API 5CT N80-1 High Collapse Casing for Deep Well Service

API 5CT N80-1 High Collapse Casing and Tubing for Deep Well Service

Introduction:

High Collapse Casing and Tubing for Deep Well Service are seamless tubes designed to withstand high external pressures in deep oil and gas wells. These High Collapse Casing and Tubing are specially manufactured such that they have improved collapse properties, well in excess of API requirements.
The external pressure on the casing is directly proportional to the depth of the well. Hence, casings in deep wells are required to sustain high internal pressures, tension loads, and collapse pressures.

Grade and Mechanical Properties:

Advantages:

1.)Unique Production Technique: The material for high collapse casing and tubing is carefully selected to insure structural homogeneity. Strict control of heat treatment and dimensional tolerance is adhered to throughout the manufacturing process
2.)Rigid Dimensional Control: Dimensional tolerances, such as roundness, straightness, outer diameter and wall thickness are strictly controlled.
3.)Specified Collapse Value: A collapse test is carried out on each production run of high collapse casing and tubing with the same frequency as the tensile test.

Ensuring High Collapse Properties:
The collapse properties of the casings are directly related to the dimensional parameters of the tube (in turn a function of the tube rolling process), and the material properties of the tube (a function of the quality of the steel and the heat-treat process of the tube). In order to guarantee the collapse properties of the casings, and to ensure consistency of these properties across batches, we maintain strict control over the entire production process, right from the melting of steel, the rolling of the tubes, to the quench & temper of the tubes. All the steel that is used for making high collapse casings is ladle refined and vacuum degassed to ensure a clean, inclusion free steel. Tube rolling parameters are tightly controlled so that ovality eccentricity, and wall thickness variation, factors that are detrimental to collapse, are minimized. 

Each tube is then carefully checked to ensure conformance with specifications.

Process Control:

1.)To control strictly the inclusions in steel via the purity steel melting technology.
2.)To control strictly the wall thickness and ovality of the tubes during the hot rolling.
3.)To guarantee the yield strength and surface quality through the temperature and atmosphere control in the furnace during the heat treatment.
4.)Through the second sizing and on line hot straightening after heat treatment, strictly control the residual stress, OD, ovality and straightness.

Collapse resistance: The minimum guaranteed collapse pressures are available on request.

Pipe inspection: A full length non destructive inspection is performed in accordance with API 5CT for external and internal, longitudinal and transverse defects with a standard notch depth equal to 5% of the specified wall thickness. The wall thickness is measured by ultrasonic method.