App G Attachment 3 Tank 27 API 653 Rprt_2008.pdf

AFCEE CONTRACT FA8903-04-D-8676, TASK ORDER 0148

TANK 27

API 653 TANK INSPECTION AND

SUITABILITY FOR SERVICE EVALUATION

Thule Air Base, Greenland

July 2008

Prepared For:

The Air Force Center for Engineering and the Environment 3300 Sidney Brooks Brooks City-Base, Texas 78235

Prepared By:

Shaw Environmental Inc.

6330 Commerce, Suite 190 Irving, Texas 75063

Prepared By:

David A. Stchyrba, P.E., API 653 Certificate No. 27187

Submitted By:

Stephen S. Brooks, P.E.

Principal, API 653 Certificate No. 17 2525 Gambell Street, Suite 200, Anchorage, AK 99503

EEI Project 08-4889

ABSTRACT

Enterprise Engineering, Inc. (EEI) has completed a comprehensive, out-of-service internal and external inspection and suitability for service evaluation of Tank 27 at Thule Air Base, Greenland in accordance with the applicable criteria of API Standard 653, Third Edition, Addendum 3, February 2008 and UFC 3-460-01 (previously 1022A). The API 653 criteria were followed in terms of procedure and evaluation to the greatest extent possible. The inspection was performed on June 8th, 2008.

This report provides inspection findings, tank suitability for service evaluation, conclusions, and recommendations for repair, prior to returning the tank to service. Recommendations for continued long-term service are also provided.

EEI recommends the next API internal out-of-service inspection be scheduled no later than June 2018 (10 years from 2008 inspection), or when a change in condition has occurred.

EEI recommends the next API external inspection be scheduled no later than June 2013 (5 years from 2008 inspection), or when a change in condition has occurred.

In accordance with API Standard 653, this report satisfies the requirement for an out-of-service, integrity inspection and as such, should remain available as a historical record for future reference.

I hereby acknowledge that being familiar with the provisions of API Standard 653, the inspection and evaluation was performed in accordance with the provisions of API Standard 653 and good engineering practices, and with the exercise of usual and customary care.

July 24, 2008 David A. Stchyrba, P.E. Date API 653 AST Inspector Certificate No. 27187

This tank inspection has determined that mandatory repairs are not required prior to return to service. Tank 27 may be returned to service. Recommended repairs have been identified, and if possible should be completed before returning tank to service.

Tank 27 – API 653 Inspection TABLE OF CONTENTS Thule Air Base, Greenland July 2008 EEI Project No. 08-4889 R043

TABLE OF CONTENTS

Page

SUMMARY

Scope General

INSPECTION ASSESSMENT

Hydraulic Integrity Structural Integrity Next Inspection

REPAIR ITEMS

Required Repairs Prior to Return to Service (Mandatory) Recommended Repairs Prior to Return to Service (Non-Mandatory) Recommended Repairs for Long Term Serviceability Coating Requirements

SUITABILITY FOR SERVICE EVALUATION

Corrosion Rates Tank Floor Corrosion Rates Hydraulic and Structural Integrity

ADDITIONAL DISCUSSION ITEMS

Gauge Tube (Stilling Well) Requirements

CLOSURE

Conclusions Project Team

APPENDICES

Tank Inspection Data Sheet and Evaluation Items...................................................Tab A Non-Destructive Examination (NDE) and Evaluation Criteria...................................Tab B Tank Drawings .........................................................................................................Tab C Tank Photographs....................................................................................................Tab D NDE Results.............................................................................................................Tab E Calculations..............................................................................................................Tab F Field Trip Report ..................................................................................................... Tab G

Tank 27 – API 653 Inspection Page 1

EEI Project No.: 08-4889 R043

TANK 27

API 653 TANK INSPECTION

SUITABILITY FOR SERVICE EVALUATION

Thule Air Base, Greenland

SUMMARY

Scope

Enterprise Engineering Inc. (EEI) has completed a comprehensive, out-of-service inspection and suitability for service evaluation of Tank 27 at Thule Air Base, Greenland. The inspection was performed on June 8th 2008, in accordance with applicable portions of API Standard 653, Third Edition, Addendum 3, February 2008 and UFC 3-460-01 (previously 1022A).

The scope of this project is to determine the structural and hydraulic condition of the tank, determine suitability for service, provide written recommendations for repairs and develop recommendations for long-term service based on visual inspection and non-destructive examination (NDE).

General

Tank 27 is a field erected above ground storage tank. The tank was fabricated and erected in 1951. The tank is 100 feet in diameter and 37 feet 6 inches high and is of welded construction with butt-welded shell plates and lap-welded floor and roof plates. The nominal shell capacity is 49,170 Bbls. Tank 27 is currently in JP-8 service. The tank is not equipped with a floating pan.

A new floor was installed in 1999-2000.

INSPECTION ASSESSMENT

The Appendices in this report include a comprehensive table identifying tank features with findings and conclusions as appropriate. The Appendices also contain numerous tables with full reporting of data taken. The following discussion only addresses key integrity issues.

Tank 27 is considered suitable for service as no mandatory repairs were identified. The following are significant findings of the inspection.

Hydraulic Integrity

Hydraulic integrity is the ability of the tank to hold product without compromise to the boundaries of the floor and shell.

Visual inspection of the tank shell found no indications of leakage. A magnetic flux leakage (MFL) scan of the tank floor found no relevant indications of corrosion on the bottom side of the floor requiring repair. A pit survey was conducted for topside corrosion and no pits were identified requiring repair. Based on this inspection and completion of the repairs, Tank 27 is in acceptable hydraulic condition.

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EEI Project No.: 08-4889 R043

Structural Integrity

Structural integrity is the capability of the tank to remain freestanding, with or without product, under the conditions of its design basis. Structural attributes include the floor, shell, roof and their attachments. Ultrasonic inspections of the shell were performed on the first course and on each course up the exterior spiral stair. From interpretation of ultrasonic test (UT) readings recorded, only plate thickness variances were noticed. Based on this inspection of the accessible components, Tank 27 is in acceptable structural condition.

Next Inspection

API 653 recommends the interval to the next internal inspection be determined based on known corrosion rates, but in no case shall the interval exceed 20 years from time of inspection. When corrosion rates are not known or well established, API 653 recommends that the tank be inspected within 10 years. A maximum interval between inspections of 10 years is also commonly used in many government and commercial facilities.

The corrosion calculations presented in API 653 suggest floor backside corrosion may exist that magnetic flux leakage scanning methods will not find as it is below a “threshold” used for scanning. The calculations for this tank assumed backside corrosion equal to 20% metal loss may not have been located. When applying a 20% metal loss over a short period of time, such as eight years as is the case with this relatively new floor, the linear corrosion rate appears excessive.

The calculated corrosion rates using the suggested approach discussed above indicate that the next API internal inspection should be scheduled no later than 6.5 years from the inspection date.

EEI advises that the 6.5 years calculated indicates that there is not enough historical information to establish a reliable corrosion rate and the 10 year interval commonly used by the government and by API for tanks of unknown corrosion rates should be followed. The dry climate and lack of observed deficiencies support the increase in the inspection interval. In the interim, a limited out-of-service inspection of the coating should be performed during any maintenance cleanings.

An external in-service inspection should be conducted in accordance with API 653 requirements no later than June 2013, or sooner if change in condition has occurred.

REPAIR ITEMS

Based upon the API field inspection, engineering judgment and knowledge of funding practices, recommendations developed are listed below as required (mandatory) and recommended (non-mandatory) and recommended for long term serviceability.

Required Repairs Prior to Return to Service (Mandatory)

Mandatory refers to those API 653 items that are considered critical to the hydraulic or structural integrity of the tank or are required to meet code prior to placing Tank 27 back into service.

• The inspection of Tank 18 found no mandatory repairs that would prevent the tank from returning to service.

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EEI Project No.: 08-4889 R043

Recommended Repairs Prior to Return to Service (Non-Mandatory)

The repairs listed below are not mandatory per API 653 or for structural and hydraulic integrity of the tank. EEI highly recommends these repairs for long-term preservation and integrity of the tank, and believes that the repairs should be performed concurrently with required repairs noted above.

1. Line relieving / differential thermal relief (LR/DTR) at the 10 inch Issue nozzle is set at 25 psi while the thermal relief loop piping is set at 200 psi. The following repair is recommended:

• Remove the LR/DTR piping.

2. A double block and bleed (DB&B) plug valve is present on the Low Fuel Piping to isolate it from the Issue Piping. The LR/DTR piping relieves into the pipeline rather than into the tank. The following repair is recommended:

• Remove the LR/DTR on the Low Fuel Piping.

3. Body cavity relief (BCR) is present on the valves at the Issue and Fill nozzles. The BCR currently relieves into the tank rather than into the pipeline. The following repair is recommended:

• Revise the BCR to relieve into the pipeline.

4. The float for the Shand & Jurs tape gauge is not functional. The following repair is recommended:

• Provide a new tape gauge head, float, tape and springs.

5. Tank 27 has been equipped with two 10 inch pressure/vacuum vents. The following repair is recommended:

• Disassemble and clean the pressure/vacuum vents.

6. Tank 27 is equipped with two 2 inch ¼-turn ball valves in the dead shell that provide a means of leak detection. The flanges have been blinded. The following repair is recommended:

• Remove the blind flanges to allow monitoring of the interstitial space.

7. Localized coating failures and corrosion were observed on the exterior shell, floor extension, shell appurtenances, stairs, roof and roof appurtenances. The following repair is recommended:

• Remove the coating from the affected areas, clean and recoat to prevent further degradation.

8. Replace the gasket for the manway prior to reinstalling the manway cover plate.

9. Provide surface preparation and recoat all interior and exterior repair areas, new materials and areas damaged as a result of repairs in accordance with Coating Requirements.

1459962847E Highlight

1459962847E Highlight

1459962847E Highlight

1459962847E Highlight

1459962847E Highlight

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EEI Project No.: 08-4889 R043

Recommended Repairs per Current Military Criteria: The following recommended repairs are in accordance with UFC 3-460-1 (formerly MIL-HDBK-1022A):

1. The 12 inch Fill Piping includes a diffuser with a 12 inch x 19 inch opening and appears to be undersized. Section 8.3.9 of UFC 3-460-01 limits the velocity to 12 ft/s at maximum flow and 3 ft/s until the fill piping is submerged. The following repair is recommended:

• This item withdrawn after discussion with operations personnel.

2. The floor and lower 4 feet of the interior tank shell and columns of Tank 27 are coated.

Section 8.3.7 of UFC 3-460-01 states that vertical tanks storing aviation fuel should be 100% coated, including floor, shell and underside of roof. Rust was observed falling from the underside of the roof during the inspection. The following repair is recommended:

• Coat the remaining interior surfaces of the tank.

• Note: The decision to proceed with this recommendation requires consideration of multiple variables such as the difficulty of applying coatings at low temperatures and the low corrosion rate of uncoated plate steel in the ambient dry air.

3. Tank 27 is not equipped with a product recovery system per Section 8.3.12 of UFC 3-460-01.

The following repair is recommended:

• This item withdrawn after discussions with operations personnel.

4. Table 2 of UFC 3-460-01 describes appurtenances for atmospheric storage tanks. Tank 27 is not equipped item (dd) striker plates under all openings used for manual gauging. The following repair is recommended:

• Provide a ¼ inch thick x 12 inch diameter round striker plate.

• Seal weld the reinforcing plate to the shell. The completed repair shall have no cracks and shall have complete penetration and complete fusion with the shell plate.

• Provide visual examination, vacuum box testing (BT) and either liquid penetrant testing (PT) or magnetic particle testing (MT) of the completed repair.

• (Note: It was reported that POL use the same gauge hatch as the ATG where a datum plate is present and would act as a striker plate. Although this is acceptable in the short term, the installation of a new striker plate on the floor may be required when the next generation ATG system with gauge tubes is executed.)

Recommended Repairs for Long Term Serviceability

1. Table 2 of UFC 3-460-01 describes appurtenances for atmospheric storage tanks. Tank 27 is not equipped with item (j) an automatic level alarm system independent of the gauging system. The following repair is recommended:

• Provide an independent level alarm for the HI, HI-HI and Low levels.

• Note: The nozzles and fittings may be installed while the tank is out of service. The alarm system may be installed at a future date.

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EEI Project No.: 08-4889 R043

2. The portion of the shell below the new floor is commonly referred to as the “dead shell”.

The new floor has been continuously welded to the dead shell. Although not clearly prohibited by 653 to our knowledge, the welding of the deadshell to the underside of the floor is not considered an acceptable enginnering practice when a full strength fillet weld is provided. The floor, welded top and bottom, can no longer act as a hinge, permitting rotation of the shell above the floor when the tank is emptied and filled. Many tank engineers are concerned that laminar tearing of the floor plate can occur with full strength welds to shell above and dead shell below. API 650 Appendix I does however address this condition, and requires an engineeirng analysis of the condition if a full strength weld is to be used. A decision is required by the government as to the long term acceptability of this condition.

The anticipated repair includes grinding out the excessive weld on the underside of the new floor (floor to dead shell weld). Alternative means to prevent water introduction below the tank by using a sealant is required.

3. Program the tank for an API external in-service inspection in 5 years, and an API out-of-service internal inspection no later June 2018.

4. Test all level alarms and switches as part of on-going maintenance.

Coating Requirements

All repairs involving steel surface grinding, cutting, and welding shall be preceded by proper coating removal. At this time it is not known if any of the existing coating layers have significant lead or chromate components. The contractor shall be responsible for testing coating systems for lead and chromate levels, and develop engineered controls to prevent worker safety hazards, and spread of contaminated dusts. Coating removal method shall be contractor determined, to suit contamination levels and follow-up steps.

Coating System at Localized Repair Locations Only (Interior and Exterior) Provide repair of localized areas of failed and damaged coatings on the interior and exterior of the tank and areas affected by the repair work. Provide a coating system that complies with MIL-PRF-4556F (superseding MIL-C-4556), two-coat application, 4 to 8 mils DFT per coat.

Provide surface preparation in accordance with the coating manufacturer’s recommendations to ensure adhesion of the coating system. For tank interior coating, provide surface preparation in accordance with the coating manufacturer’s recommendations for immersion service. Provide 2 to 3 mil surface profile unless recommended otherwise by the coating manufacturer. Prior to surface preparation, test surfaces for soluble salts, oil, and grease and clean as required to remove contaminants. Tank interior coatings shall cure for not less than 14 days prior to introducing fuel into the tank. Provide longer cure time when recommended by manufacturer.

MIL-PRF-4556F (superseding MIL-C-4556) is an epoxy polyamide coating system that was used for coating the interior of storage tanks prior to the development of the MIL-DTL-24441 epoxy polyamide coating system and is still used on the interior of filter separators and other process vessels.

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EEI Project No.: 08-4889 R043

SUITABILITY FOR SERVICE EVALUATION

Corrosion Rates

Corrosion rates for the tank shell and roof were calculated using assumed nominal metal thicknesses when the tank was constructed in 1951. The corrosion rate for the floor was calculated using an assumed nominal metal thickness when the floor was installed in 2000. The corrosion calculations are also based upon the plate thicknesses obtained from UT thickness measurements at the time of the inspection. The corrosion rates are summarized as follows:

Floor: 0.00675 inches per year (See Table 1 below)

Shell: 0.00072 inches per year

Roof: Negligible – Plate thickness is within mill tolerance

Tank Floor Corrosion Rates

Bottom side corrosion with small volumetric metal loss may be present and not detected by MFL scanning. The metal loss used to establish the bottom side corrosion rate was conservatively calculated using the average thickness of the floor minus a 20% threshold value for undetected bottom side pits per API. The MFL floor scanner is not setup to indicate (alarm) for minor metal loss.

The minimum remaining floor thickness (MRT) used in the calculations is based on API 653 Section 4.4.7 and Table 6-1. The assessment of the floor found that the tank floor coating, with an average thickness of 10.7 mils, is a lining as defined in API RP 652. The tank has the means to provide detection and containment of a bottom leak. Based on this information, the MRT used in the calculations is 0.050 inch.

Table 1 – Tank 27 Floor

Age of Floor 8 years based on installation in 2000.

Original thickness Annular Ring 7 mm (0.276”) General Floor Plate 6 mm (0.236”)

Average Thickness of General Plate Tave = 0.228” based on 2 thickness measurements per plate

Average Thickness of Annular Ring Tave = 0.268” based on 2 thickness measurements per plate

Floor Product Side Corrosion

Maximum Depth of Product Side Pitting 0.000” (No pits were identified.)

Minimum Remaining Thickness RTip = 0.228” – 0.000” = 0.228” (general plate) RTip = 0.268” – 0.000” = 0.268” (annular ring)

Product Side Corrosion Rate StPr = Pit Depth / year = 0.000” / 8 yr = 0.00 in/yr Corrosion rate is justified given that the floor is adequately coated and the coating has a remaining life of 20+ years.

Floor Bottom Side Corrosion

Minimum Remaining Thickness at Areas of Bottom Side Corrosion Detected by MFL Scanning

RTbc = 0.217” (general plate) RTbc = 0.251” (annular ring)

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EEI Project No.: 08-4889 R043

Table 1 – Tank 27 Floor

Depth of Bottom Side Pitting Not Detected by MFL Scanning (Assumption)

MFL = 20% of Tave RTbc = 0.228” – 0.20 x 0.228” = 0.182” (general plate) RTbc = 0.268” – 0.20 x 0.268” = 0.214” (annular ring) Governs for RTbc

Bottom Side Corrosion Rate

UPr = (Tave – RTbc) / years UPr = (0.228” – 0.182”) / 8 = 0.00575 in/yr (general plate) UPr = (0.268” – 0.214”) / 8 = 0.00675 in/yr (annular ring)

Minimum Thickness Required at Next Inspection

Floor – General 0.050” for tank bottom/foundation design with means for detection and containment of a bottom leak.

Floor at Annular Ring Per API 653 Table 4-4 the minimum thickness is 0.170” for bottom shell course < 0.750” and stress < 24,300 psi.

Floor at Critical Zone Per API 653 the minimum thickness is the smaller of 50% of tmin of the bottom shell course (0.50 x 0.591” = 0.296”), 1/2 of the original thickness of the floor (1/2 x 0.276” = 0.138”), but not less than 0.100”.

For the critical zone, 0.138” controls.

Minimum Remaining Thickness (Based on an In- Service Interval Or = 20 yrs)

Floor – General

MRT = (Minimum of RTbc or RTip) – Or x (StPr + UPr) MRT = (0.182” or 0.228”) – 20 x (0.00 + 0.00575) MRT = 0.182 – 20 x 0.00575 = 0.067” > 0.050” OK The general tank floor plate thickness will not be reduced below the limiting MRT at a 20-year inspection interval.

Minimum Remaining Thickness (Based on an In- Service Interval Or = 20 yrs)

Floor at Annular Ring

MRT = (Minimum of RTbc or RTip) – Or x (StPr + UPr) MRT = (0.214” or 0.268”) – 20 x (0.00 + 0.00675) MRT = 0.214 – 20 x 0.00675 = 0.079” < 0.170” NG The annular ring thickness will be reduced below the limiting MRT at a 20-year inspection interval.

Minimum Remaining Thickness (Based on an In- Service Interval Or = 20 yrs)

Floor at Critical Zone

MRT = (Minimum of RTbc or RTip) – Or x (StPr + UPr) MRT = (0.214” or 0.268”) – 20 x (0.00 + 0.00675) MRT = 0.214 – 20 x 0.00675 = 0.079” < 0.138” NG The tank floor plate thickness at the critical zone will be reduced below the limiting MRT at a 20-year inspection interval.

In-Service Interval (Or)

Floor at Annular Ring

Or = (RTbc – MRT) / UPr Or = (0.214” – 0.170”) / 0.00675 in/yr Or = 6.5 years The service interval is limited to 6.5 years based on the assumed corrosion rate applied to the annular ring.

In-Service Interval (Or)

Floor at Critical Zone

Or = (RTbc – MRT) / UPr Or = (0.214” – 0.138”) / 0.00675 in/yr Or = 11.3 years The service interval is limited to 11.3 years based on the assumed corrosion rate applied to the critical zone.

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EEI Project No.: 08-4889 R043

Hydraulic and Structural Integrity

The following table summarizes the hydraulic and structural integrity of Tank 27:

HYDRAULIC AND STRUCTURAL INTEGRITY

Evaluation Item

Findings Comments

Foundation Tank 27 rests on a gravel mound. The tank passes API 653 criteria for levelness and differential settlement.

Acceptable

Floor Visual inspection of the floor joints found no relevant indications. MFL scanning of the tank floor found no relevant indications of corrosion on the bottom side of the floor. A pit survey was conducted for topside corrosion and no pits were identified requiring repair.

No localized bulges or depressions of the floor were found during the inspection

Based upon the calculated corrosion rate, the annular floor plate thickness will be reduced below the requirements for minimum floor plate thickness of 0.170 inch at a 20-year inspection interval.

Refer to “Inspection Assessment – Next Inspection” for further discussion.

Shell Inspection found no indications of damage or deterioration to the shell.

Acceptable

Roof Inspection found no indication of damage or deterioration of the roof.

Acceptable

Internal Fluid Pressure

Hoop stresses caused by internal fluid pressure passes API 653 criteria.

Acceptable

Hydrostatic Test

Shell is adequate to resist the internal fluid pressure caused by a full height hydrostatic test with water.

Acceptable

Brittle Fracture The API 653, Section 5, Figure 5-2, Brittle Fracture Considerations has been evaluated with the following findings:

1. Does the tank meet API 650(7th edition or later, 1980): No, built in 1951.

2. Has a prior hydrotest been performed demonstrating fitness: Yes.

3. Is the tank shell thickness < 0.5 inch: No.

4. Does the tank operate at metal temperature above

60 deg F?: No.

5. Is the tank membrane stress below 7 ksi?: No.

6. Tank steel exempt per API 650, Figure 4-1 or API 653 Figure 5-2: No.

7. Tank full at lowest one day temperature per API 650 Figure 2.2: Yes.

The tank, having been hydrotested after the installation of the new floor, does not fit the API 653 at-risk profile for brittle fracture failure.

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EEI Project No.: 08-4889 R043

HYDRAULIC AND STRUCTURAL INTEGRITY

Evaluation Item

Findings Comments

Seismic Seismic calculations were performed in accordance with API 650 Appendix E.

The calculations indicate that the tank is considered to be stable against overturning and that the longitudinal stresses are acceptable.

Calculations were performed utilizing the specific gravity for JP-8, an earth foundation, seismic parameters Ss = 0.37, S1 = 0.15 and an importance factor of 1.0.

No exception taken.

Wind Evaluation

A wind analysis was performed per API 650, Section 3.11.

Calculations were performed using an importance factor of

1.1 and a wind velocity of 135 mph.

The tank is not anchored. The evaluation determined that an empty unanchored tank is at risk of overturning.

Evaluation of the shell buckling determined that shell stiffeners are required for the design wind speed.

There is no requirement to upgrade the tank to current API 650 standards for anchorage.

Damaged shell plate was replaced and shell stiffeners were installed as part of the 1999-2000 repair project.

ADDITIONAL DISCUSSION ITEMS

Gauge Tube (Stilling Well) Requirements

Overall Requirements and Decisions Required

Although gauge tubes were not included in the scope of work, the findings are presented herein as an aide to those who may execute the work in future. The requirements for stilling wells have been reviewed. These requirements are based on our latest understanding for the upcoming SPAWAR executed ATG system, as issued by PMO of DESC and other agencies. There have been ongoing discussions with respect to modifications to the current published requirements.

At this time, the criteria are still under refinement and formal direction has not been published.

The comments below represent concept solutions for this tank and we believe are consistent with the latest DESC direction (June 30, 2008). We recommend the concept be submitted to DESC for ratification or redirection at the time a need to execute is identified.

This facility is a prime candidate for the next generation ATG system as the present is an ITT Barton system. The next ATG system will likely be a system manufactured by MTS or ENRAF.

The decision between the two systems should be based upon successful service in the Arctic with temperatures to -65 deg F. As these tanks do not, and we understand, will not ever get floating pans, the need for gauge tubes must be verified at the time of execution. We understand the current thinking is any location of displacer type level measurement must have a gauge tube for repeatable, accurate measurement. For discussion we will address gauge tube needs based on worse case, that of a tank needing full gauge tube application. One of the differences between each system is that two gauge tubes would be required for MTS while three are required for ENRAF. Although the number of gauge tubes for ENRAF could be reduced with the use of the 10”/2” combo gauge tube, DESC appears to be moving away from this recommendation.

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EEI Project No.: 08-4889 R043

Site Specific Tank Parameters Affecting Gauging and Stilling Wells

The Tank is a typical aboveground tank with a cone-down floor, one center low point sump and no floating pan. The sump is 4 feet in diameter and 18 inches deep. Within the sump is the 2” Water Draw-Off Piping, 3” Diameter Low Fuel Piping and a 6” Roof Support Pipe Column. The roof rafters are supported on a plate welded to the top of the center pipe column. The diameter of the support plate appears to be less than the diameter of the sump. There are currently no means to gauge water in the sump.

Current Requirements: SK-1, SK-2 and SK-3

Strict adherence to SK-1, SK-2 and SK-3 as provided by the government may not be practical or possible due to the configuration of the tank structure and lack of a floating pan. It is our understanding that they are no longer appropriate and should not be followed.

Manual Gauging

Manual gauging is currently performed at the ATG thief hatch. The tank is equipped with a separate 8 inch thief hatch, with no gauge tube, approximately 10 feet from the center sump.

It is our understanding that a gauge tube is desirable, but not a mandatory requirement for manual gauging and sampling in a tank lacking a floating pan. Therefore, the present thief hatch for manual gauging should be acceptable for use as is. In the event a gauge tube is required, it should be constructed as noted for the ATG gauge tube.

Combination Water/Temperature Probe Location

The current ITT Barton temperature sensor and the ATG level sensor probe are both located within an 8 inch thief hatch near the tank shell. An 8 inch gauge tube with a datum plate is present on the tank floor. The datum plate is at the same elevation as the chine. However, the gauge tube is only 4 feet tall and is not equipped with slots. This location is undesirable for water probe sensing, but is acceptable for the level sensor. There appears to be adequate space available to locate a water/temperature probe directly over the sump. The probe must be located with a minimum clearance of 2 inches to any steel object, such as the sump wall and the piping.

To install the probe, it will be necessary to cut a hole in the steel roof and position it between roof rafters. The center compression plate must not be altered. Nozzle and gauge tube requirements follow.

Temperature/water probe Option 1 – No Gauge Tube

Option 1 consists of cutting a hole in the steel roof plate and installing an 8 inch flanged spool above the opening. The hole must be located between roof rafters and over the sump.

Temperature/water probe Option 2 – Gauge Tube Below Roof

Option 2 includes a 10 inch roof nozzle with an 8 inch aluminum gauge tube supported from the roof or floor. It is our understanding that the DESC preference is 8 inches to permit greater flexibility in the future with a variety of manufacturers. There appears to be sufficient clearance for a gauge tube to line up over the sump. But if not, it can be located within several feet of the sump, which is also acceptable to DESC. The preference is to support the tube from the floor and guide with a slip-collar to a riser in the roof. The bottom of the tube must be installed a

Tank 27 – API 653 Inspection Page 11

EEI Project No.: 08-4889 R043 minimum of 24 inches above the floor. If lateral bracing is required to stabilize the tube, it can be attached to the center roof support pipe column.

As the tank is 37 feet 6 inches tall, the installation of a single pre-assembled gauge tube would require a crane. It would likely be more practical to fabricate the gauge tube in multiple flanged sections for assembly within the tank. The length of tubes could suit shipment to the site via the military air freight system. Since the tank is not equipped with a floating pan, flanges would not be an issue.

ATG Servo Float Stilling Well Requirements

The current ATG level sensor and temperature sensor are located within an 8 inch thief hatch near the tank shell. An 8 inch gauge tube with a datum plate is present on the tank floor.

However, the gauge tube is only 4 feet tall and is not equipped with slots. This location is acceptable for the level sensor. . It is not clear why the tank is equipped with such a short tube, and in fact it was found in-effective as in one case, the gauge sensor was landed outside of this tube.

The Tank is equipped with two spare flanged roof nozzles; a 10 inch near-shell and an 8 inch near-center nozzle. Neither is equipped with a gauge tube. It is recommended to use the 10 inch near-shell nozzle since it is located farther from fill piping diffuser and any swirl effects.

The ATG level sensor gauge tube may have a diameter of 4, 6 or 8 inches. It is our understanding that the DESC preference is an 8 inch aluminum tube to permit greater flexibility in the future with a variety of manufacturers. The preference is to support the tube from the floor and guide with a slip-collar to a riser in the roof as noted above for the temperature/water probe gauge tube.

CLOSURE

Conclusions

Based on the extent of this inspection, Tank 27 is considered suitable for service.

Project Team

Site Team

David A. Stchyrba, P.E. Structural Engineer, API 653 Aboveground Storage Tank Inspector Certificate No. 27187, API Inspector of Record.

Kelly B. Waring, P.E. Mechanical Engineer, API 653 Aboveground Storage Tank Inspector Certificate No. 21992

Todd O. Lichtenberg NDE Technician, Level II Inspector

Kevin D. Moore NDE Technician, Level II Inspector

Support Team

Stephen S. Brooks, P.E. Technical Advisor, QA Review, API 653 Aboveground Storage Tank Inspector Certificate No. 17

APPENDIX A

Tank Inspection Data Sheet and Evaluation Items

AST TANK INSPECTION DATA SHEET

Tank No. 27

Owner/Operator: U.S. Air Force Location Thule Air Base, Greenland

API 653 INSPECTION

Type: Internal & External w/ Suitability for Service Date: June 8th, 2008

By: Enterprise Engineering, Inc.

2525 Gambell Street, Suite 200 Anchorage, Alaska 99503

(907) 563-3835

EEI Project No: 08-4889

TANK DATA

API 653 Inspector: David A. Stchyrba

ANSI/API-653 AST Inspector Certificate No. 27187

Type: Vertical AST Diameter: 100’ – 0”

Shell Height: 37’ – 6” Configuration: Butt Welded Shell w/ 5 courses

Foundation: Gravel Pad Leak Detection: Two detection ports in interstitial space

Date Erected: 1951, New floor installed 1999-2000 API Standard: New floor to API 650, 9th Ed. Addendum 2 1995

Original construction assumed 12C 9th Ed. 1950 Designed By: Unknown Manufacturer Unknown

Erector: Unknown Fuel Stored: JP-8

Design Specific Gravity: 0.82 Operating Fill Height: 34’ – 0” (From facility)

Max Fill Height: 36’ – 9” (Name plate) Nominal Capacity: 49,170 Bbls (Name plate)

Strapped Capacity: 53,510 Bbls (Strapping chart) Change In Service: None

Current Tank Cleaner: Shaw subcontractor Date Last Strapped: Strapped after installation of new floor

Date of Last Inspection: Unknown Date of Previous Cleaning: Unknown

As-Built Drawings, Specifications: Design drawings for new floor available

EVALUATION CRITERIA

API Standards: API 650, 11th Edition, June 2007

API 653, 3rd Edition, Addendum 3, Feb 2008 Ground Snow: 25 psf (UFC 3-310-01)

Wind Speed: 135 mph (UFC 3-310-01) Seismic: Ss = 0.37, S1 = 0.15 (UFC 3-310-01)

APPENDIX A AST Tank Inspection Data Sheet Tank 27 – API 653 Inspection July 2008

AST EVALUATION ITEMS

TABLE OF CONTENTS

PAGE

FOUNDATION

FLOOR

SHELL

ROOF

COATINGS

APPURTENANCES

PIPING

APPENDIX A AST Evaluation Items - TOC Tank 27 – API 653 Inspection July 2008

APPENDIX A - AST Evaluation Items Page 1 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

FOUNDATION

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

FOUNDATION

Type The tank sits on a gravel mound.

Levelness The maximum differential between max and min elevations is 0.17 feet (2.04 inch).

Tank 27 passes API 653 criteria for shell levelness and differential settlement.

Rigid Body Tilt Tank 27 has small amount of tilt. The amount of tilt is 0.06 feet (0.77 inch).

Calculations of data acquired at the shell determine that the tank is slightly tilted but within acceptable limits.

Height Above Dike Floor The new floor is 29 inches above the gravel base.

Material Below Tank Floor The material below the tank floor could not be inspected. Design drawings indicate that the interstitial space is filled with concrete.

Drainage Around Tank Drainage around the tank is adequate.

Tank Anchors Tank 27 is not equipped with anchors.

Containment Dike Tank 27 sits within a lined containment dike. The liner batten strips are attached to and angle and plate welded to the old floor.

Secondary Containment Tank 27 has a double bottom.

Settlement Calculations indicate that Tank 27 passes API 653 criteria for settlement.

Erosion/Washouts No indications of washouts or erosion were observed.

Sealed at Foundation The tank rests on a gravel pad. It is not sealed.

No further action recommended.

Additional Foundation Items, Comments or Notes:

None.

APPENDIX A - AST Evaluation Items Page 2 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

FLOOR

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

TANK FLOOR

Type The tank has a double bottom. The new floor configuration is cone down with an annular ring and lap welded steel plates.

Nominal Thickness The floor consists of 7 mm (0.276 inch) thick annular floor plates and 6 mm (0.236 inch) thick floor plates.

Annular Ring Plates Tank 27 has been provided with a butt-welded annular ring.

Thickness The average thickness of the annular ring plates is 0.268 inches. The average thickness of the interior floor plates based on 5 UT readings per floor plate is 0.228 inch. The exterior floor extension (chine) has an average thickness of 0.265 inch based on twelve locations.

Interior Width The average floor plate width is 8 feet.

Floor seam welds No relevant indications were found on the floor plate seam welds.

MFL Floor Scan MFL of the accessible areas of the floor found no indications requiring an ultrasonic test (UT) prove-up.

Bottom Side Floor Pitting/Corrosion

Based on MFL and UT examination, bottom side pitting/corrosion is not prevalent.

Top Side Floor Pitting/Corrosion

No pits were identified requiring repair.

Patch Plates No patch plates were observed on the floor.

Doubler/Support Plates The interior piping supports for the Fill, Issue, Low Fuel and Water Draw-Off lines have support plates that have been seal welded to the floor.

Plug Welds No plug welds were observed.

Weld Artifacts No significant weld artifacts were noted.

Vacuum Box Testing The floor-welded seams are coated. A vacuum box test was not performed.

Helium Leak Testing HLT was not performed.

APPENDIX A - AST Evaluation Items Page 3 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

FLOOR

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

Floor Bulges, Depressions No significant bulges or depressions were noted.

Oil Canning/Flexing No significant flexing of floor plates was observed.

Edge Settlement Edge settlement was not noted.

Measurements taken for edge settlement at eleven equidistant locations pass API 653, Appendix B criteria.

Floor Critical Zone No significant corrosion or deflection was observed within the critical zone.

Floor Profile The floor is cone down. The average differential height from the shell to the center of the tank is 2.19 feet. The tank floor has a 4.35% slope to the center sump.

Sumps Tank 27 is equipped with a 46 inch diameter center sump.

Secondary Liner Below Floor There is no secondary liner below the original tank floor.

See “Foundation – Secondary Containment”

Leak Detection Below Floor There are two ¼ turn ball valves with blind flanges within the dead shell. The extent of piping below the floor is unknown.

Recommend removing the blind flanges to allow monitoring of the interstitial space.

Cathodic Protection Below Floor

Tank 27 is not equipped with cathodic protection.

Additional Floor Items, Comments, Notes:

APPENDIX A - AST Evaluation Items Page 4 Tank 27 – API 653 Inspection July 2008

SHELL

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

TANK SHELL

Nominal Thickness UT Thickness Coating See Exterior Coatings section.

1st Course 0.591 inch 11.0 mils

2nd Course 0.459 inch 11.0 mils

3rd Course 0.344 inch 11.1 mils

4th Course 0.242 inch 10.7 mils

5th Course 0.249 inch 12.1 mils

Rim Angle Unable to access.

Plumbness Visual observations found no noticeable out-of-plumbness.

Roundness The tank was measured across two diagonal locations with no out-of-roundness noted.

Dents/Buckles No significant dents or buckles requiring repairs were observed. It was reported that plate was previously damaged. The 1999-2000 repair work included replacing the damaged shell plates and installing wind girders.

Banding/Peaking No significant banding or peaking was observed.

Interior Shell pitting/corrosion No pits or corrosion were observed on the interior 1st course. The upper courses of the interior shell were not accessible.

Exterior Shell pitting/corrosion No significant pits were observed on the exterior shell as viewed from the ground elevation.

Insert plates Two 12 inch diameter insert plates were observed in the dead shell.

Welded Patch Plates No welded patch plates were observed on the exterior or interior shell surfaces.

Floor Extension The floor extension (chine) extends an average of 2 inches out from shell.

Interior Shell Welds Visual inspection of accessible interior shell welds found no indications for further inspections or examinations.

APPENDIX A - AST Evaluation Items Page 5 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

SHELL

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

Exterior Shell Welds Visual inspection of accessible exterior shell welds found no indications for further inspections or examinations.

Original weld seams were inspected by trepanning.

Door sheet No door sheets were observed.

However, full course height sections were likely removed for the installation of the new floor.

Shell-to-Floor Weld – Interior Visual inspection of the interior shell-to-bottom welds found no indications for

Shell-to-Floor Weld – Exterior Visual inspection of the exterior shell-to-floor welds found no indications for

Floor-to-Dead Shell - Exterior The new floor is welded to the dead shell.

No remedial work is recommended at this time.

Shell Manways Two 36 inch diameter round manways located in the 1st shell course.

Flush Cleanouts Tank 27 is not equipped with a flush cleanout.

Shell Reinforcing Plates

Manway

(Size, Thickness, Telltale Hole)

Manway #1

36 inch diameter, 0.640 inch thick neck

(UT).

Diamond reinforcing plate 90 inch wide x 76 inch high x 0.643 inch thick (UT).

A telltale hole is not present.

The reinforcing plate does not meet current API 650 criteria for open telltale holes. However, it is not recommended to install one at this time.

Manway #2

36 inch diameter, 0.642 inch thick neck

(UT).

Diamond reinforcing plate 90 inch wide x 76 inch high x 0.652 inch thick (UT).

A telltale hole is not present.

The reinforcing plate does not meet current API 650 criteria for open telltale holes. However, it is not recommended to install one at this time.

Receipt/Fill

(Size, Thickness, Telltale Hole)

12 inch diameter nozzle, 0.538 inch thick neck (UT).

Diamond reinforcing plate 32 inches wide x 26 inch high x 0.653 inch thick

(UT).

A telltale hole is not present.

The reinforcing plate does not meet current API 650 criteria for open telltale holes. However, it is not recommended to install one at this time.

APPENDIX A - AST Evaluation Items Page 6 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

SHELL

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

Pressure Relief for Fill

(Size, Thickness, Telltale Hole)

1 inch diameter nozzle, 0.184 inch thick neck (UT).

A reinforcing plate is not present.

A reinforcing plate is not required.

Issue

(Size, Thickness, Telltale Hole

10 inch diameter nozzle, 0.497 inch thick neck (UT).

Diamond reinforcing plate 28 inches wide x 22½ inch high x 0.643 inch thick

(UT).

A telltale hole is not present.

The reinforcing plate does not meet current API 650 criteria for open telltale holes. However, it is not recommended to install one at this time.

Pressure Relief for Fill

(Size, Thickness, Telltale Hole)

1 inch diameter nozzle, 0.178 inch thick neck (UT).

A reinforcing plate is not present.

A reinforcing plate is not required.

Low Fuel/Drain

(Size, Thickness, Telltale Hole)

3 inch diameter nozzle, 0.292 inch thick neck (UT).

Diamond reinforcing plate 13½ inches wide x 10½ inch high x 0.638 inch thick

(UT).

A telltale hole is not present.

The reinforcing plate does not meet current API 650 criteria for open telltale holes. However, it is not recommended to install one at this time.

Water Draw-Off

(Size, Thickness, Telltale Hole)

2 inch diameter nozzle, 0.220 inch thick neck (UT).

A telltale hole is not present.

A reinforcing plate is not required.

Fire

(Size, Thickness, Telltale Hole)

Two 3 inch diameter nozzles with injection ports at top of 5th course.

Shell Vents Tank 27 is not equipped with shell vents.

Overflow Ports Tank 27 does not have any overflow ports.

Wind Girders and Shell Stiffeners (Size & Elevation)

Tank 27 is equipped with two internal shell stiffeners located in the 4th and 5th shell courses.

APPENDIX A - AST Evaluation Items Page 7 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

SHELL

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

Tank Nameplate Data (Complete as Possible):

Repaired/Altered to API 653 Edition 2nd Dec 1995

Reconstructed by Jens Pilegaard WS A/S Contract No. F61101-99-C0010

Date Completed 2000.07.07

Original Standard API Tank No. 27 Tank Dia. 100’ Height 40’ Specific Gravity 0.85

Design Pressure -5/+8 psf Original Construction Date 1951 Year Reconstructed 1999-2000

Liquid Level Max 36’9” Capacity 49170 BBL Maximum Operating Temperature 100 Deg F

Shell Course

2 x ¼”

1 x 11/32”

1 x ½”

1 x 5/8”

Additional Shell Items, Comments or Notes:

Stenciled on shell:

Tank 27

JP-8

APPENDIX A - AST Evaluation Items Page 8 Tank 27 – API 653 Inspection July 2008

ROOF

(A blank in comments column indicates lack of significance, or condition is acceptable.)

TANK ROOF

Type Fixed cone-up with 16 pipe columns.

Roof Plate Thickness (Outer/Mid/Inner)

The roof consists of 3/16 inch (0.188 inch) thick roof plates. Average thickness for the plates is 0.184 inch.

Roof Topside pitting/corrosion No significant pitting or corrosion was identified on the topside of the roof.

See “Roof Exterior” under Coatings section.

Roof Bulges/Depressions No significant bulges or depressions were identified. No major water ponding areas were observed.

Roof Joints Visual inspection of the topside roof welds found no relevant indications for further inspection or examination.

Frangible Joint (Size/Condition) 3/16 inch nominal roof plates, lap welded to rim angle. The roof connection at the shell meets the definition of a frangible joint for emergency venting.

Roof Vents (Size & Type) Tank 27 is equipped with two 10 inch diameter Shand & Jurs Kaneko pressure/vacuum vents.

Recommend disassembling and cleaning the pressure/vacuum vents.

Roof Manways The roof is equipped with two 24 inch diameter manways. There is an access ladder into the tank at one manway.

Roof Hatches Tank 27 is not equipped with any roof hatches.

Roof Nozzles Roof nozzles include an 8 inch near perimeter thief hatch for the ITT Barton ATG system, two 1 inch threaded plugs, an 8 inch diameter near center thief hatch for manual gauging, a 10 inch near shell with blind, a 10 inch with blind at center, an 8 inch with blind near center, a 10 inch near shell with blind and the penetrations for tape gauge float and guide wires

APPENDIX A - AST Evaluation Items Page 9 Tank 27 – API 653 Inspection July 2008 EEI Project No.: 08-4889 R043

ROOF

Evaluation Item Finding(s) Comments/Recommendations (A blank in comments column indicates lack of significance, or condition is acceptable.)

Handrails Handrails exist at the spiral stair access platform. A perimeter handrail is present at the roof level. The handrail includes a 4 inch kicklate.

Roof Access From Ground Roof access is by spiral stair.

Roof Access to Adjacent Tank None

Roof Framing/Roof Underside Condition

The interior roof structure appears to be in good condition with no twisting or bending of components. Visual inspection of the roof underside from the floor found no indications for further examination.

Roof Elevation The center of the cone roof is raised above the shell elevation.

Interior Columns There are sixteen 6 inch diameter pipe columns with base plates. Each column has been provided with a mousehole. A number of base plates do not meet current API 650 weld clearance requirements to the floor joints.

The columns are welded to the base plates and the base plates are welded to the floor.

No further action is recommended at this time with respect to the clearance requirements.

Although the columns and bases were welded in violation of API 650, no repair is recommended at this time. Thule AB is located in a Seismic Zone 1 region, thus there is low probability of damage due to seismic activity. No evidence of distress in the floor was observed.

INTERNAL FLOATING ROOF

Type Tank 27 does not have an internal floating pan.

SEE TANK APPURTENANCES FOR ATG, GAUGING, LEVEL ALARMS, ETC.

Additional Roof Items, Comments or Notes:

APPENDIX A - AST Evaluation Items Page 10 Tank 27 – API 653 Inspection July 2008

COATINGS

(A blank in comments column indicates lack of significance, or condition is acceptable.)

Exterior Coatings

Shell

Type/age An epoxy polyamide system. The age of the coating is not known.

General Condition In general, the exterior coating system on the shell and appurtenances is in good condition with minor areas requiring repair.

Recommend removing the coating from the affected areas and…