Abstract
Hydrochloric acid is one of the most difficult corrosives for passive alloys to handle. They are susceptible to serious corrosion problems, including high corrosion rate, localized corrosion and hydrogen embrittlement. Stainless steels tolerate very low concentrations of chlorides. Nickel-based alloys may tolerate high concentrations of chlorides, but the temperature cannot be high. Even with the presence of oxidizing impurities, titanium is not compatible with strong acids. Tantalum is impressive with respect to its resistance to hot, strong acids. It is, however, susceptible to hydrogen embrittlement.
Like tantalum, zirconium resists attack by hot, strong acids. Zirconium resists better than tantalum to hydrogen embrittlement when oxidizing impurities are absent. In fact, zirconium prefers reducing conditions. It is the oxidizing condition that may induce corrosion problems in zirconium.
The performance of zirconium in HCl solutions is greatly affected by many factors. Zirconium gives optimal performance in HCl environments when affecting factors are properly addressed. This paper discusses metallurgical, design, fabrication, environmental and maintenance issues that affect the performance of zirconium in HCl solutions. Examples will be given on the successes and failures of zirconium in HCl services.
