
ISO M (Metric) and UN (Unifi ed National) UNJ (controlled root radius) Whitworth (BSW)
Use: Fittings and pipe couplings for gas, water, and
| Use: All branches of mechanical industry. | Use: Aircraft and space industry. | sewer lines (replaced by ISO). | |
| American Buttress | NPT (American National Pipe Thread) | BSPT (British Standard Pipe Thread) |
1/2 D play
1/2 D2 play axis of screw taper 1:16 taper 1:16
1/2 D1 play axis of screw
Use: Fittings and pipe couplings. Use: Fittings and pipe couplings. Use: Pipe thread for steam, gas, and water lines.
nut 1/2 D play 1/2 D play
1/2 D1 play 1/2 D2 play
| screw | 1/2 D1 play | 1/2 D2 play | ||
| A = 0,0307 P | ||||
| B = 0,3707 P—x D play | A = 0,4224 P | |||
| C = 0,3707 P—(D1 play—D2 play) | B = 0,4224 P—x D play |
Use: Mechanical industry for motion Use: Acme-General is used in mechanical industry for C = 0,4224 P—(D1 play—D2 play)
transmission screws. motion transmission screws. Use: Where normal Acme is too deep.
pitch line
taper = 62,5mm per metre on diameter
NOTE: Taper shown exaggerated.