Multiple Choice Question (MCQ)
Question: What is the relation between pitch and lead in multistart thread?
A.
Lead = No. start x pitch
B.
Lead = Pitch
C.
Lead = 1/2 pitch
D.
Lead = 1/3 x pitch
Correct Answer: Lead = No. start x pitch
Explanation
A welding helmet, commonly referred to as a “hood,” is one of the most important pieces of personal protective equipment that a welder must have. An adequate helmet protects the eyes and skin not only from severe sparks, but also from potentially vision-damaging ultraviolet and infrared rays emitted by the arc.
Helmet with filtered colour glass is used to protect face from UV and Infra-red radiation during welding.