API Oilfield Threads Chart
| BASIC DIMENSIONS AND PITCH | |||
|---|---|---|---|
| API thread family | Basic profile / designation | Dimensional standard | Dimension set |
| Line pipe | Round thread | API Spec 5B | OD, TPI, taper, engagement and gaging |
| Casing | Round thread (short/long) and buttress | API Spec 5B / 5CT | OD, TPI, taper, coupling and gaging |
| Tubing | Non-upset / external-upset | API Spec 5B / 5CT | OD, TPI, taper, shoulder and gaging |
| Drill pipe | Rotary shouldered connection | API Spec 7-2 | OD, pitch, taper, shoulder and gaging |
API oilfield threads are several separate connection systems rather than one interchangeable size series. API 5B/5CT/7-2 define different dimensional tables; select the connection type and nominal OD before a numeric size chart can be specified.