- ULSD contains low level of lubricity.
- Natural lubricity is provided by oxygen and nitrogen compounds aromatics ,hydrocarbons and sulphur.
- Refining process reduces these chemicals.
- Engine and fuel oil system rely heavily on lubricity for proper operation.
- Insufficient lubricity leads to premature failure of wear related fuel system components including fuel pump and injector.
- ULSD is hygroscopic fuel .This means it absorbs water from atmosphere
- Water weaks havac in diesel fuel system causing corrosion and failure of metal componets such as fuel tanks, pumps and injectors .
- Water leads to microbial contamination which results in plugged fuel lines and filters
- In cold climate water freezes resulting in reduced power and total engine shutdown.
Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole is lesser in size than the corresponding circular hole. More over it is prime concern to have a smoothed generous radius at the corners to eliminate stress concentration. Hence other geometrical shapes like rectangle and square are ruled out. To compensate for the loss of material in the shell due to opening, a doubler ring has to be provided around the opening. The thickness of the ring depends on the axis length along the dirrection in which the stresses are maximum and the thickness of the shell. It is important to align the minor axis along the length of the vessel, as the stress in this direction is maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t= thickness of the shell plating Circumferential stress: Pd/4t More over a considerable material and weight saving is achieved as minor is along the direction of maximum stress.