Characteristics TDI
Product safety data sheets may be available from various sources. For safety preparation, until the specific product safety data sheet can be obtained, the following information should be used. In reference to the IBC/BCH code the Master should request the specific product safety data sheet before commencement of loading. The safety data sheet posted must be in a language understood by ship’s officers and crew (English). A product safety data sheet for TDI (Toluene diisocyanate) must be posted and observed.
Synonyms:
Benzene,1,3-diisocyanatomethyl-; 2,4-diisocyanatotoluenene; TDI; 2,4-toluene; Diisocyanate; Toluene-2,4-diisocyanate; 2,4-tolulene diisocyanate.
Commercially available In 3 Isomer ratios:
100% 2.4
80% 2.4 20% 2.6 (the most common shipped)
65% 2.4 35% 2.6
Freezing points:
100% 2.4 21.5 C,
80% 2.4 20% 2.6 14 C (the most common carried)
65% 2.4 35% 2.6 8.5 C
Flash point >130 F
Specific gravity liquid 1.22 @ 25 C
Coefficient of expansion 0.00008 per degree C
Vapor density (air =1.0) 6.0
Vapor pressure @ 20 C low, 0.01 mmHg
Heat adjacent 39C
Solubility soluble in organic solvents
REACTS VIOLENTLY WITH WATER
MAIN HAZARDS:
Suspected carcinogen. By skin absorption liquid is extremely harmful.
Exposure to low concentration can cause severe respiratory problems. Vapour inhalation of low concentration can cause ASTHMA-like symptoms. Note the odour threshold is at least ten times the TLV rating of 0.02ppm and a hazardous concentration exists at this level.
REACTIVITY:
Reacts with compounds containing hydrogen, can be VIOLENT, TDI will react with heat and water, and moisture in air, even at levels as low as 100 ppm, rapidly evolving C02 (carbon dioxide) at sufficient rate to rupture cargo tank bulkheads.
INSTABILITY:
Prolonged heating above 45 C may cause polymerisation.
SAFETY:
Full protective clothing and self contained breathing apparatus when handling hoses, valves, connections, tank cleaning machines.
RESISTANCE:
ALWAYS CONSULT CARCO HOSE RESISTANCE LIST.
Following hose material IS resistant to TDI
Stainless steel,
Butyl rubber
Polyethylene (atl chem)
Viton rubber
Teflon
Following is NOT resistant to TDI
Natural rubber
Buna rubber
Neoprene rubber
Hypalon rubber
Chemicals & Equipment needed for Cleaning / Personal Protection:
1. Approximately 8-10 cu m per tank, of Chlorinated Solvent MEC (Methylene Chloride) or Trichloroethylene or Perchloroethylene. Charterer will supply.
2. Sufficient quantity of Diiso Octyl Phalate (DOP) to fill the cargo pump cofferdam before the loading.
3. Sufficient Toluene for TDI line filling, say 200 ltrs for each hose length x 2 (loading and discharging).
4. Sufficient Chlorinated Solvent for MDI line filling, say 200 ltrs for each hose length x 2 (loading and discharging).
5. 200 ltrs Aqua Ammonia
6. 200 ltrs Iso Propyl Alcohol (IPA)
7. 1 gallon Tincture of Green Soap
8. Sufficient extra hoses (not ship’s normal hoses) and/or Stainless Steel pipe to reach the manifold area from the pump stack.
9. 2 Stainless Steel spool pieces, each with 1” drain valve fitted.
10. 2 Stainless Steel portable valves.
Prior to Loading
Clean tank to water white.
Pressure test heating coils for leaks, then air blow water condensate from coils, followed by nitrogen blowing to ensure moisture free. Blind off both inlets and returns.
Check/test function of PV Valve.
Air blow PV vent line to ensure no water trapped in Line (especially if slight list or trim).
Mop dry cargo pump deepwell.
Pressure test cargo pump cofferdam, repair seals If necessary. If aII satisfactory, purge out cofferdam with nitrogen and fill completely with Diiso Octyl Phalate (DOP).
Test high level alarms.
Test/calibrate remote temperature readout.
Test tank gauging system and portable gauging units.
Check tank hatch packing and ullage/tank cleaning hatch packing and replace if necessary.
Fit pressure gauge to tank, either hatch or vent line so tank pressure can be monitored during loading, voyage and discharge.
Connect spool pieces, valves and hoses and pressure test for leaks.
Prepare/connect vapour return system. Calculate Pressure Drop.
Prepare 200 ltrs of Neutraliser In case of spills:
80 ltrs freshwater, 100 ltrs IPA, 20 ltrs Aqua Ammonia.
Prepare a solution of 99% IPA and 1% Tincture of Green Soap for personal protection.
Loading TDI or MDI
Cargo tank will be purged with nitrogen to minus 40 deg C dewpoint or 0.25% by shore and pressure may be as high as 10 bars, therefore leave tank cleaning hatch and ullage hatch open as well as PV valve to ensure whole system is purged and not overpressured.
When nitrogen purging is complete and shut down, secure the tank and put PV valve in normal operating position.
Ensure safety shower in operation.
Ensure drum of Neutraliser and barrel pump ready for use, 80 ltrs water, 100 ltrs IPA and 20 ltrs Aqua ammonia.
Draeger tubes must be ready for use around the cargo area.
When shore ready to start. Open valves at shore connection and pumpstack.
All measurements and sampling to be conducted closed.
On Completion Loading
When sampling, upon completion of loading, use the portable closed sampling device.
When loading is completed and cargo samples taken, the line must be blown with nitrogen from shore for at least 15 minutes. For final line clearing (ship’s responsibility) ensure the lines are clear of all product.
If loading more than one tank, be sure that each line is blown independently, also for 15 minutes.
If any spill occurs during hose disconnection, spray the area immediately with the neutralizer.
When the line clearing has completed (all valves and flanges closed) secure the pumpstack valve in closed position with a rope or wire.
Without allowing air/moisture into the cargo line, immediately after line clearing, fill the cargo line with Toluene (for TDI) or Chlorinated Solvent (for MDI). Filling from the lowest point drain valve (on spool piece) to the highest point,. To ensure hoses are 100 percent full connect a hose to the high point drain valve (usually at the manifold end) and place into a clean and dry drum on top of the manifold. When Chlorinated Solvent/Toluene starts to come out of hose then line/hoses are completely full. Fill using barrel pump at slow speed.
Leave the Toluene/Chlorinated Solvent in the line for 3 days. During the 3 days period, operate the valve in the manifold crossover (without removing the end flanges) to dissolve trapped residues. Before draining the cargo line, operate all drain cocks while flushing some Chlorinated Solvent/Toluene into a bucket.
Upon completion of draining the cargo line, thoroughly blow the cargo line with nitrogen without allowing air/moisture into the line system. Secure the line, unsecured the pump stack valve.
Wash hoses with warm water 50-60 C, steam and drain. Any polymerised product remaining can be cleaned out, particularly MDI.
Voyage
Heat as per charterer’s instructions by Adjacent Heated Cargo ONLY, unless ship has thermal oil heating,
(TDI Normally 21-35 C range, MDI normally 37-45 C range)
Do not have any ballast in any double bottom tanks under the cargo or in any adjacent cargo tank for the period of carriage.
Maintain nitrogen blanket at positive pressure, minimum 50 mb.
Discharging
Connect hoses, valves as per loading, pressure test and then purge with nitrogen to remove moisture.
Obtain confirmation from Charterer and local agent that vapour return hose will be supplied. DO NOT DISCHARGE without vapour return hose. Contact Charterer/EPS immediately.
When discharging, the tank must be inerted with N2 from shore during the entire operation (Via the vapor return line).
Connect vapour return, open valves at pumpstack and shore hose connection and commence discharge, maintain positive tank pressure.
Any leaks or spills to be spray neutralised.
Strip tank as well as possible utilising the pumpstack valve, then close the valve. Cargo hoses to be blown with nitrogen from the shore.
Close all valves when completed.
Pre-Cleaning
1. Ensure that the tank and tank cleaning equipment is resistant to the particular chlorinated solvent being used.
2. Ensure that the selected chlorinated solvent is handled/stored under dry conditions (e.g. dry lines and storage tank).
3. The chlorinated solvent should be heated to a point above the melting point of the Isocyanate to be cleaned. Ensure that the temperature of the chlorinated solvent is kept below the boiling point of the selected chlorinated solvent.
4. Open PV valve. (In case of rapid pressure increase when solvent added.)
5. Transfer a sufficient quantity (approximately 10 M3) into the tank to be recirculated.
6. Prior to placing the portable cleaning machines, supply and maintain a positive N2 pressure throughout the cleaning operation (Closely monitor the pressure).
7. When recirculating, via the pump stack or manifold, all tank cleaning locations must be used.
8. Recirculate the selected chlorinated solvent for a minimum of 2 hours.
9. Vent line, cargo line, drop line and stripping line must also be flushed with chlorinated solvent as part of the cleaning procedure.
10. Chlorinated solvent may be reused in additional tanks by repeating this procedure.
11. Pump the washings ashore. After stripping blow line with nitrogen, stop shore nitrogen supply to tank and batten down tank until at sea.
12. When shore hose finally disconnected fill ship’s hose/line chlorinated solvent.
NOTE: IF SHORE UNABLE TO ACCEPT SL OPS AND THESE ARE BEING TAKEN TO ANOTHER PORT FOR DISPOSAL, REMOVE TANK CLEANING MACHINES AND BATTEN DOWN TANK TO AVOID MOISTURE ENTERING.
SLOP SHOULD NOT BE CARRIED FOR LONG PERIODS AS POLYMERISATION CAN OCCUR, DAMAGING COATING/STAINLESS STEEL AND POSSIBILITY OF 8-10 M3 SLOSHING AROUND AND DAMAGING HEATING COILS.
Cleaning at Sea
After disposal of solvent/slops clean tank as if it had contained whichever solvent was used. The cargo record book entry should be the cleaning solvent.
Blow cargo hoses, rig tank cleaning machines.
Blow Diiso Octyl Phalate (DOP) from pump cofferdam and flush with MEC then blow dry with nitrogen.
Remove blanks from heating coils and flush with MEC, then fresh water, then commence tank cleaning:
1. Apply steam to heating coils during cleaning.
2. Warm (50 C) wash 1 hour, rising temperature to 70-80 C for a further 3 hours.
3. Steam tank for 3 hours, then mechanically ventilate for 6-8 hours.
After ventilation completed, test tank for safe entry. When conditions are met to satisfactorily complete a work permit issue the permit to permit entry for fresh water wash and inspection.
Some brownish discoloration may be expected on the tank surfaces. Wiping with 3m Scotchbrite type abrasive pads may remove the discoloration. However, this will cause TDI/MDI dust.
Polymerised bubbles with liquid cargo underneath may be found. These will need to be neutralised.
TDI and MDI are extremely poisonous. The correct safety equipment must be used at ALL times.