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Fastener Resources

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
A
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
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
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
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
E
ET
External Thread
EXT.
External Tooth Lock Washers
F
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
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)
H
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
I
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
J
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
K
Short hand for the number 1000 (also see M)
ksi
Thousand of pounds per square inch
L
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
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
N
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
O
OH (OV)
Oval Head
P
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
R
Radius
RD
Round Head or Right Hand Thread
RT
Rolled Threads
S
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
T
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
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
W
WAC
Width across Corners, measurement used on nuts, bolts and screw heads
WAF
Width across Corners, 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
Y
YS
Yield Strength
Z
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

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