OCTG pipe refers to Oil Country Tubular Goods, a collection of rolled metal products, more commonly known as drill pipe, casing and tubing which are manufactured according to API specification. It used both onshore and offshoreiIn petroleum industry.

Drill pipe is a seamless tube that rotates the drill bit and circulates drilling fluid. It is hollow to allow drilling fluid to be pumped down the hole through the bit and back up the annulus. The annulus of an oil well is the space between any piping tubing or casing and the piping, tubing or casing immediately surrounding it. The presence of an annulus gives the ability to circulate fluid in the well. Drill pipe is subjected to high torque by drilling, axial tension by its dead weight and internal pressure by purging of drilling fluid.

Casing is the pipe used to line the borehole, which is the actual hole dug into the ground to get to the oil. Like the drill pipe, it too is subject to axial tension. However, it differs in that while needing to handle internal pressure from the oil itself, there is also external pressure from the rock and sediment it has been bored into. It too is extremely heavy duty and crucial to OCTG.

Tubing is the pipe that goes inside the casing pipe. This is the pipe that the oil itself will eventually make its way out of. The most simplistic of the OCTG family, tubing pipes can usually be found in segments of about 9m (30 ft), with threaded connections on each end, which can be protected with drill pipe protectors during transportation and storage. These protectors also help protect against any corrosion that could happen during storage, which could cause major problems when tons of oil are being pumped through.