API Casing Color Code

To determine the strength of various casing materials, API has designated defined grades. This grading system consists of a letter and number as P-110, L-80. The number is an arbitrary one (e.g. K-55) representing the min yield strength of the casing (Casing performance Properties), the number is an arbitrary one (e.g. N-80). There are also non-API casings that we use in special cases as deep wells or in high-corrosive environments. The API has defined a color code for the different grades of steel used for making casing and collars. These are shown below.

API Casing Color Code
GradeColor Coating on CoupingColor Band on CoupingColor Band on Pipe BodyDrawing
H-40 color code
J-55GreenLetter “J” (Yellow)One Green band
J-55 color code
K-55GreenTwo Green bands
K-55 casing
N-80RedOne Red band
N-80 API color code casing
L-80RedOne Brown bandOne Red band and One Brown band
L80-CR9RedTwo Yellow bandsOne Red band, One Brown band and Two Yellow bands
 casing color code
L80-CR13RedOne Yellow bandThis API Casing Color Code had One Red band, One Brown band and One Yellow bands
C-90PurpleOne Purple band
C-95BrownOne Brown band
T-95SilverOne Silver band
P-110WhiteOne White band
API Casing Color Code For P-110
Q-125OrangeOne Orange band
API Casing Color Code

In the design of casing and tubing strings, the minimum yield strength of the steel is taken as the basis of all strength calculations

GradeMinimum Yield Strength (PSI)Maximum Yield Strength (PSI)Min Tensile Strength (PSI)
H 4040,000 PSI80,000 PSI60,000 PSI
J 5555,000 PSI80,000 PSI70-95,000 PSI
C 7575,000 PSI80,000 PSI70-95,000 PSI
N 8080,000 PSI110,000 PSI100,000 PSI
L 8080,000 PSI95,000 PSI100,000 PSI
C 9090,000 PSI105,000 PSI100,000 PSI
C 9595,000 PSI110,000 PSI105,000 PSI
P 110110,000 PSI140,000 PSI125,000 PSI
Q 125125,000 PSI150,000 PSI135,000 PSI
API Casing Color Code / Grade Strengths

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