MARINELINE® & CHEMLINE® COATINGS FOR INDUSTRY

MarineLine® E-Newsletters

Profitable Tanker News about Marine Cargo Tank Coatings
Issue 04
2nd in a 3-Part Series on...
Taking Care of Your Cargo Tank Coating
In the last issue of ‘Profitable Tanker’ Advanced Polymer Coatings showed how proper application and heat curing are the first steps to a successful MarineLine® 784 coating system. Now we turn our attention to tank cleaning, and provide cleaning suggestions from users of MarineLine®. NOTE: This information is a GUIDE ONLY. APC does not guarantee any information regarding these cleaning methods or materials.


PROPER TANK CLEANING PRESERVES COATING INTEGRITY

MarineLine® 784 has an ultra-smooth, glossy, low energy surface that reduces venting time, uses less cleaning chemicals and less fuel/energy for cleaning equipment, and leads to faster turnaround. A wide range of approved cleaning detergents and chemicals can be used to clean and prepare the coating for next cargoes allowing the shipowner to maintain the coating with minimal effort.

A number of shipowners have provided some examples of their MarineLine® cleaning practices through the years, which APC shares in this ebulletin. These include practices when switching cargoes as shown below. APC is not responsible for the success of these suggestions, but cleaning suggestions are given in good faith, based on their experiences. Results may vary depending on tank cleaning machine capability and operations, cargo tank configurations and portable tank cleaning machines used for cleaning lower areas of bulkheads, shadow areas of fixed machines and between bands of fixed machine pitch.

Properly cleaned and maintained MarineLine® tank
Just like a newly completed coating project, a properly cleaned and maintained MarineLine® tank should provide excellent service for many years.

MarineLine® General Tank Cleaning Suggestions

Here are General Tank Cleaning Suggestions for Palm Oil, Palm Fatty Acid, (also for Palmitic/ Stearic/ Oleic Acids), MEG, Methanol, BTX, and CPP Cargoes:
Machine cycles and drops to be increased or decreased according to ship’s experience. Spot cleaning of heating coils, clamps, angle bars, and pumps to be carried out as required.
Save fuel by using distilled water or di water for rinsing the tank to reduce chloride instead of steaming the tanks.
Avoid steaming of cargo tanks as far as possible. If steaming is inevitable, then suggest to keep to a minimum. Steam for about 2-4 hours keeping ambient temperature inside cargo tanks to maximum 60°C during steaming.
After discharge of methanol do not steam the tanks. Ventilate cargo tanks with dehumidified air (RH less than 80%) for at least 24 hours after the discharge of methanol.
Marpol and Safety procedures, PPE use as per Company’s SMS and ICS Chemical Tanker Safety Guide.
Note A
For each cargo tank, cargo lines, stripping lines, super stripping lines, drop lines, heating coils, clamps, manifolds, and drains shall also likewise be washed with water washing, chemical recirculation, freshwater washing, steam blowing and air blowing as appropriate.

Palm Oil to Methanol/MEG/DEG/BTX See "A"

1) Hot freshwater wash (at maximum discharge temperature plus 20°C) for 1 (one) cycle using portable machines at mid drop after empty tank certificate is obtained. Avoid steaming as much as possible.

2) Hot seawater wash 3 (three) cycles at each drop using portable machines and bottom drop 4 (four) cycles at discharge temperature plus 20°C. (Take wall wash, if required, then go to Step 3 or otherwise to go Step 5.)

3) Alkaline detergent/Accell recirculation using portable machines for 2 (two) cycles each drop and 4 (four) cycles at bottom drop or spray as required. If white powder is present, recirculate with 5% phosphoric acid based detergent using portable machines as above or spray otherwise go to Step 4.

 

4) Ambient seawater wash using portable machines for 1 (one) cycle each drop and 2 (two) cycles bottom drop.

5) Spot clean, freshwater wash.

6) Di water wash/ steam if required.

7) Educt, mop, ventilate dry 24 hours.

Alkaline detergents (mostly pH 11 and above) tend to form white powder. Accell clean pH 7.5 does not form white powder and also improves color.

If the next cargo is not a wall wash cargo, suggest Steps 1, 2, 5, and 7.


Palm Fatty Acid to Methanol/MEG/DEG/BTX See "A"

1) Hot freshwater wash (at maximum discharge temperature plus 20°C) for 1 (one) cycle using portable machines at mid drop after empty tank certificate is obtained. Avoid steaming as much as possible.

2) Hot seawater wash 3 (three) cycles at each drop using portable machines and bottom drop 4 (four) cycles at discharge temperature plus 20°C. (Take wall wash, if required, go to Step 3 or otherwise to go Step 5.)

3) Alkaline detergent/Accell recirculation using portable machines for 2 (two) cycles each drop and 4 (four) cycles at bottom drop or spray as required. If white powder is present, recirculate with 5% phosphoric acid based detergent using portable machines as above or spray, otherwise go to Step 4.

4) Ambient seawater wash using portable machines for 1 (one) cycle each drop and 2 (two) cycles bottom drop.

 

5) If white powder is present, recirculate with 5% phosphoric acid based detergent using portable machines for 2 (two) cycles each drop and 4 (four) cycles at bottom drop, or spray as required, otherwise go to Step 7.

6) Ambient seawater wash using portable machines for 1 (one) cycle each drop and 2 (two) cycles bottom drop.

7) Spot clean, freshwater wash.

8) Di water wash/ steam if required.

9) Educt, mop, ventilate dry 24 hours.

If the next cargo is not a wall wash cargo, suggest Steps 1-7, and 9.


CPP to Methanol/MEG/DEG/BTX See "A"

1) Ambient seawater wash (30°C) for 2 (two) cycles using fixed machines at coarse pitch (Close cycle Annex I washing). Collect in slop tank. Strip tanks dry and drain all to Slop P.

2) Hot seawater wash 75°C for 2 (two) cycles at each drop using portable machines and bottom drop 4 (four) cycles. (Take wall wash and, if required, go to Step 3, otherwise go to Step 5.)

3) Detergent/Accell recirculation using portable machines for 2 (two) cycles each drop and 4 (four) cycles at bottom drop or spray as required. Detergent using portable machines as above or spray, otherwise go to Step 4.
  If dyed cargo, then recirculate with 2% dye out (Bleach with chlorine content about 12-15%) with portable machines as above, as required.

4) Ambient seawater wash using portable machines for 1 cycle each drop and 2 cycles bottom drop.

5) Freshwater wash.

6) Di water wash/ steam, if required.

7) Educt, mop, ventilate dry 24 hours.

If the next cargo is not a wall wash cargo, suggest Steps 1,2, (3 as required), 4,5 and 7.

Benzene/Toluene/Xylene (BTX) to Methanol/MEG/DEG See "A"

1) Ambient wash (30°C) for 2 (two) cycles using fixed machines at coarse pitch.

2) Ambient seawater wash (30°C) using portable machines for 1 (one) cycle each drop and 2 (two) cycles bottom drop.

3) Freshwater wash.
  4) Di water wash/ steam, if required.

5) Educt, mop, ventilate dry 24 hours.

If the next cargo is not a wall wash cargo suggest Steps 1,2,3 and 4.

MEG/DEG/BTX to Palm Oil/Palm Fatty Acid See "A"

1) Ambient seawater wash(30C) 4 (four) cycles.

2) Freshwater wash.

3) Di water wash/ steam, if required.
  4) Educt, mop, ventilate dry 24 hours.

If the next cargo is not a wall wash cargo suggest Steps 1,2,3 and 4.

Methanol to Palm Oil/MEG/DEG/BTX See "A"

1) Ventilate 24 hours.

2) Freshwater rinse.
  3) Educt, mop, ventilate dry for 24 hours.

Methanol to CPP See "A"

1) Ventilate 24 hours.

2) Dry pump sump and lines.
  3) Inert tanks.


If you have more questions on the importance of proper cargo tank cleaning, contact your Advanced Polymer Coatings’ representative to see why MarineLine® 784 is unique in the maritime industry.