A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Proactive mitigation of PCTFE-related ignition hazards in oxygen systems: II. Testing of inventoried 'at-risk' PCTFE parts and hazard analyses of corresponding ground service equipment at the Kennedy Space Center
Revelations of excessive property variation in PCTFE (polychlorotrifluoroethylene) semifinished and finished parts led to concerns that leaks or part failure could occur in service, possibly leading to catastrophic component or system failure by flow friction and/or kindling chain mechanisms. Such concerns led to the issuances of an internal KSC (Kennedy Space Centre) problem advisory and a Government-Industry Data Exchange Program materials advisory on PCTFE. The advisories led to an engineering analysis review of PCTFE-containing ground support equipment used in 'at-risk' high pressure oxygen and air systems at KSC. Representative PCTFE replacement parts used in 'at risk' systems were removed from inventory and tested. Tests included determination of (1) dimensional stability by thermomechanical analysis and metrology, (2) percent crystallinity by specific gravity, and (3) the effect of annealing on engineering tolerances. While dimensional instability was determined not to be a major issue in existing inventories, establishing traceability back to the semifinished article (starting rod or sheet stock) was often not possible. Percent crystallinity varied widely depending on part origin and thickness. Annealing was found to lead to out of-tolerance parts occasionally. The pneumatic impact ignition threshold of PCTFE in enriched air was also determined at pressures up to 41.4 MPa. Results show that ignition does not occur at ambient oxygen concentrations. Last hazard analyses were performed on 'at risk' systems. Two problematic designs were discovered but based on operational histories, a recommendation was made to redesign or repair and replace on a noninterference basis.
Proactive mitigation of PCTFE-related ignition hazards in oxygen systems: II. Testing of inventoried 'at-risk' PCTFE parts and hazard analyses of corresponding ground service equipment at the Kennedy Space Center
Revelations of excessive property variation in PCTFE (polychlorotrifluoroethylene) semifinished and finished parts led to concerns that leaks or part failure could occur in service, possibly leading to catastrophic component or system failure by flow friction and/or kindling chain mechanisms. Such concerns led to the issuances of an internal KSC (Kennedy Space Centre) problem advisory and a Government-Industry Data Exchange Program materials advisory on PCTFE. The advisories led to an engineering analysis review of PCTFE-containing ground support equipment used in 'at-risk' high pressure oxygen and air systems at KSC. Representative PCTFE replacement parts used in 'at risk' systems were removed from inventory and tested. Tests included determination of (1) dimensional stability by thermomechanical analysis and metrology, (2) percent crystallinity by specific gravity, and (3) the effect of annealing on engineering tolerances. While dimensional instability was determined not to be a major issue in existing inventories, establishing traceability back to the semifinished article (starting rod or sheet stock) was often not possible. Percent crystallinity varied widely depending on part origin and thickness. Annealing was found to lead to out of-tolerance parts occasionally. The pneumatic impact ignition threshold of PCTFE in enriched air was also determined at pressures up to 41.4 MPa. Results show that ignition does not occur at ambient oxygen concentrations. Last hazard analyses were performed on 'at risk' systems. Two problematic designs were discovered but based on operational histories, a recommendation was made to redesign or repair and replace on a noninterference basis.
Proactive mitigation of PCTFE-related ignition hazards in oxygen systems: II. Testing of inventoried 'at-risk' PCTFE parts and hazard analyses of corresponding ground service equipment at the Kennedy Space Center
Waller, Jess M. (author) / Murray, Karl A. (author) / Staveland, Allen R. (author) / Faughnan, Patrick D. (author) / Tyre, Dean (author) / Smith, Sarah R. (author) / Gallus, Timothy (author) / Newton, Barry E. (author) / Hshieh, Fu-Yu (author) / Beeson, Harold D. (author)
2006
12 Seiten, 5 Bilder, 4 Tabellen, 22 Quellen
Conference paper
English
Polychlortrifluorethylen , Kunststoffprodukt , Kunststoffhalbzeug , Qualitätskontrolle , Brandgefahr , technische Beschreibung , Maßunbeständigkeit , Glühen , Qualitätsüberwachung , Raumfahrt , Raumfahrttechnik , Bewertungsmethode , Standardprüfmethode , Einflussfaktor , Betriebsdaten (technische Parameter) , Risikoanalyse , Sauerstoff , Druckgas , Hochdruck (Mechanik) , reibungsbehaftete Strömung , Entflammbarkeit , Entzündbarkeit , Entzündung (Entflammung)
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