Corrosion Inspection and Testing
New detection technology
1. Phased Array Inspection Technology for Small Nozzle Welds
Due to their small size and limited on-site operational space, conventional phased-array inspection equipment cannot effectively detect defects in small nozzle welds. Through laboratory application research, Zhongke Weier has specifically developed a series of tools and methods tailored for phased-array inspection of defects in small nozzle welds, enabling full coverage of the sound beam and thereby addressing the issue of missed detections commonly encountered with traditional phased-array techniques when inspecting small nozzles.
Applicable scenarios
● Testing conditions: The component is in a shutdown state, with approximately 100 mm of the weld seam being ground. The entire circumference is ground thoroughly. After grinding, no anti-corrosion paint or weld spatter remains, exposing a smooth metal surface.
● Applicable materials: carbon steel, stainless steel, etc.
● Detectable defect types: cracks, inclusions, lack of fusion, and incomplete penetration
● Detection accuracy: Defects or cracks with a diameter of Φ2mm
● Fitting specification requirements: DN20 × 2.5 mm or greater
01
Automated ultrasonic phased-array inspection with continuous recording for the circumferential welds of pipeline pipes provides comprehensive coverage of the welds, thereby improving on-site inspection efficiency and detection rates.
02
Cover the material being inspected and generate an image of internal discontinuities in the inspected material.
03
By placing the probe in one position, it is possible to generate a complete image of the object being inspected, enabling automated electronic scanning and allowing detection of objects with complex shapes.
04
This technology is radiation-free and pollution-free, and can adapt to multi-task, three-dimensional, intersecting work sites.
2. Pulse Eddy Current Testing Technology for Crawling Robots
Using magnetic suction wheels that crawl along the pipe surface and are driven by a motor, this system carries our company’s self-developed pulsed eddy-current inspection probe. Employing pulsed eddy-current technology, it performs non-contact, non-destructive testing on metal pipelines to assess the corrosion condition of equipment. This technology not only enhances detection safety and reduces detection costs but also allows access to remote locations that are difficult for inspection personnel to reach, significantly improving detection efficiency.
Applicable scenarios
Inspection of power plant water-cooled walls, refinery furnace tubes, tower walls, and tank walls; inspection of bare pipes with diameters exceeding DN100; and non-insulated carbon steel components in suspended areas such as storage tanks and flare tower bodies.
Case Study: Combining Crawlers with Vortexes
During eddy current inspection of overhead pipelines using a crawler, thinning was detected near the bend in the straight pipe section. The wall thickness of the straight pipe section ranges from 7.8 to 8.0 mm, while the measured thickness at the thinned area is 6.3 mm, representing a thinning rate of 21.25%.
Photographs of on-site inspections at high-altitude locations and eddy current results diagrams
3. Low-Frequency Guided Wave Inspection Technology
The low-frequency guided wave inspection technique, which utilizes the magnetostrictive principle to detect wall loss and circumferential cracks both on the inner and outer surfaces of pipelines, enables remote detection of hard-to-reach areas and can be performed while the equipment remains in service. By analyzing signal strength and characteristics, the technique classifies the severity of pipeline damage and identifies defects.
Applicable scenarios
Identification of external corrosion hazards at refineries (including under insulation layers) and detection of defects in long-distance pipelines, etc.
Low-Frequency Guided Wave Inspection Case
Guided-wave testing was used to inspect the furnace tubes of a catalytic external heat exchanger at a certain enterprise. A spot check of three furnace tubes revealed that all three tubes showed varying degrees of wall-thinning signals. The overall wall thickness on the outer surface of the furnace tubes had decreased. The wall-thickness measurements at the areas covered by the guided-wave probe ranged from 6.4 to 6.5 mm. The guided-wave-induced thinning rates were between 1.6% and 6.9%, indicating significant corrosion. Ultrasonic re-measurements yielded wall-thickness values ranging from 4.3 to 6.5 mm. The relative thinning rate was 33.84%, and the relative specification-based thinning rate was 46.25%, confirming the effectiveness of the guided-wave inspection results.
| Name | Extracatalytic unit external heat exchanger furnace tubes | Number | — |
| Temperature | Room temperature | Pressure | — |
| Pipe specifications | DN100 * 8.0mm | Probe position wall thickness value | 6.4-6.5mm |
| Probe excitation frequency | 64KHz | Speed of sound | 3100m/s |
| Probe positive direction | Facing upward | Probe in the negative direction | Facing downward |
Detection spectrum
4. Other detection technologies
● Electromagnetic testing methods (such as far-field eddy current testing, leakage flux testing, and magnetic memory testing)
● Acoustic testing methods (acoustic pulses, high-frequency guided waves, TOFD inspection, rotating ultrasonic testing, etc.)
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