REG NASA-LLIS-6149-2012 Lessons Learned - Don抰 Purge Dead-Headed Hydrogen Lines With Helium Downstream Of Source.pdf

1、Public Lessons Learned Entry: 6149 Lesson Info: Lesson Number: 6149 Lesson Date: 2010-11-1 Submitting Organization: MSFC Submitted by: Kristen Kinder Subject: Dont Purge Dead-Headed Hydrogen Lines With Helium Downstream Of Source Abstract: Residual hydrogen in the fill and drain line during the term

2、inal count down sequence could lead to a catastrophic failure. The best practice is to connect the purge line to the propellant line as closely as possible to the dead headed end of the line to ensure complete purging on the line. Description of Driving Event: In the Space Shuttle Program, three loc

3、ations exist where helium is injected into hydrogen lines several feet from the dead headed end of the line. These locations were the External Tank (ET) Ground Umbilical Carrier Plate (GUCP) location, the hydrogen high point bleed location, and the hydrogen fill and drain line location. Testing at M

4、arshall Space Flight Center (MSFC) has shown that not all the hydrogen vapor is removed from the fill and drain line during the terminal count sequence. Residual hydrogen in the fill and drain line during the terminal count down sequence could lead to a catastrophic failure and is a constraint to la

5、unch. Lesson(s) Learned: Residual hydrogen in certain locations in feed systems for liquid propulsion can create potentially catastrophic conditions at launch. Piping design and plumbing practices affect the integrity of purge systems to completely purge critical propellant lines. The allowance of a

6、 length of piping between the helium injection connection to the dead-headed end of a hydrogen line does not allow the helium gas to purge all hydrogen vapor from the lines prior to launch. Experience on the Space Shuttle Program suggests the best practice is to connect the purge line to the propell

7、ant line as closely as possible to the dead headed end of the line to ensure complete purging on the line. Recommendation(s): For future designs where purging of hydrogen systems are required, purge lines should be connected as physically closely as possible to the dead-headed end of the line to com

8、pletely sweep the unwanted vapor from the system. Design engineering should make this a rule of thumb and a best practice. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: N/A Mission Directorate(s): Exploration Systems Space Operations Provided by IHSNot for ResaleNo r

9、eproduction or networking permitted without license from IHS-,-,-Additional Key Phrase(s): 1.Spacecraft 1.Flight Operations 1.Vehicle concepts 1.Level II/III requirements definition 1.Launch Systems 1.Propulsion 1.Cryogenic Systems 1.Launch Vehicle Additional Info: Project: Shuttle / New Launch Vehicle Approval Info: Approval Date: 2012-03-09 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-