Case Study · Hydrocarbon & Chemical
Process Tube High Emissivity Coating: Decoke Interval Extended from 9 to 30+ Months
| Industry | Hydrocarbon & Chemical |
|---|---|
| Asset | Process tubes (Incoloy) |
| Customer or location | Major petrochemical company, Texas, USA |
| Products used | Emisshield tube-exterior coating |
| Headline metric | Decoke interval 9 to 30+ months |
| Secondary metric | 3 to 5× improvement |
| Also measured | 7+ years consistent performance |
A major petrochemical company ran a continuous coking study with various feeds on Emisshield-coated Incoloy process tubes. Third-party coking index data confirmed a dramatic reduction in coking; in service, the interval between decokes rose from about nine months to more than thirty, and performance has stayed consistent for more than seven years.
01
What was the challenge?
Coke laydown inside process tubes forced decoking roughly every nine months, with the hot spots and non-uniform heat flux that drive coking also shortening tube life. The goal was to determine whether Emisshield could reduce or eliminate coking.
02
What was applied?
Emisshield was applied to the exterior of Incoloy process tubes, prepared in accordance with the relevant NACE guidelines. Coking was measured across feeds against uncoated tubes to establish a coking index.
03
What were the results?
| Metric | Uncoated | Coated |
|---|---|---|
| Coking index | Baseline (varies with tube metallurgy) | Dramatically reduced |
| Decoke interval | ~9 months | 30+ months |
| Heat flux | Hot spots, non-uniform | Uniform |
| Coke character | Baseline | Lower volume, smaller, granular, easier to remove |
| Performance duration | 7+ years |
Improved uniform heating reduced hot spots and non-uniform heat flux; the coke that did form was lower in volume and easier to remove, cutting maintenance cost and downtime.
04
Why did it work?
Coke forms fastest at the hottest point on a tube. A coated tube exterior evens radiant absorption around and along the coil, lowering peak wall temperature. See Production Increase, run length.
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