What is OCTG? It includes Drill Pipe, Steel Casing Pipe and Tubing

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What is OCTG? It includes Drill Pipe, Steel Casing Pipe and Tubing

OCTG is the abbreviation of Oil Country Tubular Goods, it mainly refers to the piping products that applied in the oil and gas production (drilling activities). OCTG pipe normally is manufactured based on API or related standard specifications. It also could be taken as a collective name of Drill pipe, Steel Casing Pipe and Tubing pipe, Couplings, Connections and Accessories, used in petroleum industries that onshore and offshore.

According to the API (American Petroleum Institute) standardized specifications, through the control on the chemical properties and adopts different heat treatment, OCTG pipe is classified into different performances material more than ten grades.

Types of Oil Country Tubular Goods (OCTG pipes)

There are three main types of Oil Country Tubular Goods, which includes Drill pipe, Casing pipe and Tubing pipe.

For to get you a better understanding, we will explain the meaning of each of the three to help you understand their work and their use.

OCTG Drill pipe – Pipe for Drilling

Drill pipe is a heavy, seamless tube that rotates the drill bit and circulates drilling fluid. It allows the drilling fluid to be pumped through the bit and back up the annulus. The pipe is subject to axial tension, extremely high torque and high internal pressure. That is why the pipe is extremely strong and vital in OCTG endeavour.

Drill Pipe normally mean for the Durable steel pipe used in drilling, standards in API 5DP and API SPEC 7-1.

If you don’t understand the annulus of an oil well, it is the space between the casing and the piping or any piping tubing, casing or piping immediately surrounding it. Annulus allows the fluid to circulate in the well. So when we are talking about strong or heavy duty OCTG pipe, we are talking Drill pipe.

Steel Casing pipe – Stabilize the wellbore

Steel casing pipe is used to line the borehole that is being dug into the ground to get oil. Just like the drill pipe, the steel pipe casing is also subject to axial tension. This is the large diameter pipe inserted into a drilled borehole and held into place with cement. The casing is subject to axial tension by its dead weight, external pressure by the rock surrounding it and internal pressure by the fluid purging. When it is well cemented in place, the drilling process is aided in the following ways:

· Casing sticks the drill string and prevents unstable upper formation from caving in.
· It prevents water well zones contamination.
· It allows smooth internal bore for installing production equipment
· It prevents contamination of production zones and fluid loss.
· It seals off high-pressure zone from the surface
· And much more

The casing is extremely heavy duty pipe which is vital to OCTG.

OCTG Casing Pipe standard

Steel Casing pipe standards usually referred to API 5CT, Common Grades in J55/K55, N80, L80, C90, T95, P110 etc. Common length in R3 which nominal at 40 ft / 12 meters. Casing pipe ends connection types usually in BTC and LTC, STC. And premium connections also required in large quantity in a oil and gas piping project.

Steel Well Casing Pipe Price

Steel Casing Pipe cost is lower than drill pipe or the OCTG tubing cost, it is usually higher 200 USD than the regular API 5L pipe. Considering the Threading + Coupling cost or the heating treatment.

OCTG Tubing Pipe – Transporting Oil and Gas to the Surface Ground

OCTG Tubing pipe goes inside the casing pipe because it is the pipe through which oil makes its way out. Tubing is the simplest part of OCTG and it is normally found in the segment of 30 ft (9 m), with threaded connection at both ends. The pipe is either used to transport natural gas or crude oil from the producing formation to the facilities where it will be processed after drilling is complete.

This tubing must be able to withstand pressure during the extraction process and adequately resist loads and deformations that have to do with production and workovers. Just like casing is manufactured, tubing is also manufactured the same way but the additional upsetting process is applied to make it thicker.

OCTG Tubing pipe standard

Same like casing pipe standard, OCTG tubing also in API 5CT in same material grades (J55/K55, N80, L80, P110 etc), different is Tubing diameters is upto 4 1/2”, and tubing ends in various types as BTC, EUE, NUE and premium. Most common is thicken connections EUE.

How steel casing pipe and tubing working together

OCTG pipe Casing and Tubing Specifications

Casing and Tubing Chemical composition in API 5CT
API 5CT Casing and Tubing Data Sheet Download

Mechanical Properties Tensile Strength and Yield Strength

Features for OCTG pipe

All OCTG pipe have a standard requirement of dependable hardness. So whether it is OCTG tubing, OCTG pipe or OCTG drill pipe, there is a certain required standard which is always about super hardness. To meet the standard, manganese and chromium are used as the main alloys to confirm the cohesion and durability.

There has been recent development to eliminate sulphide stress cracking which is the major problem with the manganese and chromium. Alloy and Molybdenum are blended together to overcome the chromium and manganese limitations. So OCTG pipes are now harder than ever and the fear of sulphide stress cracking has been eliminated.

Looking to buy OCTG Pipe with assured quality at a good price?

Unlike in the past when sulphide stress cracking is a major issue, OCTG pipes are now harder than ever before and are well protected against cracking. If you are looking for the best OCTG distributor, look no further because we are a responsible OCTG distributor.

We make sure our drill pipe, casing and tubing are made to the best quality from guaranteed raw steel material, with the competitive prices all over China. All the Oil Country Tubular Goods we supplied comply to API standards and under witness inspection from third parties, where is dedicated to use for decades to save your cost in a long run.

As a recognized professional manufacturer, supplier and distributor, we provide a piping solution for oil and gas companies. Contact us for top-quality OCTG pipe today.