Two plates of the same metal having equal thickness are to be butt welded with electric arc. When the plate thickness changes, welding is achieved by

Preheating before welding is done to

Generally cylindrical parts produced by powder metallurgy should not have non uniform cross section and a length to diameter ratio exceeding . . . . . . . . . . . . . . .

The ratio of acetylene to oxygen is approximately ................ for neutral flame used in gas welding