Quality Assurance Activities for Corrosion Resistant Membranes in Pressure Vessels
The operating conditions of several process vessels in the hydrometallurgical sector are so severe that engineers employ carbon steel with corrosion-resistant cladding such as titanium, zirconium and tantalum; high nickel alloy weld overlay; or the use of corrosion resistant membranes. Corrosion resistant membranes may be constructed of halogenated synthetic rubbers, vinyl ester resins, fluoropolymers, bituminous mastic, or homogeneously bonded lead. The quality and integrity of such membranes is of the utmost importance to the safe operation and 20+ years of service life for such vessels. The authors have employed a number of the above noted membranes in acid leach reactors, oxidation autoclaves, hydrogen sulfide (H2S) precipitation reactors, pressure letdown vessels, and off-gas cyclones. This paper presents an outline of the quality control activities undertaken by the authors for several recently completed and on-going hydrometallurgical projects, including prequalification, validation testing, material verification, contamination control, discontinuity (holiday) testing, nondestructive examination and assisted/enhanced visual inspection.