The main NDT methods for spiral welded steel pipes include ultrasonic testing, radiographic testing, eddy current testing, magnetic particle testing, and penetrant testing. Ultrasonic testing is frequently used. Ultrasonic testing has high sensitivity for area-type defects inside spiral welded steel pipes. It detects defects along the entire wall thickness, and most importantly, it can detect internal wall defects, which is a limitation of other methods.
The NDT equipment for spiral welded steel pipes includes: a feeding mechanism, an ultrasonic probe and tracking system, a crossbeam and traveling system, a rotating roller system for the steel pipe, a feeding and feeding device, a water supply system, an air supply system, a steel pipe inspection and monitoring system, channel ultrasonic instruments, an electrical control system, and a marking system. The mechanical part uses rotating wheels to drive the spiral welded steel pipe to rotate, and the probe tracking and inspection system travels on the crossbeam via linear guide rails to complete the inspection of the entire spiral welded steel pipe.
For general metallic materials, it’s impossible to visually inspect the internal defects of spiral steel pipes. This is where ultrasonic testing comes in. When ultrasonic waves propagate through a metal workpiece, they exhibit reflection. If a defect is encountered, and its size is equal to or larger than the ultrasonic wavelength, the waves will be reflected from the defect. The reflected sound waves are displayed on a screen, allowing us to determine the size and location of the defect based on the reflected waves. Spiral steel pipes have good directionality; the higher the frequency, the better the directionality, radiating into the medium with a very narrow beam, making it easy to pinpoint the location of defects.
The ultrasonic automatic flaw detection system for spiral steel pipes is suitable for inspecting spiral welded steel pipes with diameters of 219-1620mm and wall thicknesses of 8-16mm. This system employs a combination of computer control and real-time signal acquisition and processing technology. Utilizing a multi-channel digital flaw detector supported by a high-speed computer, the probe moves linearly relative to the weld seam on the spiral steel pipe via a linear guide rail and probe tracking system. This allows for the complete flaw detection of the weld seam and the entire pipe body. It can automatically detect and evaluate defects, display and record (defect) echo amplitude, store and print inspection data, and automatically generate inspection reports according to user-required formats.
Types of defects inspected in spiral steel pipes include: incomplete welds, lack of penetration, internal and external penetrating damage, folds, inclusions, cracks, fissures, pits, and other surface and near-surface defects. The spiral steel pipe is conveyed to the inspection area via roller conveyor, and the detection probe descends to perform high-precision weld seam flaw detection. The system monitors the presence of defects in the spiral steel pipe and provides corresponding control signals. The equipment’s electrical control is PLC-controlled, ensuring high reliability and enabling fully automated flaw detection. Manual operation and standard sample debugging are also possible. Conveying, inspection, and alarm functions are all automatically controlled in real-time by the PLC.
Post time: Apr-24-2026