Lined valves provide long-term benefits to gas-producing chemical plant

Paul Boughton

When building a new production plant, the Anderson Development Company turned to ITT Engineered Process Solutions Group (EPSG) for lined ball valves that could provide the safety, performance and longevity required for hard to handle chemicals.
The Anderson Development Company is a speciality chemicals company located in Michigan, USA. In 1995, Mitsui decided to move into the production of chemicals to support the semiconductor industry. As part of this move, the company built a new production facility in Adrian, Michigan to mirror an existing Nitrogen Trifloride (NF3) plant in Japan.
Nitrogen Trifloride is a high-purity gas (99.9999 pure) that is used in the semiconductor industry, primarily for etching computer chips and cleaning out chemical vapour disposition ovens. The gas is also used in the fabrication of liquid crystal displays.
The production of Nitrogen Trifloride involves the handling of extremely corrosive and toxic chemicals. The process involves bringing in the raw material of anhydrous hydrofluoric acid by rail car or truck. Once the raw material enters the plant, it is hydrated and becomes hydrofluoric acid, which needs to be transported through a number of processes in the plant.
During the planning of the new plant, the customer was looking for ball valves that could handle the corrosion and permeation of the acid. According to Dan Ellis of Engineered Process Solutions Group: “The flourine molecules in the hydrofluoric acid are extremely small and they tend to make their way through valve linings over time.” The customer had a choice of using a high-alloy valve – which can be very expensive – or use a PFA-lined (perfluoroalkoxy) valve product.
In the construction of the plant, Anderson built a state-of-the-art chemical handling and containment system. ITT EPSG came to Anderson with PFA-lined KNA ball valves with a superior stem packing arrangement.
During the production of Nitrogen Triflouride, the hydrofluoric acid is combined with ammonia to form ammonia biflouride. Using electrolysis and a series of purification steps, the high-purity Nitrogen Triflouride gas is produced. According to the customer, PFA-lined valves are used in applications that have anything to do with the flow of hydrofluoric acid through the plant. These applications include unloading, sampling ports, sealing around instrumentation, and waste handling in the electrolyte process where they are used in pump-out applications. The valves are used at temperatures ranging from 60?F to about 150˚F.
During the construction of the plant, both PFA-lined and stainless steel valves were used in certain applications. Stainless steel valves tended to freeze up if they were not actuated frequently. These valves are being replaced with Richter PFA-lined valves.
The Anderson plant started out as a small facility – producing about 25 metric tons of Nitrogen Triflouride. The facility has since grown to produce over 130 metric tons per year. The plant is currently undergoing an expansion that will include new Richter valves. v

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