Standard requirements API 5L X52 seamless pipe
1. Cracks, folds, folds, exfoliation, scabs and scales are not allowed on the inner and outer surfaces of steel pipes. These defects should be thoroughly eliminated.  The grinding of surface defects should be smooth and smooth. The gap depth shall not exceed the negative deviation of nominal wall thickness. The actual thickness of the defect removal zone should be no less than the minimum allowable wall thickness of the steel tube. Welding method shall not be used.


2. The diameter of the straight line appearing on the inner and outer surface of the steel tube must be grinded. The gap depth shall not exceed the negative deviation of nominal wall thickness. The actual thickness of the defect removal area should not be less than the minimum allowable wall thickness of the steel tube.


3. End Shape: Both ends of the steel tube should be cut at right angles and burrs removed.


4. Welding joints are not allowed in pipes.


Dimensional tolerance of API 5L X52 seamless pipe
1. Diameter and ellipticity
Diameter deviation: +0.01D, maximum not more than +4 mm;
Elliptical deviation: 0.02D, maximum 10 mm.


2. Wall thickness deviation
The deviation of pipe wall thickness is -5%+20%, but the average wall thickness of each pipe should not be lower than the prescribed wall thickness.


3. Straightness deviation of steel tube
One. The total deviation of the total length of the steel tube from the straight line should be less than 0.2% of the length of the steel tube.
The local deviation of the straight line should be less than 4 mm for each 1000 mm section length of the bay.