API is the abbreviation of American Petroleum Institute. API standard is one of the production standards for petroleum pipeline. Other standards are also API 5B, API 5L, etc.
OCTG are steel pipes in the oil well or gas well, and they have three basic types, which are drill pipes, casing and tubing. The tubing is used to transport oil and gas to the ground, and the casing is used to protect and support the wall of the well. The consumption of casing is more than 70% of all OCTG.
The classification of steel grade is as follows:
The 1st group: H(40), J(55), K(55), N(80), R(95)
The 2nd group: C(95/110), L(80), M(65), T(95)
The 3rd group: P(110)
The 4th group: Q(125)
According to the manufacturing method, the tubing and casing are divided into two main categories: seamless pipe and welded pipe. Except that the six steel grade pipes of L80-9Cr, L80-13Cr, C90-1, C90-2, T95-1, T95-2 must be made of seamless pipes, other steel grade pipes can be made of longitudinally welded pipes by electric resistance welding or electric induction welding.
In order to adapt the special geological conditions of oil field, the global standard of casing and tubing is not only API standard, but also the non-API standard, including high strength tubing and casing for low temperature oil and gas wells, high Anti-collapse Oil Casing, anti-H2S stess corrosion tubing and casing for oil and gas wells with H2S, super strength casing and tubing for deep well, etc.