OCTG refers mainly to casing and tubing but also can refer to line pipe and
other pipe used in producing or transporting gas and oil. Casing is the pipe
that is used while drilling the well. It is placed in the well, cemented in place,
and is what keeps the hole from sloughing in while drilling or producing.
.jpg) |
| Picture Source : http://www.aogr.com |
It
“cases” the open hole. It comes in sizes ranging from 30” to 3 ½” in diameter.
Usually several “strings” of casing are using in each well. Tubing is the pipe
that is inserted in the well during well completion operations. This is the
pipe by which the oil and gas flows to the surface. It is frequently removed
from a well during workover or completion operations.
Tubing
comes in sizes from 4 ½” to 1 ½” diameter. Casing and tubing each use special
connectors in order to screw the joints together. These connectors are called
connections and come in all types of sizes and thread profiles depending on the
intended use.
 |
| Picture source : http://www.imoa.info |
A joint
of tubing or casing is made up of the “tube” and the “connection.” Connections
are sometimes separate items called couplings or they can be integral or a part
of the tube. Again, the intended use dictates that type of connection. Line
pipe is a separate type of tube from tubing and casing. Line pipe is what makes
up a pipeline. Pieces are connected together by welding. Line pipe is less
expensive and less rigorously used than tubing or casing. Companies that
manufacture these items are Tenaris, Vallourec, Sumitomo Steel, JFE and others.
