Attachment J2 - Dugway-Fac 4057 (Tank 4057)-FINAL-2007.pdf

FORMAL API 653

INTERNAL AND EXTERNAL TANK INSPECTION

TANK NO. 4057

DUGWAY PROVING GROUNDS

DUGWAY, UTAH

Prime Contract No. W9128F-05-D-0013 Task Order No. 001

U.S. ARMY CORPS OF ENGINEERS

Omaha District 106 South 15th Street

Omaha, Nebraska 68102

POND & COMPANY

3500 Parkway Lane

Suite 600 Norcross GA 30092

Telephone: 678-336-7740 Facsimile: 678-336-7744 www.pondco.com

SEPTEMBER 2007

POND PROJECT #06010.001.03

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TABLE OF CONTENTS

SECTION 1 ................................................................................................................................ 1-4

EXECUTIVE SUMMARY ......................................................................................................... 1-4

1.1 GENERAL .......................................................................................................... 1-4

1.2 SIGNIFICANT FINDINGS ................................................................................ 1-4

1.2.1 Tank Bottom and Foundation ..................................................................... 1-4

1.2.2 Shell, Shell Nozzles and Appurtenances .................................................. 1-5

1.2.3 Fixed Roof, Roof nozzles and Appurtenances......................................... 1-5

1.2.4 High Level Alarms and Gauging System .................................................. 1-5

1.3 RECOMMENDATIONS .................................................................................... 1-5

1.3.1 REPAIRS REQUIRED TO RETURN THE TANK TO SERVICE........... 1-6

1.3.2 REPAIRS AS PART OF REGULAR MAINTENANCE ............................ 1-6

1.3.3 REPAIRS REQUIRED TO FULLY COMPLY WITH API 653 ................ 1-6

1.3.4 REPAIRS REQUIRED TO FULLY COMPLY WITH UFC 3-460-01 ..... 1-6

SECTION 2 ................................................................................................................................ 2-1

2.0 INTRODUCTION ............................................................................................... 2-1

2.1 TANK PHYSICAL AND HISTORICAL DATA................................................ 2-2

2.2 OVERVIEW (Safety Check) ............................................................................ 2-3

2.3 FOUNDATION INSPECTION.......................................................................... 2-4

2.4 FOUNDATION SETTLEMENT SURVEY ...................................................... 2-5

2.5 BOTTOM INSPECTION ................................................................................... 2-7

2.6 SHELL INSPECTION ..................................................................................... 2-10

2.7 SHELL THICKNESS EVALUATION ............................................................ 2-11

2.8 SHELL NOZZLES AND APPURTENANCES INSPECTION.................... 2-13

2.10 FIXED ROOF INSPECTION.......................................................................... 2-18

SECTION 3 ................................................................................................................................ 3-1

3.1 NDT INSPECTION SCOPE-OF-WORK ........................................................ 3-1

3.2 NDT SIGNIFICANT FINDINGS....................................................................... 3-1

3.3 FLOOR EXAMINATION ................................................................................... 3-1

3.4 FLOOR PLATE WELD EXAMINATION......................................................... 3-2

3.5 FLOOR-TO-SHELL WELD EXAMINATION.................................................. 3-2

3.6 SHELL ULTRASONIC THICKNESS READINGS ........................................ 3-2

3.7 SHELL NOZZLE EXAMINATION ................................................................... 3-2

3.8 FIXED ROOF NOZZLE EXAMINATION........................................................ 3-2

3.9 FIXED ROOF PLATE ULTRASONIC THICKNESS READINGS............... 3-2

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SECTION 4 ................................................................................................................................ 4-1

4.1 REPAIRING THE TANK .................................................................................. 4-1

4.2 REPAIRS REQUIRED TO RETURN THE TANK TO SERVICE............... 4-1

4.3 REPAIRS AS PART OF REGULAR MAINTENANCE ................................ 4-1

4.4 REPAIRS REQUIRED TO FULLY COMPLY WITH API 653 .................... 4-1

4.5 REPAIRS REQUIRED TO FULLY COMPLY WITH UFC 3-460-01 ......... 4-1

4.6 INSPECTION INTERVAL ................................................................................ 4-2

DRAWINGS

DRAWING D-1 FLOOR PLATE LAYOUT……...………………………………… .2-8

DRAWING D-2 SHELL PLATE LAYOUT................................................................ 2-14

DRAWING D-3 FIXED ROOF LAYOUT.................................................................. 2-16

TABLES

TABLE T-1 FLOOR ULTRASONIC THICKNESS READINGS.............................. 2-9

TABLE T-2 SHELL PLATE ULTRASONIC THICKNESS READINGS............... 2-12

TABLE T-3 NOZZLE AND APPURTENANCES TABLE ...................................... 2-15

TABLE T-4 FIXED ROOF ULTRASONIC THICKNESS READINGS ................. 2-17

TABLE T-5 COATING THICKNESS TABLES........................................................ 2-19

APPENDICES

Photographs

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SECTION 1

EXECUTIVE SUMMARY

1.1 GENERAL

Tank 4057 located at Dugway Proving Grounds in Dugway, Utah is an all-welded steel aboveground storage tank that was constructed in 1990. The 25,000 gallon tank is 14’-0” in diameter and 22’-0” high.

The design code standard for the tank is API 650. At the time of the inspection, in September 2007, the tank was out of service and had been emptied, cleaned and certified as “gas free.” The results of this inspection will aid in identifying the repairs and upgrades required for the tank’s continued service.

The testing and inspection was performed in accordance with the Third Edition of API 653. The tank is in good condition with no indication of significant thinning or corrosion on the shell, floor, or fixed roof.

The tank is constructed on a concrete ring foundation with no cathodic protection or release detection.

The tank rests in a concrete dike with vertical walls.

Contained in this report is a detailed account of the tank visual inspection, a summary of the non-destructive testing and the conclusions derived from the inspection and testing. Also included are calculations and a list of recommendations for repair and/or upgrades identified by the inspection.

1.2 SIGNIFICANT FINDINGS

The following information identifies the significant findings found during the tank inspection.

1.2.1 Tank Bottom and Foundation

1. The tank sits on a concrete ring foundation located inside a concrete containment area.

2. The tank bottom is constructed of steel lap-welded plates with a cone down configuration.

3. The tank bottom is equipped with a center sump.

4. There is no cathodic protection to protect the tank bottom.

5. There are no release detection ports or pipes.

6. The tank is equipped with nine (8)-3/4” anchor bolts.

7. The tank bottom was scanned utilizing MFL and ultrasonic thickness measurement techniques. The bottom was found to be in good general condition with no signs of significant metal loss.

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8. The internal coating exhibited continuous indications from the low-voltage holiday test.

There are no visual signs of bubbling, flaking, or peeling.

9. The suction piping and water draw-off piping does not rest on the internal supports.

10. The inlet diffuser is fixed to the tank bottom.

1.2.2 Shell, Shell Nozzles and Appurtenances

1. There is no name plate.

2. The grounding cables are in solid connections and in good condition.

3. The gage board brackets are not seal-welded to the shell.

4. Small areas on the shell exhibit coating failure.

5. No weep holes in repads.

1.2.3 Fixed Roof, Roof nozzles and Appurtenances

1. The roof is a cone-up construction with lap-welded steel plates.

2. The roof is a self-supported structure.

3. The roof is equipped with a 10” center emergency vent and a 2” normal vent.

4. The tank is equipped with a 3” slotted stilling well which is not utilized.

5. Areas on the fixed roof exhibiting coating failure.

1.2.4 High Level Alarms and Gauging System

1. The tank is equipped with a gage board-type level indicator. The board gage does not work per facility personnel.

2. The tank is equipped with a MTS ATG system, which is not installed in a stilling well. The ATG serves as the alarms for the tank.

3. There is a HLCV on the receipt of the tank.

1.3 RECOMMENDATIONS

Based on results of the tank testing and inspection, repair recommendations for Tank 4057 have been identified. The inspection checklist in Section 2 outlines the findings as discovered during the tank inspection. This checklist is similar to the recommended checklist included in Appendix C of API 653.

Section 3 outlines the scope of work performed for Non-Destructive Testing (NDT). Section 4 provides more in-depth information on repair and upgrade recommendations.

• The next formal external inspection of the shell and fixed roof should be scheduled in five (5) years (September 2012).

• The next external inspection of the shell and fixed roof with UT measurements should be scheduled in fifteen (15) years (September 2022).

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• The next formal out-of-service inspection should be performed in twenty (20) years (September 2027).

1.3.1 REPAIRS REQUIRED TO RETURN THE TANK TO SERVICE

There are no mandatory repairs to return the tank to service.

1.3.2 REPAIRS AS PART OF REGULAR MAINTENANCE

Recommendation 1: Caulk chime and ring wall joint.

Recommendation 2: Clean and re-apply coating at the roof and shell where coating failure has occurred and corrosion exists.

Recommendation 3: Raise supports for internal piping to provide bearing.

Recommendation 4: Provide a seal weld at the gauge board brackets.

1.3.3 REPAIRS REQUIRED TO FULLY COMPLY WITH API 653

Recommendation 5: Monitor the tank shell at N3 (receipt) for stresses or distortion. API 650 requires a perpendicular weld angle from the re-pad periphery weld to the bottom-to-shell weld.

Recommendation 6: Provide tell-tale holes in shell nozzle reinforcing pads.

1.3.4 REPAIRS REQUIRED TO FULLY COMPLY WITH UFC 3-460-01

Recommendation 7: Install independent high-high, high, and low level alarms on the shell with manual testers and ready access from stairway or platform.

Recommendation 8: Repair or replace the board gauge level indicator system.

Recommendation 9: Install cathodic protection system.

Recommendation 10: Apply internal coating to 100% of shell and roof of tank.

POND & COMPANY Owner: Defense Energy Location:

Support Center (DESC) Dugway, Utah

API-653 CHECKLIST Tank Number: Page Number:

Field Notes 4057 2-1

SECTION 2

VISUAL INSPECTION AND NON-DESTRUCTIVE TESTING

2.0 INTRODUCTION

Section 2 is a reproduction of the field checklist completed by the API Inspector during the inspection. The checklist was developed to include all of the items found in the API 653 Appendix

C checklist. A description of each item to be inspected is given in the left hand column of the checklist and the observations by the inspector are recorded in the adjacent right hand column.

The current condition and construction details of the tank and appurtenances that are not in compliance with API 653 are noted in the checklist. Other conclusions and recommendations are discussed in Section 1, “Executive Summary” and Section 4, “Conclusions and Recommendations.”

Data from the non-destructive testing performed is recorded by the inspector in the field and by a data collector built into the ultrasonic measuring device. The information is then arranged in the appropriate tables of this section.

Field Notes 4057 2-2

2.1 TANK PHYSICAL AND HISTORICAL DATA

OWNER: Defense Energy Support Center (DESC)

TANK NUMBER: 4057

LOCATION: Dugway Proving Grounds, Utah MANUFACTURER: Unknown

DESIGN STANDARD: API 650

YEAR BUILT: 1990

PRODUCT: JP-5 (SG=0.84) Capacity= 25,000 gallons

DIAMETER: 14’-0”

HEIGHT: 22’-0”,

FOUNDATION: Concrete Ring wall; H = 1’-3” BOTTOM CONSTRUCTION: Steel lap welded plates; cone-down; center sump; A-36 steel SHELL CONSTRUCTION: Steel butt welded plates; A-36 steel FIXED ROOF CONSTRUCTION: Steel lap welded plates; cone-up; self-supporting FLOATING ROOF CONSTRUCTION: No Floating Roof

PRIMARY SEAL: N/A

SECONDARY SEAL: N/A

CATHODIC PROTECTION: No HEATED: No BOTTOM COATING: Epoxy SHELL COATING INTERNAL: Epoxy SHELL COATING EXTERNAL: Paint FIXED ROOF COATING: Paint

FLOATING ROOF COATING: N/A

STAIRWAY CONSTRUCTION: Caged Ladder

FLOATING ROOF ACCESS: N/A

NOMINAL FLOOR PLATE THICKNESS: 0.250”

MEASURED FLOOR PLATE THICKNESS: 0.262”

NOMINAL FIXED ROOF PLATE

THICKNESS:

0.250”

MEASURED FIXED ROOF PLATE

THICKNESS:

0.252”

PREVIOUS FORMAL INSPECTION: None since date of construction CRITICAL RECORDING CRITERIA: <0.150” Remaining Plate Thickness

Field Notes 4057 2-3

2.2 OVERVIEW (Safety Check)

Description Yes No N/A

1. Check that tank has been cleaned, is gas free, and safe for entry.

2. Check that the tank is completely isolated from product lines, all electrical power, and steam lines.

3. Check that roof is adequately supported, including fixed roof structure and floating roof legs.

4. Check for presence of falling objects hazards, such as corroded-through roof rafters, asphalt stalactites, and trapped hydrocarbons in unopened or plugged equipment or appurtenances, ledges, etc.

5. Inspect structural welds on access ways and clips.

6. Inspect for slipping hazards on the bottom and roof decks.

7. Check surfaces needing inspection for a heavy-scale buildup. Note areas needing more cleaning, including blasting.

Field Notes 4057 2-4

2.3 FOUNDATION INSPECTION

Item Description Comments

1 Foundation description Elevated concrete ring wall. Height=1’-3”

2 Inspect for foundation damage or cracking.

Minor cracking.

3 Evidence of bottom leakage or stains.

No evidence noted.

List all significant cavities or erosion around the foundation.

Acceptable. No erosion or cavities noted.

Inspect for vegetation under and around tank perimeter.

No vegetation present in containment area.

Does tank have proper water runoff and drainage away from the tank?

Acceptable. The tank foundation appears to have adequate water runoff and drainage away from the tank.

One common dike drain with Tank 4056.

Is grade or other material covering the floor-to-shell weld or chime bottom plate?

Acceptable

Is any visual settlement noted around the tank perimeter?

Acceptable. No visual settlement noted. Refer to 2.4, “Foundation Settlement Survey” for data.

What is the general condition of the dike area?

Berms are constructed of what material Is dike drain area clean?

Generally good condition. Seam caulking needs to be reapplied in some areas.

The dike is constructed with concrete walls and floor.

The dike area is clean.

Notes:

Tank exists in same containment area as Tank 4056 (JP-8 AST)

Field Notes 4057 2-5

2.4 FOUNDATION SETTLEMENT SURVEY

Station # Feet Shell* 2' 3' 5' Z U S 1 0 0.00 -1.25 -2.25 -2.25 0.05 -0.05 -0.10 2 5.50 0.00 -0.50 -1.50 -2.25 -0.11 0.11 0.14 3 11.00 -0.13 -0.25 -1.25 -2.25 -0.13 0.00 -0.05 4 16.49 0.00 -1.00 -1.75 -2.50 0.01 -0.01 0.10 5 21.99 0.00 -1.50 -2.50 -2.75 0.23 -0.23 -0.40 6 27.49 0.75 -2.25 -3.50 -3.75 0.39 0.36 0.55 7 32.99 0.25 -1.75 -3.00 -3.50 0.41 -0.16 -0.33 8 38.48 0.25 -1.75 -2.50 -3.00 0.27 -0.02 0.09

Maximum Allowable "out of plane" deflection = 0.09”

Distance between stations: 5.50’ around circumference Total Measured Circumference around tank: 43’-11 ½” Settlement survey stations were measured CW from reference shell Manway A (0’).

* The shell readings recorded are interior rod readings (in inches) on the floor plates, which are used to calculate the differential settlement of the shell between stations.

Z = Calculated, rigid body tilt settlement (inches) U = Out of plane settlement (API 653, App. B) (inches) S = Out of plane deflection (API 653, App. B) (inches)

SHELL SETTLEMENT CHART

Shell Settlement Evaluation

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

1 2 3 4 5 6 7 8 0 0

Station Numbers

Edge Settlement

Rod Readings

Best Fit Cosine Curve Assuming Rigid Body Tilt (Z)

Rod Readings

Field Notes 4057 2-6

Allowable Shell Deflection

Equation (based on API 653 Section B.3.2)

Allowable Deflection S <= (L2 x Y x 11) 2[(E x H)]

Where:

Variable Meaning Tank Specific S Deflection, in inches 0.09 L Arc Length between Measured Points, in feet 5.5 Y Yield Strength, in PSI 30,000 E Young's Modulus, in PSI 29,000,000 H Height of Tank, in feet 22.00

The maximum measured out of plane shell deflection is 0.55 inches and the maximum allowable deflection is 0.09 inches; therefore the tank is not within API 653 acceptable limits. However the deflection of the tank bottom is not accurately represented by the above analysis due to the small size of the tank.

Field Notes 4057 2-7

2.5 BOTTOM INSPECTION

Conduct visual inspection of bottom plate lap welds and internal shell-to-bottom weld.

Acceptable

2 Perform vacuum box bubble test of lap welds.

N/A-Internal coating.

3 Perform visual inspection on the internal shell-to-bottom weld.

Acceptable

4 Perform MFE floor scan and visual exam of the tank bottom.

Acceptable

6 Perform ultrasonic thickness readings on each floor plate.

Refer to Table T-1, “Floor Plate Ultrasonic Thickness Readings” for data.

7 Locate unacceptable voids under the floor plates.

None noted.

8 Indicate the number and condition of sumps.

(1)-Center Sump. Diameter=2’-6”’ Depth=1’-0” Average thickness = 0.321”

Any areas of edge settlement, bulges or low areas that don’t drain.

None noted.

10 Is there a protective coating on the tank bottom, what is the condition?

The protective coating is intact, but the holiday test exhibited continuous indications.

Refer to Drawing D-1,”Floor Plate Layout” for Low-Voltage Holiday Testing results.

Are there striker plates under the vacuum breakers and floating roof legs?

N/A

12 Visually inspect roof support columns and lateral clips.

N/A-Self-supported roof.

Conduct visual inspection of reinforcements.

Do all piping supports have support pads?

Acceptable

Yes, but the issue and water draw-off pipes are not bearing on the pipe supports. The inlet diffuser is fixed to the tank bottom.

Inlet diffuser fixed to bottom Issue and water draw-off piping not bearing on pipe supports Height of suction from bottom of tank approximately 5”

INTERVAL TO NEXT BOTTOM INSPECTION:

Based on the NDE results, the bottom plate corrosion rate is negligible; therefore the recommended interval for the next out-of-service inspection is twenty (20) years.

Field Notes 4057 2-8

DRAWING D-1 FLOOR PLATE LAYOUT

Entire coated portion of floor and lower 18” of shell failed the low-voltage holiday test. Coating is intact, with no visual signs of flaking, bubbling, or peeling.

Field Notes 4057 2-9

TABLE T-1 FLOOR ULTRASONIC THICKNESS READINGS (PLATE)

PLATE F-1 PLATE F-2 PLATE F-3

.247 .283 .275 .269

.291 .247 .255

.247 .245 .269 .271

AVG. .261 .263 .266

Average = 0.263”

TABLE T-1 FLOOR ULTRASONIC THICKNESS READINGS (CIRCUMFERENTIAL)

0' 2' 4' 6' 8' 10' 12' 14' 16' 18' 20' 22' 24' 26' 28'

.261 .261 .256 .276 .246 .250 .267 .288 .248 .250 .254 .250 .246 .248 .252

30' 32' 34' 36' 38' 40'

.248 .264 .251 .255 .259 .269

AVG. 0.257

0' = Manway; locations are 6-inches in from shell-to-floor weld, clockwise around tank.

Thickness measurements are in inches.

Field Notes 4057 2-10

2.6 SHELL INSPECTION

Inspect shell ladders, stairways, platforms and walkways.

Acceptable. Minor surface corrosion due to coating failure.

Inspect shell for significant distortions, creases and buckling.

No significant signs of buckling.

3 Visually inspect shell for out-of-roundness.

Acceptable

4 Inspect shell support welds for corrosion or damage.

Minor surface corrosion

5 Inspect wind girder for corrosion or damage.

N/A

Inspect external shell for leaks or significant corrosion areas.

Acceptable. No shell leaks or significant corrosion areas noted.

Inspect exterior shell-to-bottom weld area for corrosion, defects or thinning of the chime bottom plate.

Acceptable

Inspect shell coating for failure, peeling or fading.

Overall condition:

Acceptable general condition. Surface corrosion on shell due to coating failure.

Good overall condition. Internal coating exists from bottom of shell to approximately 5’ up.

Inspect both the internal and external shell for pitting, corrosion, rubbing or grooving.

None noted

Inspect horizontal and vertical seams for weld or rivet joint details.

Acceptable

11 Inspect shell overflows for corrosion and screening.

N/A

12 Inspect shell for any lap patches.

None

Is the tank grounded?

Are the cables and clips in good condition?

Yes Lightning rods on roof of tank The grounding cables are in good condition.

14 Does the tank have a legible data plate?

No

Field Notes 4057 2-11

INTERVAL TO NEXT SHELL INSPECTION:

Based on a comparison of nominal shell thicknesses and the ultrasonic readings taken during the inspection, the shell corrosion rate is negligible;

therefore the required interval to the next formal external inspection with UT Measurements is Fifteen (15) years.

2.7 SHELL THICKNESS EVALUATION

Shell Thickness Variables

Tank Height (ft): 22.00 D (ft): 14.00

G (Water): 1.00 G (Product): 0.84

Cours e

Course Height

(ft) H (ft)

Allowabl e Stress

S (Psi)

Joint Efficienc y E CA (in) 1 7.00 22.00 24,900 0.85 0.010 2 8.00 15.00 24,900 0.85 0.010 3 7.00 7.00 27,400 0.85 0.010

Check

No.

Measured Thickness* Check Calculated Thickness Limit

1 t(ave) > = t(LV) = t(min) + CA 2 t1 > = t(LV) = t(min) + CA 3 t2 > = t(LV) = 0.6 x t(min) + CA 4 tp > = t(LV) = 0.5 x t(min)

Check #1 Check #2 Check #3 Check #4 t(ave) t(LV)* ** t1 t(LV)* ** t2 t(LV)* ** tp t(LV)* **

Course (in) (in) P/F (in) (in) P/F (in) (in) P/F (in) (in) P/F 1 0.251 0.110 P N/A N/A -- N/A N/A -- N/A N/A -- 2 0.248 0.110 P N/A N/A -- N/A N/A -- N/A N/A -- 3 0.249 0.110 P N/A N/A -- N/A N/A -- N/A N/A --

Tank 4057 exhibits no corrosion or pitting, therefore there is no t1, t2, or tp.

Controlling Safe Fill Height Fluid Height (ft) Water NR Produc t NR

NR= No Restriction

Field Notes 4057 2-12

TABLE T-2 SHELL PLATE ULTRASONIC THICKNESS READINGS

Circumferential weld C4

PLATE 3-1 PLATE 3-2 PLATE 3-3

.249 .249

.250 .250

SHELL COURSE 3

.248 .249

AVG. .249 .249

Circumferential weld C3

PLATE 2-1 PLATE 2-2 PLATE 2-3

.246 .244

.251 .250

SHELL COURSE 2

.247 .247

AVG. .248

Circumferential weld C2

PLATE 1-1 PLATE 1-2 PLATE 1-3

.251 .252 .247 .248 .251 .251 .255 .255 .256

.252 .248 .249 .250 .250 .253 .251 .257 .258

SHELL COURSE 1

.249 .249 .247 .250 .249 .250 .256 .256 .254

AVG. .249 .250 .255

Circumferential weld C1

Thickness readings below were taken around the external circumference of the shell every 3’ at 2”-4” above the chime.

0' 2' 4' 6' 8' 10' 12' 14' 16' 18'

.261 .261 .256 .276 .246 .250 .267 .288 .248 .250

20' 22' 24' 26' 28' 30'

.254 .250 .246 .248 .252 .248

AVG. 0.256

Field Notes 4057 2-13

2.8 SHELL NOZZLES AND APPURTENANCES INSPECTION

1 Inspect nozzle flanges and bolting for leaks and corrosion.

Acceptable

2 Inspect nozzles for pipe strain or misalignment.

Acceptable

3 Inspect valves for thermal relief, leaks or damage.

Inlet and Suction have thermal relief. No signs of leaks or damage.

Is Tank equipped with High Level Control Valve and High Level Alarms?

MTS ATG serves as level alarms.

No independent alarms.

HLCV on inlet.

Gauging system.

Manual Stilling Well?

Type of Float Gauge?

Type of Automatic Gauging System?

3” slotted stilling well extending to bottom of tank

Gage board-type level indicator. Needs calibration per facility personnel.

MTS ATG; no stilling well.

Inspect manways, nozzles and attachments for signs of corrosion or defects.

None Noted

7 Do all nozzle reinforcement pads have tell-tale hole?

No, none have tell-tale holes.

Verify adequate reinforcement around nozzles and appurtenances.

Acceptable

Verify adequate nozzle and appurtenances weld spacing (horizontal and vertical weld seams and distance between reinforcement pads).

Receipt re-pad is circular and terminates into chime to shell weld. API 650 states re-pads must terminate at a 90° angle to the bottom weld.

10 Verify interior nozzles have been back welded to the shell.

Yes, acceptable.

Check reinforcement pads for adequate fillet welds around pads.

Acceptable

Visually inspect welds for defects on all nozzles and appurtenances.

Acceptable

13 Does the inlet nozzle have a diffuser?

Yes, the piping supports are welded directly to the tank floor.

Notes:

Board Gauge does not work, board brackets not seal welded to shell

Field Notes 4057 2-14

DRAWING D-2 SHELL PLATE LAYOUT

Field Notes 4057 2-15

TABLE T-3 NOZZLE AND APPURTENANCES TABLE

NOZZL

E

NOZZLE SIZE

(Diameter or

Width/Height)

REPAD

SHAPE

REPAD

SIZE

REPAD

THICKNESS

NOZZLE

CENTERLINE

ELEVATION

(H1)

WELD

CLEARANCE

(H2)

NOZZLE

LOCATION

(Measured circumferentially from Manway A)

NOZZLE

THICKNESS

NOZZLE FUNCTION

(If Known)

MWA 24" B 48" .252 36" 11" 0' .253 MANWAY

N1 6" B 16" .252 18" 10" 6' 2" .277 ISSUE

N2 1½" - - - 6" - 9' 1" THREADED SENSOR

N3 6" B 16" .248 6" FLUSH 12' 2" .275 RECEIPT

N4 2" - - - 21' 10" - 12' 2" THREADED HLCV

N5 2" - - - 20' 4" - 12' 2" THREADED HLCV

N6 1½" - - - 4" - 34' 4" THREADED WATER DRAW

N7 24" B 45" .254 24" FLUSH ROOF .323 HATCH

N8 10" B 22" .278 87" 76" ROOF .394 VENT

N9 4" B 8" .254 10" 6" ROOF THREADED NOZZLE (CAPPED)

N10 2" - - - 25" - ROOF THREADED TAPE GAGE

N11 2" - - - 25" - ROOF THREADED TAPE GAGE

N12 2" - - - 25" - ROOF THREADED TAPE GAGE

N13 3" - - - 15" - ROOF THREADED VENT

N14 4" B 10" .251 15" 10" ROOF .224 NOZZLE

Repad Shape:

Field Notes 4057 2-16

DRAWING D-3 FIXED ROOF LAYOUT

Field Notes 4057 2-17

TABLE T-4 FIXED ROOF ULTRASONIC THICKNESS READINGS

PLATE R-1 PLATE R-2 PLATE R-3 PLATE R-4

.255 .247 .250 .247 .253 .253

.254 .253 .251 .252 .253

.254 .254 .251 .252 .255 .253

AVG. .254 .250 .252 .253

Average Roof Plate Thickness = 0.252”

Thickness measurements are in inches.

Field Notes 4057 2-18

2.10 FIXED ROOF INSPECTION

Inspect fixed roof protective coating system.

Minor surface corrosion due to coating failure.

Inspect frangible joint / eave angle for corrosion, defects and coating failure.

Acceptable

Inspect fixed roof for low spots and external corrosion.

None noted

Conduct visual / UT inspection on roof nozzles and appurtenances.

Acceptable. Minor corrosion.

Visual inspection of internal roof supports, girders, columns and bases.

N/A

Verify open roof vents have screens and covers.

Acceptable

7 Verify handrails and tie-off supports are in good condition.

Acceptable; partial handrail

Measure any significant bulges and creases in the roof plates.

Acceptable. No creases or bulges noted.

Do any roof nozzles or appurtenances have bolt-on type reinforcement pads?

No

Field Notes 4057 2-19

TABLE T-5 COATING THICKNESS TABLES

Shell Coating Thickness

Average Standard Deviation Number of Readings Minimum Maximum Internal* 10.5 3.533 20 4.191 21.87 External 7.746 3.12 30 3.438 17.31

* First Shell Course Only

Internal Coating Thickness

Average Standard Deviation Number of Readings Minimum Maximum Tank Bottom 8.675 2.272 25 5.487 14.82

Fixed Roof Coating Thickness Average Standard Deviation Number of Readings Minimum Maximum

7.494 1.878 20 4.079 11.11

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SECTION 3

NON-DESTRUCTIVE TESTING (NDT)

3.1 NDT INSPECTION SCOPE-OF-WORK

The following Non-Destructive Testing examinations were performed to evaluate the integrity of the tank.

• Low-Voltage Holiday Test on the tank floor and lower internal portion of the shell coating.

• Magnetic Flux Leakage (MFL) floor scan of the tank bottom, for significant internal and underside metal loss.

• A Visual Test (VT) was performed in areas inaccessible to the MFL, floor plate lap welds, interior corner weld, under low internal piping and areas of concern.

• Ultrasonic Testing (UT) of MFL indications, for remaining plate thickness.

• Ultrasonic (UT) thickness readings of the tank floor plates.

• Ultrasonic (UT) thickness readings of the fixed roof plates.

• Ultrasonic (UT) thickness readings of the tank shell courses.

• Ultrasonic (UT) thickness readings of the shell and roof nozzles and appurtenances.

• Internal settlement survey.

3.2 NDT SIGNIFICANT FINDINGS

The MFL floor scan showed several indications due to the presence of mechanical gouges believed to have occurred during initial construction. Ultrasonic thickness readings were taken and found no significant material loss.

The Low Voltage Holiday Test on the inner coating identified the whole tank bottom as having a thinned coating. Although indications were found, no areas of coating failure (peeling, flaking, or bubbling) were visually found.

3.3 FLOOR EXAMINATION

The floor plates were examined utilizing the MFL floor scan, Ultrasonic Testing (UT) and Visual

Testing (VT) methods.

Refer to Drawing D-1 “Floor Plate Layout” and Table T-1, “Floor Ultrasonic Thickness Readings

(Plate)” for plate thickness data. Table T-1,” Floor Ultrasonic Thickness Readings (Circumferential)” provides data collected from UT readings at two feet intervals around the circumference of the tank approximately 6” in from the shell to floor joint.

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3.4 FLOOR PLATE WELD EXAMINATION

Floor plate welds were visually inspected and found to be in good condition. The inspection was limited due to the internal coating.

3.5 FLOOR-TO-SHELL WELD EXAMINATION

The internal floor-to-shell weld was visually inspected and found to be in good condition. The inspection was limited due to the presence of the coating.

3.6 SHELL ULTRASONIC THICKNESS READINGS

Ultrasonic thickness readings were taken at nine (9) locations on each plate for the lower shell course and at each course up the stairway. Refer to Table T-2, “Shell Plate Ultrasonic Thickness

Readings” for data.

3.7 SHELL NOZZLE EXAMINATION

The shell nozzles and reinforcing pads were inspected by Ultrasonic and Visual Testing methods.

Refer to Table T-3, “Nozzles and Appurtenances” for data.

3.8 FIXED ROOF NOZZLE EXAMINATION

The fixed roof nozzles and reinforcing pads were inspected by Ultrasonic and Visual Testing methods. Refer to Table T-3, “Nozzles and Appurtenances” for data.

3.9 FIXED ROOF PLATE ULTRASONIC THICKNESS READINGS

The fixed roof deck plates were inspected utilizing Ultrasonic thickness measurements. A total of five (5) readings were taken on each roof plate and four (4) were taken on each sketch plate. Refer to Table T-4 for ultrasonic thickness readings on the fixed roof plates.

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SECTION 4

RECOMMENDATIONS

4.1 REPAIRING THE TANK

The following subsections outline the itemized tank repairs/upgrades.

4.2 REPAIRS REQUIRED TO RETURN THE TANK TO SERVICE

There are no mandatory repairs to return the tank to service.

4.3 REPAIRS AS PART OF REGULAR MAINTENANCE

Recommendation 1: Caulk chime and ring wall joint.

Recommendation 2: Clean and re-apply coating at the roof and shell where coating failure has occurred and corrosion exists.

Recommendation 3: Raise supports for internal piping to provide bearing.

Recommendation 4: Provide a seal weld at the gauge board brackets.

4.4 REPAIRS REQUIRED TO FULLY COMPLY WITH API 653

If the tank is to be brought into full compliance with API 653, then the actions listed below should be performed:

Recommendation 5: Monitor the tank shell at N3 (receipt) for stresses or distortion. API 650 requires a perpendicular weld angle from the re-pad periphery weld to the bottom-to-shell weld.

Recommendation 6: Provide tell-tale holes in shell nozzle reinforcing pads.

4.5 REPAIRS REQUIRED TO FULLY COMPLY WITH UFC 3-460-01

If the tank is to be brought into full compliance with UFC 3-460-01, then the actions listed below should be performed:

Recommendation 7: Install independent high-high, high, and low level alarms on the shell with manual testers and ready access from stairway or platform.

Recommendation 8: Repair or replace the board gauge level indicator system.

Recommendation 9: Install cathodic protection system.

Recommendation 10: Apply internal coating to 100% of shell and roof of tank.

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4.6 INSPECTION INTERVAL

The interval between inspections of a tank (both internal and external) should be determined by its service history. Inspection intervals can be adjusted when corrosion rates are known for a tank. The corrosion rates regarding the tank are negligible, so the maximum intervals set forth by API 653 can be used. These inspections should include:

1. Routine in-service inspections from the ground to monitor the external condition of the tank and connected piping should be performed on a monthly basis. Leaks, shell distortions, signs of settlement, and corrosion should all be monitored along with the foundation condition, paint coatings and appurtenances. The roof should be visually inspected for signs of corrosion and damage.

2. Formal visual external inspection by an API certified inspector every five (5) years or at the quarter corrosion-rate life of the shell, whichever is less. Based on the review of shell thickness readings in Section 2, the five (5) year time period will govern the next formal visual external inspection.

3. Ultrasonic thickness measurements of the shell plates can be performed with the tank in service and can be scheduled at intervals not exceeding fifteen (15) years or RCA/2N years (where RCA is the Remaining Corrosion Allowance in mils and N is the shell corrosion rate in mils per year).

Because the corrosion rate on the tank shell is negligible, the next inspection interval for external with UTM is fifteen (15) years.

4. Out-of service inspections are normally based on bottom corrosion rates. Since the bottom corrosion rate of the tank bottom is negligible, the next out-of-service inspection interval is twenty

(20) years.

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Appendix A

Photographs

Overall of Tank 4057 (right) Receipt

ATG with Coating Failure Overall of Inside

Interior Shell External Coating Failure