Flush-coupled casing tubes have a box thread at both ends and are connected together by a pin-to-pin coupling. This allows couplings to be replaced when pin threads become worn or damaged. It also means that the casing tube can have a thinner wall than the coupling, allowing the overall weight of the casing string to be minimized. This can be important when drilling to greater depths.
Flush-jointed casing has a heavier wall section than coupled casing and has integral pin and box threads. The heavier wall section provides internal and external mating shoulders for the threads to butt-up against, providing twice the contact area of coupled casing which helps prevent the threads climbing under heavy torque. This is by far the most popular casing used for geotechnical applications.
Casing drive adaptors and casing bits and casing shoes are available with both T.C. and diamond cutting edges.
| X Series Flush-coupled Casing | ||||
| Size | Tube O.D. in. (mm) |
Tube I.D. |
Coupling I.D. in. (mm) |
Threads per inch |
| NX | 3.500" (88.9) | * | 3.000" (76.2) | 8 |
| HX | 4.500" (114.3) | * | 3.960" (100.6) | 5 |
| PX | 5.500" (139.7) | * | 4.875" (123.8) | 5 |
| SX | 6.625" (168.3) | * | 5.875" (149.2) | 5 |
| Standard effective lengths are 3000, 1500 and 750 mm. Other lengths manufactured to order. *Casing tube ID can be variable. | ||||
| W Series Flush-jointed Casing | |||
| Size | Tube O.D. in. (mm) |
Tube I.D. in. (mm) |
Threads per inch |
| BW | 2.875" (73.0) | 2.375" (60.3) | 4 |
| NW | 3.500" (88.9) | 3.000" (76.2) | 4 |
| HW | 4.500" (114.3) | 4.000" (101.6) | 4 |
| PW | 5.500" (139.7) | 5.000" (127.0) | 3 |
| SW | 6.625" (168.3) | 5.937" (150.8) | 3 |
| UW | 7.625" (193.7) | 6.937" (176.2) | 3 |
| ZW | 8.625" (219.1) | 8.000" (203.2) | 3 |
| Standard effective lengths are 3000, 1500 and 750 mm. Other lengths manufactured to order. | |||
