Try to avoid the longitudinal seam opening of the cylinder. If it is unavoidable, the flaw detection ratio should be increased (take 1.5 times the diameter of the cylinder mouth as the radius, and carry out 100% RT flaw detection on the welds within the circle). The distance between the centers of two adjacent openings (calculated according to the arc length of the curved surface distance) should be not less than twice the sum of the diameters of two holes, and the minimum distance should be not less than 50 mm