The B-type sleeve repair is composed of a pair of semi-circular steel protective plates covering the defect of the pipeline, which are welded together through longitudinal butt welds. The end of the sleeve is fixed to the pipeline by circumferential angle welding. The B-type sleeve is a pressure bearing sleeve that can withstand the internal pressure of the pipeline and also withstand the axial stress caused by the lateral load on the pipeline.
B-type sleeve
B-type sleeves are suitable for repairing various types of defects, including leaks and circumferential defects, but cannot repair defects on pipe bends
The thickness of the sleeve should not be less than the nominal wall thickness of the pipeline to be repaired; The material grade of the sleeve is generally the same as that of the pipeline to be repaired, and the specific material can be determined according to the actual situation
The design and installation of B-type sleeves should meet the following conditions
a) The distance between the end corner weld of the sleeve and the original damaged weld of the pipeline should not be less than the nominal diameter of the pipeline and not less than 150 mm
b) The distance between the fillet welds of adjacent sleeves should not be less than 1/2 of the nominal diameter of the pipeline. If the distance between the fillet welds of two sleeves is less than 1/2 of the nominal diameter of the pipeline, the sleeves cannot be welded to the pipe body, and another sleeve should be used to connect the two sleeves
c) The gap between the sleeve and the pipe body should not exceed 2.5mm
d) If the length of the sleeve is greater than 4 times the nominal diameter of the pipeline, temporary support measures should be taken for the pipeline during repair, and layered backfilling should be carried out to avoid impacting the pipeline
e) When repairing leakage defects, the leakage should be sealed in advance and a sleeve should be installed, which can be achieved by using sealing fixtures or installing branch pipes on the sleeve
f) The welding of the sleeve side seam should use full penetration welding technology, and other in-service welding requirements should comply with the relevant provisions of Appendix C.