Casing pipe, also called “encasement pipe,” is used in underground construction. Casing pipes safeguard many kinds of utilities, like water mains, electrical high-voltage lines, natural gas lines and fiber-optic communication lines from damage. These utilities need protection from human activity and natural elements. The construction of deep foundations also makes use of steel casing pipes.

Casing pipe is used in different types of horizontal underground boring, where the pipe is jacked into an augered hole in segments and then connected together by welding or by threaded and coupled ends, or other proprietary pipe connectors. The steel casing pipe can also be set up and welded into a “ribbon” and then directionally pulled through a previously drilled hole under highways, railroads, lakes and rivers.

Dimension Tolerance

Chemical Composition

Mechanical properties

Oil casing is used to support the oil, gas wells of steel pipe, in order to ensure the drilling process and the completion of the entire well after the normal operation. Each well has several layers of casing depending on the drilling depth and geology. Casing down to use cement cementing, it and the tubing, drill pipe is different, can not be reused, a one-time consumption of materials. Therefore, the casing of the total consumption of more than 70% of the wells. Casing according to the use can be divided into: catheter, surface casing, casing technology and oil casing.

Manufacturing

The production of casing pipes are from steel smelted in electric furnaces, treated with synthetic slag and cast by continuous casters. This steel-making process guarantees the attainment of chemically pure steel, given the phosphor and sulfur contents. This provides highly ductile, malleable and corrosion-resistant pipes, which can operate at low temperatures in a number of corrosive media. Steel grades and heat-treatment regime application allows production of high-strength pipe.

Specifications

Steel casing pipes should have minimum yield strength of 35,000 psi. Casing pipes need to have smooth walls and be exceptionally straight and round. Casing pipe and joint construction should be of uniformly thick steel to avoid any matter leaking from the casing. The outside diameter, size and wall thickness should conform to ASTM Designation A252. Use pull-on or wrap-around rubber varieties of “casing end seals” to seal the ends of the steel casing pipe. Apply corrosion-proofing water-based paint to the exterior pipe surface to safeguard against atmospheric corrosion during shipping and storage.

Quality Control

In accordance with the requirements of ANSI/AWS D1.1, all welding should be performed by qualified welding operators. Complete one reduced section tension test specimen for each lot of 1,000 feet of each size and wall thickness. Verify that the tensile strength is not less than 95 percent of the minimum strength specified for the grade of steel used, except when waived by the customer. No hydrostatic testing is required. Examine all connections to make sure they are free of injurious defects at the time of shipment. Otherwise, prior to shipping, reject and repair that section.

Characteristic of casing pipe

Casing is important to oil drilling equipment, and its main equipment includes drill, core pipe and casing, drill collars and drilling small diameter steel pipe and so on.

The casing is used to support oil and gas wall of the pipe, to ensure that the drilling and completion of the process of the normal operation of the wells. Depending on the drilling each well depth and geological conditions, to use several layers of casing. Casing cementing go down after using it with tubing, drill pipe are different, can not be reused, a one-time consumable materials. Therefore, the total consumption of the casing is 70% of the oil well pipe. Casing can be divided according to usage: catheter, surface casing, casing and production casing. Casing is a large-diameter pipe, play a fixed oil and gas wells, or wellbore wall effect. The casing is inserted into the well hole, fixed with cement to prevent the formation and borehole spaced borehole collapse and to ensure circulation of the drilling mud to the drilling mined.

Casing is mainly used for drilling oil wells during drilling and after completion of the support wall to ensure that the conduct of the drilling process and completion of the wells after the regular oil casing normal operation. OCTG mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drilling pipe, oil casing, pump tubing. Oil drill pipes are mainly used to connect the drill collar and drill and pass drilling power. Casing is mainly used for drilling and completion of the right wall of the support, to ensure that the conduct and completion of the drilling process after the normal operation of the wells. Pumping wells at the bottom of the tubing will mainly oil, gas transported to the ground.

Casing is to maintain the wells run lifeline. As different geological conditions, underground complex stress state, pulling, pressing, bending, torsional stress acting on the combined effect of the tube, which the casing itself, the quality of the higher requirements. Once the casing itself is damaged for some reason, could lead to the whole production wells, or even scrapped.

Production Standard, Grade, Steel No:

• API 5L PSL1 L175/A25, L210/A, L245/B, L290/X42, L320/X46, L360/X52, L485/X70
• PSL2 L245R/BR, L290N/X42N, L320N/X46N, L360N/X52N, L415/X60N
• API 5CT PSL1, PSL2, PSL3, H40, J55, K55, N80
• GB/T 9711.1 L175, L210, L245, L290, L320, L360
• GB/T 9711.2 L245NB, L290NB, L360NB
• GB/T 9711.3 L245NC, L290NC, L360NC

Delivery Condition: Annealed, Normalized, Normalized and Tempered

API Spec 5CT Casing pipe

API Spec 5CT – Specification 5CT/ISO 11960, Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.

Standard: API SPEC 5CT

API 5CT PIPE SIZE (MM):

• Outer Dimensions: 6.0mm – 219.0mm
• Wall Thickness: 1.0mm – 30 mm
• Length: max 12000mm

Application: gas, water and oil transportation in both oil and natural gas .

THE MAIN STEEL GRADE OF API 5CT:

Packing: Bare/bundles/crates/crate protection at the both sides of tubes or as per customers’ requirements .

This International Standard is applicable to the following connections in accordance with ISO 10422 or API Spec 5B:

• Short round thread casing (STC);
• Long round thread casing (LC);
• Buttress thread casing (BC);
• Extreme-line casing (XC);
• Non-upset tubing (NU);
• External upset tubing (EU);
• Integral joint tubing (IJ).

For such connections, this International Standard specifies the technical delivery conditions for couplings and thread protection.

For pipes covered by this International Standard, the sizes, masses, wall thicknesses, grades and applicable end finishes are defined.

This International Standard may also be applied to tubulars with connections not covered by ISO/API standards.

Chemical Composition of API 5CT

MECHANICAL PROPERTIES OF API 5CT