PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

25521Valve,safety Relief

Moog Inc. Dba Ampac-Isp Corp · NSN 4820-00-351-2445 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-351-2445 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-351-2445. Primary manufacturer part number: 25521.
Features
  • Valve,safety Relief — FSC 4820
  • Flow Control Device: BALL
  • Material: STEEL CORROSION RESISTING OVERALL
  • Thread Series Designator: UNF FIRST END
  • Valve Operation Method: AUTOMATIC
  • Style Designator: STRAIGHT THRU
  • Connection Type: THREADED EXTERNAL BOSS FIRST END
  • Connection Style: EXTERNAL SEAT FOR GASKET SEAL (BOSS) FIRST END
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Steel Corrosion Resisting Overall construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-00-351-2445, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Moog Inc. Dba Ampac-Isp Corp. Government technical data includes 11 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 9 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-351-2445
Primary Part Number25521
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerMoog Inc. Dba Ampac-Isp Corp
StatusACTIVE
Flow Control DeviceBALL
MaterialSTEEL CORROSION RESISTING OVERALL
Thread Series DesignatorUNF FIRST END
Valve Operation MethodAUTOMATIC
Style DesignatorSTRAIGHT THRU
Connection TypeTHREADED EXTERNAL BOSS FIRST END
Connection StyleEXTERNAL SEAT FOR GASKET SEAL (BOSS) FIRST END
Thread DirectionRIGHT-HAND FIRST END
Thread Class2A FIRST END A
Nominal Thread Size0.438 INCHES FIRST END IN
Disk Loading MethodSPRING
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 9
4210-00-035-949025521 INTERCHANGEABLE
Extinguisher,fire
Tyco Fire Products Lp
3110-00-100-0545 INTERCHANGEABLE
Cup,tapered Roller Bearing
4730-00-106-7319 INTERCHANGEABLE
Bushing,tank
5365-00-278-4990113933H INTERCHANGEABLE
Plug,machine Thread,magnetic
Navistar Intl Corp Truck Br Ohio Plant
6685-00-723-55472552-1 INTERCHANGEABLE
Gage,pressure,dial Indicating
Rochester Sensors, Llc
4710-01-012-495325521 INTERCHANGEABLE
Tube Assembly,metal
Williams International Co., L.l.c.
5950-01-210-4433U-37A INTERCHANGEABLE
Transformer,power
Mpc Products Corporation Dba Woodward Mpc, Inc.
5330-01-356-5061101644 INTERCHANGEABLE
Retainer,packing
Paccar Winch Inc Dba Paccar Winch Division
5998-01-422-78973174AS7271 INTERCHANGEABLE
Holder,electrical Card
Naval Air Systems Command Managed Original Design Activity Not Material/parts Supplier
Cross-Reference Index
Part NumberManufacturer
25521 PRIMARY Moog Inc. Dba Ampac-Isp Corp (USA)
600-27330PC18 Moog Inc. Dba Ampac-Isp Corp (USA)
Related Parts
4210-00-035-9490INTERCHANGEABLE
EXTINGUISHER,FIRE
25521
3110-00-100-0545INTERCHANGEABLE
CUP,TAPERED ROLLER BEARING
4730-00-106-7319INTERCHANGEABLE
BUSHING,TANK
5365-00-278-4990INTERCHANGEABLE
PLUG,MACHINE THREAD,MAGNETIC
113933H
6685-00-723-5547INTERCHANGEABLE
GAGE,PRESSURE,DIAL INDICATING
2552-1
4710-01-012-4953INTERCHANGEABLE
TUBE ASSEMBLY,METAL
25521
5950-01-210-4433INTERCHANGEABLE
TRANSFORMER,POWER
U-37A
5330-01-356-5061INTERCHANGEABLE
RETAINER,PACKING
101644
5998-01-422-7897INTERCHANGEABLE
HOLDER,ELECTRICAL CARD
3174AS7271

Frequently Asked Questions

What is NSN 4820-00-351-2445?

NSN 4820-00-351-2445 is a Valve,safety Relief, manufactured by Moog Inc. Dba Ampac-Isp Corp, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-351-2445?

NSN 4820-00-351-2445 has 2 cross-referenced part numbers: 25521 (Moog Inc. Dba Ampac-Isp Corp), 600-27330PC18 (Moog Inc. Dba Ampac-Isp Corp).

What NSN replaces 4820-00-351-2445?

There are 9 known substitutes for 4820-00-351-2445: 4210-00-035-9490, 3110-00-100-0545, 4730-00-106-7319 and 6 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 25521?

Key specifications for 25521: Flow Control Device: BALL; Material: STEEL CORROSION RESISTING OVERALL; Thread Series Designator: UNF FIRST END; Valve Operation Method: AUTOMATIC. 11 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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