Salts in the Ballast Tanks

Not acceptable. The surface fails the specification on chlorides regardless of how good the profile and appearance are.

• SSPC-SP 10 is a visual cleanliness standard. It says nothing about ionic contamination - a blasted surface can look perfect and still be loaded with chloride.
• The measured 9–12 µg/cm² is three to four times the 3 µg/cm² limit. In an immersion/ballast service that is a serious risk: residual chloride drives osmotic blistering (water is drawn through the film toward the salt concentration) and supports cathodic disbondment and localized corrosion cells under the lining.
• The pattern matters: the highest readings are at the bilge and weld toes, exactly where salts concentrate in pits, undercut weld profiles and crevices. Salt in a pit is not removed by a general blast pass.
• Note that the profile reading of 3.2 mils is fine and the appearance is fine - that is the trap. Only the salt test tells you the true condition, which is why the spec calls for it and why testing must include welds and low points.

Do not release the surface for coating.

No - it can make things worse.

• The abrasive itself is out of spec: extract conductivity 320 µS/cm exceeds the 250 µS/cm purchase limit, so every blast pass deposits more salt on the steel.
• Dry blasting can drive contamination deeper into pits and weld crevices and can smear salt across the surface rather than remove it.

Procedure to require:

1. Quarantine the abrasive lot and require a replacement lot with a manufacturer's certificate of extract conductivity within the 250 µS/cm limit; test each delivered lot.
2. High-pressure fresh-water wash of the blasted surface (potable or better, tested for chloride), with brush scrubbing, working pitted areas and weld toes specifically. Add a salt-removing additive only if the manufacturer approves it.
3. Allow to dry fully.
4. Re-blast with the compliant abrasive to restore the 2.5–3.5 mil profile - washing will not damage profile, but the reblast is needed to remove any flash rust and to reach the profile requirement.
5. Re-test at the same mapped locations plus additional pits and weld toes, and repeat the wash/blast/test cycle until readings are ≤ 3 µg/cm² across the area.

Verification: keep the Bresle patch area, injected volume and time consistent; convert conductivity to chloride per unit area using the same method each cycle; also run a dust test (ISO 8502-3) and confirm no visible residue. Coat within the specified hold time after final testing.

Build a chain that lets anyone reconstruct the decision years later:

• Salt test records: a map/numbered sketch of every test location, method (ISO 8502-6 extraction volume and time, ISO 8502-9 conductivity), the instrument serial number and calibration, the raw conductivity reading and the conversion to µg/cm², plus date, air/steel temperature and RH.
• Abrasive records: supplier certificate for every lot, the conductivity result against the 250 µS/cm limit, the rejected lot number and its quarantine/disposal disposition, and delivery tickets.
• Water records: source and chloride test of the wash water.
• Nonconformance report describing the failing readings, the contractor's proposed fix, the accepted corrective procedure, and the re-test results that closed it.
• Hold-point sign-offs: pre-blast, post-blast/visual, post-wash salt test, post-reblast profile and salt re-test, and coating release - each with time and inspector signature.
• Photographs of the blast condition, the test patches in place, and the final accepted surface.

If the contractor proceeds without a closed record, you have no evidence the limitation was ever corrected - and in a ballast tank, blistering typically shows up after the ship has sailed, far from the paper trail.