Model: 51B221-21H

Close Tolerance Screw

Properties:

Thread Class

Thread Direction

Right-hand

Thread Length

0.276 inches

Fastener Length

Between 1.573 inches and 1.620 inches

Head Style

Modified pan

Head Diameter

Between 0.361 inches and 0.381 inches

Head Height

Between 0.103 inches and 0.118 inches

Grip Diameter

Between 0.1885 inches and 0.1895 inches

Shank Unthreaded Hole Diameter

0.070 inches first hole

Internal Drive Style

Offset cruciform (torque set)

Thread Diameter

0.190 inches

Grip Length

Between 1.298 inches and 1.328 inches

Thready Qty Per Inch (tpi)

Min. Tensile Strength (psi)

180000 pounds per square inch

Distance From Head Largest Bearing Surface To Shank Hole Center

1.456 inches first hole and 1.503 inches first hole

Surface Finish

32.0 microinches grip

Material

Steel comp 4140 or steel comp e4340 or steel comp 6150 or steel comp 8735 or steel comp 8740

Material Specification

Mil-s-5626 military specification 1st material response or mil-s-5000 military specification 2nd material response or mil-s-8503 military specification 3rd material response or mil-s-6098 military specification 4th material response or mil-s-6049 military specification 5th material response

Surface Treatment

Cadmium and chromate

Surface Treatment Specification

Qq-p-416, type 2, class 3 federal specification single treatment response

Thread Series Designator

Unc

NSN

5305-00-801-7103

Part Number

51B221-21H

Description

Screw,close Tolerance

CAGE

06950

A screw, machine or screw, cap, socket head whose unthreaded portion is of specified grip length, plated or unplated, and is machined to a tolerance of one thousandth (0.001 in.) (0.025 mm) or less of a specific diameter for items (1.000 in.) (25 mm) or less in diameter. Items over (1.000 in.) (25 mm) in diameter shall have a tolerance of fifteen ten thousandths (0.0015 in.) (0.038 mm) or less. The nominal major diameter of the threads shall be at least one thousandth (0.001 in.) (0.025 mm) below the minimum shank diameter, but not below the minimum major diameter for applicable class of fit, as shown in the screw thread standards, fed std h28 and/or other nationally recognized standards. The head is designed to be held or driven with an inserted driver. It is not designed for rotation by the thumb and fingers. A locking feature may be incorporated in the design of the head or threads.

Part 51B221-21H NSN 5305-00-801-7103

INC

FIIG

Concept No.

App. Key

Cond. Code

Status

INC:

29294

FIIG:

A003B0

Concept No.:

App. Key:

Cond. Code:

Status:

Material Classification

Hazardous material, precious metals, criticality, enviroment, and electrostatic discharge indicators

HMIC

PMIC

ESD/EMI

ENAC

MMAC

CRITL

HMIC:

PMIC:

ESD:

MMAC:

CRITL:

Packaging & Shipping

Est. Pack Size

Est. Pack Weight

Est. Item Weight

Est. Item Dim.

Pack Size:

Paclk Weight:

0.1000lbs

Item Weight:

Item Dim:

OPI

SPI No.

SPI Rev.

SPC Mkg.

LVL A

LVL B

OPI:

SPI No.:

SPI Rev.:

SPC Mkg:

LVL_A:

LVL_B:

Freight Classification

NMFC

UFC

LTL

LCL

WCC

TCC

SHC

ACC

NMFC:

093486

UFC:

48950

LTL:

RATING VARIABLE

LCL:

WCC:

713

TCC:

SHC:

ACC:

Construction Materials

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Schedule B and Export

Schedule B: 7318152000
SITC: 69421
End Use: Iron and steel products, other
NAICS: 332722
USDA: 1

Freight Class: Bolts and bolts and their nuts or washers exported in the same shipment