scope:

Purpose

This NASA Technical Specification establishes and implements the manufacturing and test requirements and applications guidelines for normally closed (NC) parent metal shear-section valves. The NASA Technical Specification is a guide for design engineers to develop more detailed requirements for specific pyrovalve applications. Adherence to these requirements will reliably prevent NC parent metal valve leakage or other failure-induced release of hazardous fluids (liquids or gases) from NASA payloads on Expendable Launch Vehicles (ELVs). This NASA Technical Specification does not address NC parent metal valve sizing, pressure drop, and other requirements.

This NASA Technical Specification may be called out in procurement specifications or other programmatic documentation to ensure valves meet structural requirements and are considered to be equivalent to other hazardous fluids pressure components such as tubing, tanks, and fittings, and that any mode of external or internal leakage of the contained hazardous fluid is extremely improbable (3 × 10-5) in accordance with NASA-STD-8719.24, NASA Expendable Launch Vehicle Payload Safety Requirements, and AFSPCMAN 91-710, Air Force Space Command Range Safety User Requirements Manual, or equivalent document for the applicable range.

Appendix A of this NASA Technical Specification presents a checklist of documents to be prepared for NASA and/or Range Safety. The checklist is provided for manufacturers of NC pyrovalves used in personnel hazardous applications. It is a tool for documenting the detailed compliance to the intent of the safety specification. The checklist also provides an aid for payload safety, Range Safety engineers, and other subject matter experts in reviewing the documentation. Letter designations after the checklist item number refer to the following requirement sources:

A. NESC-RP-10-00614, Pyrovalve Reliability Assessment for Expendable Launch Vehicle Payloads.

B. NSTS 1700.7B, Safety Policy and Requirements For Payloads Using the Space Transportation System.

C. NASA-STD 8719.24 and AFSPCMAN 91-710.

D. NASA-SPEC-5022, NASA Manufacturing and Test Requirements for Normally Closed Pyrovalves for Hazardous Flight Systems Applications.

For the purposes of this NASA Technical Specification, hazardous valve applications involve hazardous flight hardware pressure systems as defined by NASA-STD-8719.24 and AFSPCMAN 91-710, Volume 3, Chapter 12, Section 12.1.

Applicability

This NASA Technical Specification applies to NC pyrotechnically operated valves (pyrovalves), as well as to valves that use a different means of applying force, e.g., memory shape alloys to break out a section of a parent metal section allowing flow. The parent metal shear sections and interface tubes are defined by the term "parent metal" when they are machined from a single, certified bar of high-purity metal alloy with no welds.

This NASA Technical Specification is intended to be applied when these NC parent metal shear-section valves are used to prevent failure-induced release of hazardous fluids (liquid or gas) from spacecraft. It is primarily applicable to ELV payloads subject to NASA Payload Safety and United States Air Force (USAF) Range Safety Requirements, where a consistently high level of reliability and safety is required.

This NASA Technical Specification is approved for use by NASA Headquarters and NASA Centers and Facilities, and applicable technical requirements may be cited in contract, program, and other Agency documents. It may also apply to the Jet Propulsion Laboratory (a Federally Funded Research and Development Center [FFRDC]), other contractors, recipients of grants and cooperative agreements, and parties to other agreements only to the extent specified or referenced in applicable contracts, grants, or agreements.

Verifiable requirement statements are designated by the acronym NCPR (Normally Closed Pryovalves Requirement), numbered, and indicated by the word "shall"; this NASA Technical Specification contains 80 requirements. Explanatory or guidance text is indicated in italics beginning in section 4. To facilitate requirements selection and verification by NASA programs and projects, a Requirements Compliance Matrix is provided in Appendix D.