Fastener Abbreviations

18-8

Stainless Steel with 18% Chrome and 8% Nickel

2, 5 or 8

Strength grade of screw or nut

2A (3A)

Class of Thread Fit for inch screws

2B (3B)

Class of Thread fit for inch nuts

2H

Nut strength level designation (ASTM A194 Grade 2H Heavy Hex Nut)

6g

Class of thread fit for metric screws

6H

Class of thread fit for metric nuts

A325

Heavy Hex Structural Bolt (ASTM A325), similar to Grade 5

A490

Heavy Hex Structural Bolt ASTM A490), similar to Grade 8

A574

Strength grade for Socket head cap screws (ASTM A574)

AISI

American Iron and Steel Institute, specifies chemical composition of steels

ANSI

American National Standards Institute

AS

Alloy Steel

ASME

American Society of Mechanical Engineers

ASTM

American Society for Testing and Materials

B

When followed by a number (ex B-90) hardness measured on the Rockwell B Scale or an abbreviation for Boron

Bake (Bake-Out)

Heat Treat process used in plating to prevent Hydrogen Embrittlement

Bevel

Style of washer (square with a taper) used with I beams

Belleville

Style of lock washer, also called conical spring washer

BHCS

Button Head Cap Screw

BHN

Hardness measured with a Brinell Hardness Tester

BS

British Standard

C

When followed by a number (ex C-35) hardness measured on the Rockwell C Scale or an abbreviation for Carbon

CH

Case hardened (type of heat treatment)

C/R

Cross Recess Drive (typically Phillips style) or Chamfer/Radius

Cad

Cadmium Plating

 

Cad/Wax

Cadmium Plating with a topcoat of Wax

COO

Country of Origin

CRES

Corrosion resistant steel (usually refer to 18-8 or 316 stainless steel)

CS (cs)

Carbon Steel or Countersunk

DAC (Dac 320)

Dacromet Coating (Registered Trademark of Coatings International)

D/C Nut

Double Chamfered Nut (distinguish from washer faced)

D/E

Double Ended Stud

DIN

German Standards Organization

Deltaseal

Magnigard coating (registered trademark of Magni Engineered Coatings)

Dorrltech

Magnigard coating (registered trademark of Magni Engineered Coatings)

Driseal

Pipe Thread (registered trademark of Parker Hannifin)

ET

External Thread

FB

Flange Bolt

F436

Hardened flat washer with dimensions per ASTM F436

FHCS

Flat Head Cap Screw

FIM

Full Indicator Measurement

Flng

Hex Flange Bolt or Nut

FW

Flat Washer

galv

Galvanized, typically refers to Hot Dip Galvanized

Gr

Grade, refers to strength level of screw or nut (ex: Grade 2, Grade 5 or Grade 8)

Hardened

A product that has been heat treated

HB

Hex bolt or Hardness reading measured on the Brinell Scale

H.T.

Heat Treated

HCS

Hex Cap Screw or High Carbon Steel

H.D.G.

Hot Dip Galvanized

Hex Bolt

Can refer to either a "bolt" or a "cap screw"

HHCS

Hex Head Cap Screw (also an abbreviation for Heavy Hex Cap Screw)

HRB

Hardness measured on the Rockwell B scale

HRC

Hardness measured on the Rockwell C scale

HWH

Hex Washer Head

ID

Identification (usually refers to manufacturer logo)

IFI

Industrial Fastener Institute

IH

Indented Head

in.

Inch

ISO

International Standards Organization

ISIR

Initial Sample Inspection Report

IT

Internal Thread

J429

SAE standard that specifies strength levels of screws

J995

SAE standard that specifies strength levels of nuts

k

Short hand for the number 1,000

Keps

Nut with a permanently attached washer

Kips

1,000 pounds

ksi

Thousand of pounds per square inch

lb (lbs)

Pounds

Lb

Body Length on screws

LCS

Low Carbon Steel

Lg

Grip Length (distance from head to full threads) on screws

LH

Left Hand Thread

L/W

Lock Washer

M

Metric or short hand for the number 1,000

Magnigard

Magni Coating (Registered Trademark of Magni Engineered Coatings)

Mfg

Manufacturer

mm

Millimeter

MS

Machine screw

MTR

Material Test Report

#3 (or #7)

Refers to head design of a plow bolt

NC

Unified National Coarse Thread

NE (NU, NTE, NTU)

Designations that define the thickness of Nylon Insert Lock Nuts

NF

Unified National Fine Thread

Nom

Nominal (reference dimension)

NPT

National Tapered Pipe Thread

p

Thread Pitch

P/B

Plow Bolt

Ph Dr

Phillips Drive (cross recess)

Pl

Plain finish

P/N

Part number

Phos (P & O)

Phosphate and Oil Coating (typically Zinc Phosphate and Oil)

Pozi Drive

Special cross recess (registered trademark of Camcar Textron)

PPAP

Production Part Approval Process

psi

Pounds per square inch

PZ

Pozi-Drive style of cross recess

R

Radius

Rb (RB or HRB)

Hardness measured on the Rockwell "B" scale

Rc (RC or HRC)

Hardness measured on the Rockwell "C" scale

RT

Rolled Threads

SAE

Society of Automotive Engineers when used with washers it means "small OD" when used with screw or nuts means fine thread

Screw

Can refer to any type of externally threaded fastener but typically a sheet metal screw

Sems

Screw with a permanently attached washer

Serrated

Locking serrations on bearing face of screw or nut

SHCS

Socket Head Cap Screw

Sl

Slotted Drive

SMS

Sheet Metal Screw

Sq

Square, can refer to square head bolt or square nut

SS or S/S

Stainless Steel

St

Steel

Taptite

Special triangular thread forming screw (registered trademark of Reminc)

T.H.

Through Hardened (type of heat treatment)

TIR

Total Indicator Reading

T/S

Tapping Screw

Torx

6 Lobe Drive (Torx Drive, registered trademark of Camcar Textron)

TPI

Threads per Inch

TT (TR)

Taptite thread (registered trademark of Reminc), also called Tri-Roundular

TTH

Threaded to Head

Type 1 (23, 25)

Special thread forming or cutting tapping screws

Type AB (F, T)

Special thread forming or cutting tapping screws

UNC

Unified National Coarse Thread

UNRC

Unified National Coarse Thread with Radius Root (standard rolled thread form)

UNF

Unified National Fine Thread

UNRF

Unified National Fine Thread with Radius Root (standard rolled thread form)

UNJ

Unified National Thread with Large Radius Root (special fatigue resistant thread)

UNR

Unified National Thread with radius root

USS

United States Standard when used with washers it is for large OD when used with screws or nuts it means coarse thread

UTS

Ultimate Tensile Strength

WAC

Width Across Corners

WAF

Width Across Flats

W/F

Washer Faced (can refer to a Nut or Cap Screw)

Whitworth

British Thread Standard (not the same as UN threads)

Y

Yellow Chromate

YS

Yield Strength

Zn

Zinc, usually referencing zinc plating (assumed to be zinc with clear chromate)

Zn/C (ZC)

Zinc Plating with Clear Chromate topcoat

Zn Phos

Zinc Phosphate and Oil (same as Phos and Oil)

Zn/Wax

Zinc Plating with a topcoat of wax

Zn/Y (ZY)

Zinc Plating with Yellow Chromate topcoat