**NESC Review of the 8-Foot High Temperature Tunnel (HTT) Oxygen Storage
Pressure Vessel Inspection Requirements**

**March 16, 2006**

Table of Contents

**Volume I: Technical Consultation Report**

[**1.0** **Authorization and Notification**
3](#authorization-and-notification)

[**2.0** **Signature Page** 4](#signature-page)

[**3.0** **Team Members, Ex Officio Members, and Consultants**
5](#team-members-ex-officio-members-and-consultants)

[**4.0** **Executive Summary** 6](#executive-summary)

[5.0 Consultation Plan 8](#consultation-plan)

[**6.0** **Description of the Problem, Proposed Solutions, and Risk
Assessment**
9](#description-of-the-problem-proposed-solutions-and-risk-assessment)

> [6.1 Description of the Problem 9](#description-of-the-problem)
>
> [6.2 Proposed Solution 9](#proposed-solution)
>
> [6.3 Risk Assessment 10](#risk-assessment)

[**7.0** **Data Analysis** 11](#__RefHeading___Toc128562529)

[8.0 Findings, Recommendations, and Observations
11](#findings-recommendations-and-observations)

> [8.1 Findings 11](#findings)
>
> [8.2 Recommendations 13](#recommendations)
>
> [8.3 Observations 13](#observations)

[**9.0** **Lessons Learned** 14](#lessons-learned)

[10.0 Definition of Terms 14](#definition-of-terms)

[**11.0** **Minority Report (Dissenting Opinions)**
14](#minority-report-dissenting-opinions)

[**Addendum. Summary of Activities from September 8, 2005 to October 7,
2005**
15](#addendum.-summary-of-activities-from-september-8-2005-to-october-7-2005)

[**Volume II: Appendices**](#volume-ii-appendices)

[Appendix A. ITA/I Request Form (NESC-PR-003-FM-01)
20](#appendix-a.-itai-request-form-nesc-pr-003-fm-01)

[Appendix B. LOX Run Tank Sketches
23](#appendix-b.-lox-run-tank-sketches)

[Appendix C. LOX Run Tank Analyses 25](#__RefHeading___Toc128562541)

[Appendix D. NESC Risk Assessment 28](#__RefHeading___Toc128562542)

[Appendix E. List of Acronyms 29](#__RefHeading___Toc128562543)

**[List of Figures]{.underline}**

[4.0-1 Schematic Drawing of the 8-Foot HTT for Air Breathing Propulsion
Testing
[6](#figure-4.0-1.-schematic-drawing-of-the-8-foot-htt-for-air-breathing-propulsion-testing)](#figure-4.0-1.-schematic-drawing-of-the-8-foot-htt-for-air-breathing-propulsion-testing)

[6.3-1 5 x 5 Risk Acceptance Matrix
[10](#figure-6.3-1.-5-x-5-risk-acceptance-matrix)](#figure-6.3-1.-5-x-5-risk-acceptance-matrix)

**Volume I: Technical Consultation Report**

# **1.0 Authorization and Notification** {#authorization-and-notification .unnumbered}

The request to conduct a consultation on the 8-Foot HTT Liquid Oxygen
(LOX) Storage Pressure Vessels was submitted to the NASA Engineering and
Safety Center (NESC) on June 6, 2005.

The initial evaluation of the request was presented to the NESC Review
Board (NRB) and the consultation was approved on August 12, 2005. The
consultation review was held on September 7-8, 2005, and a report
documenting findings, recommendations, observations was written.

On October 5, 2005, the consultation team reconvened to review
additional information and results pertaining to the LOX Run Tank
fatigue and fracture analysis results. After reviewing the new
information, the consultation team developed revised recommendations.
The revised recommendations, documented in the Addendum to this report,
were approved by the NRB on October 6, 2005, and presented to the NASA
Langley Research Center (LaRC) Executive Council on October 7, 2005.

# **2.0 Signature Page** {#signature-page .unnumbered}

**Consultation Team Members**

Original signed on file

Michael Gilbert, NESC Lead Eric Hoffman, LaRC

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Ivatury Raju, NESC Robert Piascik, NESC

Kenneth Cameron, NESC Michael Kirsch, NESC

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Pappu Murthy, GRC George Hopson, NESC

Owen Greulich, HQ Wayne Frazier, HQ

# **3.0 Team Members, Ex Officio Members, and Consultants** {#team-members-ex-officio-members-and-consultants .unnumbered}

Michael Gilbert, NESC Chief Engineer, Team Lead

Eric Hoffman, LaRC Materials

Pappu Murthy, GRC Structures

Wayne Frazier, HQ Safety & Mission Assurance (S&MA)

Owen Greulich, HQ S&MA

George Hopson, NESC Propulsion Discipline Engineer and Technical Warrant
Holder

Ivatury Raju, NESC Structures Discipline Engineer and Technical Warrant
Holder

Robert Piascik, NESC Materials Discipline Engineer and Technical Warrant
Holder

Kenneth Cameron, NESC Deputy for S&MA

Michael Kirsch, NESC Principal Engineer

Terri Derby, Swales Administrative Support

# **4.0 Executive Summary** {#executive-summary .Style-Heading-1-+-Times-New-Roman-14-pt}

The 8-Foot HTT (refer to Figure 4.0-1) is used to conduct tests of
air-breathing hypersonic propulsion systems at Mach numbers 4, 5, and 7.
Methane, Air, and LOX are mixed and burned in a combustor to produce
test gas stream containing 21 percent by volume oxygen.

![](media/image1.png){width="6.497916666666667in"
height="4.010416666666667in"}

# Figure 4.0-1. Schematic Drawing of the 8-Foot HTT for Air Breathing Propulsion Testing {#figure-4.0-1.-schematic-drawing-of-the-8-foot-htt-for-air-breathing-propulsion-testing .unnumbered}

The NESC was requested by the NASA LaRC Executive Safety Council to
review the rationale for a proposed change to the recertification
requirements, specifically the internal inspection requirements, of the
8-Foot HTT LOX Run Tank and LOX Storage Tank. The Run Tank is an 8,000
gallon cryogenic tank used to provide LOX to the tunnel during
operations, and is pressured during the tunnel run to 2,250 pounds per
square inch gage (psig). The Storage Tank is a 25,000 gallon cryogenic
tank used to store LOX at slightly above atmospheric pressure as a
supply source for the Run Tank. Both tanks consist of an inner pressure
vessel surrounded by an external shell, with space between the shells
maintained under vacuum conditions.

The proposed changes to the inspection requirements include:

-   LOX Run Tank: from 10 years internal/external inspection to
    internal/external inspection after 1,000 pressure cycles.

-   LOX Storage Tank: from 10 years internal/external inspection to 10
    year visual external inspection only.

In reviewing the rationale for the proposed changes, the NESC Review
Team determined that the fracture analysis was deficient and that the
LOX Run Tank was not a "Leak-Before-Burst" (LBB) vessel. The NESC Review
Team recommended immediate stand-down of the 8-Foot HTT until either the
analysis deficiencies were corrected or the tank was inspected. The
recommendation was accepted and the 8-Foot HTT stood-down operations on
September 8, 2005. Efforts to correct the analysis deficiencies began
immediately thereafter.

The NESC Review Team also determined that there were no analyses
supporting changes to the LOX Storage Tank requirements and recommended
that such analyses be performed.

#   {#section .Style-Heading-1-Char-+-Times-New-Roman-Bold-14-pt .unnumbered}

# 5.0 Consultation Plan {#consultation-plan .Style-Heading-1-Char-+-Times-New-Roman-Bold-14-pt .unnumbered}

The NESC assembled a team of technical experts, NESC Discipline
Engineers, Discipline Technical Warrant Holders, and S&MA personnel, led
by the LaRC's NESC Chief Engineer.

The team met on September 7-8, 2005, to conduct a review and
accomplished the following:

-   Toured the facility.

-   Reviewed the materials, stress, fatigue, and fracture analyses
    results.

-   Interviewed the analysts that performed the analyses.

-   Reviewed the fabrication, service, and repair history of the tanks.

-   Interviewed Facility, S&MA, and Pressure Systems Managers.

-   Consulted with a Non-Destructive Evaluation expert.

# **6.0 Description of the Problem, Proposed Solutions, and Risk Assessment** {#description-of-the-problem-proposed-solutions-and-risk-assessment .Style-Heading-1-Char-+-Times-New-Roman-12-pt1}

# **6.1 Description of the Problem** {#description-of-the-problem .unnumbered}

Both the LOX Run Tank and LOX Storage Tank were due for internal
inspection and recertification in calendar year 2000. A review by the
Pressure Systems Subcommittee of the NASA LaRC Executive Safety Council
in late 2004 identified that the 8-Foot HTT LOX Storage and Run tanks
had not been recertified. Systemic issues related to the missed
recertification are being addressed by the NASA LaRC.

It was determined by the LaRC Pressure Systems Subcommittee that
continued operation of the facility beyond the recertification date was
warranted based on the following conditions:

**LOX Run Tank (Refer to the sketches in Appendix B)**

-   The tank was determined to be LBB by analysis.

-   Monitoring of the vacuum level between the inner pressure shell and
    the external shell would identify the presence of through-cracks in
    the pressure shell and allow the facility to stop operations before
    catastrophic failure would occur.

**Storage Tank**

-   The tank operates at constant temperature and pressure, whereas
    crack growth is a function of temperature and pressure cycles.

-   The tank has an operational safety factor of 8 on ultimate material
    strength.

-   The allowable working pressure of the tank is 100 psia. The tank
    nominally operates at 45 psia.

# 6.2 Proposed Solution {#proposed-solution .unnumbered}

The Pressure Systems Subcommittee recommended to the NASA LaRC Executive
Safety Council, based on contracted analyses, that the recertification
requirement for the 8-Foot HTT LOX tanks be changed as follows:

1.  Change LOX Storage Tank requirement to time-based visual external
    inspection techniques only.

2.  Change LOX Run Time Tank to use 1,000 pressure cycles instead of 10
    years in operation as basis for inspection.

# 6.3 Risk Assessment {#risk-assessment .unnumbered}

There were no immediate safety risks at the time the review request was
evaluated. The analyses at that time indicated that sufficient margins
existed to allow continued operations even though the tanks were at
approximately 150 percent of the required inspection interval. The risk
assessment is shown in Figure 6.3-1. Refer to Appendix D for a
description of the NESC Risk Assessment likelihood and consequences.

![](media/image2.png){width="5.55625in" height="2.5145833333333334in"}

> **S -- Safety NV -- National Visibility MS -- Mission Success**

# **Figure 6.3-1. 5 x 5 Risk Acceptance Matrix** {#figure-6.3-1.-5-x-5-risk-acceptance-matrix .unnumbered}

**Safety**

-   Probability: Very low probability of immediate failure, based on
    large analytical margins.

-   Consequence: Explosion and/or fire in proximity to inhabited
    buildings.

**National Visibility**

-   Probability: Very low probability of immediate failure, based on
    large analytical margins.

-   Consequences: Publicity from failure to address Office of Inspector
    General (OIG) audit report.

**Mission Success**

-   Probability: Very low probability of immediate failure, based on
    large analytical margins.

-   Impact: Assumed hardware loss between \$10M - \$100M; no immediate
    impact to flight projects, might impact Exploration initiative.

[]{#__RefHeading___Toc128562529 .anchor}**7.0 Data Analysis**

The NESC Review Team reviewed the stress, fatigue, and fracture analyses
of the LOX Run Tank. The individuals that performed these analyses were
interviewed by the NESC Review Team to gain full understanding and to
resolve any questions. The results of the data analyses are documented
in Section 8.1, Findings.

Refer to Appendix C for key analyses figures reviewed by the team.

#  {#section-1 .Style-Heading-1-Char-+-Times-New-Roman-Bold-14-pt .unnumbered}

# 8.0 Findings, Recommendations, and Observations  {#findings-recommendations-and-observations .Style-Heading-1-Char-+-Times-New-Roman-Bold-14-pt .unnumbered}

# **8.1 Findings** {#findings .unnumbered}

**F-1.** The damage tolerance analyses are insufficient to demonstrate
LBB for the LOX Run Tank for the following reasons:

-   Critical crack size is predicted to be less than the tank wall
    thickness.

-   Fracture mechanics analyses did not account for weld material
    properties or residual stresses.

-   The structural finite element models do not capture changes in
    thickness, geometry, loading, and material properties.

The tank, as constructed, contains welded-in forgings for the upper
access port and nozzles at both the top and bottom of the tank. The
properties of the weld material and the forgings differ from the
properties of the material used for the tank walls, even though both the
tank wall and forgings are 347 Stainless Steel. The crack growth
analysis assumed uniform material properties for all sections of the
tank and did not include analyses of the welds. In addition, material
properties for 304 Stainless Steel were used in the analyses as being
representative of 347 Stainless Steel because material properties for
347 Stainless Steel were not readily available.

Although a critical crack size less than the tank wall thickness was
predicted, it was assumed that the crack would also grow perpendicular
to the thickness until reaching an adjacent nozzle opening, which would
act as a crack stop. The crack would then be stable (not growing) and be
more than twice the wall thickness in length, thus satisfying LBB
criteria.

> This assumption did not account for the weldments or the changes in
> material properties along the assumed path of the crack and,
> therefore, is invalid. Also, the NASA standard for LBB is crack length
> 10 times the wall thickness, whereas the analysis was based on crack
> length 2 times the wall thickness. Refer to Observation O-3.

**F-2.** The fatigue analysis method used is inconsistent with the
original fabrication inspection performed on the LOX Run Tank for the
following reasons:

-   The fatigue analysis was performed according to the American Society
    of Mechanical Engineers (ASME) Section VIII, Division 2. Application
    of this analysis is based on construction of the tank to ASME
    Section VIII, Division 2, which requires stringent manufacturing
    inspections. These inspections set the initial crack size to be used
    in subsequent fatigue analyses based on the actual minimum
    detectable flaw size at the time the inspections were conducted.

-   The LOX Run Tank was actually constructed to ASME Section VIII,
    Division 1, with much less stringent quality assurance, inspection,
    and process controls.

-   The ASME Section VIII, Division 2, fatigue analysis was performed
    based on an *assumed* crack size rather than the minimum detectable
    size from the manufacturing inspection process.

**F-3.** The LOX Run Tank fatigue life calculations do not currently
account for pre-LaRC use. The tank was manufactured in 1959, but was
first put into service at the HTT in 1989. Since 1989, the LOX Run Tank
has been subject to about 600 pressure cycles. The tank operational
history prior to service at the HTT is not accounted for, nor has it
been demonstrated that the tank was restored to \"zero-time\" status in
1989.

**F-4.** All previous tank inspections have revealed cracks and/or
crack-like indications that were repaired or removed. The inspection
history, shown below, suggests that cracks continually initiate or that
the inspections may not have found all flaws.

-   1965: Cracks in 4-inch boss weld repaired

-   1986: Four linear indications found and ground out

-   1991: Six linear indications found and ground out

**F-5.** No analysis or prior inspection data was available to establish
a rationale to change the inspection requirements for the LOX Storage
Tank.

**F-6.** The physical location of the LOX Run and Storage Tanks
necessitated a waiver to requirements on proximity of LOX tanks to
occupied buildings. The waiver has as an acceptance rationale
maintaining the tanks in a certified state.

# **8.2 Recommendations** {#recommendations .unnumbered}

**R-1.** Remove the LOX Run Tank from run-time pressure service until
the LBB rationale is verified and the risk of continued operation is
accepted, or until an inspection is performed and any detected flaws are
properly dispositioned (F-1, F-2, F-3, F-4 and F-6).

**R-2.** Develop analyses to support a rationale for changing the LOX
Storage Tank inspection requirements (F-5).

-   The tank can continue in current operation while rationale is
    developed.

-   The Storage Tank must be determined to be LBB or fracture-critical
    to establish appropriate inspection intervals.

# **8.3 Observations** {#observations .unnumbered}

**O-1.** Inspection intervals should be determined by *both*
cyclic-loading and maximum time, based on industry practices and
standards. Lengthening of inspection intervals should include as
rationale prior inspection history and data.

**O-2.** During the review, the team inquired about the Oxygen Hazards
analysis for the HTT. Retrieval of records was not completed by the time
the review team meeting ended.

**O-3.** The "ten times the thickness" NASA standard is applicable to
thin-walled pressure vessels and pipes. For thick-walled pressure
vessels (such as LOX Run Tank of 4.73 inches in thickness), the NASA
standards are not clearly defined and the Nuclear Industry Code for LBB
conditions should be used. The Nuclear Industry Code LBB conditions
require the development of a through-the-thickness crack with sufficient
crack opening for the fluid to leak and be detected.

# **9.0 Lessons Learned** {#lessons-learned .unnumbered}

There were no lessons learned during this consultation.

# 10.0 Definition of Terms {#definition-of-terms .unnumbered}

::: Definition
Corrective Actions Changes to design processes, work instructions,
workmanship practices, training, inspections, tests, procedures,
specifications, drawings, tools, equipment, facilities, resources, or
material that result in preventing, minimizing, or limiting the
potential for recurrence of a problem.
:::

::: Definition
Finding A conclusion based on facts established during the
assessment/inspection by the investigating authority.
:::

::: Definition
Lessons Learned Knowledge or understanding gained by experience. The
experience may be positive, as in a successful test or mission, or
negative, as in a mishap or failure. A lesson must be significant in
that it has real or assumed impact on operations; valid in that it is
factually and technically correct; and applicable in that it identifies
a specific design, process, or decision that reduces or limits the
potential for failures and mishaps, or reinforces a positive result.
:::

::: Definition
Observation A factor, event, or circumstance identified during the
assessment/inspection that did not contribute to the problem, but if
left uncorrected has the potential to cause a mishap, injury, or
increase the severity should a mishap occur.
:::

::: Definition
Problem The subject of the technical assessment/inspection.
:::

::: Definition
Requirement An action developed by the assessment/inspection team to
correct the cause or a deficiency identified during the investigation.
The requirements will be used in the preparation of the corrective
action plan.
:::

Root Cause Along a chain of events leading to a mishap or close call,
the first causal action or failure to act that could have been
controlled systemically either by policy/practice/procedure or
individual adherence to policy/practice/procedure.

# **11.0 Minority Report (Dissenting Opinions)** {#minority-report-dissenting-opinions .unnumbered}

There were no dissenting opinions during this consultation.

# **Addendum. Summary of Activities from September 8, 2005 to October 7, 2005** {#addendum.-summary-of-activities-from-september-8-2005-to-october-7-2005 .unnumbered}

**Summary of Activities from September 8, 2005 to October 7, 2005**

On September 8, 2005, following a two-day review, the NESC 8-Foot High
Temperature Tunnel (HTT) Oxygen Storage Pressure Vessel Inspection
Requirements Technical Consultation team issued a safety recommendation
to the Director, Safety and Mission Assurance (S&MA), NASA Langley
Research Center (LaRC), to immediately stand-down operations of the HTT
until deficiencies in the fatigue and fracture analyses of the LOX Run
Tank could be corrected. This recommendation was based on the fact that
deficiencies in the analyses negated the then current
\"Leak-Before-Burst\" (LBB) result for the LOX Run Tank.
\"Leak-Before-Burst\" was an essential part of the rationale for
continuing to operate the tank 5 years beyond its specified inspection
and certification date. The Director, S&MA, LaRC, accepted this
recommendation and ordered the immediate stand-down of HTT test
operations. The findings, recommendations, and observations developed by
the NESC Technical Consultation Team from the review on September 7-8,
2005, are fully documented in the main body of this report.

Subsequent to the HTT stand-down, an analysis team was formed by the
NASA LaRC to update the fatigue and fracture analyses. The NESC provided
technical assistance to, and consulted with, the Center analysis team in
critical areas of materials properties and fatigue and fracture analysis
methods. As a result of improved models, materials data, and revised
analytical techniques, the Center analysis team determined:

a.  The LOX Run Tank is fracture-critical and ***not*** a LBB design.

b.  Conservative damage tolerance analyses showed large analytical
    margins (factor of 10+) for a limited number (\<100) of additional
    LOX Run Tank pressure cycles.

On October 5, 2005, the NESC Technical Consultation Team reconvened via
telecon to review the results \[ref. 1\] of the NASA LaRC HTT LOX Run
Tank re-analysis efforts. The NESC Technical Consultation Team concurred
with the results (items a. and b. above) and developed a set of revised
recommendations and additional observations (listed below). This set of
revised recommendations and additional observations were reviewed and
approved by the NESC Review Board on October 6, 2005 and presented (in
briefing format) to the NASA LaRC Executive Safety Council on October 7,
2005. The NASA LaRC Executive Safety Council accepted the NESC
recommendations as written.

**Revised and Additional Recommendations**

R-1 (Revised). Based on conservative analysis assumptions and large
analytical margins in the revised fatigue and fracture analyses, the
NESC Technical Consultation Team's position on the LOX Run Tank is:

-   Completion of the Air Force Research Lab (AFRL) Ground Demonstration
    Engine test program is acceptable, based on an assumed test program
    of less than 100 additional pressure cycles of the LOX Run Tank.

-   The LOX Run Tank should be inspected and recertified immediately
    following the completion of the AFRL tests before any additional
    test programs are conducted.

R-2 (Revised). Written and approved rationale for external inspection on
the vacuum shell only of the LOX Storage Tank is required.

R-3 (New). Stennis Space Center and other NASA facilities should be
consulted and surveyed for high-pressure LOX tank inspection methods,
techniques, and capabilities.

**Additional Observations**

O-4. Atmospheric pressure load modeling in the revised analysis needs to
be updated; the overall effect is expected to be very minor (order of
14/2250 psi).

-   The atmospheric pressure acts on the external vacuum jacket shell
    and transfers to the LOX Run Tank pressure shell as point loads
    through standoffs, not as a uniform load on the pressure shell.

O-5. Changes to the baseline inspection requirements may require changes
to the NASA HQ-approved site waiver for the tank locations.

-   \"Waiver-of-the-waiver\" approval requirements to conduct the AFRL
    tests, if any, needs to be determined.

O-6. Vacuum monitoring of the LOX Run Tank as a safety precaution may
lead to a false sense of security.

**Reference**

1\. Forth, S.C.; Harvin, S.F.; Gregory, P.B.; Mason, B.H.; Thompson,
J.E.; and Hoffman, E.K. "Damage Tolerance Analysis of a Pressurized
Liquid Oxygen Tank", NASA/TM-2006-214274, 2006.

# Volume II: Appendices  {#volume-ii-appendices .unnumbered}

A ITA/I Request Form (NESC-PR-003-FM-01)

B LOX Run Tank Sketches

C LOX Run Tank Analyses

D NESC Risk Assessment

E List of Acronyms

# **Appendix A. ITA/I Request Form (NESC-PR-003-FM-01)** {#appendix-a.-itai-request-form-nesc-pr-003-fm-01 .unnumbered}

![](media/image3.jpeg){width="5.297916666666667in"
height="6.679861111111111in"}

![](media/image4.jpeg){width="5.647222222222222in"
height="7.295833333333333in"}

![](media/image5.jpeg){width="5.731944444444444in" height="7.40625in"}

# **Appendix B. LOX Run Tank Sketches** {#appendix-b.-lox-run-tank-sketches .unnumbered}

![](media/image6.jpeg){width="6.084722222222222in"
height="4.590972222222222in"}

![](media/image7.jpeg){width="7.072916666666667in"
height="4.606944444444444in"}

[]{#__RefHeading___Toc128562541 .anchor}**Appendix C. LOX Run Tank
Analyses**

![](media/image8.wmf){width="7.4118055555555555in"
height="5.060416666666667in"}

![](media/image9.wmf){width="5.25in" height="5.10625in"}

**LOX Run Tank Model**

![](media/image10.jpeg){width="3.2604166666666665in"
height="2.2083333333333335in"}

![](media/image11.jpeg){width="3.2604166666666665in"
height="2.2083333333333335in"}

**LOX Run Tank Top Stresses**

[]{#__RefHeading___Toc128562542 .anchor}**Appendix D. NESC Risk
Assessment**

![](media/image12.png){width="0.5700787401574803in"
height="0.5425196850393701in"}

[]{#__RefHeading___Toc128562543 .anchor}**Appendix E. List of Acronyms**

AFRL Air Force Research Laboratory

ASME American Society of Mechanical Engineers

GRC Glenn Research Center

HQ Headquarters

HTT High Temperature Tunnel

LaRC Langley Research Center

LBB Leak-Before-Burst

LOX Liquid Oxygen

NASA National Aeronautics and Space Administration

NESC NASA Engineering and Safety Center

NRB NESC Review Board

OIG Office of Inspector General

psig pounds per square inch gage

S&MA Safety & Mission Assurance

**Approval and Document Revision History**

  ----------- ------------------------------------------------- -- --------- --
  Approved:   Original signed on file                              3/24/06   

              NESC Director                                        Date      
  ----------- ------------------------------------------------- -- --------- --

  --------- ---------------------------------- ------------------- -----------
  Version   Description of Revision            Office of Primary   Effective
                                               Responsibility      Date

  1.0       Initial Release                    NESC Chief          
                                               Engineer's Office   
  --------- ---------------------------------- ------------------- -----------