How Are Glass Lined Vessels
How Are Glass Lined Vessels
How Are Glass Lined Vessels
It’s safe to
assume that our readers have a diverse level of knowledge when it comes to glass-lined steel. Maybe you’re an
experienced customer with glass-lined reactors currently operating in your facility. Or perhaps you’ve heard about glass-
lined steel but don’t have a solid understanding of how this unique material of construction can benefit your process. Some
of you maybe have even stumbled upon this blog post having zero familiarity on the subject but are interested in learning
about its basic properties and what makes glass-lined equipment so great compared to standard stainless steel and alloy
vessels?
To gain a full appreciation for glass lining and its versatility, you don’t need to be an expert, but it is helpful to better
understand the fundamentals by knowing the steps involved in making a vessel. The manufacture of glass-lined steel
equipment is a combination of three processes: production of the glass, steel fabrication, and combining the glass and
steel. Here’s a comprehensive look at these processes and exactly what happens at each phase of fabrication.
To prevent contamination, each batch is processed separately, in closed containers. The end product, referred to by DDPS
as “3009 glass”, is manufactured at our world headquarters in Zinswiller,
France and is shipped to De Dietrich sites throughout the world, ensuring the same high quality at a global level. The next
steps, steel fabrication and the glass lining, are performed for all North American orders at our state-of-the-art
manufacturing plant located in Corpus Christi, Texas.
Steel Fabrication
Glass-lined vessels are constructed to have a very unique geometry, so the steel
fabrication is an equally important part of the manufacturing. Once the heads are
received, the first step is to punch pilot holes locating the nozzles. The nozzle area
is heated until the steel becomes ductile and a die can be hydraulically forced
through the pilot hole. This action is called “swaging”.
It is important to note here that nothing can be welded to the outside of the finished
vessel. Therefore, provisions for attaching the jacket, drive mountings, and other
exterior accessories must be made before the vessel is glassed. The following
welds are conducted to fuse the parts of the vessel body together and prepare the
vessel for jacket installation:
The inner shell to the head (in the case of close-welded reactors)
The bottom head to the inner shell
The jacket closure ring to the vessel bottom head around the outlet
nozzle(s)
The jacket closure ring to the vessel top head around the knuckle radius
Finally, the entire interior and exterior is steel grit blasted and prepped for glassing.
Watch the video of a vessel being extracted, red hot, from the electric furnace and getting transferred to a cooling booth (you
might want to turn the volume down a notch on your PC when you watch this):
After Glassing
When the glassing process is finished the vessel then enters the welding area to have the jacket installed. The jacket shell
and jacket head have already been welded together and are now ready to be welded onto the closure rings that are on the
vessel. A diaphragm is welded to the closure ring to compensate for expansion and contraction of the jacket. A hydro test,
in which the vessel is filled with water, is performed for quality assurance. Following completion, the vessel is blasted and
prepped for painting and then moved to the paint booth. Based on the specifications of the order, nozzles will be supplied
with the appropriate ANSI Class split loose flange (these flanges are preferred over one-piece flanges for glass lined vessels
because they eliminate heavier nozzle forgings that could cause glassing problems.) Finally, an additional quality control
check and spark test are conducted and the vessel is ready to ship.
Whether this technology is new to you or not, glass-lined steel is not new; it has existed for over 300 years. While its usage
has changed over time and manufacturing practices have certainly improved, its fundamentals are evergreen. Today,
companies choose to use glass-lined equipment for the same reasons they did centuries ago:
Corrosion resistance – glass is extremely resistant to corrosion by acids and alkalis (except for hydrofluoric acid
and hot concentrated phosphoric acid)
Anti-stick – many substances will not stick to glass, but will stick to metal
Purity – glass has high quality standards for food and drug applications
Flexibility – glass can handle a diverse range of chemical conditions.
Ease of cleaning – glass-lining surface enables quick, easy cleaning and sterilization.
Absence of catalytic effect – eliminates the possibility of catalytic effect that can occur in vessels made with various
exotic metals.
Economy – the cost is comparable to stainless steel and most alloys.
By following the procedures outlined in this post, glass-lined vessels are meticulously produced with an impermeable
surface finish that achieves an optimum balance of corrosion resistance, thermal properties and mechanical strength. For
more information about these properties inherent of glass-lined equipment download our Introductory Guide to Glass-Lined
Equipment.