PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

M18182-31UUnion,pipe

Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M · NSN 4730-00-277-8657 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-00-277-8657 — this item is cataloged by the U.S. Government under National Stock Number 4730-00-277-8657. Primary manufacturer part number: M18182-31U.
Features
  • Union,pipe — FSC 4730
  • Material: STEEL OVERALL
  • Style Designator: SCREWED
  • Thread Series Designator: NPT ALL ENDS
  • Media for Which Designed: WATER-OIL-GAS SINGLE RESPONSE
  • Nominal Thread Size: 2.000 INCHES ALL ENDS IN
  • Nominal Overall Length: 3.437 INCHES IN
  • Operating Pressure: 3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
Applications
  • Fluid conveyance
  • Hydraulic system plumbing
  • Pneumatic line routing
  • Applications requiring Steel Overall construction
General Description

The Union,pipe, cataloged under National Stock Number 4730-00-277-8657, 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 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M. 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: Cancelled.

Technical Specifications
ParameterValue
NSN4730-00-277-8657
Primary Part NumberM18182-31U
Item NameUnion,pipe
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerMilitary Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
StatusCANCELLED
MaterialSTEEL OVERALL
Style DesignatorSCREWED
Thread Series DesignatorNPT ALL ENDS
Media for Which DesignedWATER-OIL-GAS SINGLE RESPONSE
Nominal Thread Size2.000 INCHES ALL ENDS IN
Nominal Overall Length3.437 INCHES IN
Operating Pressure3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
Nondefinitive Spec/std Data2 CLASS AND A STYLE
Specification/standard Data81349-MIL-U-18182/CANCELED GOVERNMENT SPECIFICATION
Surface TreatmentCADMIUM NUT
Connection TypeTHREADED INTERNAL PIPE ALL ENDS
Seat TypeBEVELED
Connection StylePLAIN (PIPE) ALL ENDS
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 12
4730-00-066-1110XS1V3-4 INTERCHANGEABLE
Union,pipe
Catawissa Valve and Fittings Co
4730-00-076-8608 INTERCHANGEABLE
Union,pipe
4730-00-222-1860 INTERCHANGEABLE
Union,pipe
4730-00-222-1862 INTERCHANGEABLE
Union,pipe
4730-00-222-1863252H3-4 INTERCHANGEABLE
Union,pipe
Crane Co Div Valve Div
4730-00-222-1864 INTERCHANGEABLE
Union,pipe
4730-00-222-1865 INTERCHANGEABLE
Union,pipe
4730-00-222-1866 INTERCHANGEABLE
Union,pipe
3030-00-253-836625-12280 INTERCHANGEABLE
Belt,v
Gates Corporation
4730-00-277-5507 INTERCHANGEABLE
Union,pipe
Cross-Reference Index
Part NumberManufacturer
M18182-31U Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
MIL-U-18182 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
2125SIZE2 Itt Grinnell Corp (USA)
252H Crane Co Div Valve Div (USA)
Related Parts
4730-00-066-1110INTERCHANGEABLE
UNION,PIPE
XS1V3-4
4730-00-076-8608INTERCHANGEABLE
UNION,PIPE
4730-00-222-1860INTERCHANGEABLE
UNION,PIPE
4730-00-222-1862INTERCHANGEABLE
UNION,PIPE
4730-00-222-1863INTERCHANGEABLE
UNION,PIPE
252H3-4
4730-00-222-1864INTERCHANGEABLE
UNION,PIPE
4730-00-222-1865INTERCHANGEABLE
UNION,PIPE
4730-00-222-1866INTERCHANGEABLE
UNION,PIPE
3030-00-253-8366INTERCHANGEABLE
BELT,V
25-12280
4730-00-277-5507INTERCHANGEABLE
UNION,PIPE
4730-00-973-8750INTERCHANGEABLE
UNION,PIPE
2244
4730-01-113-4546INTERCHANGEABLE
UNION,PIPE

Frequently Asked Questions

What is NSN 4730-00-277-8657?

NSN 4730-00-277-8657 is a Union,pipe, manufactured by Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M, classified under FSC 4730 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 4730-00-277-8657?

NSN 4730-00-277-8657 has 4 cross-referenced part numbers: M18182-31U (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M), MIL-U-18182 (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M), 2125SIZE2 (Itt Grinnell Corp), 252H (Crane Co Div Valve Div).

What NSN replaces 4730-00-277-8657?

There are 12 known substitutes for 4730-00-277-8657: 4730-00-066-1110, 4730-00-076-8608, 4730-00-222-1860 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of M18182-31U?

Key specifications for M18182-31U: Material: STEEL OVERALL; Style Designator: SCREWED; Thread Series Designator: NPT ALL ENDS; Media for Which Designed: WATER-OIL-GAS SINGLE RESPONSE. 13 total characteristics are documented in the Federal Logistics Information System.

Is NSN 4730-00-277-8657 still in active supply?

NSN 4730-00-277-8657 is currently cancelled. Check with the Defense Logistics Agency for current availability and authorized substitutes.

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