Chapter 31 welding questions Flashcards
How is acetylene produced?
Acetylene is produced by mixing calcium carbide (CaC2) with water (H2O).
Why is it not safe to use acetylene above 15 psig (100 kPag)?
Because of the instability of acetylene, it must never be used at pressures above 15 psig (100 kPag) or subjected to any possible electrical shock, excessive heat, or rough handling.
Where is the highest temperature and where is the greatest heat produced in a neutral oxyacetylene flame?
The high temperature produced by the oxyacetylene flame is concentrated around the inner cone. The greatest heat is produced in the outer envelope; the outer envelope produces 963 Btu per cubic foot of gas (36 kg-cal/m3).
What are methylacetylene-propadiene fuel gases used for?
Many different methylacetylene-propadiene (MPS) gases are in use today as fuel gases for oxyfuel cutting, heating, brazing, metallizing, and to a limited extent, welding.
Which fuel gas has the strongest odor and is easiest to detect?
MAPP would be the gas that has the strongest odor and is easier to detect.
What is the major advantage of using propane or natural gas?
The major advantage of propane and natural gas is that they are often used for heating the shop.
Why should coat hangers not be used as gas welding filler metal?
Using such substitutes can cause weld failure. Coat-hanger wires were not manufactured for welding purposes, and their chemistry varies greatly.
Explain the significance of the AWS filler metal classification RG45.
Mild steel and low alloy gas welding rods are classified by the AWS as RG45, RG60, and RG65. The R refers to the welding rod, and the G refers to the ability to use gas for welding. The two digits indicate the minimum tensile strength range of the weld metal deposited.
