USS C100 Steel: A Controlled Yield Strength Material for Deep Sour Service Wells
Reference: API 5CT, NACE TM0177
Abstract
The USS C100 steel grade, a proprietary product of U.S. Steel, is specifically tailored for deep sour service wells where the controlled yield strength is crucial. This article examines the mechanical properties of USS C100 steel, its suitability for sour service applications, and the standards it complies with, including API 5CT and NACE TM0177.
Introduction
Deep sour service wells are characterized by high pressures and the presence of hydrogen sulfide (H2S), which necessitates the use of steel materials with enhanced resistance to sulfide stress cracking (SSC). USS C100 steel is designed to meet these challenges, offering a balance of strength, ductility, and SSC resistance.
Material Properties
USS C100 steel is defined by its mechanical properties:
- Yield Strength: With a minimum yield strength of 100,000 psi and a maximum of 115,000 psi, USS C100 provides a controlled range of strength to ensure reliable performance under stress.
- Tensile Strength: The minimum tensile strength of 110,000 psi indicates the steel's ability to withstand significant tensile forces without breaking.
- Hardness: The maximum hardness of 28.0 HRC ensures durability and resistance to wear, while maintaining the necessary toughness.
Suitability for Sour Service
USS C100 steel is generally used in deep sour service wells due to its controlled yield strength and compliance with SSC standards, making it resistant to the detrimental effects of H2S.
Standards Compliance
The steel meets the following industry standards:
- API 5CT: Inspection, testing, and dimensions of USS C100 adhere to the API 5CT specifications for C90 and T95 grades, ensuring quality and reliability.
- NACE TM0177: The steel is tested for SSC resistance as per NACE TM0177, Method A, at a threshold stress of 85% of the specified minimum yield strength, confirming its suitability for sour service applications.
Conclusion
USS C100 steel is a specialized material designed for the demanding conditions of deep sour service wells. Its controlled yield strength, coupled with compliance with API 5CT and NACE standards, makes it a robust choice for applications where H2S is present.
References
- API 5CT. "Specification for Casing and Tubing." American Petroleum Institute.
- NACE TM0177. "Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking in H2S Environments." National Association of Corrosion Engineers.
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