Abstract: Briefed here in the paper is the detection range of an ultrasonic inspection system for the spiral submerged arc welded pipe(SSAW pipe).Elaborated are the detection method and the operation mode of the detection probe of the said detection system.Also analyzed are the detection mechanism and the software system of the detection system.The said detection system is totally equipped with 68 channels(including 16 stand-by channels for weld seam detection,4 channels for detection of 25 mm-wide base metal on both sides of the weld seam,and 48 channels for detection of the pipe body base metal),being capable of meeting the requirements by the ultrasonic detection criterion for the petroleum pipe industry.The system is suitable for 100%coverage continuous detection of both longitudinal and transversal defects of the welded seam of the pipe,100% coverage detection of the lamination defect of the 25 mm-wide base metal on both sides of the weld seam,and over 75% coverage detection of the pipe body base metal lamination defect.Moreover the interface for 100%coverage rate location detection is reserved.The detection speed can reach 30 m/min;the blind area of the pipe end weld seam is less than or equal to 200 mm,while the blind area of the pipe end base metal is less than or equal to 50 mm.