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What are some best practices for working with glass-lined equipment?

By following these best practices, you can ensure you don’t inadvertently reduce the life of your equipment for a reason that could have been easily prevented.

1. Make sure you use plastic or PTFE-lined tools to ensure safety of the glass-lining

DON’T use any glass or metallic instruments during operation or maintenance of the vessel

This mistake is easy to make and also simple to avoid. Obtaining hand samples through the manway, scraping product build-up off vessel walls, and cleaning debris around the bottom outlet nozzle are all examples of regularly scheduled services and tests that your vessel may go through on a regular basis. As quick and careful as you may be, it is always safest to use products that won’t damage the glass lining. Plastic and PTFE-lined tools are the way to go.


2. Make sure you inspect new equipment and check accessories upon arrival

DON’T assume your equipment arrives in perfect condition

While DDPS follows rigid guidelines for manufacturing, packaging and shipping your order, there are unexpected things that can happen between the time your equipment leaves our facility and gets to yours. In the rare instance that damage does occur in transit, it’s important to document this immediately and contact us to rectify the situation. Upon arrival, a full inspection of the interior and exterior of the equipment should be performed to confirm its condition. This tip applies to every shipment you ever receive – always check the condition of the product!


3. Make sure you are aware of the design limitations of the unit in operation

DON’T operate equipment outside of the design conditions

Pressure and temperature ranges are assigned to each vessel manufactured and clearly labeled on the vessel nameplate. These design limits are based solely upon the steel pressure vessel only in accordance with the ASME code. It is crucial to the well-being of the equipment and the safety of the operating personnel that these ranges are adhered to at all times. Any deviance can result in significant damage to the equipment or serious personal injury. If your process requires extreme pressures or temperatures, you can contact us to talk about customized options available to find specialized equipment that exceeds standard limitations.


4. Make sure you wear clean, rubber-soled shoes when entering a vessel

DON’T have loose items in your pockets when leaning over a vessel

Glass-lined equipment requires a moderate dress code. It’s essential to remove anything you have hanging around your pockets such as loose change, pens, and other metal objects that can cause minimal but significant damage to the glass lining upon accidental contact. For this reason, vessel inspectors should also take care to remove any jewelry such as watches or rings and wear the appropriate footwear. Also, when it comes to footwear, it is a good idea to have special shoes that haven’t been worn for normal day-to-day activities. Small pebbles or other debris can get stuck in the treads of the shoes and scratch or otherwise damage the lining in the vessel.

5. Make sure you keep the vessel nameplate visible at all times

DON’T remove the vessel nameplate or cover it with paint or insulation

The nameplate of all De Dietrich glass-lined equipment contains the following information:

  • Manufacturers Identification Number (Serial Number)
  • National Board Registration Number
  • Vessel Design Pressure
  • Vessel Design Temperature Range
  • Vessel Capacity
  • Year Vessel Fabricated
  • Type of Glass Lining

It is important to keep the identity of the vessel prominent for insurance purposes and as a reference for future rework. As a safety measure, we recommend that all data on the nameplate be copied and stored with all other documents pertaining to the vessel. Replacement nameplates are available if they are lost or destroyed, however, an effort should be taken to keep the nameplate intact and in readable condition as replacements can be costly. Care should be taken to the exterior of the vessel so the nameplate doesn’t rust off.


6. Make sure you contact DDPS if any modifications need to be made to your vessel that would require welding

DON’T weld components onto the equipment interior or exterior

Welding and glass surfaces are generally are not a good combination due to the risk of thermal shock; welding on a glass-lined piece of equipment will almost always cause glass damage. Any major modifications can be made to the vessel during reglassing, such as changing the nozzle sizes, adding a nozzle, or adding supports.

7. Make sure you have your equipment spark tested by trained personnel who are thoroughly familiar with the procedure

DON’T us spark testers other than those recommended by the manufacturer

Spark testing is an important maintenance technique used on glass-lined equipment. It is used to locate defects in the glass lining of vessels and accessories, to perform routine preventive maintenance checks, to verify suspected failure, and to locate areas to be repaired. In-plant spark testing involves a 6000-volt source, either AC or DC. Higher voltages can damage the glass lining! The voltage potential is applied across the clean, dry glass surface by an insulated, hand-held fault probe. Any exposed metal causes a visible spark to jump between the probe and the flaw, alerting the operator to its location. Remember – spark testing can be a destructive test, especially when not done properly. We offer training seminars to teach your personnel the best way to inspect your equipment and identify potential areas of concern.


8. Make sure you flush spills immediately with water and neutralize all surfaces

DON’T allow spilled chemicals to remain on the vessel exterior

Exterior corrosion can eventually cause damage to the interior glass lining so it is a best practice to maintain cleanliness of the entire vessel, not just the inside. When cleaning the exterior of the vessel remember to be aware of the vessel temperature and the temperature of the liquid in order to not thermal shock the glass. Safe temperature differentials must be observed.


9. Make sure you monitor and approve all products prior to adding them into the vessel

DON’T charge materials through nozzles without filtering the contents

Filtering is extremely important because you want to make sure there are no foreign materials or large particles present that could cause damage to the glass. Any solid could impact the glass on the vessel or agitator blades and scratch the fire polish. Additionally, filtering your product will aide in the creation of a more homogenous solution.


10. Make sure you adhere to the minimal level requirements to ensure safe mixing

DON’T operate the agitator with the liquid level at the blade level

When the agitator is run with the fluid in the vessel below the blade level, fluid flow causes the shaft to “skate”, resulting in excessive stresses and runout in the seal area and upper end of the agitator. This can cause premature seal failure and even glass damage on the agitator itself. The simple fix is to make sure there is the right volume of product in your vessel before turning on the agitator. If this becomes a regular problem, then it’s time to look into get a different sized reactor to meet your process needs.


11. Make sure you close and secure all openings to the vessel when they are not being used

DON’T leave the manway cover open

Anytime a manway cover is left open and unattended you run the risk of it accidentally slamming shut, an event that could cause serious fracturing of the glass and injury to your personnel. Furthermore, leaving a manway in the open position increases the risk of damage to the vessel from objects falling through the opening and impacting the internal lining. Always keep the manway in the closed position when you are not using it and consider a manway assist to avoid a cover slamming shut.


12. Make sure the vent is open when filling the vessel jacket

In the case of jacketed vessels, DON’T keep the jacket vent closed

The vent in the jacket is required to allow the air to escape the jacket when filling it with liquid. If the vent is not opened during filling you will run the risk of air pockets in the jacket, which will lead to poor performance and other potentially harmful problems.


We recommend consulting our free eBulletin “Installation and Maintenance Manual for De Dietrich Glass-Lined Steel Equipment” for even more information about caring for your glass-lined equipment. And don’t forget to check back next week for the conclusion of this article!