Corrosion in piping and storage tanks is a significant risk for companies that must avoid discharges. 

The right kind of lining will protect the tank from chemicals like hydrochloric acid (HCL) and sulfuric acid. Tank linings, which extend the life of vessels, require materials based on the nature of the chemicals, temperatures, transportation, and other factors. 

For starters, a company must protect tank exteriors from the environment (epoxy coatings are popular). Similarly, metal tank interiors are vulnerable to corrosive chemicals without an effective rubber lining. Perforations can form, leading to costs associated with lost productivity, repairs, and any environmental effects. 

Keep these factors in mind when selecting a protective barrier that is designed to avoid instances of tank deterioration. A tank lining should: 

• Serve as a durable barrier
• Correctly adhere to the tank
• Cover any gaps
• Be installed per specifications

Chemical concentrations help companies determine the optimal lining to use for storage tanks. 

For HCl, 37% is the maximum concentration level. Learn about Blair Rubber’s Marflex^®  PG70, an amber, soft, high-quality pure gum natural rubber lining for concentrated HCl. FDA compliant, PG70 has been the preferred choice of leading chemical companies for more than 40 years.

Dilute HCl

Any HCl concentrations below 30% are considered dilute and must have a strong lining that can repel water. Water can permeate pure gum natural rubber, leading to swelling and lining failure. Enduraflex^®  VE611BN 60 durometer natural rubber has a lower rate of water permeation, providing a longer lifespan in dilute HCl. 

Another option for acid storage is Marflex^® HB50HT, a bromobutyl tank lining known for its physical properties, chemical resistance, lower permeability, and higher temperature resistance. 

Sulfuric Acid

Based on the application, sulfuric acid concentrations can vary. When the strong mineral acid is in the 50% to 70% range, Blair Rubber recommends the Marflex^® HB50HT bromobutyl tank lining. When the concentration falls below 50%, it is best to use chlorobutyl linings like Enduraflex^®  VE621BC.  

Maintenance Tips

1.  Follow an established inspection and maintenance program.
2. Tank covers should be removed with great care. For example, improper drops by a crane can distort steel and create lining cracks. 
3. Pipes should not directly touch rubber linings (vibration could chafe a hole in the lining). 
4. In most cases, rubber linings could age prematurely when exposed to excessive temperatures (over 200°F (93°C)). 
5. Workers should routinely check thermocouples and other temperature controls to make sure they operate properly. 
6. When inside a tank, workers should wear overshoes or clean rubber soled shoes. 
7. Yellowish or green stains on the exterior could be indicators of acid seepage. 
8. Watch out for moist, frothy deposits that will form on the outside of the tank before a clear leak emerges. 
9. Inspect the interior lining on a regular basis. Examine the lining at the seams (it should be tight without portions dotted with “blisters” that could be from gas pockets behind the lining). 
10. Look for surface cracking (surface oxidization). 
11. Use a spark tester to detect “pinhole” leaks. 

Repair Decisions

Here are a few questions to consider before making a repair: 

• How extensive is the failure?
• Is replacing the rubber lining a more viable option?
• What time frame is required?
• What facilities and equipment are necessary to complete the job? 

For safety, any tank should be neutralized, thoroughly rinsed, and aired out. Evaluate the tank before entering to ensure the atmosphere has the correct oxygen content and no toxic fumes.