35. (a) How are boiler flues prepared for re-tipping?
(b) Sketch a simple jig for holding such pieces in place for welding.
36. (a) Describe how lengths of various sized pipe can be welded together end to end.
(b) What precautions are necessary when executing such welds?
37. (a) When welding large steel castings why is it almost always advisable to preheat the work?
(b) Why is preheating so necessary on vanadium and other alloyed steels?
38. Why is it desirable to chip out the sand and thin scale formations, in and around blow-holes in steel castings before filling in?
39. (a) Why do the majority of good welders bend their steel “filler-rods” at right angles about 6 inches from the end?
(b) Why isn’t this being done on cast iron?
40. (a) What advantage is there in making a vertical weld from the top down, rather than starting from the bottom and working up?