Oil casing pipe is used for oil well drilling, mainly used to support the well wall during the drilling process and after completion, to ensure the progress of the drilling process and the normal operation of the entire oil well after completion. The following requirements are imposed on the inner and outer surfaces of oil casing pipe:
1. The inner and outer surfaces of the oil casing shall not have folds, hair lines, delamination, cracks, creasing and scarring. These defects should be completely removed, and the depth of removal should not exceed 12.5% of the nominal wall thickness. 2. The outer surface of the coupling shall not have defects such as folding, hairline, delamination, cracks, creasing, and scarring. 3. The surface of the oil casing and coupling thread should be smooth, without burrs, tears and other defects that are sufficient to interrupt the thread and affect the strength and tight connection.
The domestic casing is in accordance with SY/T6194-96, the casing length is variable, and the range is 8-13m. But bushings not shorter than 6m can be provided, and the quantity shall not exceed 20%.
Tips: Petroleum casing pipes can be pided into different steel grades according to the strength of the steel itself, namely K55, J55, N80, L80, C90, T95, P110, Q125, V150, etc. Different well conditions and depths have different steel grades. In corrosive environments, the casing itself is also required to have corrosion resistance, and in places with complex geological conditions, it is also required to have anti-collapse performance.
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