Matheson Gas Products and CP Industries, Inc. collaborated to produce the MIRR0-CLAD®, the first world-class bulk specialty gas container for corrosive and reactive gases. The MIRR0-CLAD® container’s inner surface consists of polished, electrolytically deposited nickel-200, with externally threaded end connections made from Hastelloy C-22TM. This configuration ensures that all wetted areas of the container are made from corrosion resistant materials. Although the package can be used for nearly all specialty gases, it has been shown to be especially effective with corrosive gases.

Experiments conducted to measure the performance of the MIRRO-CLAD® ton unit clearly demonstrated the improvement of the gas package over conventional gas delivery containers. Surface roughness measurements on the Nickel surface exhibited an average Ra value of 6.6 micro inches (0.17 micro meters), whereas conventional bulk containers are unpolished with a typical surface roughness of >100 micro inches (2.5 micro meters).

Iron contamination has been a major metallic impurity in HCI when delivered in conventional carbon steel packages. Before the advent of the MIRRO-CLAD® bulk container, with its inner surface of polished, electrolytically deposited nickel-200, the iron specification in HCI gas was responsible for the majority of metal impurities allowed from the cylinder. The iron specification for 99.997% pure HCI is listed as 1000 ppb. A metals analysis was conducted by sampling HCI gas. The aqueous HCI acid was then analyzed. After HCI had been introduced into the MIRRO-CLAD® container, it was allowed to remain in the cylinder for 60 days before collecting the initial metals sample. Results revealed an iron concentration of less than the detection limit of the instrument (<13 ppb). A second metals sample was obtained more than one year after the initial sample. This analysis revealed an iron concentration of 18 ppb. As the results indicate, the iron concentration is very low and no longer a major contributor to the total metals emitted from the gas package. Based on the duration of HCl exposure, it appears that the container package is not as susceptible to corrosion as are conventional carbon steel ton units.

Source:

* Torres, Robert, Joe Vininski, Erik Hennig, and John W. Felbaum, "Ultra-High Purity Bulk Specialty Gas Package for 300 mm Wafer Fabrication." Semicon West Conference Proceedings, Workshop on Gas Distribution Systems. July 1999, San Francisco, CA, pp. I1 – I10.