|Coating Vessel||Glass line Vessel|
|No limitation of chemicals.||Limitation of Alkyl and fluorine.|
|Completely non-stick.||It is sticky.|
|Easily replaceable at site.||Much higher cost of replacing.|
|A coating is applied to a thickness of 10 microns to 1500 microns
(0.01mm to 1.5mm).
|On the other hand lining can be between
3 mm to 5 mm or 3000 microns to 5000 microns.
|Coating involves a thorough cleaning of surface with required roughness of the surface to be coated (through grit blasting), creating a better bond with the metal through a primer. The required thickness of material (Fluoropolymer) is than developed through multiple coats of the same material. Each time, each layer is baked in the oven and ultimately the thickness is reached. This way there is no air gap between the metal and the total thickness of the coated Fluoropolymer. Hence, it is a perfect system to be used in vacuum condition and also, because of relatively less thickness of the Fluoropolymer as against the lining the heat transfer and sensing is better.||Fluoropolymer lining is normally a sheet of Teflon
/PFA/Tefzel/PVDF material either stuck to the shape of the vessel/item to be lined and various lined sections. Fluoropolymer are then welded together by same polymer welding rod.
This is a procedure for big storage vessels. Some times no glue is applied and various sections are simply welded together. As you can see there will be some air entrapped between the liner and the metal. Because of this when the lined vessel or pipeline is heated and cooled, there are chances that the lining will get buckled / collapsed and the lining then fails.
Also since the lining is only mechanically bonded to metal, it might fail in vacuum conditions.