Crankcase explosion causes and prevention have been discussed in this article, with experiences of fellow Marine engineers. This explosion is a phenomenal which can lead to complete loss of propulsion power of the ship. As name suggest such explosion will take place inside the crankcase, and will have high intensity of explosion leading to damage to everything that comes into its way.
Here first we will discuss as what causes an explosion of such kind to happen.
Crankcase Explosion
As name suggest it is an explosion related to crankcase.
When engine is running, crankcase has lubrication oil all around. For some reasons if there is a hot spot inside the crankcase, it will be acting as a heated surface. When the oil comes in contact with such surface, it will form vapors and will rise up.
When these vapors, reaches to the places where the temperature is much lesser than the hot spots, vapors tends to condense and form mist.
Mist formed is highly flammable in nature and can ignite if the presence of oxygen and heat source is there. Over the time this mist will be accumulating inside. As this mist comes again in contact with the heat spot, it will not ignite. This ignition will lead to an explosion. The effect of this explosion will be to come out of the crankcase. This is called as primary explosion, and the intensity is not much because of limited availability of oxygen.
This initiates a chain reaction in which more fresh air comes in and makes an explosion which is bigger than the primary explosion. And the intensity is so much that it will damage anything that comes in the way. It is called as secondary explosion
Secondary explosion will have serious consequences on the material, property and personal around it. For secondary explosions, crankcase relief doors are fitted which relieves the pressure inside and also prevents the fresh air from outside coming inside, in case of primary explosion.
Crankcase Explosion Causes
Follow reasons contributes to the crankcase explosion:
-Lubrication Failure
-Too much wear and tear of bearings
-Crankshaft Misaligned
-Malfunction of the crankcase relief doors which leads to secondary explosion, which is more far more severe than the primary explosion and needs to be avoided at all the costs.
- Serious damage to the stuffing box and lubrication failure
- Serious blow-by to the engine crankcase and leading to hot spots
Explosion Prevention
Following practices are effective in prevention of such explosion from happening.
- Regular check of bearing clearances and in case of clearances are found to be out of maximum or minimum limits, same to be changed as soon as possible.
- Check the lubrication passages are clear and there is a adequate flow of oil from the passages.
- Check the quality of lubrication oil is good quality and the accumulation on the filters to be checked for metals and other deposits.
- Rubbing surfaces like crosshead guide, stuffing box- Piston rod are to be checked for lubrication, wear and tear.
- Check working of oil mist detector and other setups like crankcase doors for proper working.
So this was all from the article on crankcase explosion. Won’t you want to read the article on as what actions to be taken in case of crankcase explosion.
