The casing and tubing pipe grades

The API 5CT standard encompasses both seamless and welded casing and tubing pipes used for oil and gas transportation. The materials for casing pipes include grades such as H-40, J-55, K-55, N-80, L-80, C-90, T-95, P-110, and Q-125.

Different steel grades are utilized based on the well's conditions and depth. Casing must be corrosion-resistant in corrosive environments and collapse-resistant under complex geological conditions. Although most casing steel grades share similar chemical compositions, they differ mainly due to the heat treatment applied. These grades vary in yield strength, tensile strength, and hardness.

According to API 5CT, the products are divided into four 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 tests specified by API 5CT ensure each casing grade is suitable for its intended application.

Common Application Casing:

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:

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:

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 H40, J55, C75, N80, and P110. Union Steel Industry maintains an extensive stock of oil casing pipe and OCTG pipe according to API 5CT standards. For inquiries, please contact: sales@union-steels.com