PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

P66-673Valve,safety Relief

Circor Aerospace, Inc. Dba Circor Aerospace Inc · NSN 4820-00-331-3537 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-331-3537 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-331-3537. Primary manufacturer part number: P66-673.
Features
  • Valve,safety Relief — FSC 4820
  • Thread Direction: RIGHT-HAND FIRST ENDRIGHT-HAND FIRST END
  • Thread Series Designator: NPT SECOND ENDNPT FIRST END
  • Connection Type: THREADED EXTERNAL PIPE SECOND ENDTHREADED EXTERNAL PIPE SECOND END
  • Media for Which Designed: FUEL/OIL, HYDROCARBON SECOND RESPONSEAIR FIRST RESPONSE
  • Operating Pressure: 200.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
  • Maximum Operating Temp: 250.0 FAHRENHEIT SINGLE RESPONSE250.0 FAHRENHEIT SINGLE RESPONSE DEGF
  • Connection Type: THREADED INTERNAL PIPE FIRST ENDTHREADED INTERNAL PIPE FIRST END
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Steel Corrosion Resisting Flow Control Device construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-00-331-3537, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Circor Aerospace, Inc. Dba Circor Aerospace Inc. Government technical data includes 27 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 3 commercial cross-references from 3 manufacturers, enabling identification through both NSN and commercial part number lookups. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-331-3537
Primary Part NumberP66-673
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerCircor Aerospace, Inc. Dba Circor Aerospace Inc
StatusACTIVE
Thread DirectionRIGHT-HAND FIRST ENDRIGHT-HAND FIRST END
Thread Series DesignatorNPT SECOND ENDNPT FIRST END
Connection TypeTHREADED EXTERNAL PIPE SECOND ENDTHREADED EXTERNAL PIPE SECOND END
Media for Which DesignedFUEL/OIL, HYDROCARBON SECOND RESPONSEAIR FIRST RESPONSE
Operating Pressure200.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
Maximum Operating Temp250.0 FAHRENHEIT SINGLE RESPONSE250.0 FAHRENHEIT SINGLE RESPONSE DEGF
Connection TypeTHREADED INTERNAL PIPE FIRST ENDTHREADED INTERNAL PIPE FIRST END
Connection StylePLAIN,OPTIONAL END(PIPE) FIRST ENDPLAIN,OPTIONAL END(PIPE) FIRST END
Nominal Thread Size0.250 INCHES SECOND END0.250 INCHES SECOND END IN
Media for Which DesignedNITROGEN, GASEOUS THIRD RESPONSEFUEL/OIL, HYDROCARBON SECOND RESPONSE
MaterialSTEEL CORROSION RESISTING FLOW CONTROL DEVICE
Opening Pressure Setting20.0 POUNDS PER SQUARE INCH LBS
Media for Which DesignedNITROGEN, GASEOUS THIRD RESPONSE
Connection StylePLAIN (PIPE) SECOND ENDPLAIN (PIPE) SECOND END
Thread DirectionRIGHT-HAND SECOND ENDRIGHT-HAND SECOND END
Thread Quantity Per Inch18 SECOND END18 SECOND END
Nominal Pipe Size Accommodated0.250 INCHES FIRST END0.250 INCHES FIRST END IN
MaterialSTEEL CORROSION RESISTING FLOW CONTROL DEVICECOPPER ALLOY SEAT
Disk Loading MethodSPRINGSPRING
Thread Series DesignatorNPT SECOND END
Nominal Thread Size0.250 INCHES FIRST END0.250 INCHES FIRST END IN
Nominal Pipe Size Accommodated0.250 INCHES SECOND END0.250 INCHES SECOND END IN
Style DesignatorSTRAIGHT THRU
Flow Control DevicePOPPETPOPPET
Valve Operation MethodAUTOMATICAUTOMATIC
Thread Quantity Per Inch18 FIRST END18 FIRST END
MaterialCOPPER ALLOY SEATCOPPER ALLOY BODY
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
5305-00-012-1832121832 INTERCHANGEABLE
Screw,machine
Us Army Aviation and Missile Command
6240-00-014-5416 INTERCHANGEABLE
Lamp,incandescent
6240-00-057-19661634 INTERCHANGEABLE
Lamp,incandescent
Lamp Industry for Use with Industry Designations and Abbreviations for Lamps
5905-00-106-7007C600012885 INTERCHANGEABLE
Resistor Set,matched
Kearfott Corporation Div Guidance and Navigation Division
5315-00-193-64658A7188 INTERCHANGEABLE
Pin,straight,headless
Napco International Llc Dba Napco International Inc
5950-00-289-98841783709-34 INTERCHANGEABLE
Transformer,audio Frequency
Honeywell International Inc. Dba Honeywell International
5330-00-362-2115F400A336 INTERCHANGEABLE
Gasket
Sealcraft Corporation
5306-00-449-39881634 INTERCHANGEABLE
Bolt,machine
Quincy Compressor Division of Coltec Industries Inc Dba Quincy Compressor Div Quincy Compressor
4730-00-517-8062 INTERCHANGEABLE
Fitting,lubrication
8135-01-030-1634030-1634 INTERCHANGEABLE
Seal,strapping
Caprice Electronics, Inc
Cross-Reference Index
Part NumberManufacturer
P66-673 PRIMARY Circor Aerospace, Inc. Dba Circor Aerospace Inc (USA)
65A81C1037 Naval Air Systems Command Managed Original Design Activity Not Material/parts Supplier (USA)
1634 PRIMARY Rgi Inc Dba Rgi Inc (USA)
Related Parts
5305-00-012-1832INTERCHANGEABLE
SCREW,MACHINE
121832
6240-00-014-5416INTERCHANGEABLE
LAMP,INCANDESCENT
6240-00-057-1966INTERCHANGEABLE
LAMP,INCANDESCENT
1634
5905-00-106-7007INTERCHANGEABLE
RESISTOR SET,MATCHED
C600012885
5315-00-193-6465INTERCHANGEABLE
PIN,STRAIGHT,HEADLESS
8A7188
5950-00-289-9884INTERCHANGEABLE
TRANSFORMER,AUDIO FREQUENCY
1783709-34
5330-00-362-2115INTERCHANGEABLE
GASKET
F400A336
5306-00-449-3988INTERCHANGEABLE
BOLT,MACHINE
1634
4730-00-517-8062INTERCHANGEABLE
FITTING,LUBRICATION
8135-01-030-1634INTERCHANGEABLE
SEAL,STRAPPING
030-1634
4820-01-033-2207INTERCHANGEABLE
DIAPHRAGM,VALVE,FLAT
1634
4820-01-062-3839INTERCHANGEABLE
SLEEVE ASSEMBLY,VALVE
1028-5-3400

Frequently Asked Questions

What is NSN 4820-00-331-3537?

NSN 4820-00-331-3537 is a Valve,safety Relief, manufactured by Circor Aerospace, Inc. Dba Circor Aerospace Inc, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-331-3537?

NSN 4820-00-331-3537 has 3 cross-referenced part numbers: P66-673 (Circor Aerospace, Inc. Dba Circor Aerospace Inc), 65A81C1037 (Naval Air Systems Command Managed Original Design Activity Not Material/parts Supplier), 1634 (Rgi Inc Dba Rgi Inc).

What NSN replaces 4820-00-331-3537?

There are 12 known substitutes for 4820-00-331-3537: 5305-00-012-1832, 6240-00-014-5416, 6240-00-057-1966 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of P66-673?

Key specifications for P66-673: Thread Direction: RIGHT-HAND FIRST ENDRIGHT-HAND FIRST END; Thread Series Designator: NPT SECOND ENDNPT FIRST END; Connection Type: THREADED EXTERNAL PIPE SECOND ENDTHREADED EXTERNAL PIPE SECOND END; Media for Which Designed: FUEL/OIL, HYDROCARBON SECOND RESPONSEAIR FIRST RESPONSE. 27 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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