Fiberglass Tank Inspection Levels, Testing & Inspection Intervals

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FRP Tank Inspection, Testing & Inspection Intervals

Basic Level FRP Tank Inspections

Intended to catch problems before they become too advanced and expensive to inspect, investigate and repair.

Non-Destructive Basic Tank Inspection and Testing Includes:

  • Visual observation of corrosion barrier
    • Determine extent of liner degradation visually by analyzing the depth and penetration of chemicals.
    • Analyze depth of stress cracks
  • Barcol Hardness tests (ASTM D2583)
  • Wall thickness measurements (ASTM E797)
  • Inspection report

Intermediate Level FRP Tank Inspections

This is typically not needed if basic inspections are performed regularly however, if deep chemical permeation is suspected based on the basic level inspection:

Destructive tests are performed:

  • Grind surface FRP layer in areas of concern for sampling
  • Chemical tests (eg. pH) on FRP layers to determine depth of permeation
  • Peel off strength test

Advanced Level FRP Tank Inspections

If an unusual event occurred, for example a high pressure excursion creating a tank burst advanced level inspection may be performed:

  • Core samples from tank (very rare). Obtain core samples and perform lab analysis
  • Loss on ignition test (ASTM D2584)
    • Resin to glass ratio
    • Laminate sequence
  • Barcol Hardness (ASTM D2583)
  • Acetone Sensitivity Tests
  • Mechanical Stress Analysis

FRP Tank Inspection Intervals

Chemical in Service Inspection Intervals Reline Intervals Life of FRP Tank
Bisulfite (NaHSO3) 5 years 15-25 years 40-50 years
Caustic (NaOH) 5 years 15-25 years 40-50 years
Sulfuric Acid (H2SO4) 5 years 15-25 years 40-50 years
Sulfuric Acid (H2SO4) 2 years 10-12 years 35-40 years
Phosphoric Acid (H3PO4) 5 years 15-25 years 40-50 years
Sodium Hypochlorite (NaOCl) 2 years 10-12 years 35-40 years
  • The list above is for the common storage chemicals in FRP tanks. If your chemical is not listed, please contact us and we can provide an answer.
  • After a problem is observed, the inspection frequency should be every year after that until the problem is addressed.
  • Routine inspection and relines will extend the life of an FRP tank to 30-50 years.

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