T.D. Williamson Introduces Spiral Magnetic Flux Leakage Inspection Tool

Special to Pipeline & Gas Journal
February 2011, Vol. 238 No. 2

TDW's SMFL tool is said to be able to detect and characterize a much wider range of pipeline defects.

Buyer's Guide

T.D. Williamson, Inc. (TDW) recently announced the debut of its patent-pending spiral magnetic flux leakage (SMFL) inspection tool.

The company said the unit is the latest addition to its range of magnetic flux leakage inspection tools and is capable of inspecting for long, narrow defects in the pipe wall and long-seam weld.

It is said to combine MFL and transverse field inspection (TFI) capabilities to offer unprecedented detection capability. TDW explained, whereas traditional axial MFL technology detects volumetric pipeline anomalies, general corrosion and wide circumferential flaws, the new SMFL tool makes it possible to detect long, narrow defects in a pipe body and in long seam welds.

TFI tools are designed to detect general corrosion, as well as long and narrow metal loss features.

According to Enzo Dellesite, general manager - Middle East Operations for TDW, “By combining the capabilities of the standard TFI tool with those of a conventional axial MFL system, the new SMFL tool fills a niche in the market for a system that combines inspection technologies.

“By doing so, operators can detect and characterize a much wider range of pipeline defects that simply was not possible until now,” he added.

Enhanced Characterization Of Anomalies
The high-resolution SMFL tool offers several benefits, according to TDW. For example, while TFI technology relies upon two magnetizers, the SMFL tool requires only one. As a result, the SMFL tool can be paired with MFL technology without having to extend the length of the tool to accommodate it. The ability to pair tools means that multiple datasets are generated in a single run. TDW says it uses these datasets by overlaying them, which greatly enhances characterization of anomalies that are revealed during an inspection run.

The company cited a recent example where TDW ran separate runs with each system in a 16-inch pipe with a .250-inch wall thickness. While the axial MFL tool did not detect an external axial gouge, data generated by the SMFL tool revealed an external gouge measuring 6 inches long x .25-inch wide x 40% deep.

TDW_SMFL Gouge Screen Capture (2).jpg
This image depicts an external axial gouge (center), and the anomaly characterization data generated by the SMFL tool vs. the traditional axial MFL tool. While the axial MFL tool did not detect an external axial gouge, data generated by the SMFL tool revealed an external gouge measuring 6 inches long x .25-inch wide x 40% deep.

With a sampling frequency of up to 750 samples per second, the SMFL tool has an operating pressure range of 300-2,000 psi (21-137.8 bar) and an inline temperature range of 14-131°F (-10 to 55°C.)

It has a minimum bend radius of 1.5D and can travel at up to 8.3 ft/second. The company says this makes it an extremely adaptable and efficient inspection system.

The addition of the SMFL tool further extends TDW’s pipeline inspection services which feature the recently launched 48-inch Gas Magnetic Flux Leakage (GMFL) inspection tool. This GMFL tool operates at a steady speed despite variations in gas pressure that tend to cause other tools to stall and surge as they move through a gas line.