Astm stp 1596 2016

Te frst paper, submitted by NASA White Sands Test Facility, highlights improvements to autogenous ignition testing by using induction heating.. Te third paper, submitted by NASA White Sa

Editors: Samuel Edgar Davis, Theodore A Steinberg

Flammability and Sensitivity

ISBN: 978-0-8031-7637-9

ISSN: 0899-6652

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When citing papers from this publication, the appropriate citation includes the paper authors, “paper title,” STP title, STP number, book editor(s), ASTM International, West Conshohocken, PA, year, page range, Paper doi, listed in the footnote of the paper A citation is provided on page one of each paper Printed in Eagan, MN

July, 2016

THIS COMPILATION OF Selected Technical Papers, STP1596, Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: 14th Volume, contains peer-reviewed papers that were presented at a symposium held April 13–15, 2016,

in San Antonio, Texas, USA Te symposium was sponsored by ASTM International Committee G04 on Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres

Symposium Chairpersons and STP Editors:

Samuel Edgar DavisNASA, George C Marshall Space Flight Center

Huntsville, AL, USATeodore A SteinbergQueensland University of TechnologyBrisbane, Queensland, Australia

Foreword

Test Methods

A Method for Autogenous Ignition Temperature Determination of Metal Through

Joel Stoltzfus and Timothy D Gallus

Statistical Considerations for Adiabatic Compression Testing 37 Barry E Newton and Theodore A Steinberg

Improved ASTM G72 Test Method for Ensuring Adequate Fuel-to-Oxidizer Ratios 49 Alfredo Juarez and Susana A Harper

Autogenous Ignition Test Approach for Hyperbaric Oxygen (HBO2) and Other

Low-Pressure Oxygen Applications 62 Gwenael J Chifoleau, Richard Barry, Barry E Newton, and Nicholas Linley

Cleaning and Contamination Control

Results of the Test Program for Replacement of AK-225G Solvent for Cleaning

NASA Propulsion Oxygen Systems 76 Nikki M Lowrey and Mark A Mitchell

NASA Independent Assessment of Ambient Pressure Liquid Oxygen (LOX) Impact Testing of Halogenated Solvents 109

H R Ross and S J Gentz

Contents

Other Oxygen-Flammable Materials for Use in Oxygen Systems 137 Susana A Harper, Alfredo Juarez, Stephen F Peralta, Joel Stoltzfus,

Christina Piña Arpin, and Harold D Beeson

Analysis of Risks to Oxygen Systems from Particulate and Fiber

Contaminants and Derivation of Cleanliness Requirements 152 Nikki M Lowrey

Factors Afecting NVR Contaminant Fire Risk 185 Bradley S Forsyth, Gwenael J A Chifoleau, Barry E Newton

Failure and Incident Investigations

Fatal Accident from an Oxygen Fire in an Indian Steel Plant in 2012: Unresolved

Stainless Steel Plug Valve Incident in High Pressure Oxygen: Delrin®

Seat and Silicone-Based Lubricant 286 Jared D Hooser, Bradley S Forsyth, Gwenael J A Chifoleau, and Barry E Newton

Research on Materials and Operations

Properties of ToughMet® 3 Copper-Nickel-Tin Alloy for Oxygen Enriched

Anand V Samant, Michael J Gedeon, Robert E Kusner, Chad A Finkbeiner,

Fritz C Grensing, and W Raymond Cribb

Detailed Investigation of the Sequence of Mechanisms Participating in Metals

Ignition in Oxygen Using Laser Heating and In Situ, Real-Time Diagnostics 308 Maryse Muller, Hazem El-Rabii, Rémy Fabbro, Frédéric Coste, Jean-Christophe Rostaing, Martina Ridlova, Alain Colson, and Hervé Barthélémy

Comparison of Combustion Products of Bulk Aluminum Rods Burning in High

Pressure Oxygen in Normal and Reduced Gravity 326 Owen Plagens and Theodore A Steinberg

Simulation of Cylindrical Rod Combustion in High-Pressure Oxygen by

S I Shabunya, V V Martynenko, V I Ignatenko, and J.-C Rostaing

Alfredo Juarez, Susana A Harper, and Horacio Perez

Promoted Ignition-Combustion Tests of Brazed Aluminum Heat Exchanger

Samples in Cold Supercritical Oxygen 374 Thomas A McNamara, Joseph F Million, Ravi Pahade, and James White

Oxygen Endurance Testing of Oxygen Cylinder Valves 393

T Kasch, C Binder, N Treisch, M Szypkowski, and A Woitzek

Evaluation of a Near-Adiabatic Compression Process to Increase Fire Safety Within Oxygen Systems, Focusing on Non-Metals 405 Maria Ryan, Theodore A Steinberg, and Barry E Newton

Oxygen Partial Pressure and Oxygen Concentration Flammability:

Can They Be Correlated? 413 Susana A Harper, Alfredo Juarez, Horacio Perez III, David B Hirsch, and

Harold D Beeson

STP1596 is the fourteenth set of Special Technical Papers (STP) originating from the ASTM Committee G04 focusing on the Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres Te thirteen previous STP volumes originating from the ASTM G04 committee are: 812, 910, 986, 1040, 1111, 1197, 1267, 1319, 1395,

1454, 1479, 1522, and 1561 Copies of these STP volumes are available from ASTM International

Te ASTM Committee G04 on Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres continues to grow in its international appeal Te fourteenth symposium was attended by a number of professionals representing several countries Tese included the United States, Australia, Germany, Canada, France, India, the United Kingdom, and Belarus A number of professionals from other nations also attended the symposium and shared important information in person even though they were unable to submit a formal paper for publication

As with the past STPs, the fourteenth volume expands upon the objectives that have been carried forward since the frst ASTM Committee G04 STP was published

in 1983 Tese objectives include:

?? Review the current research on polymers and metals ignition and combustion;

?? Overview principles of oxygen systems design and issues related to materials compatibility with oxygen;

?? Contribute to the knowledge on the most current risk management concepts, practices, approaches, and procedures used by individuals and organization involved in the design, use, retroftting, maintenance, and cleaning of oxygen systems;

?? Review of accident/incident case studies related to oxygen systems and oxygen handling procedures;

?? Provide research on new compounds or techniques to clean oxygen systems in order to make these systems safer for users;

?? Provide the most current data related to the fammability and sensitivity of materials in oxygen-enriched atmospheres to designers, users, manufacturers and maintainers of oxygen components and systems and to support Committee G04’s Technical and Professional Training Course on Fire Hazards in Oxygen Systems;

Overview

Committee G04 on Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres; and

?? Provide a readily accessible reference addressing oxygen compatibility

Te fourteenth volume consists of a group of peer-reviewed papers that were presented at the Committee G04’s Fourteenth International Symposium held in San Antonio, Texas, USA, in April 2016 Te volume consists of twenty-four papers on topics related to ignition and combustion of metals and non-metals, ignition and combustion of metals, oxygen compatibility of components and systems, analysis

of ignition and combustion, failure analysis and safety, cleaning and cleanliness verifcation, new test methods, failure investigations, and includes aerospace, military, scuba diving, and industrial oxygen applications

Te papers presented in the fourteenth volume are arranged into fve groups that ofer a variety of valuable information Te frst paper is a keynote address that was provided by Walter D Downing of the Southwest Research Institute (SwRI) located

in San Antonio, Texas Tis address outlines how standards developed by ASTM play

an important role in the research work conducted at SwRI

Te second group of papers consists of four papers focusing on test methods, including proposals for new test methods and modifcations of existing test methods

to improve the data derived from them Te frst paper, submitted by NASA White Sands Test Facility, highlights improvements to autogenous ignition testing by using induction heating Te second paper, submitted by WHA International, focuses on the importance of statistical issues with the data generated by adiabatic compression testing Te third paper, submitted by NASA White Sands Test Facility, proposes improvements to ASTM G72 by improving the fuel to oxidizer ratios Te fourth paper, submitted by WHA International, deals with testing in low pressure oxygen applications, such as those used in hyperbaric systems

Te third group of papers consists of fve papers focusing on cleaning methods, cleaning solvents, cleanliness verifcation, and contamination control Te frst paper, submitted by NASA Marshall Space Flight Center, provides a thorough overview

of the test program conducted by NASA to determine an adequate replacement for the current standard NASA oxygen system and hardware cleaning solvent, AK-225G, and the replacement solvent selected Te second paper, submitted

by NASA Stennis Space Center, highlights the independent assessment program that NASA implemented for the AK-225G replacement selection efort Te third paper, submitted by NASA White Sands Test Facility, provides recommendations for improving the compatibility test methods that will ultimately lead to permitting the limited use within oxygen systems of materials that are fammable in oxygen

Te fourth paper, submitted by NASA Marshall Space Flight Center, evaluates the risks that fbers and particulates pose in oxygen systems and the rationale behind the

centers on the issues with non-volatile residues and their efect on the risks of fres

in oxygen systems

Te fourth group of papers consists of fve papers focusing on investigations

of incidents and failures involving oxygen systems in the government and private industries Te frst paper, submitted by the Indian Institute of Technology, pro-vides an accurate and thorough evaluation of the fatal oxygen fre that occurred in

2012 at a steel plant in India Te second paper, submitted by NASA White Sands Test Facility, highlights a hydrocarbon fre that occurred inside one of their test chambers Te third paper, submitted by AEI Corporation of Colorado and WHA International, provides a detailed analysis of a fre that took place in a liquid oxy-gen bulk delivery tank Te fourth paper, submitted by WHA International, details the failure analysis of a gate valve fre within a liquid oxygen system Te ffh paper, submitted by WHA International, provides information about an incident involving a stainless steel plug valve that used silicone lubricant and an acetal resin valve seat

Te ffh group consists of nine papers that discuss research being conducted on materials and operations for oxygen systems Te frst paper, submitted by Materion Corporation, highlights the qualities of ToughMet 3, a new material developed

by Materion that may be well suited for oxygen system applications Te second paper, submitted by the ParisTech National Research Center in France, details the mechanisms and diagnostics for metals ignition in oxygen by utilizing a laser ignition mechanism Te third paper, submitted by Queensland University of Technology

in Australia, provides a comparison of the combustion products of bulk aluminum burning in oxygen at both the normal gravity of Earth and a reduced gravity Te fourth paper, submitted by the National Academy of Sciences of Belarus in the Republic of Belarus, proposes steady-state jet modeling techniques for the combustion

of cylindrical aluminum rods in high-pressure oxygen Te ffh paper, submitted

by NASA White Sands Test Facility, highlights the methods to use containment boxes to mitigate fres in oxygen-enriched conditions Te sixth paper, submitted by Praxair Corporation, proposes a new promoted ignition-combustion test method for aluminum comprising heat exchangers Te seventh paper, submitted by the BAM Federal Institute for Materials Research and Testing in Germany, proposes a new international standard for oxygen endurance test for oxygen cylinder valve materials

Te eighth paper, submitted by Queensland University of Technology in Australia, proposes a method to increase fre safety in oxygen systems by evaluating nonmetals

in a near adiabatic compression process Te ninth paper, submitted by NASA White Sands Test Facility, details the facility’s research on correlating the fammability of materials conducted at diferent oxygen concentrations and partial pressures

Te fourteenth volume of Flammability and Sensitivity of Materials in Oxygen- Enriched Atmospheres provides a diverse source of new information to air

oxygen and other industrial gases service, manufacturers of materials intended for oxygen service, and users of oxygen and oxygen-enriched atmospheres, including aerospace, medical, industrial gases, chemical processing, steel and metals refning,

as well as military, commercial, or recreational diving

Samuel Edgar DavisMaterials and Processes LaboratoryNational Aeronautics and Space AdministrationGeorge C Marshall Space Flight Center

Huntsville, AL, USA

Teodore A SteinbergSchool of Engineering SystemsFaculty of Built Environment and EngineeringQueensland University of TechnologyBrisbane, Queensland, Australia

Walter D Downing1

Space Exploration and Fire

Technology at Southwest

Research Institute—Learning

from the Past and Preparing

for the Future

Citation

Downing, W D., “Space Exploration and Fire Technology at Southwest Research Institute—

L earning from the Past and Preparing for the Future,” Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: 14th Volume, ASTM STP1596, S E Davis and

T A Steinberg, Eds., ASTM International, West Conshohocken, PA, 2016, pp 1–14, doi:10.1520/ STP159620160027 2

ABSTRACT

Tragedies involving fires, explosions, or heat-induced structural failures areamong the leading causes of property loss, injuries, and deaths in space travel.The risk is acute in oxygen-enriched environments or where other oxidizers arepresent Working with the National Air and Space Administration’s (NASA) spaceprogram since the agency’s inception in 1958, staff have collaborated in thetesting, research, and development resulting from the Apollo 1, Challenger, andColumbia accidents Expertise has developed from conducting extensiveprograms dedicated to fire research and testing Specialized staff perform fireresistance testing, material flammability testing, and research in fire technology

on a wide range of projects supporting the engineering development ofmaterials performance standards, materials certification, and productdevelopment With the retirement of the shuttle fleet, NASA has shifted its focustoward the development of technologies and capabilities to carry humansbeyond low-Earth-orbit (LEO), with an emphasis on lightweight materials toreduce costs This requirement drives greater use of composites and synthetic

Manuscript received February 8, 2016; accepted for publication April 5, 2016.

1 Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238-5166

2 ASTM 14th International Symposium on Flammability and Sensitivity of Materials in Oxygen-Enriched

Atmospheres on April 13-15, 2016 in San Antonio, TX.

Copyright V 2016 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

STP 1596, 2016 / available online at www astm org / doi: 10 1520/STP159620160027

materials whose fire resistance, flammability, smoke, and toxicity characteristics

in spaceflight environments and microgravity conditions are not as well-known

as more conventional materials Consequently, there is a need to conduct fireresearch under microgravity conditions and atmospheric environments moreclosely representing spacecraft Opinions expressed in this paper are the views

of Southwest Research Institute

Keywords

fire technology, fire research and testing, NASA space program, spaceflight research, spaceflight industry, manned spaceflight, space hardware, oxygen- enriched environments, microgravity environments, Southwest Research

Institute

Introduction

Humans have a remarkable capacity for remembering where they were and whatthey were doing at the exact moment they saw or heard about a particularly historicevent More often than not these events are, unfortunately, tragic For example,although we remember the occurrence of all-too-frequent terrorist events thesedays, most do not make the same impact on personal recollection as the attack onthe World Trade Center on September 11, 2001 Indeed, this tragedy made such alasting impact that one need only mention “9/11” in a conversation to convey a pre-cise meaning of time, place, and circumstance, and to invoke individual thoughts,impressions, and emotions

An inevitable and important reaction to such a tragic event is to conduct aninvestigation to determine exactly what happened, why it happened, and to explorewhat can be done to prevent it from happening again The role of the investigator is

to systematically search out, examine, study, and inquire into the particulars ofsuch an event to learn the facts about something that was previously hidden,unknown, unforeseen, or unique to the situation in an attempt to identify the cause

or causes Ideally, if the causes can be identified, they can be eliminated, prevented,avoided, or mitigated in the future In a way, an investigator is like an explorer or aresearcher Each investigates the unknown but often for very different reasons andwith different end results in mind

As you look back in time, are you old enough to remember where you wereand what you were doing on Saturday, February 1, 2003, on Tuesday, January 28,

1986, or on Friday, January 27, 1967? If so, can you recall personal memories aboutthe space shuttle Columbia breaking apart during reentry, the space shuttle Chal-lenger exploding after launch, or the Apollo 1 command module flash fire during atest on the launch pad, which occurred on these respective dates? These tragedieswere shockingly unexpected and led to investigations that changed forever theNational Aeronautics and Space Administration (NASA) manned space explorationprogram

On the day after the space shuttle Columbia accident, NASA representativesinitiated experimental tests to ascertain the cause Based upon ground-based obser-vations during the launch, NASA suspected that insulation foam separated fromthe main fuel tank and struck somewhere along the Columbia’ s left wing, damagingthe thermal protection system NASA provided thermal tiles and reinforcedcarbon-carbon composite leading-edge samples mounted to a structural frame tosimulate the shuttle wing Using a compressed gas gun with a specially designedbarrel to fire foam blocks at the test article, a series of experiments were conducted

at a variety of impact locations and impact angles These initial tests produced onlycracks or surface damage to the test samples After further analysis from the Colum-bia’s flight data recorder narrowed the probable impact site to one single panel, afinal round of testing was conducted on July 7, 2003, that created a large hole in thepanel, demonstrating the probable cause of the accident (Fig 1) Later, additionaltests and analytical modeling were performed in order to establish a safe operatingenvelope for the space shuttle return-to-flight program

Following the Challenger accident, NASA initiated a complete review of allspace shuttle program failure modes and effects analyses and associated criticalitems This review identified the space shuttle auxiliary power units (APUs) as criti-cal items because they provided power for the orbiter’s three independent hydraulicsystems, and two of the three had to function for the orbiter to function The APUswere operated on launch and reentry but remained off while in orbit Therefore, thehydrazine-powered turbines in the APUs went from dormant ambient conditions

to 81,000 rpm with gas temperatures of 1,700?F generating 135 hp within 9.5 s ofstart-up These extreme operating conditions led to turbine blade cracking Turbineblade inspections and failure analyses identified the cause of cracking (Fig 2)

FIG 1 Hole in space shuttle wing mock-up following impact testing.

Statistical analyses provided a working hypothesis on the potential for future ing as well as providing reliability estimates for the life expectancy of each APU.Certainly everyone attending the ASTMInternational Committee G04’s Sym-posium on Compatibility and Sensitivity of Materials in Oxygen-Enriched Environ-ments is well aware of the Apollo 1 tragedy because it is perhaps the most notableexample of a fatal fire in an oxygen-enriched environment and, in fact, led industryand government to establish this committee in 1975 One outcome of the subse-quent investigation was a command module fire extinguisher of special design foroperation in weightlessness The device, which weighed less than eight pounds, uti-lized compressed Freon gas to dispense fire-smothering foam These extinguisherswere deployed on each of the subsequent manned flights in the Apollo programand Skylab (Fig 3) One of these extinguishers is now exhibited at the National Airand Space Museum The program received NASA’s Silver Snoopy award in recogni-tion for outstanding achievements related to human flight safety.

crack-Tragedies involving fires, explosions, or heat-induced structural failures areamong the leading causes of property loss, injuries, and deaths in all modes oftransportation, not just in space travel The risk is particularly acute in oxygen-enriched environments or where other oxidizers are present As a result, there is agreat need for continued fire and explosion research and testing with a focus ondeveloping innovative technologies to mitigate the risk associated with these haz-ards (Fig 4) Indeed, the controlled use of fire for practical purposes is an earlymilestone in the history of technology; the need for improvements in this areabegan almost as soon as man started to first use fire several thousand years ago

FIG 2 Eddy current probe and automated system for inspecting space shuttle turbine blades.

NASA Collaboration History

Many research organizations have worked collaboratively with NASA over theyears on any number of projects In 1945, a mechanical engineer at the CornellAeronautical Laboratory by the name of Martin Goland published the results ofhis research on the aerodynamic behavior of a uniform cantilever wing, developing

an accurate numerical model for predicting wing flutter that became known as the

FIG 4 Fire technology video ( www.swri.org/Video/html/01-ft.htm ).

FIG 3 Apollo command module fire extinguisher developed.

“Goland Wing” (Fig 5) This model and its variations remain the basis for namic response analysis to the present.

aerody-From 1952 to 1958, Goland was chairman of the National Advisory Committeefor Aeronautics (NACA) Subcommittee on Aircraft Vibration and Flutter, and hebecame the first chairman of NASA’s Research Advisory Committee on StructuralDynamics

In 1956, an aeronautical engineer named Dr H Norman Abramson, a member

of the National Academy of Engineering in the late 1950s and early 1960s, led retical and experimental studies of liquid dynamics in rocket propellant tanks tohelp solve fuel sloshing problems In 1966, Dr Abramson and his team publishedNASA SP-106, The Dynamic Behavior of Liquids in Moving Containers, known inthe aerospace industry as the “handbook of sloshing.”

theo-In 1977, a space physicist named Dr James Burch started to build a spaceresearch program Dr Burch has been the principal investigator on two NASA mis-sions, including the first medium-class explorer mission (Imager for Magneto-pause-to-Aurora Global Exploration, or IMAGE) in 1996, and the MagnetosphericMultiscale Mission (MMS) that launched from Cape Canaveral in March 2015

On July 14, 2015, nine years after launch, the whole world watched as theNASA New Horizons spacecraft sped past the Pluto system and on to the KuiperBelt (Fig 6) Alan Stern is the principal investigator of the mission, leading the sci-ence team He also led a team that designed and built two of the instruments on theNew Horizons mission and is responsible for science payload operations, datareduction, and archiving It will take months for the data from this first reconnais-sance of the dwarf planet Pluto and its icy moons to be transmitted to Earth, butthe results are already being used to rewrite science books

In 1998, NASA’s Ames Research Center, working collaboratively with others,was inducted into the Space Technology Hall of Fame for the development of an

FIG 5 Video of “Goland Wing” model ( www.youtube.com/watch?v¼L8dOEJ6GERo ).

open-cell polyurethane-silicon plastic foam cushion for transportation seatsintended to provide better impact protection and comfort during long flights Thematerial is known as temper foam (because it softens when warmed and stiffenswhen it cools) or memory foam (because it will conform to the shape of animpressed object and return to its original shape even after up to 90 %compres-sion) (Fig 7) The technology was subsequently licensed to and commercialized byTempur-PedicV R

for a variety of spin-off applications such as orthopedic supportcushions, sports safety equipment, mattresses, and pillows

In 1984, NASA’s Lewis Research Center (now NASA’s Glenn Research Center)requested development of probabilistic structural analysis methods to evaluate thereliability of space propulsion system components representative of the space shuttlemain engine During this ten-year research program, a computer program calledNESSUSV R

(which stands for Numerical Evaluation of Stochastic Structures UnderStress) was created, which combines advanced reliability modeling with finite elementand boundary condition tools NESSUS has been commercialized (Fig 8) and applied

to a diverse range of structural problems in the aerospace, biomechanics, energy,automotive, and defense industries NESSUS received an R&D 100 Award in 2005

In 1986, NASA’s Johnson Space Center requested development of software toperform fracture control analysis of space hardware The resulting product, known

as NASGRO (Fig 9), was later adopted by the NASA/Federal Aviation tion (FAA)/Department of Defense (DoD) Aging Aircraft Program as the preferred

Administra-FIG 6 Photo taken by New Horizons spacecraft on closest approach to Pluto.

package for further development to address fatigue crack growth analysis of aircraftstructures Additional funding from this group of government clients led to newversions of NASGRO with significant improvements in capabilities, making it a morevaluable structural integrity analysis tool for a much larger number of aerospace/aircraft companies This interest led to a Space Act Agreement under which anindustry consortium provides guidance and support for future NASGRO developmentand user services In 2003, NASGRO version 4.0 received the NASA Software of theYear Award and an R&D 100 Award NASGRO version 8.0 was released on July 24,

2015, and the NASGRO Consortium is in its fifth three-year cycle (2013–2016)

FIG 8 NESSUS software is used to evaluate the reliability of space propulsion system components.

FIG 7 Temper foam conforms to the shape of an impressed object.

The use offluids in microgravity environments poses unique and complex lems Examples of research activities in this technical area are noted in the followingsections.

prob-FIG 9 NASGRO software developed by Southwest Research Institute (SwRI) to

perform structural analysis of space hardware.

FIG 10 Compression mass gage used to measure quantities of cryogenic liquids in

microgravity.

Some space flights require large fuel tanks that need accurate fuel mass toring This can be accoumplished using a compression mass gage to measure thequantity of cryogenic liquid propellant in a spacecraft tank in microgravity (Fig 10).Another example is a spinning slosh test rig that simulates spinning conditionsexperienced by satellites during deployment and operation (Fig 11) This apparatus

moni-is used to investigate the stability of satellites with liquid motion excitation inmicrogravity environments

The International Space Station (ISS) has a carbon dioxide compressor for itswater production system To meet the challenging design requirements and con-straints, the compressor is a water-cooled, electric motor-driven, oil-less, two-stage,reciprocating machine (Fig 12)

Fire Technology for Future Space Exploration

What is the future of the manned space program, and what is in store for fire nology? As with many other areas of scientific inquiry, the answer is probably thatthe future is mixed and uncertain But it is possible to point out areas of growthand those that are stagnant or declining

tech-With the retirement of the shuttle fleet and cancellation of the Constellationprogram, NASA has shifted its focus toward the development of technologies andcapabilities to carry humans beyond low-Earth-orbit (LEO) Current plans are tosend astronauts to an asteroid by 2025 and to Mars in the 2030s; however, thesegoals were developed in 2010, and it remains to be seen what priorities the newpresident and Congress will establish after the 2016 election To achieve these goals,NASA’s Marshall Space Flight Center is developing a newrocket for deep space ex-ploration known as the Space Launch System (SLS) Having completed the critical

FIG 11 Spinning slosh test rig for studying liquid motion in microgravity.

design review in 2015, plans are for the first launch from Kennedy Space Center in

2018 SLS will build upon technologies from the shuttle and other space explorationlaunch systems Boeing is developing the core stage to store liquid hydrogen andoxygen for shuttle-type Aerojet Rocketdyne RS-25 engines Orbital ATK is develop-ing shuttle-derived solid rocket boosters to assist in launch Initial capability forboosting beyond LEO will be a United Launch Alliance liquid hydrogen and oxygeninterim cryogenic propulsion stage based upon the Delta IV family of rockets.Future configurations will have larger exploration upper stages with more liquidhydrogen and oxygen capacity

SLS will carry astronauts on deep space missions in a new spacecraft named

“Orion.” The design is more similar in concept to the Apollo crew capsule than tothe shuttle Having been started under the Constellation program, Orion is fartheralong in development than SLS The first test flight of Orion launched atop a Delta

IV from Cape Canaveral in December 2014 (Fig 13)

NASA will rely more on spacecraft developed by private industry for futureLEO missions, such as Commercial Resupply Services (CRS) contracts for the Inter-national Space Station, which has been extended to the year 2024 or beyond Thefirst CRS contracts were awarded to SpaceX and Orbital ATK in 2008 SpaceXbegan flying resupply missions in 2012, using Dragon cargo spacecraft launched

FIG 12 Carbon dioxide compressor for the International Space Station’s water

production system.

atop Falcon 9 rockets Orbital ATK began deliveries in 2013, using Cygnus craft launched atop Antares rockets These are unmanned robotic spacecraft similar

space-to those that have been used by other countries for ISS resupply missions for manyyears In January 2016, NASA awarded a second round of CRS contracts worth up

to $14 billion through the year 2024 to incumbents SpaceX and Orbital ATK alongwith Sierra Nevada The latter will use their Dream Chaser lifting-body spaceplaneslaunched atop Atlas V rockets for the missions In addition, in 2014, NASAawarded contracts to SpaceX and Boeing to develop human-rated spacecraft capa-ble of delivering astronauts to and from the ISS beginning in 2017

The private spaceflight industry is very active and is investing heavily in thefuture Business opportunities for private spaceflight include satellite servicing andresupply; deployment of communications, television, and radio satellites; manufac-turing in microgravity environments; on-orbit propellant depots; asteroid mining;commercial spaceflight; and space tourism There are many new ventures looking

to leverage new opportunities as high-tech companies and wealthy individuals haveentered the field

With the rise in the private spaceflight industry, competition is growing as well.Advances by relatively new companies, funded by venture capitalists, have put pres-sures on older and more established companies This competitive environmentdemands increased efficiencies in operation to reduce costs Because the cost per

FIG 13 Liftoff of NASA’s Orion spacecraft mounted atop United Launch Alliance Delta

IV heavy rocket (NASA/Bill Ingalls).

pound launched is high, there is an emphasis on lightweight materials for structuralcomponents, insulation, and spacecraft interiors This drives greater use of compo-sites and synthetic materials whose fire resistance, flammability, smoke, and toxicitycharacteristics in spaceflight environments and microgravity conditions are not aswell-known as more conventional materials.

Consequently, there is a need to conduct fire research under microgravityconditions and in atmospheric environments more closely representing spacecraft.Flames behave differently in microgravity environments than they do on Earth.Convectively fed fires do not exist under microgravity Heat rise is not the con-trolling behavior, but instead, fires exist as spheres with flames spreading in alldirections and being attracted to areas of higher oxygen concentration In addi-tion, fire-extinguishing methods are different, and the toxicity and corrosiveness

of the fire suppression media is a greater issue in spacecraft applications Previousstudies of fires under microgravity conditions have been limited to small-scale,short-duration tests performed in drop towers or in aircraft performing parabolic

FIG 14 New Horizons launch, liftoff rocket (courtesy of NASA).

arcs These experiments do not necessarily scale-up to realistic fire conditions inspacecraft One possible solution would be to build upon previous experimentsperformed in Germany and Japan utilizing aerostat-dropped test chambers.Advances in aerostat designs,flight controls,and in data telemetry might enablenew methods for employing larger test chambers for full-scale fire tests in experi-ments dropped from greater heights maintaining constant 1 g acceleration for lon-ger durations than before These are the sorts of challenging,multidisciplinarytechnical problems that must be conceptually explored to advance scientificknowledge and understanding.

Although there is much about the future of spaceflight that remains unknown,one aspect is certain: research and development projects for this vital and dynamicarea of scientific discovery will continue (Fig 14)

Joel Stoltzfus1and Timothy D Gallus2

A Method for Autogenous

Ignition Temperature

Determination of Metal Through

Induction Heating

Citation

Stoltzfus, J and Gallus, T D., “A Method for Autogenous Ignition Temperature Determination

of Metal Through Induction Heating,” Flammability and Sensitivity of Materials in Enriched Atmospheres: 14th Volume, ASTM STP1596, S E Davis and T A Steinberg, Eds., ASTM International, West Conshohocken, PA, 2016, pp 15–36, doi:10.1520/STP159620150076 3

Oxygen-ABSTRACT

To assist in the failure analysis of a rocket thruster, the ignition temperature inoxygen-enriched atmospheres of titanium and titanium alloys was investigated.The open literature indicated melting temperatures in the range of 1,660?C(3,020?F) and ignition temperatures ranging from 250 to 1,627?C (482 to2,961?F) for titanium powder and solid titanium, respectively Vertically mountedtest samples of varying diameters were ignited by induction heating in 66 %oxygen (O2)/balance nitrogen (N2) and in 99.5 þ % O2at 1,000 psia Ignition wasmeasured by either a platinum/platinum-rhodium (Type S) thermocouplecomprised of 0.05-mm (0.002 in.) and 0.076-mm (0.003 in.) diameter wireswelded to the samples or by a two-color pyrometer The ignition temperatures in

66 % O2and 99.5 þ % O2, with various surface treatments and configurations,ranged from 1,623 to 1,659?C (2,953 to 3,018?F) The lack of an effect on ignitiontemperature as a function of oxygen concentration suggests that the ignitionprocess is controlled by subsurface rather than surface-related processes Oneunexpected result was that although sample nitriding did not change the

Manuscript received August 3, 2015; accepted for publication December 8, 2015.

1 Material and Components Laboratories Office, NASA Johnson Space Center White Sands Test Facility, 12600

NASA Rd., Las Cruces, NM 88012

2 NASA Johnson Space Center White Sands Test Facility, 12600 NASA Rd., Las Cruces, NM 88012

3 ASTM 14th International Symposium on Flammability and Sensitivity of Materials in Oxygen-Enriched

Atmospheres on April 13–15, 2016 in San Antonio, TX.

Copyright V 2016 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

STP 1596, 2016 / available online at www astm org / doi: 10 1520/STP159620150076

autogenous ignition temperature (AIT), it did change the rate of combustionafter ignition.

Keywords

titanium autogenous ignition temperature, induction heating, pyrometer, oxygen concentration effects

Background

Thruster failures occurred during a ground test at White Sands Test Facility (WSTF)

A critical thruster part was fabricated from commercially pure (CP) titanium (Grade1) The WSTF Materials and Components Laboratories Office was asked to deter-mine the ignition temperature of CP titanium in oxygen-enriched atmospheres.LITERATURE SEARCH RESULTS

Because the ignition of most metals occurs at or near the melting point, literaturesearches were undertaken for published titanium melting point and ignition tem-perature data The melting points of titanium and titanium alloys found in the liter-ature are shown inTable 1

The ignition temperatures of titanium and titanium alloys found in the literatureare shown in Table 2 In all cases where the test details were discussed, the experi-menters used the “brightness temperature” to define the ignition point of titaniumand its alloys The test sample would glow increasingly bright as it was warmed up tothe ignition point, but at ignition, a dramatic increase in the intensity of the luminos-ity was observed and coined the “brightness temperature.” After consideration of all

of the test methods used to obtain the data inTable 2, WSTF researchers concluded

TABLE 1 Melting temperatures of titanium and titanium alloys.

Alloy Designation UNS No.

that the methods that most closely paralleled the incident and test geometriesreported an ignition temperature of titanium in the low 1,600?C (2,912?F) range,somewhat below—but approaching—the melting point of titanium.

Experimental

TEST SAMPLES

Two materials were tested: (1) smooth rods made from CP titanium (Grade 2) (UNSR50400) and (2) 6–32 threaded rods made from Ti-6Al-4V (UNS R56400).The testsamples were configured as 10-cm (4.0 in.) long rods having a nominal diameter of3.2 mm (1/8 in.) The compositions of the test materials are provided inTable 3.The 3.2-mm (1/8 in.) diameter smooth rods were tested with several surfaceconditions and two different oxygen concentrations.Condition A was CP titanium(Grade 2) with a naturally occurring oxide.Condition B was the same as Condition

A samples that were heated for several seconds in a 1,000 psia nitrogen ment.This heating process produced a visible nitride layer that had a matte yellowappearance.Condition C started with Condition A and was sanded with 600 gritsandpaper and buffed with crocus cloth to a bright metal appearance to remove thenaturally occurring oxide.Condition D started as Condition A and was then etchedusing a proprietary process.To compare the effect of a smooth surface with a sur-face with sharp edges, rods made from Ti-6Al-4V and threaded with a 6–32 threadwere designated Condition E.An example of each of these sample types is shown in

environ-Fig 1.The Condition D sample is shown in a shortened configuration.The actualsmooth, etched samples tested were approximately 10 cm (4 in.) long

Test Apparatus

The tests were conducted in the WSTF high pressure promoted combustion test cility.It was comprised of a 12.4 litre (757 in.3) test chamber (Fig 2), a 41.4 MPa(6,000 psi) oxygen supply system, a 20.7 MPa (3000 psi) mixed gas supply system,pressure recording equipment, and a high-speed digital camera.This is the standardconfiguration that is designed to heat samples uniformly before promoted ignition.Because this was an autogenous ignition temperature (AIT) test and instrumenta-tion could be trained only on small areas of interest, an hourglass-shaped coil was

fa-TABLE 3 Composition of test sample materials in weight percent.

Max 0.3

Max 0.015

Max 0.03

Max 0.25 99.2

Ti-6Al-4V

(UNSR56400)

Max 0.10

Max 0.40

Max 0.015

Max 0.05

Max 0.2 Balance 5.5–6.75 3.5–4.5

installed as shown inFig 3andFig 4 The digital camera was used to record the testsample ignition process The video images were recorded through a 5.1 cm (2 in.)diameter sapphire sight glass located adjacent to the bottom end of the test sample.

In both test configurations, test samples were suspended verticallyand ignited

at the center bythe application of induction energyfocused byan hourglass-shapedinduction coil A small vertical spread of the center coil wraps was designed to allowthermocouple wire access and pyrometer views

FIG 1 Typical test samples: (A) smooth, natural oxide; (B) smooth, natural oxide,

nitrided; (C) smooth, sanded; (D) smooth, etched (shown shortened, actual

samples were approximately 10 cm [4in.] long); and (E) threaded, etched.

chamber was sealed The chamber was purged three times to 3.4 MPa (500 psig)using the test gas and vented to ambient pressure After purging,the test chamberwas pressurized to the test pressure using the appropriate test gas,the data acquisitionequipment was turned on,and the test was initiated by turning on the inductionpower supply The test results were observed and recorded The test chamber wasvented,purged,and opened,allowing the sample’s posttest condition to be observed.

Instrumentation and Determination of Ignition

All tests were recorded using a high-speed video camera A remotely operated ger was used to initiate storage of the video recording data for several secondsbefore and after the trigger was activated Temperature measurements were made

trig-FIG 2 Schematic of WSTF’s 12.4 litre (757 in 3 ) promoted combustion test chamber configured for using the induction power supply to heat the test sample.

using two techniques: thermocouples and two-color pyrometers Test gas pressurewas measured using a pressure transducer Finally, a time stamp was recorded witheach measurement.

For the initial test, the thermocouple reading and the video camera trigger tracewere recorded digitally at 2,000 hertz The video camera image was recorded at 2,000hertz and keyed to the digital thermocouple readings via the video camera triggertrace During later tests, a two-color pyrometer was added Next, the thermocouplewas omitted, and only pyrometer and video camera trigger trace were recorded andkeyed to the video recording In final testing, the pyrometer was changed to a secondtwo-color pyrometer with specifications similar to the initial two-color pyrometer

Video Camera

The high-speed video camera was a Phantom Model V7.1 It was set to record at2,000 frames per second with an exposure time of 40 ls A 0.9 optical density neu-tral density filter (with transmittance of 12.5 %) was added to a Nikon 105-mmmicro lens, which was focused at approximately 12 in The F-stop was set at 32.The camera was mounted external to the test chamber and set to view the ignitionevent through the sapphire window of the chamber

FIG 3 Promoted combustion test chamber as modified to determine autoignition

temperature of titanium rods before breach.

FIG 4 Promoted combustion test chamber as modified to determine autoignition temperature of titanium rods after breach.

FIG 5 Typical smooth sample with welded thermocouple wires.

A Type S (platinum/platinum-rhodium) bare wire thermocouple was used The0.05 mm (0.002 in.) and 0.076 mm (0.003in.) diameter leads of the thermocouplewere welded to the test sample

Fig 5shows a typical smooth test sample with the welded thermocouple wires.The effective area of measurement of this configuration is the test sample materialbetween the thermocouple wire weld points The response time is infinitely fastbecause the test sample itself is included as the junction between the individualthermocouple leads Configured in this manner, the thermocouple reading willreflect the average temperature of the test sample between the attachment points

of the lead wires [15]

Pyrometers

Two two-color pyrometers (made by Process Sensors Corp.) were used Both meters view the light emitted from the test samples in the 0.9 and 1.6 lm wave-lengths The ratio of the values of those wavelengths determined the temperature ofthe viewed object Using a two-color pyrometer, the temperature of gray bodieswith the same emissivity at both wavelengths is measured without knowledge of theemissivity value This feature automatically adjusted for dust, smoke, or a dirtyviewing window between the pyrometer and the test sample

pyro-Initially, a Metis Model MQ11 pyrometer with a laser aiming light was used.The spot size was about 1.27 mm (0.050 in.) The spot was focused on the test sam-ple at a distance of approximately 25 cm (10 in.) as shown inFig 6 Later, a second

FIG 6 Temperature sensing spot size and location of first pyrometer.

Metis MQ11 pyrometer with a through-lens sighting feature was used The spotsize was about 1.65 mm (0.065 in.) The spot was focused on the test sample at adistance of approximately 25 cm (10 in.) as shown inFig 7.

The pyrometer and the high-speed camera were arranged outside the testchamber and aimed to view the test sample through the sapphire window Thehigh-speed camera was positioned to view directly through the window and thepyrometer was arranged at a 90? angle from the camera to view the test sample via

a first surface mirror The arrangement of the camera, pyrometer, mirror, and testchamber is shown inFig 8

Pressure Measurement

The test gas pressure in the chamber was measured using a Teledyne Tabor Model710A pressure indicator with a range of 1 to 103.4 MPa (0 to 15,000 psi) ThisBourdon-tube type device measured pressure with an accuracy of 60.025 % fullscale

Determination of Ignition Temperature

The ignition temperature was determined by comparing the video images with thethermocouple and pyrometer readings The ignition event was determined by theappearance of a luminosity increase on the surface of the test sample that was sig-nificantly greater than the background luminosity that occurred due to the samplebeing heated by the induction power This corresponded to the “brightness temper-ature” mentioned by various researchers in the open literature [8,11,13,14]

FIG 7 Temperature sensing spot size and location of second pyrometer.

The time at which the brightness arrived at the location of the thermocouple or thepyrometer sensing spot was correlated with the temperature data to determine theignition temperature.

In some cases, the initial brightness indicating ignition occurred at the specificlocation of the thermocouple or pyrometer sensing spot These particular testsyielded the most easily interpreted data set These test results were recorded as aspecific ignition temperature The ignition temperature yielded by these particulartests was used as a guide to assist in the interpretation of the remaining tests Insome cases, the ignition event occurred at a location that was obscured from theview of the video camera and away from the location of the thermocouple or thepyrometer sensing spot These tests yielded a data set that was difficult to interpretand thus appear as a range of possible ignition temperatures

FIG 8 Arrangement of camera, pyrometer, mirror, and test chamber.

was quenched at the copper sample holder In the nine tests conducted in 99.5 %

O2, the samples did not quench at the sample holder, but burned to completion

1,000 psia

Four tests on smooth test samples with naturally occurring oxide were conductedusing 3.2 mm (1/8 in.) diameter rods and only a welded Type S thermocouple tomeasure ignition temperature In each of these tests, the location where the ignitionoccurred was obscured at the time of ignition As a result, it was not possible to cor-relate the video data with the thermocouple data, and only a range for the ignitiontemperature could be determined

As an example of this type of test result, digitally recorded test data is shown in

Fig 9 This figure shows the thermocouple data in black By observing the time gapbetween the video camera trigger event and the occurrence of the initial brightnessassociated with ignition on the video recording and subtracting that time from thetrigger event time, the actual ignition point of the rod was determined However, in

FIG 9 Condition A Test Tested in 66 % O 2 /balance N 2 at 1,000 psia

(thermocouple ¼ black).

this case, because the point of ignition was obscured from the view of the camera,the specific time of ignition could not be determined; therefore, the specific ignitiontemperature could not be determined The ignition event occurred sometimebetween 750 and 600 ms before the video recording was triggered Therefore, theignition temperature was determined to be in the range between 1,575 and 1,740?C(2,867 to 3,164?F).

Titanium can exist in two forms, a close-packed hexagonal crystalline form(alpha form) and a body-center cubic form (beta form) Titanium transforms fromits alpha to beta form at a temperature called the beta transus [16] The beta transus

is indicated by the constant temperature segment of the thermocouple data inFig 9,occurring at approximately 900?C(1652?F) This feature was detected in all tests inwhich a thermocouple was used

The x-axis indicates the time prior to the activation of the trigger event that tiated the video recording The y-axis indicates the temperature sensed in the view-ing spot of the pyrometer By observation of the video recording, it was determinedthat the ignition event occurred 556 ms prior to the activation of the trigger Thistime corresponds to an ignition temperature of 1,644?C(2,991?F) as determined bythe digital data

ini-This method of determining the ignition temperature was typical of all the testresults reported herein

1,000 psia of Smooth Samples with a Nitrided

Surface

During the initial checkout tests, an unsanded, smooth CP titanium sample washeated in 1,000 psia nitrogen to determine the proper operational characteristics ofthe induction power supply That sample was heated with the induction power sup-ply at 45 % of maximum power for 4.4 s Later, the sample was tested in 66 %

O2/balance N2at 1,000 psia The result, measured using a welded Type S couple, indicated an ignition temperature of 1,930?C(3,506?F), far greater than themelting temperature of titanium It was determined that additional tests withnitrided samples should be performed

thermo-The result, as measured by the second two-color pyrometer, indicated an tion temperature ranging from 1,581 to 1,740?C(2,878 to 3,164?F) in one test Inthat test, the specific ignition temperature could not be determined because the igni-tion event occurred near the bottom end of the sample, and that portion of the sam-ple had dripped away before the burning event reached the location of the pyrometerspot When the brightness indicating ignition reached the pyrometer sensing spot,the burning behavior was such that it could not be correlated to the temperature mea-surement accurately enough to determine a specific ignition temperature In the case

igni-of a second test, the ignition occurred above the pyrometer sensing spot, and the