According to API 5CT standards, Oil casing and Tubing couplings should be painted one by one to distinguish different grades of steel. The color label of the oil casing and Tubing should be sprayed at any end ≥ 600mm, and the color should be painted on the whole outer surface, and then the color ring should be sprayed.
Coupling colour code | |||||
Grade | Grade Type | Colour(s) for Coupling | Number and colour of bands for product | Picture | |
Entire Coupling | Band(s) | ||||
H40 | None | Same as for pipe | None/black band at the manufacturer’s option |
| |
J55 Tubing | Bright Green | None | One Bright Green |
| |
J55 Casing | Bright Green | One White | One Bright Green |
| |
K55 | Bright Green | None | Two Bright Green |
| |
M65 | M65Pipe uses L80Type 1 Couplings | One Bright Green One Blue |
| ||
N80 | 1 | Red | None | One Red |
|
N80 | Q | Red | One Green | One Red One Bright Green | |
R95 | Brown | None | One Brown |
| |
L80 | 1 | Red | One Brown | One Red One Brown |
|
L80 | 9Cr | None | Two Yellow | One Red, One Brown, Two Yellow |  |
L80 | 13Cr | None | One Yellow | One Red, One Brown, One Yellow |
|
C90 | 1 | Purple | None | One Purple | |
T95 | 1 | Silver | None | One Silver |
|
C110 | White | Two Brown | One White, Two Brown |
| |
P110 | White | None | One White |
| |
Q125 | Orange | None | One Orange |  | |
