In an integrated steel plant, ensuring the quality of finished product requires testing the chemical composition of input raw materials, intermediate products and the final steel at different stages of production to establish proper process control. 

Optical Emission Spectrometry (OES) is one of the most versatile analytical methods for the chemical analysis of steels and cast-iron samples, capable of detecting multiple elements in a steel sample within just a few minutes. To ensure accurate analysis of nitrogen and carbon in steel samples, ultra-high-purity (UHP) argon gas (99.9990 – 99.9995 %) is essential. This allowable 5-10 ppm of impurity is in the form of hydrocarbon, nitrogen or other gases. Argon prevents contamination from air, particularly oxygen and nitrogen, which could alter the emission spectra and skew results. The argon must be extremely pure as even trace amounts of moisture or hydrocarbons can disrupt the plasma and render the analysis unusable. Since the analysis chamber is opened frequently to replace samples, and the gas naturally escapes during operation, argon must be constantly supplied to maintain the required inert environment. 

Currently, argon gas cylinders (certified as <5 ppm N2) are used alongside an ‘argon gas purifier’ equipped with 3 filters/cartridges (i. a hot titanium cartridge to absorb N2 and O2; ii. a copper cartridge to absorb hydrocarbons and carbon-based gases and, iii. a molecular sieve to absorb moisture). This setup enables approximately 3 months of uninterrupted chemical analysis of steel without requiring regeneration or maintenance of the molecular sieve. The other two cartridges need to be changed within 6 months to a year. 

Additionally, our facility is equipped with a pipeline supply of argon gas (industrial-grade, 99.9% with 1000 ppm impurity) which is not suitable for direct use in OES analysis due to its significantly lower purity.