Have you ever come across the term OCTG? If you are in the plumbing industry, you may have heard this word among your colleagues. So, if you want to know what OCTG pipe is in general, stay on this page and discover its meaning, key features, main uses and other relevant information.
Discovering what an OCTG pipe is
OCTG stands for Oil Country Tubular Goods, which then refers to the pipes used by the oil and gas producing industries. This selection of metals can be installed onshore or offshore, depending on the company.
Due to the nature of its use, OCTG pipes are created in accordance with American Petroleum Institute (API). This renowned trade association encompasses the oil and natural gas industry, pioneering the creations and advancements of key petroleum and petrochemicals.
1. Physical characteristics
OCTG pipelines are constructed according to specific guidelines developed by API. Currently, there are over ten different OCTG grades, which vary greatly depending on the materials used. Variations in physical properties often come from different chemical compositions and process heat treatments.
2. Composition of the key
They are generally made of chromium and manganese, which are very strong and cohesive alloys. But in recent years, many are now capitalizing on OCTG pipes that have both alloy and molybdenum characteristics to help address the risk of sulphide stress cracking.
3. Different variants
Moreover, they come in many sizes with unique lengths and thicknesses. The finish of the pipes also differs, either welded or seamless. In addition to physical characteristics, there are OCTG pipes created for specific performance. Thus, it is important to be able to identify the main types of OCTG pipe.
Learning the major functions of OCTG pipes according to their type
OCTG is divided into four types. Each of these types highlights a specific set of properties and functions, which you need to understand in order to distinguish them from each other.
1. Drill pipes
First on the list is OCTG drill pipe. It is a durable and heavy duty pipe used to penetrate the soil surface. These types of pipes are generally used during the initial phase of the well, which is a hole created to acquire natural elements such as oil and other gases.
During the drilling process, this seamless pipe is placed at ground level so that it can easily infiltrate the surface. Then it pivots a bit so it breaks into rock or dirt. Drill pipes are often operated at high torque, internal pressure and axial tightness for efficient fluid purge.
Moreover, these pipes are generally hollow to ensure that the fluid is conducted inside the annulus, in the space surrounding the two concentric materials or in the pipework. The annulus is a key part of an oil well or water well because its flat shape properties allow the drilling fluid to flow smoothly.
Apart from the annulus, a drill pipe consists of the tube body and the tool joint. Meanwhile, pipe joints are classified in ranges 1, 2 and 3. And in terms of dimensions, OCTG drill pipes have a lot of variety, from their dimensions to wall thickness.
In addition, pipes are expected to conform to API Specifications, especially 5DP and SPEC 7-1. Creating drill pipes according to API standards is very important because they have to withstand underground stress during the drilling process.
2. Casing
The next type is the casing, a pipe that is characterized by its large width. This large diameter pipe is accumulated and then implanted in a well. Generally, the casing remains stationary while you add cement.
The casing plays a crucial role in protecting the soil while supporting the flow of fluid or oil. It ensures the safety of underground water against possible contamination. In addition, this helps stabilize the well, preventing fluid loss, providing a solid top foundation, and ensures a smooth internal bore.
Other functions of a casing pipe include effective isolation of different areas of different pressures and adequate sealing of high pressure areas to avoid dangerous explosions. A key comparison between a drill pipe and a casing pipe is the inclusion of the external pressure that is handled by the latter.
Apart from the axial tension that accounts for its dead weight, as well as the significant internal pressure, most casing pipes must withstand external compression from their surroundings. These may include rock formations and various subsurface sediments.
Considering its importance, the casing pipes should be robust to withstand the compressive force during the piping process. Its durability protects the well against collapse and guarantees that the drilling process is carried out efficiently. As an integral part of the process, you need to choose the right diameter size.
Most casing pipes range in diameter from 4.5″ to 20″. There are also different types of casing pipes such as conductor casing, production casing and liner fixing casing among others. And steel pipes are normally referred to as API 5CT.
These OCTG pipes also have different common grades including J55, N80, T95, L80, P110 and the like. In terms of prices, steel casing pipes are mostly cheaper than drill pipes and tubular pipes.
3. Tubes
Moving forward, there is pipe pipe, which is considered the simplest of all other OCTG pipes. Although its properties are quite simple, it is nevertheless an essential element in the drilling process, mainly because it has the task of transporting the elements from the hole to the surface.
Pipes are the materials they pass through casing pipe, serving as a tube in which elements such as crude oil, natural gas or fluids are transported on the ground. After extraction, it then transports the pumped oil or deposits from the producing formation to facilities for further verification.
During shipping, many add drill pipe protection to the pipes to protect the oil from corrosion. These materials have corrosion resistance to guarantee that there is no potential oil contamination during the transport and storage stages.
And to fulfill all the tasks, tubular pipes are expected to have robust properties to withstand pressure as well as to cope with heavy loads and possible deformations due to production. And to ensure a durable material, the pipe manufacturing process is much more complicated.
Next is the normal creation of the drill pipes, with the addition of tumbling, which is the process by which the pipes are thickened. These are then graded into different sizes, normally between 1 1/4″ and 4.5″.
Moreover, the pipes are generated in segments that are approximately 30 ft. In addition, they can have threaded connections so that drill pipe connectors can be easily attached.
4. Line pipes
Finally, conduit pipes are normally made from solid high carbon steel to efficiently transport deposits such as oil, natural gas or petroleum. Like all OCTG pipe, it is manufactured in accordance with API. Meeting API requirements is vital to ensure process quality and workplace safety.
Thus, many pipe companies follow API 5L standards for steel chemistry, dimensional properties, and hardness when producing pipe. On the other hand, OCTG line pipes vary in diameter, some as small as 2 inches, while others up to 48 inches.
In addition to physical composition and size, pipes can be seamless tube or welded carbon steel. There are also some pipe ends that are plain and others that have chamfered, flanged, threaded or grooved fittings. And since the line pipes are part of the OCTG family, they are cast to withstand high pressure.
Knowledge of OCTG connections
In addition to the major types of OCTG pipe, you also need to understand the primary OCTG connections. There are actually three divisions created that should comply with API standards. The first is the API OCTG connections, which are those that meet or even exceed the standards set by the API.
The other categories are semi-premium and premium connections. These are pipelines that go beyond API standards, allowing them to work in more complex environments and even harsher settings.
Exploring different OCTG pipe manufacturers
With hundreds or perhaps thousands of options on the market, choosing the best OCTG supplier can be a tough challenge. Therefore, you need to understand the key elements of a quality OCTG pipe, whether you are looking to purchase drill pipe, pipe, tubing or pipe.
As a general rule, OCTG pipelines should meet the requirements set forth by the American Petroleum Institute. It is also essential for production facilities to follow the ISO 9001 guide, which takes the basic requirements of the quality management system.
Therefore, it is highly recommended to choose a supplier or distributor that is both API and ISO compliant, so that you save money and effort on unwanted repairs. Not only that, but choosing a reputable manufacturer with a solid reputation ensures excellent and long-lasting OCTP pipes.
Conclusion
Now that you have a thorough understanding of what an OCTG pipe is, it will be easy for you to distinguish them from other pipes. Moreover, having a solid understanding of OCTG pipe types helps you choose the best option for your needs.
