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Safe handling of Propylene oxide

What is PO? Propylene oxide is a member of a group of compounds known as alkylene oxides. Alkylene oxides react readily with compounds containing an active hydrogen atom, such as alcohols, amines, and acids.

Equipment preparation




Before and During Loading

  1. If previous cargo was acid or caustic or amines ensure all residues have been removed. The lines/system should be tested by checking the pH of the cleaning water during the final cleaning.


  2. All packings and gaskets in the cargo containment system must be checked.


  3. The cargo pump cofferdam to be purged with nitrogen.


  4. Heating coils to be pressure tested for leaks, purged with N2 and sealed off.


  5. Closed level gauging devices to be tested. To prevent incorrect readings from pressure sensor based systems, correct function and zero setting must be carried out according to manufacturers' instructions (Instructions before zero setting of top sensors in CCR).


  6. Nitrogen filling connections and equipment for maintenance of N2 blanket to be checked.


  7. All valves, piping and the tank(s) scheduled to load Propylene Oxide are to be pressure tested to ensure vapour tightness.


  8. Besides preparation of general fire fighting equipment, the sprinkler system require according regulation (IBC Code 14.8.29 and BCH Code 4.721) to be checked and tested.


  9. Closed sampling device to be checked “ready for use”, correct sampling.


  10. Use only stainless steel or HostaFlon (teflon) hoses marked: "For alkylene oxide transfer only."


  11. Manifold drip trays to be cleaned and filled with fresh water.


  12. Vapor return hoses must be clean, resistant to Propylene Oxides, and approved as vapor return hoses. (USCG).


  13. Cargo tanks for Propylene Oxide will be purged down to less than 2% Oxygen or as per customer requirements


  14. The tanks must be loaded according to regulations, i.e., using the reference temperature for calculating max. allowable ullage.


  15. Adjacent cargo tanks must be inerted and or loaded with compatible cargo.


  16. Double bottom and void spaces adjacent to the Propylene Oxide tanks must be purged down to an Oxygen level of less that 2% prior to commencement of loading. Ship's equipped with inert gas system (as per SOLAS requirement) can use the same for purging of void spaces and double bottoms.


World consumption of propylene oxide chart
Fig : World consumption of propylene oxide chart


Immediate after loading

1. Use nitrogen for clearing pipelines. 2. Cargo lines must not be drained into drip tray. 3. Immediate after loading, and after gauging and sampling - adjust tank overpressure to 150 mbar and monitor if pressure holds steady. Propylene oxide temperature & pressure requirements 1. In general the cargo temperature should be kept / maintained below 25 deg C. 2. Positive pressure between 70-150 mbar must be maintained throughout the voyage.

Monitoring & recording

1. Observe and record cargo temperature every 4 hours, tank by tank. 2. Daily measure the Oxygen content in ballast tanks and void spaces surrounding the P.O. tanks. Keep slight overpressure in these spaces, the same as for cargo tanks.


Prior to discharge preparation

1. Purge the pump(s) cofferdam by N2 before commencement of pumping. 2. Test the water sprinkler system. Discharge operation The tank atmospheric pressure to be closely monitored and kept on/around 150 mbar during the discharging. Nitrogen balancing may be necessary to maintain this overpressure. Tank washing 1. After discharge, keep the tank(s) inerted until cleaned. 2. Without opening any tank hatches, pump a few (3-4) cubic meters of fresh water into the tank from the manifold via drop line. Pump this water out of the tank. 3. Ventilate the tank (by forcing air into the tank) for two hours. If after ventilation you will get white powder residues at the bottom of the tank, you can use methanol to remove this powder.

Warning

? Propylene Oxide vapors are heavier that air, Propylene Oxide vapor may concentrate above deck-level and travel a considerable distance along deck or enter into any other tank or spaces that may be left open.

? Propylene Oxide vapors are highly soluble in water. Contact with water may result in a rapid reduction of the interior pressure. Such a sudden pressure drop could result in outside air entering the tank creating a combustible atmosphere or could result in structural damage of the tank.

Propylene oxide danger
Fig : Propylene oxide danger


First Aid:

Eye Exposure

Propylene oxide may cause severe eye irritation and possibly corneal burns. High levels of propylene oxide vapours may also irritate the eyes. If propylene oxide gets into the eyes, immediately wash them with clean water for at least 30 minutes while periodically lifting the lower and upper eyelids to enhance flushing.

Skin Exposure

Propylene oxide generally does not cause adverse effects to the skin if it can freely evaporate. Confined contact or contact with propylene oxide in aqueous solutions can cause damage ranging from irritation to severe burns. If skin is exposed, all clothing covering the affected area should be removed and the area washed with flowing water or a shower for at least 15 minutes. Do not wear contaminated clothing until it has been properly cleaned. Inhalation Propylene oxide may be irritating to the membranes of the respiratory tract and to the eyes. High concentrations may cause serious adverse effects, even death. In areas with poor ventilation, leaks or spills may result in accumulation of acutely toxic and potentially lethal concentrations. Signs and symptoms of excessive exposure may include eye and respiratory tract irritation, cyanosis, and possibly anesthesia and narcosis. If the victim has stopped breathing, give artificial respiration. Caution should be used to prevent responder exposure to propylene oxide from the victim. If breathing is difficult, oxygen should be administered by qualified personnel. Once revived, keep the victim warm and calm. Seek prompt medical attention.

Ingestion

Exposure through ingestion of propylene oxide is unlikely. If propylene oxide should be ingested, give the patient, if conscious, lukewarm water. Do not induce vomiting. Because rapid absorption may occur through the lungs if aspirated and cause a systemic effect, the decision to induce vomiting or not should be made only by a physician. When stabilized sufficiently as determined by medical authorities, the patient should be transported to a medical facility for continued treatment.









We have summarized below some of the special chemical cargoes frequently carried onboard chemical tankers

Handling benzene & methanol safety precautions
Benzene is known as a strong carcinogen and known to cause leukaemia. When handling cargoes with more than Benzene concentration of 0.5%, the Master is to ensure that all personnel involved are aware of the long term hazards. ....

Handling carcinogens requirements for certain chemical cargoes
A carcinogen is a substance that may cause cancer by contact or by inhalation. It is therefore essential that the highest safety precautions are taken when handling these cargoes. Access to deck areas must be restricted to duty personnel only. .....

Handling ACRYLONITRILE safety precautions
ACRYLONITRILE are high value and require sophisticated handling for safety, health and loss prevention reasons. They need careful consideration prior loading , tank coating compatibility, cross compatibility with other cargoes carried, environmental controls if required (inerting). .....

handling ISOCYANATES safety precautions
Isocyanates require sophisticated handling for safety, health and loss prevention reasons. They need careful consideration prior loading , tank coating compatibility, cross compatibility with other cargoes carried, special tank cleaning procedures & environmental controls . .....

handling Sulfuric acid safety precautions
Loading , carrying at sea & discharging of Sulphuric acid involve high risk and require sophisticated handling for safety, health and loss prevention reasons. They need careful consideration prior loading , tank coating compatibility, cross compatibility with other cargoes carried, environmental controls if required (inerting). .....

handling Phenol safety precautions
Phenol are high value and require sophisticated handling for safety, health and loss prevention reasons. They need careful consideration prior loading , tank coating compatibility, cross compatibility with other cargoes carried, environmental controls if required (inerting). .....

Hazards of Phenol - safe handling of Phenol on chemical tankers.
Heating instructions of the Shipper or Owners must be followed to avoid cargo related claims. Sufficient toxic gas measuring tubes must be available before commencement of loading. .....

Marine transportation of Phenol and more safety guideline
The solution of Phenol causes severe chemical burns to the intact skin, which are usually painless. It appears as white wrinkled "dead skin". In case of eye contact, permanent damage to the eye may occur.....

Handling benzene & methanol safety precautions
Benzene is known as a strong carcinogen and known to cause leukaemia. When handling cargoes with more than Benzene concentration of 0.5%, the Master is to ensure that all personnel involved are aware of the long term hazards. .....

Requirements of various grade chemical cargo heating
In a modern chemical tanker in order to maintain product quality, to minimise the potential for discoloration, and to facilitate some liquid cargo transport in a safe manner cargo heating is required. .....

Handling toxic cargoes
There are three common ways that a cargo can be toxic: swallowed (oral toxicity), absorbed through the skin, eyes and mucous membranes (dermal toxicity) or inhalation as a vapour or mist (inhalation toxicity). ....


Following detail pages explain all liquid chemical hazards & precautionary measures while carrying at sea.

  1. Toxicology and associated hazards onboard chemical tankers
  2. Hazards of vapour given off by a flammable liquid while carrying at sea
  3. Reactivity of various noxious liquid chemicals
  4. Most corrosive chemicals carried onboard chemical tankers
  5. What is putrefaction process of liquid chemicals ?
  6. Specific gravity,Vapour pressure and boiling point,Electrostatic charging & measuring Viscosity
  7. General precautions onboard chemical tankers
  8. Mooring precautions onboard chemical tankers
  9. Berth precautions onboard chemical tankers
  10. Cold weather countermeasures, avoiding electric storms
  11. Restriction on using radio equipments and other mobile devices in cargo working areas
  12. Handling precautions for carcinogens or cyanide-like substances
  13. Means of access (gangways or accommodation ladders) safety precautions
  14. Preparations for hot work and safety precautions
  15. Precautions against static electricity





Following reference publications provide useful guidance and international regulations for carrying hazardous chemicals at sea.



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