Some piping system ball valve actuators have experienced high hydraulic pressures/valve stem torques during operation. The titanium alloy ball component of these valves are coated with a Teflon™-containing material to provide for low friction in routine valve operation. It is reported that, after many operating cycles, the Teflon™ coating is worn from the ball. The heightened friction between the ball and its seals is a result of the Teflon coating wear in conjunction with the growth of marine organisms on the ball surface which has been identified during pipe inspections. The present paper describes testing conducted by the Naval Research Laboratory at both the Washington, DC (NRLDC) and Key West, FL (NRLKW) locations. The objectives of the testing were to 1) identify the best commercial coating for application to titanium balls and coupons (Ti 6AL4V UNS# R56401) leading to reductions in valve stem torque, extended valve maintenance intervals and reduced maintenance costs and 2) determine, qualitatively, whether through-pipe penetration is anticipated on 70/30 Cu/Ni (UNS# C71600) piping systems when coated with an easy release coating system and coupled to a titanium ball valve.

Subject
Holidays, Wear, Coefficient of friction, Test methods, Coating performance, Coatings, Friction, Valves, Seawater, Titanium, Immersion, Fouling, Coating systems
Keywords:
Cathodic disbondment, friction coatings, wear coatings, metalized coatings, coatings, corrosion, titanium, cupronickel, galvanic corrosion, antifoulant coatings
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2002
GOV
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