Wall Thickness Measurement of Oil & Gas Transmission Pipelines through External Anti-Corrosion Coating

The external anti-corrosion coating of long-distance oil and gas transmission pipelines provides effective protection, ensuring the stability of energy transportation, reducing the risk of leakage accidents, and safeguarding people’s lives and property.

The through-coating function of ultrasonic thickness gauges is designed for measuring the net base metal thickness of pipelines, tanks, or other metallic materials covered with paint or protective coatings. Without the need to remove the coating, the instrument enables quick and accurate measurement of metal thickness. This function works by detecting two successive back-wall echoes from the substrate. Key advantages include: no need for zero calibration, zero drift, excellent stability, and measurements unaffected by probe pressure, couplant thickness, or surface dust and stains.

For in-service pipelines and pressure vessels, ultrasonic thickness measurement helps monitor wall thinning due to corrosion, determine remaining wall thickness, calculate corrosion rates, and estimate residual service life—thereby preventing safety incidents.

According to pipeline coating inspection requirements, the “standard grade” anti-corrosion coating thickness must exceed 4.0 mm, and in many cases, coatings may be much thicker. Without removing the coating, through-coating ultrasonic thickness gauges are used for testing. 

Leveraging years of ultrasonic expertise, Shenyang Yushi Instruments has developed the PM-5 series ultrasonic thickness gauges with specialized probes for thick coating penetration, capable of accurately measuring metal thickness beneath coatings up to 20 mm (or even thicker). These probes are suitable for flat surfaces, curved surfaces, and pipelines, making inspection faster and more efficient.

For more details about the high-penetration through-coating function of our ultrasonic thickness gauges, please contact us!