Brinelling

It is the phenomenon observed in ball and roller bearing which leads to premature failure of bearings

There are two types of bearings

True brinelling

It happens due to faulty assembly of bearing , that is while fitting excessive hammering is carried out which deformates the ball and raw

False brinelling

It is due to vibration caused by machinery itself or by vibration transmitted by other machinery thus brinell may occur during machine standstill or in operation

To avoid brinelling

Reduce vibration
Top bearing of purifier is mounted on spring casing
Machine not to be kept in standstill for long term at regular intervals
After overhauling and trying out purifier it is advisablento remive bowl and keep outside to avoid damage to bearing.
Avoid excessive hammering while fitting

Comments

Why is a man hole door elliptical in shape?

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.

Marking on safety valve

Manufacturer’s name Serial number Inlet diameter Operating pressure Discharge capacity Safe working pressure Blow off pressure

Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly. In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake. The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.

MEOclassIIexamnotes

Search This Blog