1、Lessons Learned Entry: 1380Lesson Info:a71 Lesson Number: 1380a71 Lesson Date: 2003-01-01a71 Submitting Organization: WSTFa71 Submitted by: Michael J. Hallock, IISubject: Druck Pressure Transducer, Model No. PDCR 130/W/C, Failure Abstract: On March 25, 2003, during life cycle testing of the Improved
2、 Pilot Operating Valve (IPOV) in Nitrogen Tetroxide (NTO), a pressure transducer catastrophically failed in an explosion and released NTO into the test cell. Reference Government-Industry Data Exchange Program (GIDEP): DOC=QB-S-03-01 CEDATE=30-MAY-2003 DD=SA,Title: PRESSURE TRANSDUCER, SILICONE OIL
3、FILLED. Description of Driving Event: The pressure transducer was located at the inlet of the IPOV and experienced dynamic pressure fluctuations as the IPOV opened and closed for each 80 microsecond flow duration. The investigation included review of test data, analysis of the failed hardware, inves
4、tigation into the design and construction of the transducer, review of historical data on it, chemical analysis of residue in the area of the failure, and comparison of this residue with the products of silicone oil exposed to NTO in a “beaker test.” The item was purchased in 1994 and was used in a
5、helium system and then in an oxidizer system. The pressure transducer failed at a welded connection between the port housing and the sensor housing. The pressure required to fail this welded connection was calculated to be 12,700 pounds per square inch (psi). The pressure transducer is connected by
6、a ? X 0.035 wall 300 series stainless steel tubing to ? X 0.035 inch wall 300 series stainless steel tubing. The thrust from the failed pressure transducer resulted in also failing the ? inch tubing close to the ? inch tubing. The ? inch tubing showed no sign of yielding due to pressure, indicating
7、that the system pressure did not exceed the calculated 3,400 psi required to yield this tubing. Failure appears to be the result of extremely rapid over pressurization inside the pressure transducer. The pressure transducer has a silicon sensor and a 316 stainless steel isolation diaphragm between t
8、he sensor and the test media. The 0.78 ml volume between the isolation diaphragm and the sensor is filled with DC550 poly (methylphenylsiloxane) silicone oil. Poly (methylphenylsiloxane) reacts in a non-violent fashion Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
9、nse from IHS-,-,-with NTO to form nitro-substituted phenols, which tend to be shock and friction sensitive. Poly (dimethylsiloxane) silicone oil does not appear to be effected by NTO. Evidence of 2,4-dinitrophenol and 2,4,6-trinitrophenol (picric acid) was found on the failed pressure transducer par
10、ts, support bracket, and diluted in the supply of NTO downstream of the IPOV.References: Test Cell 831 Druck Pressure Transducer Failure on March 25, 2003Lesson(s) Learned: Materials used in system components must be clearly identified, especially where such materials will come into contact with ope
11、rating fluids and chemicals. Consideration must be given to providing the means to verify that materials as used in systems, subsystems, and components are compatible in all phases of build-up and as used in the end application. Such verification may require sampling after assembly or dissembling an
12、d analyzing samples by lot.Recommendation(s): N/AEvidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: JSC 8080, Manned Spacecraft Criteria and Standards; Quality StandardsMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAd
13、ditional Key Phrase(s): a71 Configuration Managementa71 Flight Equipmenta71 Flight Operationsa71 Ground Equipmenta71 Ground OperationsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Hardwarea71 Hazardous/Toxic Waste/Materialsa71 NASA Standardsa71
14、 Parts Materials & Processesa71 Policy & Planninga71 Procurement Small Business & Industrial Relationsa71 Program and Project Managementa71 Research & Developmenta71 Risk Management/Assessmenta71 Safety & Mission Assurancea71 Spacecrafta71 Standarda71 Test & Verificationa71 Test Articlea71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2004-02-09a71 Approval Name: Jan Jungewaeltera71 Approval Organization: WSTFa71 Approval Phone Number: 505-524-5161Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
