COMMON ABBREVIATIONS USED WITH FASTENERS

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)

8.8-Grade 8.8 bolt

10.9-Grade 10.9 bolt
6g - Class of thread fit for metric screws
6H - 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 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 - Computer Aided Design/Drafting
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 Handed Thread
L/W - Locked 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” 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 used with washers it is for large OD 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/silver Chromate topcoat