Date of Award

Fall 2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Robert J. Stango

Second Advisor

Raymond A. Fournelle

Third Advisor

Vikram Cariapa

Abstract

Despite advances in paints and coatings technology, protective coatings are prone to eventual corrosion, degradation and/or failure. Consequently, a corrosive layer will develop that can undermine the performance and integrity of structural components. Therefore, both the corrosive layer and defunct coating must be periodically removed, and an acceptable level of surface cleanliness and texture must be obtained prior to the reapplication of new paint. Currently, an array of processes and equipment are used for efficiently cleaning and conditioning metallic surfaces, such as grit blasting, needle guns, and a variety of non-woven and coated abrasive tools.

This research investigates the method termed the "bristle blasting" process. The process utilizes a specially designed rotary bristle tool, which is dynamically tuned to a power tool spindle that operates at approximately 2,500 rpm.

The present research suggests that the repeated collision of hardened bristle tips with a corroded steel surface results in both the removal of a friable corrosive layer and simultaneous exposure of fresh subsurface material. Surfaces generated by the bristle blast process are shown to mimic the visual cleanliness and anchor profile that is characteristic of grit blasting processes. One particular application evaluated during this research was offshore pipeline refurbishment and pre-treatment of weld seams prior to the application of protective coatings. Comparative analysis was done with conventional methods of surface treatment on the basis of visual cleanliness, surface profile generation and coating adhesion strength. The results obtained suggest that this novel technology performs better than the existing conventional power tool methods and is on an equal par with grit blasting methods. Moreover, the bristle blasting process is eco-friendly and does not use or generate hazardous waste, thereby providing a "green" approach to corrosion removal and surface preparation of steel components.