In-service inspection of pipelines is a challenging yet crucial operation, particularly for pipes buried under ground. After scanning the pipeline from the inside with the proper equipment, sections that present any anomalies are excavated. Once the specific section of the pipeline is accessible, the entire surface of the exposed pipe is sand-blasted until the coating is completely removed. Traditional surface inspections such as magnetic particle inspection (MPI) require this kind of intensive coating-removal preparation procedure. MPI is considered the standard method for detecting surface breaking cracks, including stress corrosion cracking (SCC), even though the technique has been used for pipeline inspection for decades without any major advancement. The MPI method also presents some significant disadvantages: the reliability of results is highly dependent on operator skill; when it’s raining, outdoor inspection is problematic; and there is no result traceability or information on the depth of flaws that are detected. However, these weaknesses can be resolved by using a different inspection technique: Eddy Current Array.
Eddy Current Array Semiautomated Solution for Pipeline Surface Cracking Inspection
Olympus offers a variety of solutions for surface crack detection on ferromagnetic material. One of these solutions is based on existing equipment that many Olympus customers already use for PA weld inspection: the OmniScan MX, the HydroFORM scanner and the CHAIN scanner. Here is how it works: First, the HydroFORM buggy, which is equipped with a specially designed ECA probe, is attached to the CHAIN scanner. Then, the scanner and probe assembly is connected to the OmniScan MX with the ECA module. This equipment combination enables two-axis mapping of the inspected area of the pipeline. Unlike MPI, ECA inspection is able to record data for advanced reporting and result traceability. Detection sensitivity can be adjusted to show the severity of the indication or to set an inspection threshold that will reject a specific defect depth. According to the capacity of the CHAIN scanner, this solution is applicable to pipes ranging from 1.75 to 38 in. OD.
XY mapping principle on pipes with the HydroFORM and CHAIN scanner.
Scan for stress corrosion cracking.
Originally published by Olympus IMS: