Explain the purpose of a hot pass.
What will be an ideal response?
The hot pass is used to quickly burn out small amounts of slag trapped along the edge of the root pass. This is slag that cannot be removed easily by chipping or wire brushing. The hot pass can also be used to reshape the root pass by using high current settings and a faster than normal travel speed.
Slag is mostly composed of silicon dioxide, which melts at about 3100°F (1705°C). Steel melts at approximately 2600°F (1440°C). A temperature of more than 500°F (270°C) hotter than the surrounding metal is required to melt slag. The slag can be floated to the surface by melting the surrounding metal. A high current will quickly melt enough surface to allow the slag to float free; a fast travel speed will prevent burnthrough. The fast travel speed forms a concave weld bead that is easy to clean for the welds that will follow.
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A) Legend B) Symbol C) Title block D) Application block
A wood member weighs 10 lb. It is now fully dried, i.e., until it contains no water. Its dry weight is 8 lb. What was the moisture content (MC) in its original, moist condition?
What will be an ideal response?
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