Common Thread Forms Technical Information ISO M (Metric) and UN (Unified National) Use All branches of mechanical industry American Buttress UNJ (c

Common Thread Forms Technical Information ISO M (Metric) and UN (Unified National) Use All branches of mechanical industry. American Buttress UNJ (controlled root radius) Use Aircraft and space industry. NPT (American National Pipe Thread) Whitworth (BSW) Use Fittings and pipe couplings for gas, water, and sewer lines (replaced by ISO). BSPT (British Standard Pipe Thread) Use Fittings and pipe couplings. TR DIN 103 Use Mechanical industry for motion transmission screws. Use Fittings and pipe couplings. Acme A 0,0307 P B 0,3707 P x D play C 0,3707 P (D1 play D2 play) Use Acme-General is used in mechanical industry for motion transmission screws. Use Pipe thread for steam, gas, and water lines. Acme, truncated (Stub) A 0,4224 P B 0,4224 P x D play C 0,4224 P (D1 play D2 play) Use Where normal Acme is too deep. API Casing and Tubing Round Thread Form NOTE Taper shown exaggerated.