PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MIL-DTL-18866Tee,pipe to Tube

Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M · NSN 4730-01-311-8357 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-01-311-8357 — this item is cataloged by the U.S. Government under National Stock Number 4730-01-311-8357. Primary manufacturer part number: MIL-DTL-18866.
Features
  • Tee,pipe to Tube — FSC 4730
  • Thread Class: 2A FIRST END A
  • Nominal Outside Diameter Tube Accommodated: 0.250 INCHES SECOND END IN
  • Connection Type: THREADED EXTERNAL TUBE FIRST END
  • Nominal Thread Size: 0.438 INCHES SECOND END IN
  • Connection Type: THREADED EXTERNAL TUBE SECOND END
  • Leg Length: 0.891 INCHES NOMINAL FIRST END IN
  • Nominal Outside Diameter Tube Accommodated: 0.250 INCHES FIRST END IN
Applications
  • Fluid conveyance
  • Hydraulic system plumbing
  • Pneumatic line routing
  • Applications requiring Steel Corrosion Resisting Overall construction
General Description

The Tee,pipe to Tube, cataloged under National Stock Number 4730-01-311-8357, 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 26 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 7 commercial cross-references from 4 manufacturers, enabling identification through both NSN and commercial part number lookups. 4 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4730-01-311-8357
Primary Part NumberMIL-DTL-18866
Item NameTee,pipe to Tube
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerMilitary Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
StatusACTIVE
Thread Class2A FIRST END A
Nominal Outside Diameter Tube Accommodated0.250 INCHES SECOND END IN
Connection TypeTHREADED EXTERNAL TUBE FIRST END
Nominal Thread Size0.438 INCHES SECOND END IN
Connection TypeTHREADED EXTERNAL TUBE SECOND END
Leg Length0.891 INCHES NOMINAL FIRST END IN
Nominal Outside Diameter Tube Accommodated0.250 INCHES FIRST END IN
Seat Angle37.0 DEGREES FIRST END
Nominal Thread Size0.438 INCHES FIRST END IN
MaterialSTEEL CORROSION RESISTING OVERALL
Connection TypeTHREADED EXTERNAL PIPE THIRD END
Leg Length0.891 INCHES NOMINAL SECOND END IN
Connection StyleFLARELESS (TUBE) SECOND END
Connection StylePLAIN (PIPE) THIRD END
Leg Length0.781 INCHES NOMINAL THIRD END IN
Nondefinitive Spec/std Data22D FIGURE
Furnished Items and Quantity2 TUBE COUPLING NUT W/SLEEVE
Specification/standard Data81343-J514 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD AND 96906-MS51818 GOVERNMENT STANDARD
Media for Which DesignedHYDRAULIC FLUID SINGLE RESPONSE
Connection StyleFLARELESS (TUBE) FIRST END
Nominal Thread Size0.125 INCHES THIRD END IN
Thread Class2A SECOND END A
Thread Series DesignatorUNIFIED NATIONAL JOINT FINE (UNJF) SECOND END
Thread Series DesignatorNPTF THIRD END
Seat Angle37.0 DEGREES SECOND END
Thread Series DesignatorUNIFIED NATIONAL JOINT FINE (UNJF) FIRST END
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 4
4730-00-019-1489 INTERCHANGEABLE
Elbow,tube to Boss
4730-01-031-0263 INTERCHANGEABLE
Tee,tube to Boss
4730-01-036-5064 INTERCHANGEABLE
Elbow,pipe to Tube
4730-01-192-9593 INTERCHANGEABLE
Elbow,tube to Boss
Cross-Reference Index
Part NumberManufacturer
MIL-DTL-18866 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
MS51818-3S Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
4SBUSS Parker Hannifin Corp Dba Pneutronics Div Stratoflex Products Division (USA)
4SBUSS Parker-Hannifin Corporation Dba Pneutronics Div Tube Fittings Division (USA)
MIL-DTL-18866J Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
MS51818-3SS Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
MIL-F-18866 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
Related Parts
4730-00-019-1489INTERCHANGEABLE
ELBOW,TUBE TO BOSS
4730-01-031-0263INTERCHANGEABLE
TEE,TUBE TO BOSS
4730-01-036-5064INTERCHANGEABLE
ELBOW,PIPE TO TUBE
4730-01-192-9593INTERCHANGEABLE
ELBOW,TUBE TO BOSS

Frequently Asked Questions

What is NSN 4730-01-311-8357?

NSN 4730-01-311-8357 is a Tee,pipe to Tube, 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: active.

What are the part numbers for NSN 4730-01-311-8357?

NSN 4730-01-311-8357 has 7 cross-referenced part numbers: MIL-DTL-18866 (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M), MS51818-3S (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M), 4SBUSS (Parker Hannifin Corp Dba Pneutronics Div Stratoflex Products Division), 4SBUSS (Parker-Hannifin Corporation Dba Pneutronics Div Tube Fittings Division), MIL-DTL-18866J (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M) and 2 more.

What NSN replaces 4730-01-311-8357?

There are 4 known substitutes for 4730-01-311-8357: 4730-00-019-1489, 4730-01-031-0263, 4730-01-036-5064 and 1 more. Verify interchangeability with system specifications before substitution.

What are the specifications of MIL-DTL-18866?

Key specifications for MIL-DTL-18866: Thread Class: 2A FIRST END A; Nominal Outside Diameter Tube Accommodated: 0.250 INCHES SECOND END IN; Connection Type: THREADED EXTERNAL TUBE FIRST END; Nominal Thread Size: 0.438 INCHES SECOND END IN. 26 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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