After 15 years, vinyl ester ducting still holding up in corrosive application

Semiconductor manufacturer Intel turned to Interplastic's vinyl ester for use in its corrosion-resistant ducting 15 years ago. The material is still in use today and still doing the job for which it was designed.

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Resin manufacturer Interplastic Corp. (St. Paul, Minn., USA) reports that a large ducting system it installed for semiconductor firm Intel Corp. 15 years ago is still functioning as originally designed, thanks for the most part to the use of Interplastic's CoREZYN vinyl ester resin system.

Back in the 1980s, Intel and all other semiconductor facilities were adding chip capacity at a rapid pace, which meant they needed to look at corrosion-resistant ducting to vent the waste air stream from etching operations. The waste stream contained a number of corrosive agents, including:
Strong acids such as hydrochloric, sulfuric, nitric and hydrobromic (HBr); caustic and ammonia; numerous corrosive chemicals, including chlorine gas, hydrofluoric acid and others.

They first looked at options which involved either coated stainless steel or hybrid resin systems, but these were fraught with issues. The first involved stainless steel with a Teflon coating. While this sounded good, the case history for this construction showed that the corrosive agents had a tendency to permeate through the Teflon and ultimately corrode the stainless steel. Also, there were many bolted joints in this system that were a risk to start leaking. 

The second option involved a construction using phenolic resin for the structural layer, with a thin vinyl ester-based liner on the inside. This system had some distinct advantages, primarily in the area of fire resistance, but also some came with several weaknesses. Phenolics don’t typically fare well in wet environments, and therefore couldn’t be used outside unless a protective coating was applied. The corrosion resistance was also a bit suspect, as the vinyl ester liner was normally quite thin. This system had serious drawbacks as well with little history of longevity. Therefore, Intel decided not to specify it.

Intel finally decided that the best solution was an all-vinyl ester duct. The system would be sprin- klered to protect against fire, with vinyl ester providing the corrosion resistance necessary for the process. Intel then discovered Corrosion Companies Inc.’s DuraDuct construction, made with CoREZYN VE8440 vinyl ester from Interplastic. This is a brominated, Bisphenol A-based vinyl ester resin, which provides good fire retardance and corrosion resistance. It also stands up well to wet environments, which was a major weakness of the phenolic resin system.

And because it was used throughout the laminate structure, the thick vinyl ester resin barrier would stand up to the harsh, corrosive environment from etching for years to come. This duct system is still in use today (as of June 2012), more 15 years later, with little or no corrosion attack. It is still the solution of choice for sprinklered HVAC systems in the semiconductor industry.

The initial cost of the pure vinyl ester solution was lower than the SST/Teflon® system, and compa- rable to the phenolic/vinyl ester option. And 15+ years after it was first installed, the ducting is still in service as of June 2012, far exceeding expectations! According to Chris Kellog, this system requires very low levels of ongoing maintenance when compared to other options. The simple fact is that DuraDuct® vinyl ester duct systems made with Interplastic’s CoREZYN® VE8440 have provided superior perfor- mance and return on investment to the semicon- ductor industry. 

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