PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

20210H51MValve,safety Relief

Anderson Greenwood Lp Dba Anderson Greenwood Crosby · NSN 4820-01-171-4392 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-01-171-4392 — this item is cataloged by the U.S. Government under National Stock Number 4820-01-171-4392. Primary manufacturer part number: 20210H51M.
Features
  • Valve,safety Relief — FSC 4820
  • Valve Operation Method: AUTOMATIC
  • Criticality Code Justification: ZZZY
  • Material: NICKEL ALLOY 400 OR NICKEL ALLOY R-405 FLOW CONTROL DEVICE
  • Style Designator: ANGLE
  • Material: NICKEL ALLOY 400 OR NICKEL ALLOY R-405 SEAT
  • Connection Style: GASKET SEAL (PIPE) FIRST END
  • Material: NICKEL ALLOY 400 OR NICKEL ALLOY R-405 STEM
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Nickel Alloy 400 or Nickel Alloy R-405 Flow Control Device construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-01-171-4392, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Anderson Greenwood Lp Dba Anderson Greenwood Crosby. Government technical data includes 16 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 4 commercial cross-references from 3 manufacturers, enabling identification through both NSN and commercial part number lookups. 1 verified substitute exists in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-01-171-4392
Primary Part Number20210H51M
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerAnderson Greenwood Lp Dba Anderson Greenwood Crosby
StatusACTIVE
Valve Operation MethodAUTOMATIC
Criticality Code JustificationZZZY
MaterialNICKEL ALLOY 400 OR NICKEL ALLOY R-405 FLOW CONTROL DEVICE
Style DesignatorANGLE
MaterialNICKEL ALLOY 400 OR NICKEL ALLOY R-405 SEAT
Connection StyleGASKET SEAL (PIPE) FIRST END
MaterialNICKEL ALLOY 400 OR NICKEL ALLOY R-405 STEM
Connection TypeUNTHREADED INTERNAL PIPE FIRST END
Disk Loading MethodSPRING
Bonnet Attachment MethodBOLTED
Bonnet TypeINSIDE SPRING
MaterialCOPPER ALLOY 922 BODY
Flow Control DeviceDISK
Nominal Pipe Size Accommodated0.500 INCHES FIRST END IN
Adjustable Pressure Range+45.0 TO 55.0 POUNDS PER SQUARE INCH LBS
Reference Number Differentiating CharacteristicsCLEANING, PACKAGING, AND MARKING IAW MIL-STD-1330D
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 1
4820-01-198-110420210J02S0045 INTERCHANGEABLE
Valve,safety Relief
Emerson Automation Solutions Final Control Us Lp Div Navy Product Team
Cross-Reference Index
Part NumberManufacturer
20210H51M Anderson Greenwood Lp Dba Anderson Greenwood Crosby (USA)
20210H51MCP Naval Inventory Control Point Mechanicsburg (USA)
20210H51MCP Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA)
20210H51M Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA)
Related Parts
4820-01-198-1104INTERCHANGEABLE
VALVE,SAFETY RELIEF
20210J02S0045

Frequently Asked Questions

What is NSN 4820-01-171-4392?

NSN 4820-01-171-4392 is a Valve,safety Relief, manufactured by Anderson Greenwood Lp Dba Anderson Greenwood Crosby, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-01-171-4392?

NSN 4820-01-171-4392 has 4 cross-referenced part numbers: 20210H51M (Anderson Greenwood Lp Dba Anderson Greenwood Crosby), 20210H51MCP (Naval Inventory Control Point Mechanicsburg), 20210H51MCP (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team), 20210H51M (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team).

What NSN replaces 4820-01-171-4392?

There is 1 known substitute for 4820-01-171-4392: 4820-01-198-1104. Verify interchangeability with system specifications before substitution.

What are the specifications of 20210H51M?

Key specifications for 20210H51M: Valve Operation Method: AUTOMATIC; Criticality Code Justification: ZZZY; Material: NICKEL ALLOY 400 OR NICKEL ALLOY R-405 FLOW CONTROL DEVICE; Style Designator: ANGLE. 16 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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