In mechanical engineering, the thread angle of a screw is the included angle between the thread flanks, measured in a plane containing the thread axis.[1] This is a defining factor for the shape of a screw thread. Standard values include:
| Name | Code | Angle | Profile | Standards | |
|---|---|---|---|---|---|
| Most V-threads | M | 60° | including DIN 13 / ISO, NPT and UTS | ||
| Whitworth threads | W | 55°[2] | |||
| British standard pipe thread | G | 55° | DIN / BS / EN / ISO 228-1 / ISO 7-1 | ||
| National Pipe Thread | NPT | 60° | ASME B1.20.-1983 Pipe Threads, General Purpose, Inch | ||
| Rd | 30° | [6] | DIN 405 / DIN 20400 | |
| Acme thread[7] | 29° | ASME/ANSI B1.5-1988 | |||
| Metric trapezoidal threads | Tr | 30° | DIN 103 | ||
| Buttress threads | S | 45° | DIN 2781 | ||
| German buttress threads | S | 30° | DIN 513 | ||
| Square threads | Sq | 0° (parallel) | ? | ||
| Panzergewinde, "steel conduit thread" | Pg | 80° | DIN 40430 | ||
| British Association (BA) thread | BA | 47°30'= ° | BS 93:2008 | ||
| Löwenherz thread[8] | 53°8'≈ ° | ||||
| Bodmer thread[9] | 50° | ||||
| Thury thread[10] [11] | 47°30'= ° |
