Bristle Blast Surface Treatment of Welded Joints Fabricated From Commercial Ship Construction Steel

Abstract

     The fabrication, repair and maintenance of steel structures are ongoing concerns that must be regularly addressed in order to sustain a word-wide infrastructure that relies on marine vessels for both commercial transportation and national security needs.  To this end, great care is exercised in producing and protecting welded joints because the integrity of these seams provides a cornerstone for ensuring their safety and structural longevity.  At the same time, maintenance engineers in the ship building industry are faced with the continual need for deploying new methods for surface preparation that will not compromise the surface cleanliness and anchor profile requirements that are necessary for proper adhesion of paints and coatings.

     In this paper, the recently developed bristle blasting process is used for cleaning and preparing welded joints fabricated from steels that are commonly used in the ship building industry.  Overall principles of the process are briefly reviewed and details concerning the mechanical function of the tool are examined.  Performance of the bristle blasting process is examined within the context of both cleaning and simultaneously generating a receptive anchor profile along the seam of welded joints.  The aggressiveness/material removal capacity of the tool is measured and reported using standard tool operating conditions, and the texture and surface morphology generated by the bristle blasting process is examined along the crown and toe of the weld.  In addition, the near-surface residual stresses that are imparted to the steel via the bristle blasting process are measured, in order to help assess any potential enhancement for fatigue and corrosion resistance that can be derived from the cleaning process.  Finally, the overall cleanliness of surfaces generated by bristle blasting is assessed by a direct comparison with visual standards that are commonly used for training and certification purposes in the surface preparation community.