United Kingdom

B.S.W. British Standard Whitworth
B.S.F.  British Standard Fine
T.W.F. Truncated Whitworth Form
T.W.F. with flat crests
B.S.B.  British "Standard" Brass - (no official standard exists)
M.E.  Model Engineers (60, 40, 32 & 26 t.p.i. Series
B.S.E.C.  British Standard Electrical Conduit
B.S.P.  British Standard Pipe
B.S.T.P. British Standard Taper Pipe
B.S.P.P. British Standard Parallel Pipe
B.A.   British Association
B.S.C.  British Standard Cycle (formerly C.E.I. Cycle Engineers' Institute)
S.M.M.T. British Motor Tyre Valve Thread

Threads without commonly-recognised initials:

Spark Plug Thread
Standard Buttress Thread
British Standard Metric Thread
Acme Threads
Bottle Closure Threads
Copper-tube Screw Thread
Cordeaux Thread for Telegraph Insulators
Gas Cylinders Taper Threads (1 in 8 and 1 in 5.625 tapers)
Coach Screw Threads (for wood)
Taper Threads for Porcelain Moulds
Edison Screw Threads for Lamps

Miscellaneous Whitworth-form (55-degree) Threads

Original Whitworth Pipe
Condenser Tube Gland
Drum Plugs (mild-steel, heavy-duty drums)
Endoscope Lamp Housings
Microscope Objectives and Nose Pieces
Oil Switch Gear
Optical Instrument Fine Motion & Adjustment
Optical Instrument
Camera Lens Flange Fittings (Royal Photographic Society Standard)
Leica and other makers' lens and fastener threads
Water Well Casings
Hydraulic Pipe
Suction Hose Coupling (fire) = Round or Knuckle threads
Spark Plug Threads (automotive)
Water Well Casing
B.S. Taper Pipe Thread

I.S.O. metric threads--fine-pitch series to B.S. (British Standard) 3643
I.S.O. metric threads--M designation to B.S. 3643 and S Designation to B.S. 4827
Metric Constant Pitch Threads for Model Engineers to B.S. PD6507-1982

United States of America

N.C.   National Coarse
N.F.   National Fine
U.N.C.  Unified National Coarse
U.N.F.   United National Fine
U.N.S. Unified Special Thread
Small U.N.C.
Small U.N.F.
Regular U.N.C.
Regular U.N.F.
N.E.F.  National Extra Fine
U.N.E.F. Unified National Extra Fine
U.N.M. Unified Miniature Series
U.S. National Pipe Threads (Sellers)
4.U.N.  Unified 4-Thread Series
6.U.N.  Unified 6-Thread Series
8.U.N.  Unified 8-Thread Series
12.U.N.  Unified 12-Thread Series
16.U.N.  Unified 16-Thread Series
20.U.N.  Unified 20-Thread Series
28.U.N.  Unified 28-Thread Series
32.U.N.  Unified 32-Thread Series
8 N  National 8-Thread Series
12 N  National 12-Thread Series
16 N   National 16-Thread Series
N.T.P.  National Taper Pipe Thread
Spark Plug Threads

S.A.E. Dry Seal Pipe Threads (Society of Automotive Engineers)
N.P.T.F.  Dryseal Standard Pipe Thread
P.T.F.-S.A.E.  Dryseal S.A.E. Short taper Pipe Thread
N.P.S.F.  Dryseal Fuel Internal Straight Pipe Thread
N.P.S.I.  Dryseal  Intermediate Straight Pipe Thread

Unified Thread for Thin Wall Tubing
American Acme
American 29-Degree Stub Thread
American 60-Degree Stub Thread
American Modified Square Thread
American A.P.I. Line Pipe Thread
American Parallel Pipe Thread

Europe

French  Metric Series
French Automobile Thread
German Metric Series
German Metric Uniform Pitch Series
German 0.5 mm Pitch Series (Metrisches Feingewinde D.I.N. 519)
German 1.5 mm Pitch Series (Metrisches Feingewinde D.I.N. 516)
German 2 mm Pitch series (Metrisches Feingewinde D.I.N. 247)
German 3 mm Pitch series (Metrisches Feingewinde D.I.N. 246)
German 4 mm Pitch series (Metrisches Feingewinde D.I.N. 245)
German 6 mm Pitch series (Metrisches Feingewinde D.I.N. 244)

German Löwenherz Thread--precision instruments
German Buttress (Sägengewinde or Saw Tooth)
German Sewing Machine Series
German Bottle Closure Thread
Trapizodial Metric Thread
Swiss Metric Threads
Swiss (Thury) Threads
Swiss Steinlen Threads



ISO Metric Threads