Tubing and Casing of Special Grade

Collapse & High Collapse Requirements

OCTG basically serves to maintain the well hole integrity during drilling, completion and production lifecycle of wells. Among them, the Casing, in particular, provides resistance to collapse caused by high-strength external load.The source of external load includes, pressure coming from stratum or reservoir flow in process of exploration and development, pressure from poor drillability mud and salt layer, mud system pressure, cement or seawater pressure under conductor or line pipe.

What is Collapse

Collapse resistance is a property of pipe body and defined as the limit exceeding which pipe fails in the circumferential direction when external pressure is applied.
Collapse calculation formulas were addressed in the API 5C3 or ISO 10400. Four failure modes have been defined based on failure pattern observation and mechanical rules (refer to figure below). These four domains are continuously positioned as a function of the ratio of the outside diameter to the wall thickness, or D/t ratio.

Influencing Factor

Collapse resistance is influenced by a complex combination of geometrical characteristics, material properties,
applied loads, and load conditions:
Geometry: Outer Diameter(D), Wall thickness(t),Ovality, Eccentricity or wall thickness variation .
Mechanical properties: Yield strength, Residual stress
Applied loads: Tension-Compression, Bending ,Torsion
Testing parameters: Length / D of tested sample, Parasite load due to testing equipment, Pressure gradient.

Our high collapse casing covers full range from 4-1/2” to 13-3/8” in O.D.
Grades from 80ksi to 130ksi (refer to below table).
T Series: the collapse value greater than API 5C3.
TT Series: the collapse value greater than TP-T Series  for the same size.

Corrosion Resistance Casing

We provide a complete range of steel grades for all kinds of oil and gas operations. To improve the corrosion resistance for the demanding conditions of particular oil and gas wells, TPCO has developed a variety of proprietary steel grades that extend the life span of pipe products reducing corrosion rates
 Sour service
Sweet service
Corrosion Resistant Alloy (CRA)

Product Table for corrosive environments

Material selection guidelines and their applications to corrosive well.

This material selection chart helps you choose the appropriate material for your application depending on H2S and CO2 partial pressure, and temperature range in the well.If you need more details,please contact us for finer material recommendations.

Tubing and Casing for Steam Injection Well

We have created thermal service (H) grades for application at higher temperature due to working conditions

Heavy oil reservoirs of China are widely distributed. More than 70 reservoirs had been founded at 12 basins with prognostic reserves of 30 billion tons. TP-H casings are widely used for heavy oil extraction.
When in-situ-combustion is applied during heavy oil extraction, it is a perfect choice of using TP-H Chromium rich casing as inner casing for steam-injection well and production well.

Super High Strength Tubing and Casing

High strength tubing and casing include  high strength and high tenacity property used for deep and super deep well. Fracturing project always use it.

Casing and Tubing for Low Temperature

Casing and tubing for low temperature.This pipe is suitable for low temperature store and low surface temperature well situation.