Conference sessions are tailored to chemical processing, oil and gas, material selection, fabrication advances, and other challenging processing environments. The following abstract provides a glimpse of the papers being presented at this year's event
Although few metals can survive chemical environments with high concentrations of chloride ions; reactive metals such as tantalum, niobium, zirconium, and titanium can offer superior corrosion resistance.
Of the reactive metals, only commercially pure zirconium offers both high resistance in concentrated inorganic acidic chloride solutions and has sufficient strength to be approved for construction of welded pressure vessels.
Although zirconium is generally successful in these environments, stress-corrosion cracking (SCC) and intergranular attack (IGA), can occur in hydrochloric acid concentrations >20 per cent and pitting can occur in concentrations <20 per cent. Several factors are thought to affect the corrosion resistance of Zr702 in concentrated chlorides including:
- Presence of oxidizing ions in solution, eg ferric ion (Fe3+) or cupric ion (Cu2+).
- Surface roughness of the zirconium.
- Internal stresses in the zirconium.
- Post-weld heat treatment.
- Thickness of passive oxide film.
- Impurity levels of base material, ie Fe, Ni, Cr, and Sn.
Zirconium's performance in hydrochloric acid can be dramatically improved by conditioning its surfaces through a variety of different processes. This paper will explore the results of testing intended to determine the best surface conditioning methods for the use of zirconium in hydrochloric acid environments.
Both images are from the apex of a u-bend in the parent metal. Left: Sample shows signs of severe Intergranular Attack (IGA). Large voids are from where the attack has completely dislodged the grains.
Bottom of photo shows a deep penetrating crack, possibly the result of Stress Corrosion Cracking (SCC).
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