Mechanical and chemical properties of different steel grades

Material Grades

API 5CT specifies a range of steel grades for casing and tubing, each with its own unique mechanical and chemical properties to suit different operating environments:

1. H40:
   This is a relatively low-strength grade with a minimum yield strength of around 40,000 psi. It is often used in shallow wells or in applications where the pressure and mechanical loads are not overly demanding.
2. J55:
   J55 steel has a minimum yield strength of 55,000 psi. It is commonly employed in wells with moderate pressure and depth conditions. It offers good corrosion resistance and is suitable for many general oil and gas production scenarios.
3. K55:
   Similar to J55 in terms of yield strength requirements (minimum 55,000 psi), but it may have some differences in alloy composition or processing methods to enhance certain properties like resistance to specific downhole environments. It is used in situations where better performance in terms of mechanical strength and corrosion resistance is needed for medium-depth wells.
4. N80:
   With a minimum yield strength of 80,000 psi, N80 is a higher-strength grade. It can withstand higher internal pressures and is often used in deeper wells or those with more challenging downhole conditions. There are different versions of N80, such as N80-1 and N80-Q, which may have variations in heat treatment and mechanical properties.
5. L80:
   L80 grade steel is designed for applications where good corrosion resistance along with significant strength is required. It has a minimum yield strength of 80,000 psi and is suitable for wells with corrosive environments, like those containing hydrogen sulfide (H₂S) or carbon dioxide (CO₂).
6. C90, C95:
   These are high-strength and corrosion-resistant grades with minimum yield strengths of 90,000 psi and 95,000 psi respectively. They are used in more demanding oil and gas production settings where both strength and resistance to aggressive chemical species are crucial.
7. P110:
   P110 is a very high-strength grade with a minimum yield strength of 110,000 psi. It is typically utilized in deep wells, high-pressure wells, or wells where the casing or tubing needs to bear extremely heavy loads and maintain its integrity under severe downhole conditions.
8. Q125:
   This grade has a minimum yield strength of 125,000 psi and is designed for the most extreme oil and gas applications, such as ultra-deep wells or wells with extremely high-pressure and complex geological formations.