OCTG, or oil country tubular goods, refers to a variety of steel products that are used in the drilling and extraction of oil and gas. The API 5CT standard covers a wide range of OCTG products, including tubing, casing, and couplings. OCTG products are essential for the safe and efficient operation of oil and gas wells. The API 5CT standard helps to ensure that OCTG products meet the highest standards of quality and safety. It includes requirements for material quality, dimensions, strength, threading, and testing. The API 5CT standard is an important part of the oil and gas industry, and it helps to ensure that OCTG products are safe for use in petroleum operations.
Why Choose TUSPIPE?
Since 1998, Tianjin United Steel Pipe Co., Ltd (TUSPIPE) has been committed to supplying high-quality line pipes.
With over 500,000 tons annual production capacity, the company serves various fields and industries, such as oil & gas exploitation and transmission, ship & auto-building, water & electricity, environmental protection, mechanical engineering, infrastructure construction and etc.
TUSPIPE places a premium on product quality and rigorous product quality control. In order to maintain good product quality, the company has established a Test & Inspection Center since 2004. With a series of state-of-the-art tests and inspection equipment, the test & inspection center is able to perform the tensile tests, hydro tests, impact tests, DWTT, etc.
Types of OCTG (Drill Pipe, Casing and Tubing)
OCTG stands for oil country tubular goods. It is a family of rolled metal products that are utilized in oil and gas drilling and production operations. The term OCTG encompasses a wide range of products, including drill pipe, casing, and tubing. These products are used to connect the wellhead to the downhole equipment, allowing oil and gas to be extracted from the ground. OCTG is a critical component of the oil and gas industry, and its products are essential for safe and efficient drilling operations.
Drill Pipe is a type of pipe that is used in oil and gas wells. It is made up of several different parts, including the kelly, the bit, the drill string, and the casing. The kelly is the part of the drill pipe that is attached to the rig, and it helps to rotate the drill string. The bit is the part of the drill pipe that drills into the rock, and it is usually made of steel or tungsten. The drill string is the part of the drill pipe that extends from the kelly to the bit, and it helps to provide support for the bit as it drills. The casing is the final part of the drill pipe, and it helps to protect the wellbore from collapse. All of these parts work together to help oil and gas wells function properly.
Casing and tubing are both used in the process of drilling for petroleum. The casing is placed before drilling begins and surrounds the wellbore. Its purpose is to protect the soil layers and groundwater from contamination by drilling mud and/or frac fluids. Additionally, the casing stabilizes the wellbore. Drilling and casing operations alternate – the drill string is removed at predetermined intervals and the wellbore is lined and cemented with casing.
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 the casing. Consequently, the tubing must be affixed to external support structures, such as a rig or platform, to prevent collapse due to pressure differentials.
Types of OCTG Connections
Oil Country Tubular Goods (OCTG) are pipes used in the oil and gas industry to transport crude oil, natural gas, and other fluids. They come in different sizes and grades, and each length of pipe has a specific use. OCTG connections are what join these pieces of pipe together to form a network that can transport oil and gas from one location to another.
API connections are the most commonly used type of connection in the oil and gas industry. They meet or exceed all American Petroleum Institute (API) specifications. API proposes two types of coupling: Non-Upset coupling (NU) and External Upset coupling (EU). NU connections are used for joining two pipes of the same diameter, while EU connections are used for joining two pipes of different diameters.
Premium connections are proprietary connections that offer premium features not available on API connections. Most premium connections offer a metal-to-metal seal for improved high-pressure seal integrity. Premium connections exist with features such as flush connections, recess-free bores, and special clearance. This type of connection is preferred for gas wells, high-pressure wells, as well as for wells producing corrosive effluents.
In addition, OCTG threading is a process that creates grooves on the body and end of casing pipes. These grooves form a seal when the pipe is connected to another piece of equipment or piping. The threads are typically Leak–proof, strong, and durable enough to withstand the distribution network for oil and gas. There are three different types of OCTG threading, each with specific benefits: Short round thread casing (STC), long round thread casing (LTC), and buttress thread casing (BTC).
STC is a good choice for shorter-length casing applications that do not involve high axial loads or bending. LTC is well suited for situations where some axial load is encountered but overall well conditions do not include extremes of temperature or pressure. BTC is an excellent connection for use in well situations involving higher axial loads and moderate internal pressures and temperatures. STC and LTC both feature a non–runout design of round threads, each with eight round crested threads per inch. BTC has a square thread with a flat root and crest, a runout design, and five buttress threads per inch.
Each type of OCTG threading has benefits that make it ideal for certain applications. When selecting the best type of threading for your project, be sure to consider the well conditions and the type of equipment that will be used.
Production Standards of OCTG
API 5CT is the American Petroleum Institute’s specification for oil and gaswell casing and tubing. The specification covers coupling, threading, dimensions and other mechanical properties for oil and gas industry products like casing and tubing. API 5CT is the most common standard used in oil and gas industry applications. The specification covers several grades of steel, including J55, K55, N80, L80 and P110. Coupling is a threaded connection used to join oil and gas well casing or tubing. Threading refers to the process of cuttinng threads into the end of a pipe or coupling. Dimensions vary depending on the type of casing or tubing being used. American Petroleum Institute standards are voluntary consensus standards that are not mandated by law. However, oil and gas companies often require that products used in their operations meet API standards.
Dimensions and Sizes of OCTG (Tubing and Casing)
- Specification & Size of Tubing
|DN||O. D.||Weight||W. T.||End Processing|
|Non-upset coupling-thread||Upset coupling-thread||Steel Grade|
|P——Plain；N—— Non-upset coupling-thread；U—— Upset coupling-thread； L——Integral|
- Specification & Size of Casing Pipe
|DN||O. D.||Weight||W. T.||End Machining Form|
|P——Plain；S——Short-thread；L——Long-thread；B——Buttress thread；E——Extreme thread|
Chemical Composition of OCTG (Tubing and Casing)
Mechanical Properties of OCTG (Tubing and Casing)
OCTG for Sand Control - Slotted Liner
Slotted liner is a well screening device that is used for sand control and fluid retention in petroleum wells. It consists of a series of slotted holes that are drilled into the well screen to allow fluid to flow through while retaining sand and other particulate matter. Slotted liner is an effective way to improve well productivity and prevent formation damage. It is also a cost-effective alternative to traditional well screens. Slotted liner can be used in both new and existing wells, and it is available in a variety of materials and configurations.