Category Archives: Gas Freeing

MEO Oral Exam Questions on Gas Freeing and Tank Entry

What are the advantages of inert gas purging system ?

  1. No explosive mixture can form in the tank.
  2. Reduce corrosion.
  3. Reduce pumping time because of the positive pressure in the tank at all the time.
  4. Reduce the fire risk in the event of cargo loading, transporting and discharging.

What is FO setting tank (service) gas free procedure ?

  1. Drain down the entire oil into the double bottom tank through the dumping valve.
  2. When the tank is empty, open the manhole door which located one on top and other on side.
  3. Make force ventilation by blower fan through the manhole door at least 24 hrs.
  4. Then check the tank atmosphere by Explosimeter.
  5. If the flame burns clearly, the tank atmosphere is free from explosive or fatal gas.
  6. Check the tank atmosphere for oxygen content and make sure space is well ventilated.
  7. Enter into the tank with a portable multi gas detector in possession and clear the sludge and wipe out with cotton rags.
  8. During entering the tank ventilation must be provided continuously.
  9. One competent person must stand near the entrance to keep on watch.
  10. Use spark proof torch and lamp.
  11. Naked light and smoking not allowed in the vicinity.

 What is the gas freeing procedure ?

  1. Gas freeing is essential before entering empty tanks.
  2. Prepare enclosed space entry permit.
  3. Manhole doors to be opened for at least 24 hrs before entry.
  4. Forced ventilation with air duct to be done with blower for at least 24 hrs.
  5. With forced exhausting system, minimum of 2 air changes should be completed during that time.
  6. After through ventilation, tank atmosphere tested for any toxic or explosive gases and sufficient oxygen level to support life.
  7. When the tank is gas free, the following LSA to be carried or kept ready, when entering,

————Lifeline or harness to be put on.

————Spark proof hand torch to be brought in.

————Breathing Apparatus set to be kept ready.

————Resuscitation equipment to be kept ready.

————Have rescue team, readily available and properly led.

————Competent person, stand by at entrance.

————Agree a communication system, before entry.

————Have adequate illumination.

What precaution to be taken before enter the tank ?

  1. Gas free certificate
  2. Tank entry permit
  3. Test tank atmosphere for toxic gases and oxygen.
  4. Breathing apparatus, resuscitation equipment to be kept ready at entrance.
  5. Life line to be put on.
  6. A spark proof hand torch light to be brought in
  7. Competent person to be kept on watch
  8. Smoking and naked light not allowed in vicinity.

What point to be checked after cleaning the FO service tank ?

  1. Check heating coils that is no deformation and burst.
  2. Check bolts and bracket of heating coils and their tightness.
  3. Check magnesium anode.
  4. Check float ball indicator.
  5. Check tank gauge.
  6. Check striker plate wear down.


Oral Guide by – MIN ZAR TAR