By Capt. Neeraj Bharti, Founder, Master Mariner · Published · 2 min read
Lines, pumps and heating coils: the parts of a changeover that fail inspections
Ask experienced cargo surveyors where dirty-to-clean changeovers go wrong and the answer is rarely "the tanks". The tanks get the attention: machines, hot water, mopping, inspection. The pipework gets a flush and a hope. Then the first-foot sample comes back dark, or the sulphur is off, and the residue turns out to have been sitting in a stripping line all along.
Where residue hides in the cargo system
- Cargo lines and low points. Fuel oil settles at bends, dead legs and low points where flushing flow is weak.
- Stripping lines and eductors. Smaller bore, lower flow, often overlooked.
- Cargo pumps. Pump casings and their discharge lines hold residue, especially on deepwell pumps with long columns.
- Heating coils. Black oil coats the coils and collects on supports and brackets between them.
- Drop lines, crossovers and manifolds. Every branch the clean cargo can reach needs to be clean.
- Sampling and vapour lines. Small, easily forgotten, and enough to contaminate a sample.
- Valves. Residue trapped in valve bodies and seats can be released when the valve operates.
Flushing lines and pumps properly
- Flush hot where possible. Heavy residue moves with heat. A cold flush after fuel oil often just smears it.
- Flush every line, including branches. Work through the line diagram and tick off each section, crossover and drop line.
- Run pumps during washing so casings and columns are flushed, not just the tank around them.
- Use clean wash water for the final flush, so the last thing through the system is not slop.
- Drain everything. Open drains at low points and blow lines through where the system allows, so no wash water or residue is left standing.
- Check the result. Drains should run clear; a small sample from low points tells you more than an assumption.
Heating coils
Coils need deliberate attention:
- Wash with coils heated where the design and procedure allow, which helps release residue.
- Hand-hose coil supports and the spaces between coils after machine washing.
- Inspect coils with a good torch. Black oil on a coil will fail an inspection even if the tank shell is clean.
- Check for leaking coils before loading. A coil leak can let water or residue into a clean cargo.
Build it into the plan
The simplest fix is to treat the cargo system as part of the cleaning plan, with the same detail as the tanks: a list of every line, pump, coil and branch, the method used, and a sign-off when each is done. That list also belongs in the record pack, because if a cargo goes off-spec it is the evidence that the whole system was prepared, not just the tanks.
The DPP to CPP changeover guide covers the full planning sequence, and failed tank inspection after a changeover covers recovery when something is missed.
How Cleanship helps
Our teams plan the cargo system alongside the tanks: line and pump flushing sequences, coil cleaning, draining and verification. See our DPP and CPP tank cleaning service, or send us your changeover details for a plan.
Sources & further reading
Frequently asked questions
Why do lines and pumps cause changeover failures?
Residue settles in low points, dead legs, stripping lines and pump casings where flushing flow is weak. It is released into the clean cargo during loading or discharge, even if every tank is clean.
How should heating coils be cleaned after fuel oil?
Wash with heat where the procedure allows, hand-hose coil supports and the gaps between coils after machine washing, inspect them closely, and check for leaks before loading.
Should cargo pumps run during tank washing?
Yes. Running pumps during washing flushes casings and columns. Otherwise the pump can hold residue that ends up in the next cargo.
How do you verify the lines are clean?
Drain low points and check that the drains run clear, take small samples where useful, and sign off each line, pump and branch against the line diagram.
- cargo line flushing tanker
- heating coil cleaning
- cargo pump cleaning changeover
- stripping line cleaning
- tanker pipeline cleaning
- DPP to CPP lines
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