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Technical Data Sheet
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N551 ✓ Verified by PartsTable
— · GATE VALVE
WHAT YOU NEED TO KNOW
Full open or full close only — never throttle Rising stem shows position visually
Throttling a gate valve erodes seats
PRODUCT OVERVIEW

VALVE,REGULATING,FLUID PRESSURE. Key specifications include filter: NOT INCLUDED, material: NICKEL ALLOY AND COPPER ALLOY SEAT, nut_style: SLEEVE, body_style: STRAIGHT THRU, nut_length: 0.250 INCHES NOMINAL IN, temp_rating: 165.0 FAHRENHEIT MAXIMUM DEGF. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4820-00-181-8911, 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
N551
NSN: 4820-00-181-8911
FSC: 4820
CAGE: 35795 — LESLIE CONTROLS, INC. DBA LESLIE CONTROLS INC (USA)
SPECIFICATIONS
filterNOT INCLUDED
materialNICKEL ALLOY AND COPPER ALLOY SEAT
nut_styleSLEEVE
body_styleSTRAIGHT THRU
nut_length0.250 INCHES NOMINAL IN
temp_rating165.0 FAHRENHEIT MAXIMUM DEGF
thread_class2B
boss_diameter2.375 INCHES NOMINAL OVERALL IN
thread_seriesUNF
boss_thickness0.125 INCHES NOMINAL OVERALL IN
furnished_itemsTAILPIECE AND UNION NUT
inside_diameter1.187 INCHES NOMINAL IN
NSN4820-00-181-8911
COMPONENT DIAGRAM
GATE VALVE — FULL OPEN OR FULL CLOSE ONLY Rising STEM BONNET FLOW → → FLOW SEATS — — SIZE: — · — · — PN: N551 · OEM ⚠ VERIFY BEFORE ORDERING Gate valves = FULL OPEN or FULL CLOSE only — never throttle. Partial opening causes seat erosion and vibration. ✓ BROKER TIP Rising stem shows valve position visually — easier maintenance. Non-rising stem saves headroom. PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
MEDIA FOR WHICH DESIGNED: WATER, FRESH AND WATER, SALT
•
NONDEFINITIVE SPEC/STD DATA: 2 TYPE
•
TEST DATA DOCUMENT: 81349-MILV2042 SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.).
•
FIRST END STYLE DESIGNATOR: SOCKET W/BRAZING RING
•
MATERIAL: NICKEL ALLOY STEM
•
SPECIAL TEST FEATURES: HIGH-IMPACT SHOCK TESTS ARE REQUIRED AS DIRECTED IN PARAGRAPHS 3.6 AND 4.4.2.3 OF MIL-V-2042 IN PAC TEST ABOVE IN
•
SECOND END RELATIONSHIP WITH FIRST END: IDENTICAL
TECHNICAL CHARACTERISTICS (FLIS)
MEDIA FOR WHICH DESIGNEDWATER, FRESH AND WATER, SALT
NONDEFINITIVE SPEC/STD DATA2 TYPE
TEST DATA DOCUMENT81349-MILV2042 SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.).
FIRST END STYLE DESIGNATORSOCKET W/BRAZING RING
MATERIALNICKEL ALLOY STEM
SPECIAL TEST FEATURESHIGH-IMPACT SHOCK TESTS ARE REQUIRED AS DIRECTED IN PARAGRAPHS 3.6 AND 4.4.2.3 OF MIL-V-2042 IN PAC TEST ABOVE IN
SECOND END RELATIONSHIP WITH FIRST ENDIDENTICAL
MATERIALRUBBER FLOW CONTROL DEVICE
FIRST END OUTSIDE DIAMETER TUBE ACCOMMODATED1.000 INCHES NOMINAL IN
SPECIAL FEATURESENDS W/O BRAZING RINGS INSTALLED
VERIFIED SUBSTITUTES & CROSS-REFERENCES 18
N551Interchangeable
interchangeable cross-reference
interchangeable
40399-04 50T 10Interchangeable
interchangeable cross-reference
interchangeable
40399-4 50 TO 100PSIInterchangeable
interchangeable cross-reference
interchangeable
30806005Interchangeable
interchangeable cross-reference
interchangeable
30 1IN25T60PSI N551XN667Interchangeable
interchangeable cross-reference
interchangeable
YB2310E292 - CD N667Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is N551?
N551 is a VALVE,REGULATING,FLUID PRESSURE.
What parts can replace N551?
There are 18 known substitutes for N551: N551, 40399-04 50T 10, 40399-4 50 TO 100PSI and 15 more. Substitute compatibility should be verified for your specific system.
What is the NSN for N551?
N551 is cataloged in the Federal Logistics Information System (FLIS) under NSN 4820-00-181-8911. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026