Glass Failures in Glass-lined Steel Equipment

Tom Patnaik

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G-force (bowl speed 1080 RPM at 48” diameter = 800 G’s)

Higher G’s accelerates filtration and deliquoring but increases attrition risk and can compress marginal cakes. Usually the G-force ranges from 800-1200.

Glass Failures in Glass-Lined Steel Process Equipment (Cliff Notes):

1. Purpose and Scope

  • This post aims to educate users about typical and atypical failures in glass-lined steel equipment, how to identify them, and preventive actions.
  • Failures are categorized as either typical (common, well-understood) or atypical (rare, often misunderstood and mysterious).

2. Typical Glass Failures

  • Mechanical Shock:
  • Accounts for ~75% of failures, often due to human error (e.g., improper handling, objects striking the vessel).
  • Prevention: Proper handling, training, and maintenance procedures.
  • Corrosion:
  • Glass is not completely inert; acids, alkalis, and water can corrode glass.
  • Acid Attack: Most acids are resisted except hydrofluoric acid and some concentrated acids at high temperatures.
  • Hydrofluoric Acid/Fluoride Impurities: Even low concentrations can rapidly destroy glass; vigilance and chemical analysis are required.
  • Alkaline Attack: More severe than acid; increases with concentration and temperature.
  • Water Vapor Attack: Pure water, especially as vapor, can cause significant corrosion.
  • Prevention: Monitor chemical concentrations and temperatures, and follow manufacturer corrosion charts.
  • Abrasion:
  • Caused by abrasive solids; rare alone but severe when combined with corrosion.
  • Prevention: Use of protective boots on agitators/baffles, improved glass formulations.
  • Thermal Shock and Stress:
  • Sudden temperature changes can cause glass to fracture.
  • Prevention: Adhere to safe temperature differentials, gradual heating/cooling, and use of temperature sensors.
  • Overstressing Nozzles:
  • Excessive torque or piping stress can fracture glass at nozzles.
  • Prevention: Follow torque specs, use expansion joints, and proper support.
  • Metal Repair Failure:
  • Improper installation or material choice (e.g., tantalum plugs) can lead to leaks and further damage.
  • Prevention: Correct installation, periodic inspection, and use of proper cements.
  • Miscellaneous Failures:
  • Excess pressure/vacuum, point impingement, improper vessel support, gasket failure, excessive agitator torque, and baffle tip failure.
  • Prevention: Routine maintenance, correct installation, and operational vigilance.

3. Atypical Glass Failures

  • Ladder Type Failure:
  • Horizontal cracks below jacket overflow, often due to vacuum siphoning coolant into the jacket.
  • Prevention: Use vacuum breakers and positive shutoff valves.
  • Electrostatic Discharge Failure:
  • Static buildup from immiscible liquids/agitation can puncture glass.
  • Prevention: Make reagents conductive, reduce agitation, avoid free-falling liquids, inert gas purging, use conductive glass lining
  • Nascent Hydrogen Attack:
  • Acid on steel forms hydrogen ions, which diffuse through the metal, collect beneath the glass, and expand 5X when they come together to form a molecule, thereby fracturing the glass.
  • Prevention: Immediate neutralization and cleaning of acid spills.
  • Cavitation:
  • Gas bubbles imploding at agitator/baffle blades cause chipping.
  • Prevention: Avoid low-level agitation and direct gas injection with large bubbles.
  • Other Rare Failures:
  • Aluminum chloride reactions, spark testing, alkyl chloride reactions, freezing of water in baffles stored outdoors.
  • Prevention: Specific operational controls and testing.

4. Flaw Detection and Monitoring

  • Early detection is critical; systems are available from the major glass-steel equipment manufacturers that can identify flaws before major failure.
  • Regular inspections and adherence to manufacturer guidelines.

5. Conclusion

  • Proper care, common sense, and understanding of equipment limitations are essential.
  • Real-world failures may involve multiple interacting variables.

Example Implementation:

  • Training: Ensure all operators are trained in proper handling and maintenance procedures.
  • Maintenance: Schedule regular inspections, especially after suspected mechanical or thermal shock.
  • Chemical Analysis: Test all reactants for fluoride impurities before use.
  • Operational Controls: Use temperature sensors and adhere to safe temperature differentials.
  • Repair Protocols: Use only manufacturer-approved materials and methods for repairs.

If you would like us to come in and discuss how you can get more life out of your old glass-lined steel reactors, please contact us.


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