Attachment 2 - TR0199 USAFA Air Tank Leak Inspection Report_signed.pdf

REV. ISSUE DATE COMMENTS APPROVED BY

0 April 18, 2024 Initial Release H. Adams

United States Air Force Academy

April 2024

USAFA Air Tank Leak Inspection Air Tank Leak Inspection Report

REPORT NO: TR0199

STATEMENT OF CONFIDENTIALTY:

TECHNICAL REPORT

TR0199 Page i

USAFA Air Tank Leak Inspection

Use or Disclosure of the Data, Images and Information Contained Herein is Subject to the Restrictions Set Forth on the Title Page

Table of Contents

1. Introduction

2. Visual and Bubble Leak Inspection

3. Repair Recommendations

4. Conclusion

APPENDIX A (Applied Technical Services Inspection Report) ..................................................... A-1

TR0199 Page 1

1. Introduction A site visit was performed on March 26, 2024, that included the inspection of the six air storage vessels at the United States Air Force Academy (USAFA) in Colorado Springs, CO. Each vessel is approximately 42” in diameter and 100’ long. All vessels have a manway/inspection port which was not accessible as part of this leak audit. The air tanks are in a confined space area in the basement of the Trisonic Wind Tunnel test area and are connected in series. This air system consists of three air compressors, two dryers, a main discharge line, and the six storage vessels. The system was known to have leaks when the pressure exceeded approximately 450 psig. All components and flange gaskets within this piping system including the connected pipes on the vessels were inspected for leaks.

2. Visual and Bubble Leak Inspection There were two inspections performed during this audit: visual inspection and a bubble leak inspection. For these inspections there were areas where access was limited on storage vessels #1 and #2. During the visual inspection there were multiple flange gaskets exhibiting a black substance that has seeped out of the gaskets. The air system did not appear to have corrosion and there were no concerns of future failures.

As the air compressor area was inspected, a water leak was observed that had occurred from a corroded pipe on the dryer system (See Figure 10 of Appendix A). Even though this was not part of the air system Calspan recommends replacing that run of pipe.

The bubble leak test was performed per ASME Sec. V, Art. 10, App 1. For the initial inspection, the system was pressurized up to two levels: 400 psig and 525 psig. During this inspection, there were a total of fourteen leaks found. All leaks are listed in the Applied Technical Services (ATS) report in Appendix A and ranked by severity. The leaks that were accessible were photographed and can be seen in Figures 1-8 in Appendix A. Leak 13 in Appendix A was the largest leak. During the 400 psig leak test this leak was not audible, but when the system was pressurized to 525 psig, this leak was significantly larger and easily identifiable audibly.

Once this inspection was complete, a supplemental inspection was performed at 525 psig on the pressure relief valves (PRVs) located on vessels #1 and #2. There were no leaks observed on the PRVs at any pressure. These PRVs vent to atmosphere within the confined space. For safety, it is recommended these valves be vented to a restricted area outside of the confined space area.

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3. Repair Recommendations There are 4 typical failure points that were found in the air supply system. Here are the general repair recommendations for each type.

1. NPT Connections:

Either through improper initial installation, repeated disassembly/reassembly, or age of the joint, leaks have developed through the NPT threads of various connections in the air supply system. Calspan recommends disassembly of the leaking threaded connections, thorough cleaning of the male and female threads, and reapplying a thread sealant to the male threads. Reassemble NPT connection following standard industry practices.

- Recommended thread sealants:

McMaster- Carr High Density Thread Sealant Tape Locktite 565 (Anaerobic thread sealer)

- Recommended NPT assembly process:

1. Check that the male and female threads are clean and free from burs and nicks

2. Confirm that both the female and male threads are cut properly by gaging them per the appropriate thread standard

3. Screw in and tighten the fitting until it is hand-tight

4. Count the remaining exposed threads and also mark both components in this dry-fit position, which is the hand-tight or finger-tight thread engagement point

5. Disassemble the threaded parts and correctly apply an appropriate and compatible sealant or lubricant to the male threads

6. Tighten the parts again by hand until they are at the dry fit position

7. Use a wrench to tighten the threaded joint up to the wrench-tight thread engagement point

8. For shaped fittings, wrench tighten to the minimum recommended turns past finger tight and then tighten as needed to get the desired orientation

*The wrench tight thread engagement points for NPT and NPTF fittings smaller than 1 inch is typically about 1-1/2 to 3 turns. Wrench tight for fittings from 1 inch to 2 inches is about 1 to 2-1/2 turns. Consult "Machinery's Handbook" for more detailed wrench-tight thread engagement information.

In cases where it is impractical to disassemble the threaded piping connection, it is permissible, if access allows it, to clean the exposed pipe threads and seal weld around the male to female connection to create a leak free joint.

2. ASME flange gasket leaks:

Calspan recommends that gaskets be replaced at flange locations where leaks are occurring. The leaks may be occurring due to age and degradation of the existing gaskets, or improper installation of the gaskets.

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For high pressure piping systems, Calspan specifies Flexitallic, Style CG spiral wound gasket, winding material: 304 / Flexcarb. Outer ring material: Carbon steel. Size of gasket is dependent on the class of flange (likely 300lb class) and flange size. Specific flange designation should be stamped on each flange

Installation bolting torque should follow the gasket manufacturer’s guidelines. ASME PCC- 1 is also an industry reference that should be followed for installation steps such as tightening sequence (star pattern, and incremental torqueing of fasteners). Check the condition of the studs and nuts during disassembly, but they should be adequate for reuse during reassembly.

3. Valve stem leaks:

Due to the age of equipment, difficulty of sourcing replacement components, and relative ease and reasonable cost, Calspan recommends replacement of the globe valve tank drains that are experiencing leaks through the valve stems. Installation process would follow the steps laid out in Item 1 for repair of leaking NPT fittings.

4. Swagelok fitting leak:

Calspan recommends the replacement of the of the sensing line with a new tube and new Swagelok fittings. Follow manufacturers guidelines for appropriate assembly of Swagelok fittings. Ensure clean tubing with no burrs or debris prior to tightening.

Number Location Description Recommended Repair

1 NPT Connection (~ 1 1/2" - 2") Replace with recommended thread sealent

2 4" Manual Valve Flange (Assumed Class 300 Flange) Replace with recommended gasket and seal with proper bolt torques per ASME PCC-1

3 4" Isolation Valve (Assumed Class 300 Flange) Replace with recommended gasket and seal with proper bolt torques per ASME PCC-1

Vessel 5 Flange to Vessel 4 U-Pipe

(Assumed Class 300 Flange) Replace with recommended gasket and seal with proper bolt torques per ASME PCC-1

8" Main Discharge Tee Flange

(Assumed Class 300 Flange) Replace with recommended gasket and seal with proper bolt torques per ASME PCC-1

6 1/4" Swagelok Connection Replace sensing line with new tube and swagelok fittings

7 Vessel 6 Drain NPT Fittings (~ 2" Assumed Class 300) Replace with recommended thread sealent

8 Vessel 4 Drain Valve Stem (Assumed Class 300) Replace drain valve

9 Vessel 3 Drain Valve Stem (Assumed Class 300) Replace drain valve

Vessel 5 Drain Valve Stem and NPT Fittings

(~ 2" Assumed Class 300) Replace drain valve and NPT fittings with recommended thread sealant

Vessel 2 Drain NPT Fittings

(~ 2" Assumed Class 300) Replace with recommended thread sealent

Vessel 1 Drain NPT Fittings

(~ 2" Assumed Class 300) Replace with recommended thread sealent

Vessel 2 Flange to Vessel 1 U-Pipe

(Assumed Class 300 Flange) Replace with recommended gasket and seal with proper bolt torques per ASME PCC-1

14 Dryer Union Fitting (~ 1 1/2" - 2") Replace with recommended thread sealent

15 Compressor System Water Line (~ 1 1/2" -2") Replace the run of pipe that is corroded (~6-10')

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4. Conclusion The supplied report identifies a number of repairable leak points in the Air Force Academy air system along with proposed repair methods for those leaks. Overall, all of these leaks can cause potential pressure loss but leak 13 will need the most attention. The Air Force Academy can use this report to directly work with a mechanical contractor to mitigate these issues. Calspan is available to source and manage this repair work for the Air Force, as additional work scope.

TR0199 Page A-1 Use or Disclosure of the Data, Images and Information Contained Herein is Subject to the

APPENDIX A (Applied Technical Services Inspection Report)

Professional Engineers and Scientists

Design • Consulting • Testing and Inspection Members in AAFS, ACS, ANSI, ASM, ASME, ASNT, ASQ, ASTM, AWS, BOMA, FSCT, IAAI, IWCA, NACE, NCSL, NFPA, SAFS, TAPPI

GEORGIA SOCIETY OF PROFESSIONAL ENGINEERS, NATIONAL SOCIETY OF PROFESSIONAL ENGINEERS In the state of North Carolina, Engineering Services will be provided by ATS Engineering, PLLC or a properly licensed subcontractor

In the state of New York, Engineering Services will be provided by ATS Engineering, LLC or a properly licensed subcontractor This report may not be reproduced except in full without the written approval of ATS. This report represents interpretation of the results obtained from the test specimen and is not to be construed as a guarantee or warranty of the condition of the entire material lot. If the method used is a customer provided, non-standard test method, ATS does not assume responsibility for validation of the method.

ATS 044, 07/2021

LEAK INSPECTION: TRI-SONIC WIND TUNNEL, USAF

ACADEMY, COLORADO SPRINGS, CO

ATS JOB # 419344

PURCHASE ORDER # PO24-00422

Prepared for

DOUGLAS ANDERSON

CALSPAN AERO SYSTEMS ENGINEERING, INC.

358 EAST FILLMORE AVE.

ST. PAUL, MN 55107

Prepared and ______________________________________________ Approved by Eric Shiner, Level III LT

Reviewed by_______________________________________________ Mason Hoff, Materials Testing

Applied Technical Services| +1(888) 287-5227 | www.atslab.com

ATS 044, 07/2021 Page 1 of 7 ATS # 413062

Contact Douglas Anderson Date March 29, 2024 Customer Calspan Aero Systems Engineering, Inc. Purchase Order PO24-00422 358 East Fillmore Ave.

St. Paul, MN 55107

Subject

Leak Inspection: Tri-sonic Wind Tunnel, USAF Academy, Colorado Springs, CO

Material

Carbon Steel

Summary

1. The pressure storage system and piping up to the isolation valve of the Tri-Sonic Wind Tunnel was inspected for leaks on March 26, 2024.

2. A total of fourteen (14) relevant leaks were observed using the bubble leak technique.

3. The north end flange on the #2 vessel had a very significant leak that appeared to exponentially increase as pressure increased.

Objective and Background

ATS Level III LT inspector, Eric Shiner, was contracted by the customer to perform a leak inspection on the Tri-sonic Wind Tunnel at the USAF Academy in Colorado Springs CO. The system consisted of piping leaving the high-pressure compressor, the dryer system, the discharge/charge piping, and the storage vessels.

There are 6 compressed air storage vessels located in a concrete containment space. The discharge line passes through the containment space into the compressor room. The compressor room contains three system air compressors, the dryer system, and the main discharge valve.

The storage vessels are approximately 42” diameter and 100’ long. The end of each storage vessel has a reducer welded to the main diameter and adapted to a bolted flange connection. These bolted flanges connect all storage vessels together in series with 14” pipes. Each storage vessel has a manway/inspection port. The #1 storage vessel also has a full diameter flange connection at the south end. A discharge pipe connects the outlet of tank #1 to the discharge valve.

A 2” charge pipe and associated valves tee into the discharge pipe within the compressor room.

Within the containment space a line tees off the discharge line. That supplemental air supply line also tees to supply two separate systems with compressed air. Each side of that tee has an isolation valve that was closed during the inspection. The piping down stream of those isolation valves was not inspected.

The system was known to have large leaks present, especially when the pressure exceeded approximately 450 psig. The inspection confirmed the system exhibited a large pressure drop at pressures above approximately 450 psig and transitioned into a slower linear drop in pressure as the system pressure dropped below 400 psig.

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ATS 044, 07/2021 Page 2 of 7 ATS # 413062

Test Procedure and Results Visual Inspection

A peripheral visual was performed. Access to overhead areas was by extension ladder and was limited on storage vessels 1 and 2 in particular on the north side. The overall condition of the system was observed as:

• There was no notable corrosion observed on the outside of the system.

• A thick brown substance was observed to seep from several of the flange gaskets.

• A water leak was observed from a corroded line on the high-pressure compressors system.

Bubble Leak Inspection

A bubble leak inspection was performed using ASME Sec. V, Art. 10, App I as a guide. The system was pressurized to at least 400 psig. Swagelok snoop bubble leak solution was used to visualize gross leakage. Many areas of the system required supplemental lighting and access did not permit observation within 24” of the area of interest. Bubble leak inspections were performed on all areas of interest including: flanged connections, NPT connections, manways, valves, and sensing lines. An initial test was performed with the test pressure at approximately 400 psig. A supplemental inspection was performed at 525 psig on the pressure relief valves (PRV’s) located on vessels 1 and 2.

Fourteen leeks were observed by means of the bubble leak inspection. Leaks that were readily accessible were photographed and are presented in Figures 1-8. Their location and significance are as follows:

Table 1: Leaks Located Number Location Description Significance

1 NPT Connection, Dryer Outlet on charge line before discharge line Low 2 4” Flange on Manual Valve, upstream of discharge line tee Low 3 4” Isolation valve, West, after tee on Supplemental Supply Line, Upper Platform Medium 4 Vessel 5 Flange to Vessel 4 on South End. U-Pipe Medium 5 Main Discharge 8” Tee Flange. Grey to White Pipe Medium 6 ¼” SS Swagelok connection. Sensing Line. Low 7 Vessel 6 Drain Valve NPT Fittings Low 8 Vessel 4 Drain Valve Stem High 9 Vessel 3 Drain Valve Stem High

10 Vessel 5 Drain Valve Stem and NPT Fittings Low 11 Vessel 2 Drain Valve NPT Fittings Low 12 Vessel 1 Drain Valve NPT Fittings Low 13 Vessel 2 Flange to Vessel 1 on North End. U-Pipe Very High 14 Dryer Vessel Union Fitting Medium

Discussion and Conclusions

The largest leak observed was Leak Number 13. Physical access to this flange was limited. It was initially observed as a medium sized leak with a 400 psig test pressure. When the test pressure was increased to 525 psig the leak became significantly larger and was easily identified audibly. The leak was inaudible at 400 psig. This leak is of particular concern. Typically, the leak rate increases proportionally with an increase in test pressure. This is a characteristic of a leak with a fixed cross-sectional area. That is, a crack, porosity or even a damaged gasket. Leak Number 13 appeared to increase exponentially with the subsequent increase in test pressure. It is recommended that this connection be further evaluated with a mechanical integrity evaluation.

No leaks were observed on the PRV’s at any pressure. The PRV’s vent directly into the atmosphere around the storage vessels. It is recommended that the outlet of the PRV’s are ducted to vent into an area of restricted access that can withstand a possible depressurization of the storage vessels should an event occur.

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Figure 1: Leak 1, NPT Connection

Figure 2: Leak 2, Flange Connection

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Figure 3: Leak 3, Flange Connection

Figure 4: Leak 4, Flange Connection

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Figure 5: Leak 5, Flange Connection

Figure 6: Leak 6, Swagelok Connection

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Figure 7: Leak 7, NPT Connections

Figure 8: Leak 8, Valve Stem

ATS 044, 07/2021 Page 7 of 7 ATS # 413062

Figure 9: Leak 9, Valve Stem

Figure 10: Corroded Water Line on Dryer system. Water Leak.

w w w . C a l s p a n . c o m - S e e c o v e r p a g e f o r c o n f i d e n t i a l i t y i n f o r m a t i o n

The information in this Technical Report is being submitted as a Diagnostic Report of the Air Tank Leak Inspection, CLIN-000601. Please sign and date confirming acceptance the milestone requirements have been met.

Approved by Authorized Signatory:

USAFA: Calspan ASE:

David Hyatt

Title: Title:

Project Manager

Date: Date:

05/21/2024

Signature: Signature: