Removing cement and clinker from cargo holds, before and after it sets hard

Why cement is different

Bulk cement is fine, dry and very dusty. It coats everything and settles on every ledge. On its own that's no harder to clean than any other dust. The problem is water. Cement reacts with water and hardens: from sweat on the steel, from a leaking hatch, from a hasty first wash that doesn't get everything off. Once set, it bonds to the steel and coating and won't come off with a broom or ordinary washing.

Clinker, the nodular material that's ground to make cement, is coarser and more abrasive. It's easier to sweep but leaves fine dust that behaves the same way when wet.

The first rule: get the dry residue out before you add water

This is the most important thing in this whole guide. Before any water goes into a hold that carried cement:

1. Sweep and remove as much dry cement as possible, from the tank top and every ledge, bracket and hopper top you can reach.
2. Brush dry dust off the upper structure wherever you can safely reach it. Blowing it about with compressed air mostly moves it somewhere else, and many ports won't allow the dust cloud anyway.
3. Clear the bilge wells of dry residue.

Then, and only then, wash. And when you wash, wash thoroughly and quickly, so thin films of wet cement don't sit long enough to set.

How to remove cement before it hardens

1. Dry removal as above
2. Seawater wash, top down, with plenty of volume. You want cement to flow, not form a paste
3. Keep the bilge wells and suctions clear. Cement slurry can block a bilge system fast
4. Fresh water rinse
5. Dry

Done promptly, that's usually enough for a normal clean, and with careful attention to the upper structure, enough for grain.

How do you remove hardened cement?

If cement has set on the steel, you need to break it physically and then, if necessary, chemically.

Mechanical removal first. Scrapers, chipping hammers, needle guns and wire brushes on the worst build-up. On large areas, high-pressure washing at the upper end of the range (500 bar and above) can cut through thinner layers. Heavier deposits may need ultra-high-pressure water jetting, which is a specialist job.

Then chemical treatment. Cement removers are acid-based products that dissolve the cement binder. They work well on thin films and stains left after mechanical removal. Use them carefully:

• Acids attack bare steel and can damage some coatings, so check compatibility and test first
• Follow the dilution and dwell time exactly
• Never mix with alkaline cleaners
• Rinse thoroughly with fresh water afterwards, so no acid residue remains
• Wear proper PPE: acid-resistant gloves, face protection, chemical suits

Keep the chemical on the cement, not the paint. Brush or spray it locally rather than flooding whole surfaces.

What chemical removes cement residue?

An acid-based cement remover, formulated for marine use and compatible with your hold coating. Marine chemical suppliers sell specific products for cement and lime scale. Check the safety data sheet, MARPOL status for the wash water, and coating compatibility.

How do you clean cement from frames?

Frames and brackets are where cement builds up most. Dust lands on the top faces and, if it gets damp, sets there. To clean them:

• Get close. A lance or scraper at arm's length is far more effective than a jet from the tank top
• Remove thick deposits mechanically
• Treat the remaining film with cement remover
• Wash and rinse thoroughly
• Inspect the top face of every bracket. That's where it hides

The upper frames on a bulk carrier are hard to reach, which is why rope access is often used for this stage.

How do you clean cement from tank tops?

Tank tops take the most cargo and the most mechanical damage, so cement settles in scratches and pitting. Sweep dry first, then wash. If it has set, use scrapers and power tools on the build-up, then cement remover on the residue, then a thorough rinse. Check the corners where the tank top meets the hopper and the bulkhead stools.

Cement to grain hold cleaning procedure

1. Dry removal of all loose cement, top down
2. Clear bilge wells of dry residue
3. Prompt, high-volume seawater wash, top down
4. Inspect for set cement on frames, brackets, hopper tops and tank top
5. Mechanical removal of hardened deposits
6. Local application of cement remover, with the correct dwell time
7. High-pressure wash
8. Fresh water rinse of the whole hold
9. Bilge wells cleaned, tested and prepared
10. Dry, ventilate and pre-inspect to grain standard

Grain surveyors look for grey film and white or grey specks on frames, so do a white-cloth test at several heights before calling them. See how to prepare cargo holds for grain for the full checklist.

Preventing the problem next time

• Make sure holds are fully dry before loading cement, and that hatch covers are weathertight
• Remove all cement as soon as possible after discharge
• Don't let a partly washed hold sit
• Keep the coating in good condition. Cement bonds more stubbornly to rough steel
• Consider a barrier coating if you trade cement regularly

If cement has already set in your holds and the load port is close, send us photos. Our shore gangs handle hardened cement with HP equipment rated to 500 bar.