Gerald W. White, P.E., White Engineering Corp.
Hydrophobia, apart from the disease connotation, means fear of water. A Seldom mentioned fact of metallurgy is that there are "Hydrophobic" metals and alloys whose very nature is to resist wetting by water. As a corollary, these same surfaces aggressively wet with oil and will maintain themselves oil wet in an oil/water flow stream by attracting oil out of the flow stream while repelling water. Since mineral scale deposition comes from the water component and not the oil, there will be a tendency for it to aggregate in the flow stream and be swept out in the flow stream. Thus the system environment, being the oil/water mixture in the flow stream can be utilized to assist in solving scaling problems, particular at pressure drops and other scaling nodes. Examples will be presented wherein high energy ion deposited thin films of hydrophobic metals and alloys have been shown to resist scale formation while providing dry metal lubricity in a variety of actual installations. In many cases, the formation of scale on a moving rod operating through an elastomeric seal will cause the seal to fail, resulting in the discharge of fugitive emissions to the environment. It has been demonstrated conclusively in many field applications involving stuffing box rubbers and lease motor valve stems that scale can either be prevented entirely or have its adhesion reduced to the point where an elastomeric seal will rub it off. The cost of such films is quite low and the economic benefits to the users in terms of increased service life alone make their use cost effective even without regard to the far more valuable consideration of reducing the incidence of and clean up costs associated with releasing fugitive emissions.