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What are some preventative maintenance you can perform in house (“DIY) on your glass-lined equipment?

Glass lining is one of the most important items to have a regular preventative maintenance schedule. We recommend at the minimum annual inspections.

For more specific guidelines read our Step-by-Step Guide to Glass-Lined Equipment Inspection post or consult our Glass-Lined Equipment Inspection eGuide.

Now that preventative maintenance is in the forefront in many plants, we can help with some recommendations on what and where to look to try and alleviate future problems and decrease downtime. These are all PM inspections that you or your personnel can perform in-house.

The following inspections should include a thorough visual inspection with a very strong light – we recommend an LED with at least 80 lumens.

Spark Testing

Spark testing the glass lining is the best way to determine if you have any damage to the lining. We recommend no more than 6K volts when spark testing. There are a lot of different types of spark testers on the market, some with variable voltage that can go as high as 20K volts. If you have a variable voltage spark tester make sure it’s set to no more than 6K volts. Higher voltage can cause damage to the glass lining.

Glass Thickness Testing

Random thickness testing should be done anytime you see a change in the surface of the glass lining. The fire polish (this is the high gloss finish you would see with a new reactor) is the indicator that something is going on with the glass. If you see a dull finish instead of the nice shiny surface, then something has happened to the glass. It doesn’t mean the lining is bad, but it serves as a reminder that you should check the thickness to make sure it is still within the proper range of 40-90 mils to provide the corrosive resistance.

Interior Repairs

Inspect all the repairs (plugs, patches, etc.), if any, to make sure they are still in good condition.

While we hope that you find all of these instructions and tips helpful, the most important piece of information to take away from this post is the importance of preventative maintenance of glass-lined equipment. If you don’t have a PM program or schedule set up to address these general safety and housekeeping items, you need to start one!

Exterior Surface

The exterior coating is there to protect the steel that the glass is adhered to, so if something is spilled on the exterior of a vessel it needs to be cleaned and neutralized as soon as possible. Depending on the chemical that was spilled, the area might need to be recoated for future protection.


Clamps can also be inspected when you are examining the vessel exterior. Make sure you have the proper number and size clamps on all the manways. Again, make sure they are at the correct torque. (Refer to our Glass-Lined Equipment Maintenance Manual for more detailed information on torqueing).

Flange Connections and Gaskets

Inspecting all the flange connections on the vessel is extremely important. The most common failures on glass-lined equipment that lead to reglass are from flange damage that starts from the outside and works its way to the inside (a.k.a. edge chipping). Since the process does not have to be interrupted to inspect the vessel interior, it is also one of the most avoidable types of damage.

Checking the flange connections also helps you to find any gasketed joints that may be leaking. If a gasket is found to be leaking you should re-torque the flange bolts in accordance with the table in our Glass-Lined Equipment Maintenance Manual. If this doesn’t stop the leak, then the gasket should be replaced once the vessel is down. Never change a gasket while the vessel is in operation!!!

Agitation System

The agitation system should also be examined while you look over the exterior. The inspection should include the following checks:

  • Examine the drive for any oil leaks.
  • Check the seal housing for any sign of barrier fluid leaking out.
  • Make sure you have the proper seal pressure applied to the seal housing.
  • Make sure all the bolting is torqued to the proper spec.
  • Check the shaft runout periodically to ensure that all is running properly.

Accessories (External and Internal)

It’s important to remember the individual components that are in and on a vessel. These parts need inspecting too, as any issues with them can result in damage to the vessel itself.

  • Check all connecting accessories to make sure they are properly torqued and not leaking.
  • Check the baffle bolting and the glass lining to make sure there is no damage. You also want to confirm it’s installed in the correct orientation.
  • Check the agitator shaft and blades for damage. This can be done during the visual internal inspection and spark test. (Note: on our GlasLock blades you will need a 6Kv AC spark tester.) Check the rotation to confirm that the agitator is rotating in the correct direction for the process.
  • Check the manway assist to make sure it’s working properly.

By following these basic steps on a regular basis, you can prevent premature failure to your glass-lined equipment. The time and investment in PM is well worth it considering the risk you take when you ignore the maintenance needs of your equipment. Inspection doesn’t require a lot of special tools and can usually be performed by someone inhouse. DDPS can also come on site and a service specialist can handle all of your preventative maintenance. Contact us to inquire more or schedule your service.

For more information on inspection frequency and additional details on procedures download our Glass-Lined Equipment Inspection eGuide and our Glass-Lined Equipment Maintenance Manual.