Site Selection Considerations

• Dependent on Region Design Gas entrance points (45°, 90°) Null points

• Regulatory considerations In an HCA (1st half & 2nd half) +1 if first time assessment

• Technically Based (RP0206) 1st site exceeding critical

• Additional considerations diameter changes, last angle

exceeding critical

NACE TEG292X: 3/16/08

Direct Examination Sites• Expose the susceptible incline (10ft coating)• Screen for metal loss with GWUT (±30’ to ±100’)• Locate worst area and excavate• Quantify metal loss (i.e., size/map) with UT

• Mark/GPS during Recon

NACE TEG292X: 3/16/08

GWUT Screening in support of DE• GWUT to examine a broad

area for metal loss• B-Scan ultrasonic testing to

confirm extent of metal loss at areas indicating corrosion

NACE TEG292X: 3/16/08

Typical GWUT Datasheet (partial)• As luck has it, this site

was (-10ft) from a metal loss anomaly

• Now… what do I do with this information?

NACE TEG292X: 3/16/08

Metal Loss Sensitivity Calcs• Pressure testing of pipelines is a mature integrity assessment

technique. • The largest defect size that can survive a hydrostatic pressure

test can be calculated using equations such as ASME B31G, RSTRENG™, or KAPA™.

• However, the actual size of these indications, whether they are associated with internal or external metal loss, or the size of any remaining anomalies is unknown following the hydrotest.

• In a similar fashion, GWUT can be used to PREDICT indications of a similar volumetric extent as would fail a hydrostatic test.

L

W

D

• This GWUT criteria is referred to as detection “sensitivity” and is used to establish the threshold inspection distance after which either signal attenuation or signal/noise ratios are less than optimum to insure the level of sensitivity necessary to effectively assess the carrier pipe.

NACE TEG292X: 3/16/08

Engineering Support – Know your criteria BEFORE you inspect

NACE TEG292X: 3/16/08

Avoid Grid UT data – use scans

NACE TEG292X: 3/16/08

ICDA Process1.Pre-Assessment:

• Data Analysis• Feasibility

2.ICDA Regions ID• Inclination Assessment• Flow Conditions

3.Direct Examination • Select & Excavate • G-Scan & B-Scan• Evaluate

4.Post-Assessment• Remaining Life• Reinspection• Effectiveness

NACE TEG292X: 3/16/08

1ST time Assessments-Measurement

• H2S and CO2 Monitoring

(June 27, 2001 to Dec 31, 2005)

0.00

1.00

2.00

3.00

4.00

5.00

6/27/2001 1/13/2002 8/1/2002 2/17/2003 9/5/2003 3/23/2004 10/9/2004 4/27/2005 11/13/2005

Date

H2S

(ppm

)

H2S Data:Avg - 1.15 ppmMin - 0.05 ppmMax - 4.47 ppm

Tariff Limit - 4 ppm

Tariff Exceeded - 3 days

May 8, 2003 to June 21, 2007

0

1

2

3

4

5

6

4/29/2003 9/26/2003 2/23/2004 7/22/2004 12/19/2004 5/18/2005 10/15/2005 3/14/2006 8/11/2006 1/8/2007 6/7/2007

Date

CO

2 (%

) Tariff Limit - 3%Tariff Exceeded - 1 days

CO2 Data:Avg - 0.53%Min - 0.38.%Max - 4.91%

NACE TEG292X: 3/16/08

1ST Time Assessments –Compare ICDA to ILI results

NACE TEG292X: 3/16/08

Is ICDA Costly?

NACE TEG292X: 3/16/08

Anticipating ICDA CostsIf subcontracted, Major steps include: • Pre-Assessment & Inclination Data analysis (30%)• Site Reconnaissance & Selection (5%)• ICDA Maps (5-10%)• Excavations & Inspections (35%)• Reporting & Engineering Evaluations (20%)

Best way to control costs…• Larger Projects• Proper planning (expectations)• Communication • Dedicated Project Management

Avg~$1,500 /mile+ excavation

NACE TEG292X: 3/16/08

Good Luck with your future ICDA projects

Steve Biagiottisbiagiotti@structint.com

(303) 792-0077

Any Questions?