Cargo tank inspections

To define and report the surface condition of (corroded) cargo tanks. As an update concerning the present surface condition or as a benchmark before loading aggressive cargoes.

Stainless Steel ( Drone ) Inspection

Standard cargo tank inspections will be executed by our inspectors from stairs and tank top.

If staging is not available , our inspector can be accompanied by a drone pilot  (Class approved ) in order to have better indication of higher area s/ spots.

Scope of inspection:

      • Visual Inspection
        • General view
        • Pitting corrosion
        • Cracks / Weld damages
      • Passivity check
      • Roughness check
      • Ferroxyl Test
      • Chemical Tests if required
      • Report with pics / tank rating / advice.
drone inspection

Surface Condition Tests

Passivity test device

Passivity test

Measuring the Thickness of Chromium Oxide layer ( defines the actual corrosion resistance / sensibility of the stainless steel surface )

Passive readings indicates a corrosion resistant surface.

Active readings indicates a not corrosion resistance surface, with high risk on pitting corrosion or general corrosion

Device: Electronic Oxilyser 3  

Roughness test

Measuring the roughness / smoothness of the surface

High roughness will accumulate impurities in / on the surface which might cause pitting corrosion.

High roughness will increase cleaning time for cargo residues will stick deeper in the surface

Device: Electronic Ra test device


For chemical tankers:

Standard  surface roughness for Clad Steel ( 3 mm stainless steel layer on mild steel)     0,5 – 2,0 Mu

Standard surface roughness for solid stainless steel : 2,0 – 3,5 Mu

Roughness test in action
Ferroxyl test and Ra Surface Roughness Tester

Ferroxyl / Blue Point test

On site chemical test to define iron / steel residues on the stainless steel surface

These impurities will decrease / remove the passive layer in that area and can cause pitting corrosion.

Device: Chemical solution and indicator paper



Chemical test


To remove slight corrosion, discolourations or cargo residue

Mostly required when tank will not pass cleanliness for next cargo or to upgrade the tank surface condition.


Chemical test demonstration

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