Our High Collapse (HC) grades exhibit higher collapse pressure than what is determined by API 5CT/ISO 11960 products.
proprietary Grade fit for high-pressure service
Tenaris provides the High Collapse Series of proprietary steel grades for oil and gas wells where high external pressures are anticipated and collapse resistances higher than API are needed.
In addition to uniform external pressures, the reservoir can exert high pressures due to ground movements or saline strata, subjecting pipes to extreme localized external pressure.
Our HC Series is available in minimum yield strengths ranging from 80Ksi to 140Ksi. These products have higher guaranteed collapse pressure than that determined by API 5CT/ISO 11960 products.
As an alternative to the HC Series, we also manufacture the Improved Collapse grades (IC grades). They are an excellent cost-efficient solution for less severe applications.
IC grades are API steel grades with improved performance. They are available in minimum yield strength of 110 ksi and 125 ksi. As an additional requirement they can be manufactured with controlled Yield Strength (ICY grades) in order to enhance the performance in Internal Yield Pressure.
Parameters for excellent collapse performance
The collapse of a pipe is related to the stiffness or rigidity of its cross section area along the pipe length. Dimensional and mechanical properties determine a true high collapse proprietary product. We pay strict attention to these variables when producing our HC Series.
The dimensional properties of a high collapse pipe depend on three factors: external diameter to wall thickness ratio, ovality and eccentricity. Low ovality, low eccentricity and the maximum wall thickness for the maximum allowed pipe weight will give the best dimensional conditions for collapse resistance.
The mechanical properties that determine high collapse are yield strength and residual stresses. Strict control of the heat treatment process to ensure optimum yield strength distribution and minimal compressive residual stresses will lead to the maximum collapse properties of the pipe.
Our HC Series consistently outperforms former API TR 5C3 & ISO/TR 10400 collapse resistance for API steel grades.