Observation

These questions posed some difficulties to the candidates as those who attempted it performed poorly. The required responses are as follows.
3a.      

(i)

b.  It is not suitable to use the main supply directly on arc welding machine because the voltage from the main supply is too high and the current too low.
c. (i) Reasons for using acetylene in gas welding are

• it is readily available;
• it is relatively cheap;
• the flame obtained produces high temperature;
• the flame is easily controlled;
• it is more efficient;
• it cuts faster;
• it saves time;
• it saves energy.

(ii) Tools used for edge preparation are

• hacksaws;
• shearers;
• chippers;
• files.