Wednesday, February 20, 2013

Process Wednesday: reglassing

Credit: De Dietrich Process Systems
When you have glass-lined steel reactors, one of the things that the chemical engineers seem to worry a lot about is damage to the glass itself. One of the things that can put pinholes into the glass, for example, is static electricity discharge from non-polar solvents like hexanes. Corrosion with certain reagents (which they try desperately to prevent by barring them, wisely) is another source of damage. My favorite (because it's so simple, yet so costly) is dropped tools -- you drop a hammer or a wrench into a glass-lined reactor, you're gonna leave a dent.

As a relatively novice process chemist, I was unaware that glass-lined steel reactors (like old cars) can be sent for refurbishing. De Dietrich Process Systems' sales brochure about it is happy to tell me about the process:
Reglassing is the process by which older or damaged glasslined steel equipment is refurbished to like-new condition. All glass-lined reactors, tanks, columns, and accessories such as covers, agitators and baffles, can be reglassed if the steel substrate is in good or repairable condition.  
The process starts once a vessel has been inspected and approved as a candidate for reglass. Next, the old glass lining is removed by grit blasting. After any steel repairs and modifications are complete, DDPS proceeds with the glassing process. Here we fuse corrosion resistant 3009 glass onto the prepared steel in our computer controlled electric furnaces. Finally external protective coatings are applied via DDPS’ epoxy system. The end product is a high quality, glass-lined steel vessel or accessory. 
Reglassing is ideal for situations when time and cost are a primary issue. The turnaround time is within weeks versus months to fabricate a new vessel and there is nearly a 50% cost savings compared to buying a new vessel. ...All vessels reglassed by DDPS come with the same standard warranty as new vessels, ensuring you are receiving a vessel “as good as new.”
Now that we're going to get that reactor back, when I can start my boiling caustic soda process? (Kidding.)


  1. "What do you mean I can't throw HF into that reactor! It's essential to my reaction product!"

  2. "Now that we're going to get that reactor back, when I can start my boiling caustic soda process? (Kidding.)"

    Oh man, you have no idea how many Young tubes I killed with that. Well, three. Now you know. I kept reusing them after the first etch and eventually they turned really white and milky and stopped giving me good shimming. Then one of them just collapsed on me into lots of pieces after I gently set it down in a beaker. Also managed to etch a few pressure tubes. That boiling caustic soda is serious stuff. It's not that bad though; I managed to get quite a few reactions out of them before throwing retiring them.

  3. "De-lamination" (pealing) of glass surfaces is a fairly common problem with abused reactors. Ranbaxy laboratories recently few several batches of generic Lipitor that had to be recalled from pharmacies in US, after significant quantity of glass flakes was found in some pills... (shudder)

  4. They routinely "spark test" our reactors to see if they have holes/cracks, though I've never actually witnessed the test and am not sure of the frequency with which they perform it.

    Here's a link to the Pfaudler website showing a spark tester ( If you look in the pdf file about half way down the webpage there's a fun picture on its last page of someone standing inside a reactor using the spark tester.

    1. I think we have a habit of spark testing whenever a reactor is down for maintenance that requires vessel entry, but I am not sure.

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