Steel Grade of Casing Pipe

Color label and english letters at the back of the 2 or 3 digits said the minimum yield strength steel grade oil casing, such as J55 said its minimum yield strength of 55000 pounds per inch (379 mpa) up to 80000 pounds per inch (552 mpa), 2 P110 minimum yield strength of 110000 pounds per inch (758 mpa) up to 140000 pounds per inch 2 (965 mpa).H, J, K, N for general strength oil bushing, C, L, M, T for qualified yield strength oil bushing, which has certain anti-sulfur corrosion resistance.

According to API 5CT, the products are divided into 4 groups:
Group 1: Grades H, J, K, M, N, and R
Group 2: Grades C, L, and T
Group 3: Grade P
Group 4: Grade Q

Additional testing specified by API 5CT ensures that each casing grade is suitable for its intended application.

Common applications of casing pipe:
Grades such as H40, J55, K55, M65, N80, and R95 are commonly used. J55, K55, and N80 are particularly popular due to their lower cost, making them suitable for wells without stringent anti-corrosion or strength requirements. M65 and R95 are newer grades with specific applications, differing mainly in yield strength and tensile strength.

Corrosion-resistant casing pipe:
Grades L80, C90, T95, and C110 are designed to resist sulfide stress cracking in H2S environments due to their lower sulfur and phosphorus limits and mandatory additional tests. L80-9Cr and L80-13Cr are suited for CO2 environments due to their higher chromium content.

Deep well casing pipe:
Grades P110 and Q125, with the highest yield strengths among API 5CT grades, are ideal for high-pressure formations in deep wells. However, due to their susceptibility to sulfide stress cracking at higher yield strengths, they should not be used in H2S environments.

Commonly used types include API 5CT J55, K55, N80, and P110. Hunan Standard Steel Co., Ltd maintains an extensive stock of oil casing pipe and OCTG pipe according to API 5CT standards. For inquiries, please contact: info@hu-steel.com

Read more: Difference between Casing pipe and Drill pipe