Application of Amorphous Metals for Plastic Pipeline Detection

Overview

Main Objective

The objective of this project is to evaluate the potential for using amorphous metal foil to enable the below ground detection of plastic pipelines.

Public Abstract

Amorphous metals lack the typical crystalline grain structure which imparts unique and often desirable properties to the metal. In general, amorphous metals are stronger, more resilient, and more corrosion resistant compared to the same alloy with a crystalline microstructure. Foils composed of amorphous metal are flexible yet tough, which makes them candidates for either embedding in the wall of plastic pipe or bonding to its exterior. However, the most useful characteristic of amorphous foils for pipeline detection comes from their unique magnetic properties, which includes having the highest known values of magnetic permeability for any metal because of the lack of a crystalline structure. High magnetic permeability allows thin sections of amorphous metals to conduct the same magnetic flux as thicker sections of conventional metals that have lower permeability. Initial modeling has shown that thin layers of amorphous foil can create magnetic field distortions of similar magnitude to those caused by conventional solid metal pipe. These results suggest that embedded or adhered strips of amorphous metal could make plastic pipe detectable using conventional magnetic locating technology, which is a highly versatile and useful detection method. Existing magnetic locators rely on passively sensing distortions in Earth's magnetic field caused by ferromagnetic objects and, therefore, do not require electrical excitation of the pipe or tracer through conductive or inductive means. The project will begin by collecting magnetic field interaction data to build a validated magnetostatic model of amorphous film within Earth's magnetic field. The model will be used to optimize the amount and type of foil necessary for detection and identify the preferred application pattern. A mock-up of a tagged section of plastic pipe will be created and used to conduct locating tests with a commercially available magnetic locator. The commercial potential for an amorphous film-based locating system will be examined as a summary task where issues such as the added cost to the pipe, foil adherence method, and potential value-added features such as a unique identification pattern will be considered. This project includes in-kind support from Metglas, the world leader in amorphous metal foil production. Metglas pioneered the process for the production of long runs of amorphous metal foil, and its company name is synonymous with amorphous foil material. All experimental work will be conducted at the University of North Dakota's Energy & Environmental Research Center, and student involvement will be incorporated by hiring a student for a semester of full-time cooperative education experience.

Summary and Conclusions

The project confirmed an amorphous foil-wrapped plastic pipe to be as magnetically detectable as all metal pipe of the same diameter. The composition of the amorphous foil did not have a significant effect on its detectability. The field distortion measurements indicated that the size and the orientation of the foil stripe impact its detectability. The design in which the foil was decoupled from the pipe was found to be the most attractive way to use amorphous foil for pipe locating. The foil stripe would ideally be orientating vertically along the pipe's entire length. This preferred orientation of the foil is also compatible with plow installation of spoolable plastic pipe and conduit, but follow-up work is needed to demonstrate combined pipe and tape installation. Overall, the locating tape based on amorphous metal foil would have the functionality of existing aluminum based detectable tape but with the added option of passive magnetic location.

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