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Technical Data Sheet
PartsTable / COMPONENT / 156D2
156D2 ✓ Verified by PartsTable
— · HOSE FITTING
WHAT YOU NEED TO KNOW
PTFE tape on tapered threads (NPT/BSPT) JIC/AN flare connections seal metal-to-metal — no tape
NPT != BSPT — look identical, NOT interchangeable
PRODUCT OVERVIEW

The NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY OVERALL, nut_style: TUBE COUPLING, nut_height: 0.562 INCHES NOMINAL IN, thread_class: 3B, thread_series: UNF, thread_direction: RIGHT-HAND. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-278-5449, indicating validated use in U.S.

government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels. Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
156D2
NSN: 4730-00-278-5449
FSC: 4730
CAGE: 0AHP5 — CURTISS-WRIGHT CONTROLS, INC. DIV ACTUATION DIVISION (USA)
SPECIFICATIONS
materialCOPPER ALLOY OVERALL
nut_styleTUBE COUPLING
nut_height0.562 INCHES NOMINAL IN
thread_class3B
thread_seriesUNF
thread_directionRIGHT-HAND
fabrication_methodMACHINED
length_to_shoulder0.433 INCHES MINIMUM AND 0.443 INCHES MAXIMUM IN
width_across_flats0.744 INCHES MINIMUM AND 0.755 INCHES MAXIMUM IN
nominal_thread_size0.625 INCHES IN
smallest_inside_diameter0.473 INCHES MINIMUM AND 0.477 INCHES MAXIMUM IN
thread_quantity_per_inch18
NSN4730-00-278-5449
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 156D2 · OEM ⚠ VERIFY BEFORE ORDERING NPT ≠ BSPT — tapered threads look identical but are NOT interchangeable. Wrong thread = leak. JIC (37°) ≠ AN (37°) ≠ SAE 45° — flare angles must match exactly. Measure thread pitch with gauge — visual identification is unreliable ✓ BROKER TIP Always use thread sealant (PTFE tape or pipe compound) on tapered threads (NPT/BSPT). JIC/AN flare fittings seal metal-to-metal — never use tape on flare connections PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
FABRICATION METHOD: MACHINED
•
SMALLEST INSIDE DIAMETER: 0.473 INCHES MINIMUM AND 0.477 INCHES MAXIMUM IN
•
THREAD DIRECTION: RIGHT-HAND
•
WIDTH ACROSS FLATS: 0.744 INCHES MINIMUM AND 0.755 INCHES MAXIMUM IN
•
NUT HEIGHT: 0.562 INCHES NOMINAL IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-B-626,CP 21 OR 22 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
•
NUT STYLE: TUBE COUPLING
•
THREAD CLASS: 3B
TECHNICAL CHARACTERISTICS (FLIS)
FABRICATION METHODMACHINED
SMALLEST INSIDE DIAMETER0.473 INCHES MINIMUM AND 0.477 INCHES MAXIMUM IN
THREAD DIRECTIONRIGHT-HAND
WIDTH ACROSS FLATS0.744 INCHES MINIMUM AND 0.755 INCHES MAXIMUM IN
NUT HEIGHT0.562 INCHES NOMINAL IN
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-B-626,CP 21 OR 22 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
NUT STYLETUBE COUPLING
THREAD CLASS3B
NOMINAL THREAD SIZE0.625 INCHES IN
THREAD QUANTITY PER INCH18
VERIFIED SUBSTITUTES & CROSS-REFERENCES 22
5509Interchangeable
interchangeable cross-reference
interchangeable
AN780-2Interchangeable
interchangeable cross-reference
interchangeable
MIL-DTL-6001Interchangeable
interchangeable cross-reference
interchangeable
3100994Interchangeable
interchangeable cross-reference
interchangeable
7106Interchangeable
interchangeable cross-reference
interchangeable
AN800-5Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 156D2?
156D2 is a NUT,TUBE COUPLING.
What parts can replace 156D2?
There are 22 known substitutes for 156D2: 5509, AN780-2, MIL-DTL-6001 and 19 more. Substitute compatibility should be verified for your specific system.
Is 156D2 still available?
156D2 is currently cancelled.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026