API 5CT Tubing Carbon Seamless Steel Pipe
OCTG means Oil Country Tubular Goods, which refers to steel used in oil and gas extraction and production processes, including Drill pipe, Casing, Tubing, Couplings, Connections and Accessories, for the oil and gas industry on land and offshore.
API 5CT is the most common and important standard to ensure the normal production and exploitation of oil and gas.
Casing and Tubing are both used in the process of drilling for petroleum.
Tubing is used to carry petroleum from the well’s depths to the surface. This is the third phase of the wellbore process. Oil and gas occasionally self-elevate to the surface; however, pumps are typically required to bring the fluids to the surface. Besides the 4 1/2-inch diameter, tubing is normally smaller in diameter than casing. Consequently, tubing must be affixed to external support structures, such as a rig or platform, in order to prevent collapse due to pressure differentials.
API 5CT Tubing Colors

Example Size
Outside Diameter (O.D) | THICKNESS (TK) | Weight | End processing form | ||||||||
Grade | |||||||||||
Inch | mm | Inch | mm | TBG | UPTBG | J55 | L80-1 | N80 | C90 | T95 | P110 |
1.900″ | 48.26 | 0.145 | 3.68 | 2.75 | 2.9 | PNUI | PNUI | PNUI | PNUI | PNUI | – |
2 3/8″ | 60.32 | 0.254 | 6.45 | 5.8 | 5.95 | – | PNU | PNU | PNU | PNU | PNU |
2 7/8″ | 73.02 | 0.308 | 7.82 | 8.6 | 8.7 | – | PNU | PNU | PNU | PNU | PNU |
3 1/2″ | 88.9 | 0.289 | 7.34 | 10.2 | – | PN | PN | PN | PN | PN | PNU |
4″ | 101.6 | 0.262 | 6.65 | 10.7 | 11 | PU | PU | PU | PU | PU | – |
4 1/2″ | 114.3 | 0.271 | 6.88 | 12.6 | 12.75 | PNU | PNU | PNU | PNU | PNU | – |
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