The Corrosion Lab at ATI Wah Chang has a long history of supporting the Chemical Processing Industry (CPI). Today the CPI industry is experiencing a surge of global growth; in support of this growth, ATI Wah Chang has upgraded the lab’s capabilities and increased its capacity.

The Corrosion Lab has many functions including: basic corrosion research, customer material selection and failure analysis support, metallurgical testing for outside customers, the development and maintenance of an extensive research database, and analysis of ATI Wah Chang products during the final certification process. The lab also administers a corrosion coupon program that allows current and prospective customers to select pre-made metal coupons they can insert into their processes and send back to the lab for further testing. Customers can also provide the lab with a sample of their process fluid and conditions so tests can be run onsite at the lab.

From Humble Beginnings

The majority of work performed in the lab supports ATI metals and alloys used in CPI applications; primarily zirconium and titanium. Even though titanium and zirconium have a high rate of success in corrosive chemical processing environments, use of these metals is relatively new, with the first commonly known applications deployed in the late 1970s. Prior to this, there was little published data on how these metals performed in various chemical environments. In order to support continued process improvements in CPI applications through the use of superior materials, it was necessary to test zirconium and titanium in various media that would be seen in typical applications. The Corrosion Lab was originally established to fill this testing need.

Since the Corrosion Lab’s inception in the late 1970s, it has continued to evolve. As customers’ processes have become more rigorous through the use of higher operating temperatures, pressures and concentrations, the lab has adapted its capabilities to simulate these process conditions. Industry process changes require the lab to make periodic improvements in equipment and facilities. The most recent remodel, completed in September of 2008, will allow the lab to perform testing in environments that can match and exceed operating conditions commonly deployed in today’s chemical processing industry.

The Corrosion Lab started with one technician who performed the testing and compiled data that built the foundation for the database in use today; a database that hosts the results of more than 10,000 corrosion and processing tests. At the time the database was started, the lab had a fume hood, stirring plates, and a balance for weighing coupons. Tests were performed in acidic solutions at room temperature and seldom exceeded seven days.

Later, the lab increased the staff size and hot oil baths were added to facilitate elevated temperature testing. An electrochemical test apparatus and tensile testing machine were also added. The lab continued to compile data in support of zirconium in CPI applications. Soon, lab professionals began presenting technical papers based on the research performed at professional society conferences, including NACE. The technical papers presented were so well received that testing capabilities were expanded to include different acids, bases, and organics.

In the mid-1980s, the Corrosion Lab expanded again, this time increasing square footage. The extra space allowed for several hoods to be installed for boiling tests, and most importantly, an area for autoclave testing. This addition of autoclaves allowed the lab to increase the temperature and pressure limits for testing. Early autoclaves were constructed using 316 stainless steel lined with Teflon (TFE). The lab learned that TFE is permeable to some corrosive gasses and that stainless steel did not hold up to all applications. As a result, the lab began using autoclaves made from nickel based alloys and zirconium manufactured at ATI Wah Chang.

Lab Improvements for Tomorrow’s Chemical Processing Industry

The recent expansion provides improved functionality and increased safety and durability throughout the facility. Additional stirred autoclaves have been added to the current inventory of static autoclaves (see sidebar). Autoclaves in all areas can now be observed through safety glass windows and the materials of construction and coatings for the lab were upgraded for improved durability. Space was also set aside for an upgraded microscope and photography area for performing failure analyses and sharing information with others via the internet.

Today the lab offers a variety of services supported by two full-time Corrosion Engineers with over 35 years of combined experience and several support technicians. Additionally, the lab shares equipment with other technical groups at ATI Wah Chang; through these synergies, the lab can reproduce, on a small scale, many of the processes performed by ATI Wah Chang manufacturing operations, including the production of small custom alloy ingots that can be rolled into plate and sheet for testing. Access to these processes also allows the lab to make autogeneous welds on coupons of various shapes and sizes which allows for more accurate failure analysis testing. Coupons can also be developed in a variety of configurations, including standard, U-Bend, and C-Ring. The lab can test at room temperature, elevated temperatures, boiling, and above boiling temperatures in our autoclaves. The Corrosion Lab’s DC electrochemical test system can define surface chemistry and study the interactions of process chemicals with the oxide layer on the surface of various metals.

Lab scale simulations of customer processes are one of the most popular services the lab offers. By using small scale heat exchangers and heat transfer fixtures, the lab can expose each side of a sample plate to a different set of conditions. This testing procedure is used to simulate the exposed inside wall of a reactor and the unexposed exterior. Additional equipment has been developed to enhance the simulation process that mimics repeated cycles of a heated batch reactor, allowing the lab to evaluate how different materials might perform after many cycles.

Expanded Lab Capabilities in Action

Thanks to the expansion and remodel, the lab recently finished a critical project that will influence how Zircadyne® 702 Zirconium is manufactured and that provides insight on how to improve the alloy for specific applications. The study chronicled the effects of variations in tin content in Zircadyne® 702 Zirconium and its performance in hot concentrated sulfuric acid. The lab performed testing in support of a new ATI Wah Chang product for CPI, OmegaBond® tubing. Extensively designed experiments utilizing the lab’s new capabilities were performed in an effort to better understand the relationship of processing variables and the end performance of zirconium in hydrochloric solutions with various oxidizing ions. More information on the results of this experiment can be obtained by contacting the Corrosion Lab at 541-812-7119.

The Corrosion Lab is a product- and customer-driven operation that anticipates the future testing, material selection, and technical services needed by the Chemical Processing Industry to support new and increasingly demanding processing applications. These needs will continue to shape the evolution of the Corrosion Lab facility.

BY: DERRILL HOLMES — ATI Wah Chang