PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

WW-U-531Union,pipe

Federal Specifications Promulgated by General Services Administration Washington DC · NSN 4730-00-266-3905 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-00-266-3905 — this item is cataloged by the U.S. Government under National Stock Number 4730-00-266-3905. Primary manufacturer part number: WW-U-531.
Features
  • Union,pipe — FSC 4730
  • Material: IRON MALLEABLE SEAT
  • Media for Which Designed: STEAM FIRST RESPONSE
  • Style Designator: SCREWED
  • Nominal Thread Size: 0.500 INCHES ALL ENDS IN
  • Seat Type: GROUND-JOINT
  • Connection Type: THREADED INTERNAL PIPE ALL ENDS
  • Nominal Overall Length: 1.735 INCHES IN
Applications
  • Fluid conveyance
  • Hydraulic system plumbing
  • Pneumatic line routing
  • Applications requiring Iron Malleable Seat construction
General Description

The Union,pipe, cataloged under National Stock Number 4730-00-266-3905, is classified within Federal Supply Class 4730 (No Item Name Available) of the Pipe, Tubing, Hose, and Fittings group. The primary manufacturer of record is Federal Specifications Promulgated by General Services Administration Washington DC. Government technical data includes 13 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. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4730-00-266-3905
Primary Part NumberWW-U-531
Item NameUnion,pipe
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerFederal Specifications Promulgated by General Services Administration Washington DC
StatusACTIVE
MaterialIRON MALLEABLE SEAT
Media for Which DesignedSTEAM FIRST RESPONSE
Style DesignatorSCREWED
Nominal Thread Size0.500 INCHES ALL ENDS IN
Seat TypeGROUND-JOINT
Connection TypeTHREADED INTERNAL PIPE ALL ENDS
Nominal Overall Length1.735 INCHES IN
Connection StylePLAIN (PIPE) ALL ENDS
Operating Pressure150.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM FIRST RESPONSE LBS
Operating Pressure300.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SECOND RESPONSE LBS
Thread Series DesignatorNPT ALL ENDS
Nondefinitive Spec/std DataA TYPE AND 1 CLASS
Media for Which DesignedWATER-OIL-GAS SECOND RESPONSE
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
4730-00-204-3392 INTERCHANGEABLE
Union,pipe
4730-00-240-1670ASMEB16.39-02-T-A INTERCHANGEABLE
Union,pipe
The American Society of Mechanical Engineers
4730-00-240-1671ASMEB16.39-06-T-A INTERCHANGEABLE
Union,pipe
The American Society of Mechanical Engineers
4730-00-240-1672ASMEB16.39-08-T-A INTERCHANGEABLE
Union,pipe
The American Society of Mechanical Engineers
4730-00-240-1674 INTERCHANGEABLE
Union,pipe
4730-00-240-1675 INTERCHANGEABLE
Union,pipe
4730-00-240-1676ASMEB16.39-15-T-A INTERCHANGEABLE
Union,pipe
The American Society of Mechanical Engineers
4730-00-240-1677 INTERCHANGEABLE
Union,pipe
4730-00-240-1678 INTERCHANGEABLE
Union,pipe
4730-00-266-3907 INTERCHANGEABLE
Union,pipe
Cross-Reference Index
Part NumberManufacturer
WW-U-531 Federal Specifications Promulgated by General Services Administration Washington DC (USA)
WWU-531-03TA Federal Specifications Promulgated by General Services Administration Washington DC (USA)
PT1280 Crane Co Div Valve Div (USA)
B16.39 American National Standards Institute Incorporated Dba American National Standards Institute (USA)
Related Parts
4730-00-204-3392INTERCHANGEABLE
UNION,PIPE
4730-00-240-1670INTERCHANGEABLE
UNION,PIPE
ASMEB16.39-02-T-A
4730-00-240-1671INTERCHANGEABLE
UNION,PIPE
ASMEB16.39-06-T-A
4730-00-240-1672INTERCHANGEABLE
UNION,PIPE
ASMEB16.39-08-T-A
4730-00-240-1674INTERCHANGEABLE
UNION,PIPE
4730-00-240-1675INTERCHANGEABLE
UNION,PIPE
4730-00-240-1676INTERCHANGEABLE
UNION,PIPE
ASMEB16.39-15-T-A
4730-00-240-1677INTERCHANGEABLE
UNION,PIPE
4730-00-240-1678INTERCHANGEABLE
UNION,PIPE
4730-00-266-3907INTERCHANGEABLE
UNION,PIPE
4730-00-266-3908INTERCHANGEABLE
UNION,PIPE
4730-00-287-0166INTERCHANGEABLE
UNION,PIPE
1631-250

Frequently Asked Questions

What is NSN 4730-00-266-3905?

NSN 4730-00-266-3905 is a Union,pipe, manufactured by Federal Specifications Promulgated by General Services Administration Washington DC, classified under FSC 4730 (No Item Name Available). Status: active.

What are the part numbers for NSN 4730-00-266-3905?

NSN 4730-00-266-3905 has 4 cross-referenced part numbers: WW-U-531 (Federal Specifications Promulgated by General Services Administration Washington DC), WWU-531-03TA (Federal Specifications Promulgated by General Services Administration Washington DC), PT1280 (Crane Co Div Valve Div), B16.39 (American National Standards Institute Incorporated Dba American National Standards Institute).

What NSN replaces 4730-00-266-3905?

There are 12 known substitutes for 4730-00-266-3905: 4730-00-204-3392, 4730-00-240-1670, 4730-00-240-1671 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of WW-U-531?

Key specifications for WW-U-531: Material: IRON MALLEABLE SEAT; Media for Which Designed: STEAM FIRST RESPONSE; Style Designator: SCREWED; Special Features: GROUND JOINT SEAT TYPE IS COPPER ALLOY. 14 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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