API 5CT Series Casing

API 5CT Series Casing

API casing is a type of steel pipe used for supporting the wall of oil and gas well. It can ensure normal running of wells whenever in the drilling process or after drilling. According to different drilling depths and geological conditions, each well uses several layers of steel casing pipes. When it is used under the well, we often use cement to achieve well cementation. Different from tubing and drill pipe, API casing is a kind of one-time consumable material so it can not be reused. The total consumption of casing occupies over 70% of the whole oil well pipe. There are mainly five end processing forms for steel casing pipe, covering plain end, short round thread, long round thread, buttress thread and special thread. Our buttress thread casing (BTC) is very popular at home and abroad.

UseAPI casing is widely applied in extracting petroleum and gas. It is typically used to enclose and surround a carrier pipe that is installed in the center of this pipe. This pipe is often used in underground construction projects to encase or protect utility lines from being damaged.

Classifications of Steel Casing Pipe1. According to usage, API casing can be divided into guide pipe, surface casing, intermediate casing and oil-string casing.
  • 2. We are able to offer petroleum casings in different grades, such as H40, J55, K55, N80, L80, C90, R95, P110, Q125, etc.
  • 3. JST can also produce some special steel casing pipes, such as anti-H2S corrosion casing, CO2 corrosion resistant casing, collapse resistant casing, ultra high-strength casing, etc.
Competitive Advantages1. Our API casings have obtained API SPEC 5CT, API SPEC 5B and ISO11960 certifications.
  • 2. Our buttress thread casing (BTC) is extremely durable and versatile. Adopting state-of-the-art and fully integrated manufacturing facilities, we are capable to produce casings from 4-1/2" to 13-3/8" (outside diameter).
  • 3. API casing is available in a complete variety of different sizes and diameters.
  • 4. JST has a set of φ273 diesel rolled tube unit featuring flexible production, wide product range, convenient replacement of varieties and specifications, and wide application. Steel casing pipes rolled by this unit are of high dimension and high-quality inner and outer surface (inner face without spiral and hexagonal bore).
  • 5. We own two heat treatment production lines that can process API casings with the length of less than 13.5 m (φ114-φ406 mm). The annual output is 150,000 tons. The lines have three process routes including quenching and tempering, normalizing, normalizing and tempering.
  • 6. Our company possesses a threading production line for steel casing pipes. This line is configured with two advanced QK1319-G CNC casing thread lathes and three Q1334H CNC tubing thread lathes. The line for API casing features high precision and high stiffness and has the tool nose radius compensation function (TNRC function). There are three sets of domestic advanced hydrostatic pressure equipment with the test specifications of φ114 mm to 406 mm, and with the maximum test pressure reaching 120 MPa. Two sets of pipe end magnetic particle inspection machine are available for our steel casing pipes. They are used for inspecting inner and outer surfaces and near-surface cracks in any direction of API casing with steel pipe end within 500 mm. JST can annually process casings up to 180,000 tons.
  • 7. JST can produce buttress thread casing (BTC) with the specifications of 114.3 mm to 323.9 mm. Product quality and dimension are usually executed complying with the requirements of order contract. We produce API casings in strict accordance with API5CT standards or JST internal control standards that set smaller dimensional tolerance range. Therefore, the wall of rolled casings acquires uniform thickness and high dimensional accuracy.
Dimension Tolerance Outer Diameter Wall Thickness
JST Inner Quality Standard  -0.0%, +0.85% -3.0%, +6.5%
API 5CT Standard  -0.5%, +1% -12.50%
Performance of API 5CT Casing

There are a series of factors to influence the sealing of steel casing pipe, such as threaded geometric tolerance, surface condition, make-up torque, position, shape and type of thread compound, pressure medium, etc. JST casing can not only produce round thread and buttress thread according to API standards, also can produce special threads. Compared to common API round thread and buttress thread, JST API casing special thread enjoys the following advantages:
1. This buttress thread casing (BTC) has good sealing property. The elastic and metal seal structure makes the casing joint sealing resistance achieve the yield pressure within the limits of the pipe body.
2. We adopt special threads to connect casing. The connection intensity meets or exceeds the strength of the pipe, basically solving the slippage problem.
3. Through the choice of materials and surface treatment process improvements, API casing improves solves the casing thread gluing problem.
4. By optimizing the structure, the joint stress distribution is more reasonable. This type of steel casing pipe is more conducive to resist stress corrosion of casing.

Parameters Data
  Range 1 Range 2 Range 3
Casing 16.0-25.0 25.0-34.0 34.0-48.0
Overall Length Range
95% and Length Range of Bigger Carload Lots
Max. Allowable Variation 6.0 5.0 6.0
Min. Allowable Length 18.0 28.0 36.0
Allowable variation of carload lots is not applicable for the contract project with less than 40 000lb order quantity. For any one carload lot of 40 000lb or more tubes without transhipment or unloading until the final destination, the allowable variation of carload lot is applicable for each vehicle capacity. If the order quantity of seamless oil pipes is more than 40 000lb, products will be delivered by train but not directly delivered to the final destination. The allowable variation of carload lot is only applicable for overall order quantity, not applicable for single vehicle capacity.

1. The length unit of API casing is inch.
2. We are able to provide custom-made buttress thread casing (BTC).
3. The specific specifications refer to the EXCEL table.

Established in 1984, Jiangyin Changjiang Steel Tube Making Factory has been engaged in manufacturing seamless steel pipes for about 30 years. We mainly supply structure pipe, fluid pipe, high pressure boiler pipe, API casing, marine pipe, alloy pipe, tubing, line pipe, etc. Our products are extensively used in metallurgy, port, ship-breaking, manufacturing, real estate, chemical engineering, transportation and other industries. Our steel casing pipes including buttress thread casing (BTC) are well appreciated for their advanced design, sophisticated manufacturing, excellent quality and full service.

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