Worldwide Fastener Abbreviations

18-8
Stainless Steel with 18% chrome and 8% nickel, also aka 304 stainless steel

2, 5 or 8
Strength grade of hex head cap screws and nuts

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 Nuts)

17
Type 17 Screw Point

17-4 PH
Martensitic Stainless Steel Alloy

2024-T4
Aluminum Alloy used on fasteners

302- 304
Common Grades of Stainless Steel Fasteners

316
Grade of Stainless Steel used for Fasteners

410
Grade of Stainless Steel used for Fasteners

6g
Class of thread fit for metric screws

6H
Class of thread fit for metric nuts

6061-T6
Aluminum Alloy used on fasteners

6262-T9
Aluminum Alloy used on fasteners

7075-T73
Aluminum Alloy used on Fasteners

A193
ASTM Spec for Alloy Steel and Stainless for Bolts, High Pressure & High Temperature

A194
ASTM Spec for Carbon and Alloy Steel for Nuts, High Pressure & High Temperature

A286
Incoloy® Alloy

A307
ASTM Spec for Carbon Steel Bolts & Studs

A325
ASTM Spec for Structural Bolts

A490
ASTM Spec for Structural Bolts

A563
ASTM Spec for Carbon and Alloy Steel Nuts

A
Type "A" Tapping Screw

AB
Type "AB" Tapping Screw

ABS
Class of Plastic Material- based on acrylonitrile-butadience-styrene copolymers

AISI
American Iron and Steel Institute, specifies chemical composition of steel

ALU
Aluminum Material, specify type (ex 6061-T6)

AN
Precedes a dimensional specification for aircraft fasteners developed by ASG

ANSI
American National Standards Institute

AS
Alloy Steel

ASME
American Society of Mechanical Engineers

ASTM
American Society of Testing and Materials

B
When followed by a number (ex B-90) hardness measured on the Rockwell B Scale, or an abbreviation for Type "B" tapping screws, or an abbrev. for Boron

Bake
Heat Treat process used in plating to prevent Hydrogen Embrittlement

BF
Type BF Thread Former/Cutter

BHN
Hardness measured with a Brinell Hardness Tester

BHSC
Button Head Socket Cap Screw

BHT
Button head Torx® socket cap screw

Bind
Binding Head

Bl Ox
Black Oxide

BR
Brass Material

BRZ
Bronze Material

BS
British Standard

BSF
British Standard Fine Thread

BSW
British Standard Whitworth Thread

BT
Bolt (on drawings)

C
When followed by a number (ex C-35) hardness measured on the Rockwell C Scale, or an abbreviation for Carbon Steel, stands for National Coarse Thread and Type C Screw T/F

CB
Carriage Bolt

CH
Case Hardened (type of heat treatment)

CL
Class (Metric Material/Strength Specifications)

CP
Cotter Pin

C/R
Cross recess drive (i.e. Phillips drive) or Chamfer/Radius

Cad
Cadmium Plating

CAD
Computer Aided Design/Drafting

Cad/Wax
Cadmium plating with a topcoat of Wax

CARR
Carriage Bolt(s)

COO
Country of Origin

CPR
Copper Material

CR
Chrome

CRS
Cold Rolled/Drawn/Finished Steel, 1008-1020 unless specified

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

CS
Countersunk Screw or Carbon Steel

CSL
Castle Hex nuts

CT
Coarse Thread

D
Type D or Type 1 Thread Former/Cutter

DAC (Dac 320)
Dacromet Coating

D/C
Double Chamfered Nut (distinguished from a washer face)

D/E
Double End Stud

Dia.
Diameter

Dich
Di-Chromate

DIN
German Standards Organization

Driseal
Pipe Thread

ET
External Thread

EXT.
External Tooth Lock Washers

F
Type F Thread Former/Cutter

F436
Hardened Flat Washer with Dimensions per ASTM F436

F844
Unhardened, general purpose flatwashers

FB
Flange Bolt

FBS
Floor Board Screws

FH
Flat Head

FHCS
Flat Head Cap Screw

Fil
Fillister Head

Flng
Hex Flange Bolt or Nut

Fndr
Fender Washer

FT
Fine Thread

FTI
Fastener Training Institute

F/T
Fully Treaded (i.e. Stud)

FW
Flat Washer

G
Grade

Galv (Galvi)
Galvanized, typically Hot Dipped Galvanized

Gr.
Grade, refers to strength level of Hex Head Screws and/or Nuts, i.e. (Gr. 5, Gr. 8)

Hardened
A product that has been heat treated

HB
Hex Bolt, or Hardness reading measured on the Brinell Scale

HD
Head

H.T.
Heat Treated

HCS
Hex Head Cap Screw

H.D.G.
Hot Dipped Galvanized

HHCS
Hex Head Cap Screws

HHMB
Hex Head Machine Bolt

HRB
Hardness measured on the Rockwell B Scale

HRC
Hardness measured on the Rockwell C Scale

HVHX
Heavy Hex Head Bolt

HWH
Hex Washer Head

HWHS
Hex Washer Head, Slotted

HX
Hex

IFI
Industrial Fastener Institute

IH (Ind Hex)
Indented Hex

In.
Inch

INT
Internal Tooth Lock Washer

Int/Ext
Internal Tooth & External Tooth Lock Washer

ISO
International Standards Organization

ISIR
Initial Sample Inspection Report

IT
Internal Thread

J429
SAE Standard that specifies mechanical & material requirements for externally threaded fasteners

J995
SAE Standard that specifies mechanical & material requirements for steel nuts

JMNT
Jam Nut

K
Short hand for the number 1000 (also see M)

ksi
Thousand of pounds per square inch

lbs
Pounds

Lb
Body length of screws or Lag Bolt

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 (see k)

MAFDA
Mid-Atlantic Fastener Distributors Association

MB
Machine Bolt

Mfg
Manufacturer

MFDA
Metropolitan Fastener Distributors Association

mm
Millimeter

Mod.
Modified

MS
Machine Screw

MSNT
Machine Screw Nut

MTR
Material Test Report

MWFA
Mid-West Fastener Association

NC
United National Coarse Thread

NCFA
North Coast Fastener Association

NE (NU,NTE,NTU)
Designations that define the thickness of Nylon Insert Lock Nuts

NEFDA
New England Fastener Distributors Association

NF
United National Fine Thread

NFDA
National Fastener Distributors Association

Nom
Nominal reference to dimensions

NPT
National Tapered Pipe Thread

NT (&NT)
Nut; or the fastener must include a Nut

OH (OV)
Oval Head

P
Thread Pitch

Pac-West
Pacific-West Fastener Association

P/B
Plow Bolt

PH
Phillips Head (Drive Recess)

Phil
Phillips Drive

Pl
Plain finish

PN
Pan Head

P/N
Part Number

Phos (P & O)
Phosphate and Oil Coating (typically Zinc Phosphate and Oil)

Pozi Drive
Special cross recess drive (registered trademark of Camcar Textron)

PPAP
Production Part Approval Process

psi
Pounds per square inch

PT
Partial Thread

PZ
Poxi-Drive style of cross recess

R
Radius

RD
Round Head or Right Hand Thread

RT
Rolled Threads

S
Slotted

SAE
Society of Automotive Engineers; used for "small" OD on washers; and fine thread

SBR
Silicon Bronze

Sc
Screw

SD
Square Drive

SEFA
Southeastern Fastener Association

SHCS
Socket Head Cap Screws

Skt
Socket

SL (Slot)
Slotted drive recess

SMS
Sheet Metal Screws

SPL
"Special"

Sq
Square, can refer to head or nut

Std
Standard

SS or S/S
Stainless Steel

SSS
Socket Set Screws

STFDA
Specialty Tools & Fastener Distributors Association

STL (st)
Steel

SWFA
Southwestern Fastener Association

TB
Tab Bolt

T/C
Thread Cutter

T/F
Thread Former

T.H.
Through Hardened (type of heat treatment)

Ti
Titanium

TIR
Total Indicator Reading

T/S
Tapping Screws

TPI
Threads per Inch

TT (TR)
Taptite Thread (Reminc), Tri-Roundular or Truss Head

TTH
Threaded to the Head

Type 1 (23, 25)
Thread Cutting or Thread Forming Screws

Type AB (F, T)
Thread Cutting or Thread Forming Screws

U
Type U Thread Former/Cutter

U/C FL
Undercut Flat Head

UNC
United National Coarse Thread

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

UNF
United National Fine Thread

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

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

UNR
United National Thread with radius root

USS
United States Standard; used on "large" OD washers

UTS
Ultimate Tensile Strength

WAC
Width across Corners, measurement used on nuts, bolts and screw heads

WAF
Width across Flats, measurement used on nuts, bolts and screw heads

W/F
Washer Face (often refers to hex head cap screws and hex nuts)

W/N
With Nuts

Wng
Wing Nuts or Screws

WS
Wood Screws

YS
Yield Strength

Zn
Zinc, usually referring to 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 & Oil)

Zn/Wax
Zinc Plating with a topcoat of wax

ZN/Y (ZY)
Zinc Plating with Yellow Chromate topcoat